Final Biological Opinion 

For Rozol Use on Black-tailed Prairie Dogs 

Registered Under Section 3 of the 

Federal Insecticide, Fungicide and Rodenticide Act 

 Photo Credit: U.S. Fish and Wildlife Service

Prepared by: 

U.S. Fish and Wildlife Service 

Ecological Services Region 6 and Region 2 

April 9, 2012 
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TABLE OF CONTENTS 

I. INTRODUCTION.............................................................................................................1 

II. BACKGROUND................................................................................................................1 

Table 1. Federally listed species and critical habitats analyzed within this BO..................3 

III. CONSULTATION HISTORY..........................................................................................4 

IV. DESCRIPTION OF THE ACTION.................................................................................7 

A. CONSERVATION MEASURES..................................................................................8 

B. ROZOL PRAIRIE DOG BAIT REGISTERED USE..................................................11 

C. ACTION AREA...........................................................................................................12 

Figure 1. The historic range of the BTPD by NatureServe as 

 presented in the EPA’s BA...........................................................................14 

V. GENERAL BACKGROUND AND EFFECTS OF THE ACTION RELEVANT 

TO ALL SPECIES IN CONSULTATION....................................................................15

A. INDANDIONE MODE OF ACTION AND TOXICITY............................................15 

B. CHLOROPHACINONE ENVIRONMENTAL FATE...............................................16 

C. ROZOL EXPOSURE AND EFFECTS ASSESSMENT.............................................17 

1. Primary Exposure...................................................................................................17 

2. Secondary Exposure...............................................................................................18 

3. Surface Presence of Poisoned Black-tailed Prairie Dogs......................................20 

4. Removal of Poisoned Black-tailed Prairie Dogs...................................................20 

5. Field Study Observations of Secondary Exposure or Toxicity.............................23 

D. REVIEW OF EPA’S ROZOL EFFECTS DETERMINATION.................................25 

1. Underestimated Risk to Avian Species.................................................................25

2. Prairie Dog Chlorophacinone Residues................................................................27

Figure 2. BTPDs scavenged at a prairie dog colony in 2005 after an 

 application of Rozol................................................................................28 

3. Risk Quotient Calculations and Uncertainty..........................................................29 

E. WILDLIFE MORTALITY INCIDENTS....................................................................30 

F. SUMMARY OF ROZOL EXPOSURE AND EFFECTS RELEVANT 

TO ALL LISTED SPECIES ADDRESSED IN THIS BO..........................................32 

VI. GENERAL CONSERVATION RECOMMENDATIONS..........................................33 

VII. SPECIES ANALYSES....................................................................................................35 

A. OVERVIEW................................................................................................................35 

Table 2. Summary of species determinations and page number 

for each species’ analysis within this BO.....................................................36 

B. SPECIES FOR WHICH NO ADVERSE EFFECTS ARE ANTICIPATED 

WITHOUT CONSERVATION MEASURES............................................................37 

1. AMERICAN BURYING BEETLE.......................................................................37 

2. BLACK-CAPPED VIREO....................................................................................38 

3. CANADA LYNX..................................................................................................40 

4. ESKIMO CURLEW..............................................................................................41 

5. GOLDEN-CHEEKED WARBLER.......................................................................42 

6. GULF COAST JAGUARUNDI............................................................................43 

7. OCELOT................................................................................................................43 

8. PIPING PLOVER..................................................................................................44 

9. WHOOPING CRANE...........................................................................................46 
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C. SPECIES FOR WHICH CONSERVATION MEASURES 

PRECLUDE ADVERSE EFFECTS............................................................................49 

1. CHIRICAHUA LEOPARD FROG.......................................................................49 

2. GRIZZLY BEAR...................................................................................................50 

3. JAGUAR................................................................................................................52 

4. MEXICAN SPOTTED OWL................................................................................52 

5. NEW MEXICO RIDGE-NOSED RATTLESNAKE............................................53 

6. PREBLE’S MEADOW JUMPING MOUSE........................................................54 

D. SPECIES FOR WHICH ADVERSE EFFECTS ARE ANTICIPATED 

WITH OR WITHOUT CONSERVATION MEASURES..........................................58 

1. BLACK-FOOTED FERRET.................................................................................58 

a. Status of the Species/Critical Habitat..............................................................58

(1) Ferret Reintroductions...............................................................................59

Table 3. Black-footed ferret reintroductions in North America 

locations, year initiated, and prairie dog species.........................59 

(2) Life History................................................................................................59 

(a) Environmental Baseline.......................................................................60 

(b) Effects of the Action............................................................................61 

 (c) Cumulative Effects...............................................................................62 

(d) Conclusion Regarding Jeopardy..........................................................64 

2. GRAY WOLF........................................................................................................66 

a. Status of the Species/Critical Habitat..............................................................66 

(1) Species description.....................................................................................67 

(2) Life history.................................................................................................67 

(a) Range and habitat.................................................................................68 

(b) Prey items.............................................................................................68 

(c) Social nature and territory size............................................................68 

(d) Dispersal..............................................................................................69 

(3) Population dynamics..................................................................................70 

(4) Status, trends, and distribution...................................................................72 

(5) Analysis of the species likely to be affected..............................................73 

 (a) Environmental Baseline.......................................................................74 

(1) Status of the species within the action area....................................74 

(2) Factors affecting the species in the action area..............................74 

(b) Effects of the Action...........................................................................74 

 (1) Factors to be considered...............................................................74 

 (2) Analyses for the effects of the action...........................................75 

(3) Species’ response to the action.....................................................76 

a. Cumulative Effects...................................................................76 

 b. Conclusion Regarding Jeopardy...............................................77 
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3. NORTHERN APLOMADO FALCON.................................................................77 

 a. Status of the Species/Critical Habitat.................................................................77 

 b. Environmental Baseline.....................................................................................81 

(1) Status of the species in the action area........................................................81 

(2) Factors affecting species environment within the action area.....................82 

(a) Land use...............................................................................................82

(b) Livestock grazing.................................................................................82 

(c) Road construction, maintenance, and use...........................................82

(d) Communications towers and power lines............................................83 

(e) Organochlorine and organophosphate pesticide contamination........83 

 c. Effects of the Action..........................................................................................83 

 d. Cumulative Effects............................................................................................85 

 e. Conclusion Regarding Jeopardy........................................................................85 

INCIDENTAL TAKE STATEMENT.......................................................................................87 

I. INTRODUCTION.............................................................................................................87 

II. AMOUNT OR EXTENT OF TAKE ANTICIPATED......................................................88 

A. Black-footed ferret.......................................................................................................88 

B. Gray wolf.....................................................................................................................89 

C. Northern aplomado falcon...........................................................................................89 

III. EFFECT OF TAKE...........................................................................................................90 

A. Black-footed ferret.......................................................................................................90 

B. Gray wolf.....................................................................................................................90 

C. Northern aplomado falcon...........................................................................................90 

IV. REASONABLE AND PRUDENT MEASURES..............................................................91 

V. TERMS AND CONDITIONS...........................................................................................92 

Reporting requirement.......................................................................................................94 

Disposition of dead or injured federally listed species.....................................................95 

VI. CONSERVATION RECOMMENDATIONS...................................................................96 

VIII. REINITIATION NOTICE.................................................................................................97 

IX. REFERENCES CITED......................................................................................................98 

APPENDIX: September 10, 2010, Label for Rozol Prairie Dog Bait........................................122 
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ACRONYMS AND ABBREVIATIONS 

AOK Audubon of Kansas 

BA Biological Assessment 

BO Biological Opinion 

BTPD Black-tailed prairie dog 

CPW Colorado Division of Parks and Wildlife 

CFR Code of Federal Regulations 

DDE dichlorodiphenyldichloroethylene 

DDT dichlorodiphenyltrichloroethane 

DOW Defenders of Wildlife 

DPS Distinct Population Segment 

EEC Estimated Environmental Concentration 

EPA U.S. Environmental Protection Agency 

ESA Endangered Species Act 

FIFRA Federal Insecticide, Fungicide and Rodenticide Act 

GPS Global Positioning System 

IPM Integrated Pest Management 

ITS Incidental Take Statement 

LC Lethal Concentration 

LD Lethal Dose 

LOC Level of Concern 

MBTA Migratory Bird Treaty Act 

MRID Master Record Identification 

NDA Nebraska Department of Agriculture 

NEP Nonessential Experimental Population 

PCE Primary Constituent Element 

PMJM Preble’s meadow jumping mouse 

RPA Reasonable and Prudent Alternative 

RPM Reasonable and Prudent Measure 

RQ Risk Quotient 

Service/FWS U.S. Fish and Wildlife Service 

SLN Special Local Needs 

TRV Toxicity Reference Value 

USC U.S. Code 

USCOE U.S. Corps of Engineers 

USDC U.S. District Court of Columbia 

USDOI U.S. Department of the Interior 

USGS U.S. Geological Services 

WAFWA Western Association of Fish and Wildlife Agencies 

WWF World Wildlife Fund 

WYNDD Wyoming Natural Diversity Database 
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BIOLOGICAL OPINION 

I. INTRODUCTION

Section 7(a)(2) of the Endangered Species Act (ESA) of 1973, as amended 

(16 U.S.C. 1531 et seq.) requires that: 

“Each Federal agency shall, in consultation with and with the assistance of the 

Secretary, insure that any action authorized, funded, or carried out . . . is not 

likely to jeopardize the continued existence of any endangered species or 

threatened species or result in the destruction or adverse modification of habitat 

of such species. . . . In fulfilling the requirement of this paragraph each agency 

shall use the best scientific and commercial data available.” 

16 U.S.C. § 1536(a)(2) 

To meet this standard, when a Federal agency determines that its proposed action may affect a 

listed species or critical habitat, it enters into consultation with the U.S. Fish and Wildlife 

Service (Service/FWS). If the effects are determined to be insignificant, discountable, or entirely 

beneficial, the lead Federal agency should make a determination that the project is not likely to 

adversely affect listed species or their critical habitats and request concurrence from the Service 

on its determination. If the effects are not insignificant, discountable, or entirely beneficial or are 

likely to be adverse, the lead Federal agency should initiate formal consultation with the Service. 

The Service then formulates its Biological Opinion (BO) on the proposed action. 

Section 7(b)(3)(A) “. . . the Secretary shall provide to the Federal agency and the 

applicant, if any, a written statement setting forth the Secretary’s opinion, and a 

summary of the information on which the opinion is based, detailing how the 

agency action affects the species or its critical habitat.” 16 U.S.C. 

§1536(b)(3)(A) 

The BO reflects the Service’s analysis as to whether the effects of the proposed Federal action, 

when viewed against the status of the species affected, the species’ environmental baseline, and 

cumulative effects, is likely to jeopardize the continued existence of those species. Likewise, the 

BO reflects the Service’s formal analysis as to whether the effects of the proposed Federal 

action, when viewed against the status of designated critical habitat, the environmental baseline 

of designated critical habitat, and cumulative effects, is likely to destroy or adversely modify 

designated critical habitat. 

II. BACKGROUND 

Rozol® Prairie Dog Bait (Rozol) is a product registered under the Federal Insecticide, Fungicide 

and Rodenticide Act (FIFRA) of 1947, as amended (7 U.S.C. §136 et seq.). Under the FIFRA, 

use of a pesticide may be restricted by how it is registered and by its use label. A pesticide use 

label provides pesticide applicators with directions that consist of legal requirements that may 

specify when, how, and where a pesticide is applied. Pesticides that are federally registered by 
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the EPA as restricted-use are limited to use by pesticide applicators that are certified, often by 

passing a written exam, in accordance with national standards. Section 24(c) of FIFRA allows 

States to register an additional use of a federally registered pesticide product, or a new end use 

product to meet special local needs. 

Rozol is an anticoagulant (hinders the clotting of blood) containing the active ingredient 

chlorophacinone. Rozol was registered in May 2009 (EPA Registration No. 7173-286) under 

Section 3 of FIFRA for use on black-tailed prairie dogs (BTPDs) (Cynomys ludovicianus) in 

10 States: Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, 

South Dakota, Texas, and Wyoming. The EPA regulates pesticide use via administration of the 

FIFRA, and registration of pesticides by the EPA is subject to compliance with Section 7 of the 

ESA. In a letter dated September 30, 2010, the EPA requested initiation of ESA Section 7(a)(2) 

formal consultation under 50 CFR Part 402.46, Optional Formal Consultation Procedures for the 

FIFRA. To intiate formal consultation, the EPA posted the following information online: 

Nation-wide Effects Determination for Chlorophacinone Relative to the Use of 

Rozol Prairie Dog Bait (EPA Reg. No. 7173-286) 

 Transmittal Letter (PDF) from Arthur-Jean B. Williams, Associate Director, Environmental Fate and Effects Division to 

Gary Frazer, Assistant Director for Endangered Species, U.S. Fish and Wildlife Service (9/30/10) (2 pp, 51K) 

 Effects Memorandum (PDF) from Jean Holmes, Acting Branch Chief, Environmental Fate and Effects Division (et.al) to 

Arthur-Jean B. Williams, Associate Director, Environmental Fate and Effects Division (9/29/10) (4 pp, 69K)

 Chlorophacinone Analysis (PDF) Nation-wide Effects Determination for Chlorophacinone Relative to the Use of Rozol 

Prairie Dog Bait (EPA Registration No. 7173-286) (9/29/10) (122 pp, 1507K) 

 Attachment I: Status and Life History for the Threatened and Endangered Species for which a May Affect 

Determination was made (PDF) (134 pp, 908K)

 Appendix A: Maps Showing the Overlap of the Initial Area of Concern and the Species Habitat and Occurrence 

Sections (PDF) (23 pp, 10703K)

 Appendix B: Risk Quotient (RQ) Method and Levels of Concern (LOCs) (PDF) (2 pp, 22K) 

 Appendix C: Estimation of Upper-bound Aquatic Exposure (PDF) (2 pp, 19K) 

 Appendix D: Literature Submitted During the Comment Period for "Receipt of Petition Requesting EPA to Suspend 

the Registration of Rozol Prairie Dog Bait and Cancel Certain Application Sites" (EPQ-HQ-OPP-2009-0684-0001) 

(PDF) (1 pg, 11K) 

 Appendix E: Summary of Ecotoxicity Data (PDF) (7 pp, 83K) 

 Appendix F: Bibliography of ECOTOX Open Literature (PDF) (26 pp, 227K)

 Appendix G: Accepted ECOTOX Data Table (sorted by effect) and Bibliography (PDF) (5 pp, 89K)

 Appendix H: The HED Chapter of the Reregistration Eligibility Decision Document (RED) for Rodenticide Cluster 

(PDF) (38 pp, 147K)

 Appendix I: Summary of Chlorophacinone Incidents (PDF) (2 pp, 45K)

 Appendix J: Calculation of Avian RQs using LD50 data (PDF) (1 pg, 10K)

The “Chlorophacinone Analysis” above is the EPA’s Biological Assessment (BA) for the 

proposed action and is titled “Risks of Chlorophacinone Use on Black Tailed Prairie Dogs to 

Federally Endangered and Threatened Species” (EPA 2010b). The BA includes adverse effects 

determinations to 21 federally listed species and 7 critical habitats, and does not address critical 

habitat for the California condor (Gymnogyps californianus) (in California) and gray wolf (Canis 

lupus) (in Michigan and Minnesota) as those critical habitats were determined by the EPA to not 

overlap with the BTPD range. The BA also excluded critical habitat for the Chiricahua leopard 

frog (Lithobates [Rana] chiricahuensis) which had not yet been proposed at the time the EPA 

initiated consultation with the Service; however, designated critical habitat for the Chiricahua 

leopard frog is addressed herein. As noted in a September 9, 2011, letter to the EPA, the Service 

reviewed the ranges of the California condor, the Sonora tiger salamander (Ambystoma tigrinum 

stebbinsi), the Salt Creek tiger beetle (Cicindela nevadica lincolniana), and the Salt Creek tiger 
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beetle critical habitat and found no overlap with the current range of the proposed use of Rozol 

on BTPDs. Therefore, these species/critical habitat are not analyzed further because we do not 

believe those species or critical habitats are affected. The table below lists the 18 species and 7 

(of 8) designated critical habitats that are analyzed in this consultation in accordance with 

Section 7 of the ESA. 

Table 1. Federally listed species and critical habitats analyzed within this BO. 

COMMON NAME SCIENTIFIC NAME

FEDERAL 

STATUS

Critical Habitat 

Designated/Analyzed?

1. American Burying 

Beetle 

Nicrophorus 

americanus Endangered Not designated 

2. Black-capped Vireo Vireo atricapilla Endangered Not designated

3. Black-footed ferret Mustela nigripes 

Endangered,

Nonessential 

Experimental 

(Portions of AZ, 

CO, MT, SD, UT, 

and WY)

Not designated 

4. Canada Lynx Lynx canadensis Threatened,

Candidate (NM) Designated/Analyzed 

5. Chiricahua Leopard 

Frog

Lithobates [Rana] 

chiricahuensis Threatened Designated/Analyzed 

6. Eskimo Curlew Numenius borealis Endangered Not designated

7. Golden-cheeked 

Warbler Dendroica chrysoparia Endangered Not designated 

8. Gray Wolf Canis lupus 

Endangered,

Nonessential 

Experimental 

(WY, AZ, NM)

Designated/Not 

Analyzed* 

9. Grizzly Bear Ursus arctos horribilis Threatened Not designated

10. Gulf Coast 

Jaguarundi 

Herpailurus (=Felis) 

yagouaroundi 

cacomitli

Endangered Not designated 

11. Jaguar Panthera onca Endangered Not designated

12. Mexican Spotted Owl Strix occidentalis 

lucida Threatened Designated/Analyzed 

13. New Mexican ridgenosed rattlesnake 

Crotalus willardi 

obscurus Threatened Designated/Analyzed 

14. Northern Aplomado 

falcon 

Falco femoralis 

septentrionalis 

Endangered, 

Nonessential 

Experimental 

(NM)

Not designated 

15. Ocelot Lepardus pardalis Endangered Not designated

16. Piping plover Charadrius melodus Threatened Designated/Analyzed

17. Preble’s meadow 

jumping mouse 

Zapus hudsonius 

preblei Threatened Designated/Analyzed 

18. Whooping crane Grus americana Endangered Designated/Analyzed

*Designated critical habitat for the gray wolf exists in Michigan and Minnesota; however, the EPA determined 

that it does not overlap with the range of the BTPD and will not be affected by the proposed action. 
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III. CONSULTATION HISTORY 

Prior to initiation of Section 7 consultation on the registration of Rozol in 10 States by the EPA, 

there was an extensive history regarding the use of Rozol for BTPD (Cynomys ludovicianus) 

control. The background information provided below includes activities/actions that occurred 

leading up to the current consultation and issuance of this BO. The list of consultation history 

items below is not intended to be all inclusive, but represents the Service’s perspective of 

milestones in the 20-year consultation history in the use of chlorophacinone, the active ingredient 

in Rozol, as a rodent-control chemical. Many events involved several agencies, groups, and 

individuals and are relevant to understanding the issues associated with Rozol use on BTPDs. 

DATE ACTIVITY 

February 26, 1991 

EPA requests formal consultation with the Service on chlorophacinone 

for use as a rodent control agent in specific geographic areas and specific 

rodent species in the U.S. (EPA 1991). This chemical was part of a 

larger suite of chemicals for which the EPA initiated formal consultation 

with the Service. 

March, 1993 

Service issues a BO that determined the proposed use of 

chlorophacinone for specific rodent control activities would jeopardize 

the continued existence of 21 listed species (FWS 1993). BO included 

Reasonable & Prudent Alternatives (RPAs) to avoid jeopardy along with 

Reasonable & Prudent Measures (RPMs) to avoid and minimize impacts 

to listed species from the proposed uses of chlorophacinone. 

Chlorophacinone or Rozol use on BTPDs was not a described use at that 

time and therefore not analyzed in the 1993 BO. 

October 20, 1993 EPA Region VII Office issues a letter to Kansas authorizing use of 

Rozol Pocket Gopher Bait for control of prairie dogs (EPA 1993). 

1990s 

Rozol Pocket Gopher Bait made with chlorophacinone is used on prairie 

dogs and begins to generate interest as a prairie dog rodenticide (Lee 

et al. 2005). 

2000s 

Six States develop Special Local Needs (SLN) labels to use Rozol on 

BTPDs (EPA 2010a). Service provides multiple letters to State 

Agricultural Departments discouraging use of Rozol on BTPDs because 

of secondary poisoning and impacts to non-target animals including 

listed species (FWS 2006a, 2006b, 2006c, 2006d). 

May 5, 2006 

Service provides a letter to the EPA on a pending proposal for a SLN 

label that would allow Rozol use in Nebraska on BTPDs (FWS 2006e). 

Service informs the EPA of expected secondary poisoning to non-target 

animals, including then-listed bald eagles, and requests that the EPA 

initiate Section 7 consultation under the ESA. 

October 1, 2006 Nebraska SLN label allows Rozol use on BTPDs to begin October 1 

(Liphatech 2006). 

November 8, 2006 Rozol is applied to a BTPD town near McCook, Nebraska (FWS 2007a).

December 6, 2006 

A bald eagle, then-listed as threatened under the ESA, is recovered near 

McCook, Nebraska, and determined to have died from chlorophacinone 

poisoning associated with a Rozol application on a BTPD colony (FWS 
5

DATE ACTIVITY 

2007a). 

January 19, 2007 

EPA, the Service, and other interested parties meet in Topeka, Kansas, 

to discuss issues related to Rozol use on BTPDs, including how to 

prevent impacts to black-footed ferrets (EPA 2007). 

December 12, 2007 

EPA, the National Marine Fisheries Service, and the Service agree that 

the Federal action for the FIFRA registration activities will be defined as 

the “authorization for use or uses described in labeling of a pesticide 

product containing a particular pesticide ingredient.” 

May 19, 2008 

EPA and the Service have a multi-region conference call to discuss 

secondary poisoning of non-target animals from Rozol use on BTPDs 

(EPA 2008). 

May 13, 2009 EPA registers Rozol under Section 3 of FIFRA for use on BTPDs in 

10 States with an application date of October 1CMarch 15 (EPA 2009a).

June 5, 2009 

World Wildlife Fund (WWF) provides a letter to the EPA that includes a 

request that ESA Section 7 consultation be completed for the FIFRA 

registration for Rozol use on BTPDs (WWF 2009). EPA treats this letter 

as a petition to consider suspension of Rozol as a BTPD rodenticide 

(EPA 2009b). 

July 10, 2009 

Defenders of Wildlife (DOW) and Audubon of Kansas (AOK) file a 

petition in the District of Columbia for judicial review of the EPA’s 

May 13, 2009, decision to register Rozol for BTPDs, noting the lack of 

ESA Section 7 consultation (DOW and AOK 2009a). 

July 15, 2009 

DOW submits a Notice of Intent to sue the EPA for use of Rozol on 

BTPDs without ESA Section 7 consultation and other issues (DOW 

2009). 

July 30, 2009 

Western Association of Fish and Wildlife Agencies (WAFWA) provides 

a letter to the Department of the Interior (DOI) Secretary Salazar 

regarding Rozol use on BTPDs requesting that DOI press the EPA to 

rescind use of Rozol until consultation is finished and secondary 

poisoning of non-target species is addressed (WAFWA 2009). 

September 8, 2009 

Service provides a letter to the EPA on the FIFRA Section 3 registration 

for Rozol use on BTPDs and requests that ESA Section 7 consultation be 

completed prior to use of Rozol on BTPDs and that Rozol use for that 

purpose be withdrawn until completion of the Section 7 consultation 

(FWS 2009a). 

September, 2009 

Black-footed ferret reintroduction site information is provided to the 

EPA in response to the EPA’s request for areas where Rozol use might 

conflict with black-footed ferrets. 

September 23, 2009 

DOW and AOK file a complaint in the U.S. District Court of Columbia 

(USDC) alleging among other things that the EPA failed to conduct ESA 

Section 7 consultation for the use of Rozol on BTPDs (DOW and AOK 

2009b). 

September 30, 2010 EPA submits a letter to the Service requesting formal ESA Section 7 

consultation on Rozol use on BTPDs (EPA 2010b). 

November 16, 2010 EPA rejects suspension of Rozol as a BTPD rodenticide in response to 
6

DATE ACTIVITY 

the WWF’s letter of June 5, 2009, which had been considered a petition 

by the EPA (EPA 2010c). 

June 14, 2011 

USDC issues a ruling on the DOW and AOK litigation against the EPA 

(USDC 2011). The Court ruled against the groups on some points but 

found that ESA Section 7 consultation must be completed. A date was 

set to hear arguments whether to suspend use of Rozol until Section 7 is 

completed. 

July 13, 2011 Service provides a signed declaration to the court indicating that a draft 

BO will be provided to the EPA by December 10, 2011 (FWS 2011a). 

August 8, 2011 

In response to the litigation outcome, the EPA issues a cancellation order 

and modifies the Rozol label to indicate that Rozol is not a labeled use in 

MT, ND, NM, or SD (EPA 2011a). Upon completion of the BO, the 

EPA anticipates a label modification to add those States back onto the 

label. 

August 26, 2011 A bald eagle picked up in Nebraska in the spring of 2011 is confirmed to 

have died of chlorophacinone poisoning (FWS 2011b). 

September, 2011 

EPA and the Service discuss conservation measures that could be 

developed and instituted to avoid and minimize adverse effects to listed 

species, agreeing to include the registrant and applicant, Liphatech, Inc., 

(Liphatech) in those discussions. 

September 28, 2011 

A conference call is held between Liphatech, the EPA, and the Service 

that included discussion on general aspects of formal Section 7 

consultation and the development of conservation measures that would 

avoid and minimize impacts to listed species from Rozol use on BTPDs. 

All parties were receptive to development of conservation measures that 

could be integrated into the proposed action. 

October, 2011 

Due to interest in the conservation measures, the Service inquires of 

Liphatech and the EPA whether the draft BO deadline of December 10, 

2011, can be extended to allow the conservation measures to be finalized 

and incorporated into the proposed action. This change in the proposed 

action is expected to significantly modify the anticipated impacts to 

listed species, and the parties agree that additional time can be afforded. 

October, 2011 

Service begins providing maps of listed species areas where Rozol use 

should be prohibited to avoid adverse affects or where the use dates of 

October 1 - March 15 would be restricted to avoid listed species 

interaction with BTPD colonies that have had Rozol applications. EPA 

provides this information to Liphatech. 

October 17, 2011 

EPA sends a response to the Service’s September 9, 2011, letter that had 

requested additional information from the 1993 chlorophacinone BO 

(EPA 2011b). EPA letter indicates that no additional information is 

available; RPAs, RPMs, and suggested animal studies from the 1993 BO 

were either not implemented or information is not available on the 

implementation. 

November 8, 2011 EPA and the Service discuss, via conference call, possible conservation 

measures and confirm the information to be provided to Liphatech. 
7

DATE ACTIVITY 

November 22, 2011 

Service provides a signed declaration to the court indicating that the 

Service will provide a draft BO to the EPA by January 16, 2012, per the 

understanding with the EPA that additional time for drafting the BO is 

warranted for development of the conservation measures (FWS 2011d). 

December 13, 2011 

EPA provides a letter to the Service and Liphatech that formalizes the 

agreed upon conservation measures to avoid and minimize impacts to 

listed species (EPA 2011c). This letter modifies the proposed action and 

the subsequent analysis in the BO is changed to reflect the new 

information. 

January 16, 2012 Service provides a draft BO to the EPA. 

January 18, 2012 EPA posts the draft BO on their website for public comment. 

March 9, 2012 EPA provides comments to the Service on the draft BO (EPA 2012a). 

April 6, 2012 

Additional Conservation Measures are agreed upon that will incorporate 

improved post application survey language and contact information on 

the Rozol label, development of a website and training materials 

intended to reduce nontarget exposure, and conduct training sessions for 

applicators in the proper use of Rozol and the importance of preventing 

exposure to nontarget animals (EPA 2012b). 

April 9, 2012 Final BO for Rozol use on BTPDs registered under Section 3 of the 

FIFRA provided to EPA. 

IV. DESCRIPTION OF THE ACTION 

The proposed action by the EPA is the administration of the FIFRA Section 3 registration of the 

single product label for Rozol (Registration No. 7173-286). Rozol is manufactured by Liphatech 

as loose-grain bait used to poison BTPDs in the 10 western States of Colorado, Kansas, 

Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, and 

Wyoming. Its use in the States of Montana, New Mexico, North Dakota, and South Dakota was 

cancelled in August 2011, pending completion of the ESA Section 7 consultation; however, the 

EPA and Liphatech propose to resume application in those States upon completion of this 

Section 7 consultation. 

All 10 States listed on the September 10, 2010, Rozol label (see Appendix) are considered 

herein. The EPA’s goal for reassessing registered pesticide active ingredients is every 15 years. 

Given the EPA’s timeframe for pesticide registration reviews, the Service’s evaluation of the 

proposed action is also for 15 years. 

The EPA adopted conservation measures during the formal consultation process and 

incorporated them as part of the proposed action (EPA 2011c, 2012b); those measures are listed 

below. The action area and items relevant to use of the product, as directed by its label, were 

described in the EPA formal consultation initiation package (EPA 2010b) and incorporated 

herein. Additionally, information regarding direct and indirect effects of the proposed action and 

potential exposure routes to federally listed species, as well as a review of the EPA’s BA, is 

provided in this BO. This information provides the context in which the subsequent individual 

species analyses were conducted. 
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A. CONSERVATION MEASURES 

Conservation measures are commitments by the EPA to avoid or minimize adverse impacts of 

the proposed action and, for the purposes of this consultation, are considered part of the proposed 

action that are then analyzed in the effects analysis in this BO. The Service identified these 

conservation measures and coordinated with the EPA and Liphatech regarding the acceptability 

of the measures as well as the best means to implement them. The measures 1-8 below were 

formally adopted by the EPA via letter dated December 13, 2011, and will be included online as 

part of the EPA’s Endangered Species Protection Bulletins (see: Bulletins Live! at 

http://www.epa.gov/espp/bulletins.htm). Measures identified on the EPA’s Bulletins Live! are 

considered an extension of the Rozol label thereby legally requiring applicators to adhere to them 

(EPA 2011c). Maps of each of the areas where Rozol use will not be allowed or restricted, along 

with any associated relevant information will be included in the EPA’s Bulletins Live! database, 

and label requirements will make clear that Rozol use in these areas is restricted or prohibited. 

On April 6, 2012, additional conservation measures were agreed upon and incorporated into the 

project proposal and described below (EPA 2012b). Noncompliance with these bulletins would 

be a violation of FIFRA. 

1. Black-footed Ferret Conservation Measure 

 Prohibit application of Rozol within current black-footed ferret reintroduction sites 

(13 sites) and future reintroduction areas to reduce the level of impact to the black-footed 

ferret. The locations will be made available via the EPA’s Bulletins Live! database.

2. Chiricahua Leopard Frog Conservation Measure 

 Prohibit application of Rozol within the five southwestern New Mexico counties of 

Catron, Grant, Hidalgo, Sierra, and Socorro to avoid impacts to the Chiricahua leopard 

frog and its critical habitat. 

3. Grizzly Bear Conservation Measure 

 Delay application of Rozol in the State of Montana by 2 months until December 1, and 

shorten the application period in the spring by 2 weeks to end by March 1, in areas where 

the range of the grizzly bear overlaps with the range of the BTPD to reduce the risk of 

impacts to the grizzly bear. 

 The areas in Montana where the timing delay applies includes all, or portions of, the 

following counties: Carbon County; Stillwater County south of I-90; Sweetgrass County 

south of I-90; Park County south of I-90; Gallatin County south of I-90; Madison County; 

Powell County; Lewis and Clark County; Cascade County; Teton County; Pondera 

County; Glacier County; and Toole County. 

4. Jaguar Conservation Measure 

 Prohibit application of Rozol within the southwestern New Mexico County of Hidalgo to 

reduce the risk of impacts to the jaguar. 

5. New Mexico Ridge-nosed Rattlesnake Conservation Measure 
9

 Prohibit application of Rozol within the southwestern New Mexico county of Hidalgo to 

avoid impacts to the New Mexico ridge-nosed rattlesnake and its designated critical 

habitat. 

6. Mexican Gray Wolf Conservation Measure 

 Prohibit application of Rozol within the four southwestern New Mexico counties of 

Catron, Grant, Hidalgo, and Sierra to reduce the risk of impacts to the Mexican gray wolf 

within the Blue Range Wolf Recovery Area. 

7. Mexican Spotted Owl Conservation Measure 

 Prohibit application of Rozol within the five southwestern New Mexico Counties of 

Catron, Grant, Hidalgo, Sierra, and Socorro to reduce the risk of impacts to the Mexican 

spotted owl and its designated critical habitat. 

8. Preble’s Meadow Jumping Mouse Conservation Measure 

 Delay application of Rozol in the fall by 1 month, until November 1, in areas where the 

range of the Preble’s meadow jumping mouse (PMJM) overlaps with the range of the 

BTPD to reduce the risk of impacts to the PMJM. 

 Areas where the timing delay applies exist within Wyoming and Colorado. Within 

Wyoming, all or portions of the following four counties are to have the above timing 

restriction: Converse, Platte, Albany and Laramie. Within Colorado, the timing 

restriction applies within the following seven counties: Larimer, Boulder, Weld, 

Jefferson, Douglas, Elbert, and El Paso. 

As previously noted, on April 6, 2012, additional conservation measures were added and the 

suggested label language below will be included, with the exception of the following statement: 

“Detailed guidance on how to conduct a line-transect search is available online at (EPA 

website)”, which EPA will add once content is developed in coordination with FWS and 

Liphatech (EPA 2012). 

“Carcass searches must be performed using a line-transect method that 

completely covers the baited area. Detailed guidance on how to conduct a linetransect search is available online at (EPA website). Transect center lines must 

be no more than 200 feet (about 60 meters) apart, and should be considerably 

less if searches are conducted in more densely vegetated sites. Transect lines may 

be traveled on foot or by vehicle at a rate not to exceed 4 mph. All dead or dying 

non-target animals must be reported to the National Pesticide Information Center 

1-800-858-7378 as soon as possible. Any apparently injured or sick Federally 

listed species must also be immediately reported by calling 303 –236 - 7540 (if 

located in Kansas, Nebraska, the Dakotas, Montana, Colorado, or Wyoming) or 

505 –248-7889 (if located in Texas, New Mexico or Oklahoma). The Black-footed 

Ferret Coordinator must also be contacted if ferrets are found during Rozol 

Prairie Dog Bait applications or carcass searches at 970-897-2730 x 224.” 
10

The EPA believes that improved Rozol Prairie Dog Bait label language in combination with 

education and outreach activities are appropriate. Therefore, EPA, with agreement from 

Liphatech, includes the following Conservation Measures: 

1. Liphatech will add language to the Rozol Prairie Dog Bait label as agreed to on the 

March 30, 2012 conference call. The Rozol Prairie Dog Bait label will also explicitly state 

that pesticide applicators are responsible for ensuring that carcass searches are performed in 

accordance with the label requirements. 

2. EPA, in coordination with FWS and Liphatech, will develop website content intended to 

achieve the following: 

a. Provide information on the importance of limiting the availability of dead and dying 

target and non-target wildlife in order to protect the listed species of concern; 

b. Describe the improved carcass search methods described in this Conservation Measure; 

and 

c. Include the website link as part of the Rozol Prairie Dog Bait label once it is developed. 

3. EPA will work with the State Lead Agencies to incorporate training sessions on secondary 

poisoning at their annual pesticide applicator recertification programs. The training will 

educate applicators on the meaning of secondary toxicity, the hazards of Rozol Prairie Dog 

Bait, the basis for the carcass search requirements and other associated label restrictions and 

the importance of minimizing risk to non-target species. EPA staff may participate directly 

in these training sessions, through webinars, by helping to arrange for other knowledgeable 

persons to give presentations, or through a combination of each. 

4. As a condition of registration Liphatech will maintain a stewardship program using the 

framework as described below: 

LIPHATECH ROZOL PRAIRIE DOG BAIT PRODUCT STEWARDSHIP PROGRAM 

PURPOSE 

The Liphatech Rozol Prairie Dog Bait Product Stewardship Program is a commitment by 

Liphatech to provide education and outreach materials and training to Rozol Prairie Dog 

Bait users (e.g., certified applicators and landowners) on carcass search and survey 

methods described on the Rozol Prairie Dog Bait label. The purpose of this program is to 

result in minimized take to the affected listed species of concern via reduction in the 

incidence of secondary poisoning. 

REQUIREMENTS 

a. On its Rozol Prairie Dog Bait product website, Liphatech will include a link to EPA’s 

Rozol Prairie Dog Bait bulletins, which provide geographically-based prohibitions on 

Rozol Prairie Dog Bait use intended to protect listed species of concern. 

b. Liphatech will provide yearly training sessions to pesticide applicators in each of the 

10 States where Rozol Prairie Dog Bait will be registered. To the extent possible, 

Liphatech will provide these training sessions prior to the 2012 Rozol Prairie Dog 

Bait use season. The training sessions will include information on proper dosing for 

Rozol Prairie Dog Bait, presentation of the carcass search and line transect survey 

methods listed on the Rozol Prairie Dog Bait label, and education on the meaning of 
11

secondary toxicity and the importance of minimizing secondary exposure to 

non-target species. 

c. Once EPA, FWS, and Liphatech have developed website content, Liphatech will 

include a link to EPA’s website on its Rozol Prairie Dog Bait product website. In 

addition, Liphatech will develop and distribute a brochure with information from the 

website to be distributed as part of its training sessions and other outreach initiatives. 

B. ROZOL PRAIRIE DOG BAIT REGISTERED USE 

The chlorophacinone concentration in Rozol is 0.005 percent or 50 milligrams per kilogram 

(mg/kg). According to Rozol label instructions (Appendix), the product is to be applied by 

certified applicators to BTPD colonies in rangelands and noncrop areas by inserting 1⁄4 cup 

(53 grams, nearly 2 ounces) by hand at least 6 inches into active prairie dog burrows only 

between October 1 and March 15 of the following year, when the prairie dogs most readily 

consume grain bait. Any bait spilled above ground or placed less than 6 inches into the burrow 

is to be retrieved and disposed of by the applicator. Prairie dogs that consume the bait are 

anticipated to begin dying within 4-5 days. The label indicates that the applicator must return to 

the site within 4 days after bait application and at 1- to 2-day intervals thereafter for at least 

2 weeks (longer if carcasses continue to be found) to collect and properly dispose of any bait or 

dead or dying prairie dogs found at the surface. These return visits to collect bait and prairie 

dogs are to occur late in the day, near sundown, to reduce the potential of nocturnal animals 

finding dead and dying animals. Carcasses may be buried onsite, at least 18 inches below the 

surface, or placed in inactive burrows, and burial must include covering and packing the soil atop 

the carcass. If onsite burial is not possible, other means of disposal to preclude scavenger access 

to carcasses is required. A second application may be made if prairie dog activity persists 

several weeks or months after the initial bait application. 

C. ACTION AREA

The action area is defined (50 CFR § 402.02) as all areas to be affected directly or indirectly by 

the Federal action and not merely the immediate area involved in the action. The EPA has 

identified the action area as follows: 

“For this assessment, BTPD range within the states of Colorado, Kansas, Montana, 

Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas and 

Wyoming and counties adjacent to this range is considered to be the action area. 

The action area considered for direct effects includes the BTPD range within the 

10 states listed above as well as counties adjacent to this range. The action area 

considered for indirect effects includes only the BTPD range with the 10 states listed 

above and does not include counties adjacent to this range. This distinction was 

made because indirect effects are not expected to extend beyond the use area. 

However, direct effects may extend beyond the use area due to exposure to 

individuals or via prey items with chlorophacinone residues that could be found 

outside of their described range. 

 

It is important to note that the historic range-wide action areas do not imply that 

direct and/or indirect effects and/or critical habitat modification are expected or are 
12

likely to occur over the full extent of the action area, but rather to identify all areas 

that may potentially be affected by the action. The Agency uses more rigorous 

analysis including consideration of available land cover data, toxicity data, and 

exposure information to determine areas where listed species and their designated 

critical habitats may be affected or modified via endpoints associated with reduced 

survival, growth, or reproduction.”

In the BA, the EPA provided a map of the historic BTPD range from NatureServe (Figure 2.2 on 

page 55 of the BA, reproduced below in Figure 1) as an indicator of the action area and 

described as the “footprint” or “initial area of concern” which covers all habitats within the 

historic BTPD range. Range maps available on the Service’s website 

(http://www.fws.gov/endangered) for federally listed species and/or their critical habitats were 

overlaid by the EPA on that historic BTPD map to determine any overlap which was used in the 

EPA’s BA to inform “May Affect” determinations for federally threatened or endangered species 

and their critical habitats. As the EPA recognized in the BA, the historic range map of the BTPD 

does not necessarily include the entire “Effects Determination Area” and additional data were 

used as appropriate to determine effects to species and critical habitats. The current range of the 

BTPD has contracted from its historic range so, in some areas, the species’ current overlap with 

federally listed species has been reduced (FWS 2009b). The consultation addresses Rozol use 

within the 10 States identified on the September 10, 2010, Rozol label (Appendix). Additionally, 

some of the conservation measures listed above further amend the EPA’s action area by 

precluding Rozol use in some areas. For the purposes of this consultation, and in accordance 

with the definition of “action area” provided above, the Service agrees with the EPA’s broad 

action area. The EPA’s demarcation of areas where direct effects versus indirect effects may 

occur is not adopted herein, as we surmise that indirect effects could occur in counties adjacent 

to the BTPD’s range. However, we agree with the EPA’s clarification that, while the action area 

includes those areas adjacent to the BTPD’s range where potential affects may occur, those 

affects are not necessarily likely or expected to occur and additional information was used to 

determine affects to listed species. 
13

Figure 1. The historic range of the BTPD by NatureServe as presented in the EPA’s BA 

(EPA 2010b).

 
14

V. GENERAL BACKGROUND AND EFFECTS OF THE ACTION 

RELEVANT TO ALL SPECIES IN CONSULTATION 

The BTPDs are considered a keystone species that have a unique and substantial influence on 

plant and animal communities and are critical to the integrity of grassland ecosystems (Kotliar 

et al. 2006). The habitat they create is associated with more than 150 species of amphibians, 

birds, mammals, plants, and reptiles as well as species federally listed for protection under the 

ESA (Kotliar et al. 2006). In western South Dakota, 40 percent of all wildlife (represented by 

134 vertebrate species) is associated with BTPD colonies (Sharps and Uresk 1990). The 

presence of mountain plovers (Charadrius montanus) and burrowing owls (Athene cunicularia), 

two species of conservation concern (FWS 2008a), is also considerably higher on BTPD colonies 

than grassland habitats without prairie dogs in eastern Colorado (Tipton et al. 2008). When 

prairie dog towns are poisoned, many other species are likely to be poisoned as well or be 

negatively affected by loss of prairie dog habitat or the species associated with that habitat. Loss 

of seasonal habitat for bird species may be of special concern. The number of bird species 

present in the summer was significantly higher on prairie dog towns than paired sites without 

prairie dog towns (Smith and Lomolino 2004). Burrowing owls, killdeer (Charadrius 

vociferous), horned larks (Eremophila alpestris), and western meadowlarks (Sturnella neglecta) 

are positively and significantly associated with prairie dog towns during summer, while horned 

larks and ferruginous hawks (Buteo regalis) are significantly associated with prairie dog towns 

during fall (Smith and Lomolino 2004). Species’ declines from the reduction of prairie dog 

habitat can result in cascading effects through the grassland ecosystem that extend beyond the 

poisoned prairie dog towns. 

A. INDANDIONE MODE OF ACTION AND TOXICITY

Chlorophacinone, the active ingredient in Rozol, is an anticoagulant chemical and, along with 

diphacinone, belongs to the indandione class of compounds. Chlorophacinone and diphacinone 

are the only indandione active ingredient rodenticides currently registered for use in the United 

States. Diphacinone was registered to poison BTPDs under FIFRA Section 24(c) for SLN, but it 

is currently registered for use only on rodents other than prairie dogs. Rozol is the only 

anticoagulant registered for use on BTPDs that is registered under Section 3 of FIFRA. 

Indandiones depress liver synthesis of vitamin K-dependent blood-clotting factors and increase 

permeability of capillaries throughout the body, resulting in systemic internal hemorrhaging 

(Reigart and Roberts 1999). Unlike the coumarin class of anticoagulant compounds (e.g., 

warfarin, brodifacoum, difenacoum), indandiones can cause neurologic and cardiopulmonary 

injury leading to death before hemorrhage occurs (Reigart and Roberts 1999, Hazardous 

Substances Data Bank 2003). Indandiones also uncouple oxidative phosphorylation (energy 

generation) which may result in fatigue and restlessness (Van Den Berg and Nauta 1975, Bryson 

1996). Clinical effects typically do not occur until several days after ingestion due to the 

persistence of blood-clotting factors. In humans, clinical effects include anemia (red blood cell 

deficiency), fatigue, dyspnea (breathlessness), nosebleeds, bleeding gums, hematuria (blood in 

the urine), melena (darkened feces associated with gastrointestinal bleeding), and extensive 

ecchymosis (large bruises) (Reigart and Roberts 1999). 
15

Indandiones are first generation anticoagulant rodenticides that are most toxic when animals are 

exposed to daily doses for multiple days (Vyas and Rattner 2012). For example, the median 

Lethal Dose (LD50) from a single exposure of chlorophacinone to Norway rats (Rattus 

norvegicus) is 20.5 micrograms per gram (μg/g), whereas a 5-day daily dose LD50 is 20 times 

lower at 0.95 μg/g (Jackson and Ashton 1992). A risk assessment by the EPA (Erickson and 

Urban 2004) reports a laboratory rat chlorophacinone LD50 of 6.2 μg/g as well as a 

0.19 μg/g 5-day LD50 for the same species (Table 9, page 34) indicating a 6-fold difference that 

is also probably attributed to differences in exposure frequency and duration. Likewise, a dietary 

toxicity test that provided a measured diphacinone-treated diet for daily consumption by eastern 

screech-owls (Megascops asio) found that repeated low-dosage exposure over 7 days increased 

diphacinone toxicity by more than an order of magnitude compared to an acute oral toxicity test 

(Rattner et al. 2011a; Vyas, pers. comm. 2011a; Vyas and Rattner 2012). Thus, the single dose 

LD50 test, which was developed to evaluate rodenticides causing acute responses such as zinc 

phosphide, is not an appropriate test for evaluating toxicity for first generation anticoagulants 

such as chlorophacinone that have their greatest toxicity from repeated daily exposures. We 

believe that acute standardized toxicity test results for chlorophacinone greatly underestimates 

risk to non-target species because indandiones are much more lethal when multiple doses are 

consumed over multiple days as opposed to a single feeding. 

The BTPDs exposed to chlorophacinone exhibit much variability in their susceptibility to 

mortality and the amount of time it takes for them to die (Yoder 2008). Death can occur when 

exposed to a chlorophacinone dose (oral gavage) as low as 0.5 milligrams per kilogram body 

weight (Yoder 2008). Mortality from LD50 tests indicate that BTPD deaths tend to occur 

9-20 days after exposure (Yoder 2008). The BTPDs exposed to chlorophacinone may not 

exhibit any symptoms prior to death, but most are symptomatic for at least 24 hours before death 

(Yoder 2008). The BTPD symptoms from chlorophacinone exposure (e.g., loss of attentiveness, 

lethargy, swollen or closed eyes) generally take days after ingestion to manifest, and this likely 

reduces bait avoidance in the interim (Yoder 2008). There is no apparent taste aversion to Rozol 

as BTPDs readily consume Rozol bait (Witmer 2011).

B. CHLOROPHACINONE ENVIRONMENTAL FATE 

The number of days for chlorophacinone to degrade by 50 percent (half-life) has been reported 

by laboratory studies that evaluate degradation by soil, water, and light. The half-life of 

chlorophacinone incorporated in soil can range from 4 to 128 days depending on laboratory 

testing conditions. In soil under dark aerobic conditions at 25°C, chlorophacinone is degraded 

steadily with an estimated half-life of 128 days (European Commission 2009); whereas, under 

artificial light on sandy clay loam soil, chlorophacinone’s half-life is 4 days (EPA 1998a). 

Although previously reported to be very susceptible to direct photolysis in water (e.g., half-life 

of 37 minutes at pH 7), the assessments used acetone (a strong photosensitizer) as a solvent to 

introduce chlorophacinone into the test system and are now considered by the EPA as invalid 

(Jones, pers. comm., 2011). Chlorophacinone is stable in water at a pH of 5, 7, or 9; thus, 

breakdown by exposure to water is not expected to be an important degradation process 

(Hazardous Substances Data Bank 2003). 
16

Few studies have evaluated the field persistence of chlorophacinone rodenticide baits; however, 

they indicate that chlorophacinone concentrations in Rozol would not degrade prior to 

consumption even under wet conditions (Merson and Byers 1985; Jones, pers. comm., 2011). A 

field study that evaluated wet weather resistance of rodenticides, including Rozol Vole Bait, 

found no difference in efficacy between wet and dry chlorophacinone pellets (Merson and Byers 

1985). A supplemental terrestrial field dissipation study reported no dissipation of 

chlorophacinone in Rozol samples for up to 10 days and actually found concentrations increased 

over this time period, perhaps as a result of insect consumption of the internal part of the grain or 

changes to bait water content (Jones, pers. comm., 2011). The ability to evaluate dissipation of 

chlorophacinone on grain samples was hampered by consumption of the grain samples, and the 

study concluded that the primary route of dissipation of chlorophacinone is through consumption 

of the treated grain (Jones, pers. comm., 2011). 

Based on the information above, we agree with the EPA’s assumption in the BA (EPA 2010b) 

that the mobility from bait into soil or water is considered a negligible exposure pathway to 

non-target organisms. We assume chlorophacinone remains undegraded in bait after applications 

and share the EPA’s assumption that the only relevant dissipation of Rozol occurs through its 

consumption. 

C. ROZOL EXPOSURE AND EFFECTS ASSESSMENT 

1. Primary Exposure 

Ingestion of Rozol (primary exposure) by non-target species can be expected for species that 

feed on grain. Twenty-nine adult domestic pigeons (Columba livia) were poisoned in Spain with 

a 0.005 percent chlorophacinone wheat grain bait after a broadcast application targeted at 

common voles (Microtus arvalis) (Sarabia et al. 2008). A common lesion associated with 

chlorophacinone toxicosis in these pigeons involved massive hemorrhage and hematoma 

formation in the subcutis of the neck; however, equally noteworthy was that chlorophacinone 

was found in the liver at 5.66 to 34.97 μg/g wet weight (ww) basis in four birds without any 

lesions suggestive of anticoagulant toxicosis (Sarabia et al. 2008). Although the label 

requirement to place bait “six inches in the burrow” is designed to limit exposure to granivorous 

birds, it does not preclude exposure to avian or other non-target species that may use BTPD 

holes. Rozol was visible in many BTPD burrows that contained angled entrances (as opposed to 

vertical entrances), and horned larks appeared to be preferentially drawn to these burrows where 

they could easily feed on Rozol (Vyas 2010a). The presence of green-stained droppings, 

indicative of exposure to Rozol bait which contains a green dye thereby making product appear 

green, was observed and suspected to be from pheasants (Phasianus colchicus), horned larks, 

and western meadowlarks. Green droppings from these birds suggest they were consuming bait; 

an assumption subsequently confirmed by detection of chlorophacinone residues in these 

droppings (Vyas, pers. comm., 2011b). 

In addition to feeding on bait within the burrow, non-target species may also feed on bait found 

on the surface. Bait spilled by applicators or not entirely placed in burrows can be difficult and 

time consuming to collect. Further, bait that is placed in burrows can be brought back to the 

surface of a colony over time by the action of prairie dogs and other animals using the burrow 
17

system (Vyas 2010a). We currently lack information concerning applicator willingness to cease 

operations and collect misplaced bait or return to the colony days to weeks later to collect and 

dispose of bait found on the surface. Absent that information, it appears that bait retrieval from 

the surface of a prairie dog colony, days to weeks post application, could be an unrealistic 

expectation of the label. Thus, even if applicators attempted to follow label instructions 

regarding retrieval and disposal of bait at the time of application, the size of bait and landscapes 

where it is used brings up the practicality of adhering to that label requirement. We are aware of 

one field study that found bait on the surface (Vyas 2010a) and have no information from 

anywhere else that indicates applicators are collecting and disposing of bait found above ground. 

The Rozol application rate of approximately 1⁄4 cup of bait (53 grams) down each active prairie 

dog burrow may be excessive and likely results in increased risk to non-target species. 

According to Liphatech, 53 grams of Rozol bait provides about two LD50 doses per BTPD, based 

on a single dose oral gavage LD50 of 1.8 μg/g (Yoder 2008). However, as previously explained, 

a 5-day LD50 would likely be around 20 times lower than a single dose LD50 and is more 

representative of exposure in the field whereby animals may consume bait over multiple days. 

Thus, 53 grams of bait may provide 10 lethal doses. Furthermore, there are on average 3.9 active 

burrow entrances for each BTPD (Biggins et al. 2006). If inactive burrows are mistakenly 

baited, then even further bait availability to both target and non-target animals would occur. To 

illustrate the point, when Forgacs (2010) treated 1,358 burrows on a 15.7 acre prairie dog plot 

where they had a visual count of 30 prairie dogs, they applied 71,974 grams of Rozol (at least 

13,580 lethal doses) on a plot with an estimated population of 348 BTPDs using a scientifically 

accepted methodology to estimate prairie dog numbers from active burrows (Biggins et al. 

2006). While that level of dosing likely ensures high lethality to prairie dogs, it likely also 

contributes to prairie dogs consuming multiple lethal doses as well as providing left-over bait to 

remain available for non-target species to consume after the prairie dogs have been killed. 

Results from other studies indicate that application rates of less than 53 grams of product per 

active burrow can be effective at killing BTPDs. Sullins (1990) reported a 96-percent reduction 

in the visible count of BTPDs after providing 0.01 percent chlorophacinone product in 

2 applications of 9 grams per active burrow for a total of 18 grams (equivalent to 36 grams of 

Rozol) applied within 48 hours. 

2. Secondary Exposure 

Species that ingest animals that consume Rozol (secondary exposure) are also at risk of being 

negatively affected, especially predators and scavengers that may gorge on poisoned prairie dogs 

and selectively feed on internal tissues (see “Prairie Dog Chlorophacinone Residues” section 

below). Five of six domestic ferrets were killed after each ferret was fed four poisoned BTPDs 

over 8 days; the authors of the study concluded that chlorophacinone may not be an acceptable 

prairie dog toxicant based on high secondary toxicity (Fisher and Timm 1987). As described 

further in the “Field Study Observations of Secondary Toxicity” section below, field 

observations indicate that the availability of BTPDs to secondary consumers is facilitated by 

prairie dogs spending time above ground after ingesting Rozol (FWS 2007a, Golden and Gober 

2010, Vyas 2010a). When subjected to poisoning, BTPDs can return to the surface of the 

colony, becoming increasingly debilitated until death. Prairie dogs in this debilitated state can be 
18

more susceptible to predation due to changes in behavior that render them more conspicuous and 

less wary and evasive in the presence of a predator (Hunt et al. 1992, Relyea and Hoverman 

2006). Avian predator hunting success increases dramatically when injured or abnormal prey are 

available (Rudebeck 1950), and scavengers, including some raptors, are attracted to easily 

obtained food sources, including poisoned prey (Chesser 1979, Vyas 1999, Vyas et al.2003). 

Some avian predators such as ferruginous hawks are attracted to Rozol-treated prairie dog 

colonies, likely due to the increased presence of moribund and dead prairie dogs and perhaps 

other non-target species (Vyas 2010a). Thus, even though Rozol-treated prairie dog colonies 

may make up only a small percentage of a predator’s overall foraging range, preferential 

selection of prey from these areas may lead to a disproportionate opportunity for exposure. 

Risk to non-target species also includes effects from chronic (long-term) secondary exposure. 

Rozol exposed prairie dogs may be debilitated on the surface for at least a month following 

application (Vyas 2010a, Lee and Hygnstrom 2007). Thus, predators may continue to feed from 

the same poisoned prairie dog town for weeks or may encounter other poisoned prairie dog 

towns that were sequentially poisoned and are within their home range or migration path. As 

described earlier, lethality of Rozol increases greatly with repeated exposure. We assume that 

many of the effects described in the above “Indandione Mode of Action and Toxicity” section 

including sub-lethal neurologic effects, cardiopulmonary effects, energy loss, and hemorrhaging 

could occur in federally listed species from chronic Rozol exposure and ultimately result in 

decreased growth, survival or reproductive effects. Further, we agree with the EPA’s assessment 

in the BA that “toxicity resulting from chronic exposure exceeding five days cannot be 

determined based on current data” and that “growth and reproductive effects cannot be precluded 

due to the absence of chronic data.” 

The BA and previous risk assessments by the EPA (Erickson and Urban 2004) indicate that 

mammals are at a greater risk from secondary chlorophacinone toxicity than birds; however, if 

sub-lethal effects are considered, then birds exposed in the field may be at equal or greater risk 

than mammals as the effects of anticoagulant rodenticide toxicosis can differ between mammal 

and avian species. For example, pulmonary hemorrhage is far more common in mammals than 

birds, but birds can have excessive external bleeding from minor superficial wounds, a condition 

not reported in mammals (Stone et al. 1999). Also, the first observed signs of secondary 

chlorophacinone toxicity in raptors include fatigue such as wing-drooping (Radvanyi et al. 

1988). For species such as raptors that rely upon speed and stamina to attain prey, 

chlorophacinone-induced fatigue can result in decreased survival by impairing their ability to 

capture prey. Because of differences in pathologies, birds may be even more susceptible to 

chronic effects than mammals. Furthermore, some avian species may be just as susceptible as 

mammals or more susceptible when sub-lethal effects are considered in conjunction with other 

factors that influence exposure and cumulative effects to birds such as: a) body condition from 

migration; b) increased susceptibility to contact injury; c) environmental conditions such as 

weather extremes; and d) high energy demands in the winter. 
19

3. Surface Presence of Poisoned Black-tailed Prairie Dogs 

The greatest pathway for effects to listed species from the proposed action comes from moribund 

or dead animals found on the surface of a prairie dog colony as a result of Rozol poisoning. The 

Service is aware of three studies that inform the issue of dead and dying prairie dogs on the 

colony surface following Rozol application, and two of the three studies repeatedly found dead 

and dying prairie dogs above ground on the surface of the prairie dog colony during multiple 

return visits (Lee and Hygnstrom 2007, Vyas 2010a). The other study (Forgacs 2010) did not 

find prairie dogs on the surface but qualified that result noting that weather conditions 

deteriorated after the application to the point that precipitation prevented researchers from even 

being able to return to some poisoned sites to search for prairie dogs. That study also noted that 

the inclement weather, which began after the Rozol application, may have contributed to 

decreased above-ground prairie dog activity (Forgacs 2010). 

Instances of dead and dying prairie dogs above-ground following application have also been 

reported to the Service’s Law Enforcement Division (FWS 2007a, Golden and Gober 2010). An 

excerpt below from an interview with a Rozol applicator after a bald eagle (Haliaeetus 

leucocephalus) poisoning incident in Nebraska illustrates both the regularity that prairie dogs 

return to the surface and the state of awareness of Rozol poisoned prairie dogs (FWS 2007a). 

REDACTED also explained that he knew poisoned prairie dogs often returned to 

the surface before dying, as evidenced by the bloody stools he often saw when he 

returned to inspect the sites. REDACTED further relayed an incident when the 

poison Rozol had been applied to the prairie dog town, as per label instructions 

and the lady owning the property watched as poisoned prairie dogs stumbled 

around the surface for two weeks after the application. REDACTED added when 

he does see prairie dogs on the surface after they have been poison, they seem to 

be in a stupor, and not wary at all. REDACTED said he could often walk right 

up to these poisoned prairie dogs and they would not run away. 

At the time this statement was provided to Law Enforcement Agents in 2007, the Rozol SLN 

label did not require collection of impaired or moribund prairie dogs but rather just retrieval of 

carcasses found on the surface. Even though the current label requires collection and disposal of 

live prairie dogs, we have encountered applicators who indicate that this is not readily 

accomplished (see following section below). Given the instances of Service Law Enforcement 

agents finding moribund and dead prairie dogs on the surface after a Rozol application (Golden 

and Gober 2010) and applicators reporting prairie dogs on the colony surface following Rozol 

applications (FWS 2007a), we believe Rozol-poisoned prairie dogs and other animals will 

regularly return to the surface of a colony and be available for secondary exposure to federally 

listed species, including the northern aplomado falcon and gray wolf. 

4. Removal of Poisoned Black-tailed Prairie Dogs 

Although the Rozol label requires return visits to the colony to search for and remove dead and 

dying prairie dogs following application, the limited information on applicator behavior indicates 

that few, if any, moribund or dead prairie dogs are collected and disposed of in a manner that 
20

substantially reduces secondary exposure (FWS 2010a, Tosh et al. 2011). This outcome may be 

due to the difficulty of finding prairie dogs on the surface as illustrated by Vyas (2010b) (click 

here for video) or because resources and commitments needed to make multiple return visits to a 

colony are not available (FWS 2010a). 

During a meeting in 2010 attended by the EPA and hosted by the North Dakota Department of 

Agriculture and Standing Rock Sioux Indian Reservation, ranchers and professional pesticide 

applicators indicated that they do not have the time, resources or inclination to conduct multiple 

return visits to a Rozol treated prairie dog colony to collect dead and dying prairie dogs, and that 

current label requirements for two return visits to treated prairie dog towns were unrealistic and 

impractical (FWS 2010a). These remarks were in response to an EPA inquiry to the attendees 

what they would think about increasing the required returns visits to a poisoned prairie dog 

colony from two times as required by the label in effect at that time (August 2010) to potentially 

many more visits. The EPA prefaced their inquiry to the ranchers in attendance that additional 

return visits might be added to the label to address comments that the EPA received from 

environmental groups about dead and dying prairie dogs on the surface of a colony. One of the 

meeting participants indicated that, if the EPA needed to increase the number of return visits on 

the label to pacify environmental groups, it may not matter since that speaker did not believe 

there was rigorous adherence for two return visits to collect prairie dogs; thus, requiring even 

more return visits would likely meet a similar fate. The Montana Department of Agriculture also 

questioned the practicality of the Rozol label, especially the retrieval of live prairie dogs, and 

expressed their belief that most applicators will have difficulty with strict adherence to the label 

(de Young 2009). Of particular note from that North Dakota meeting was that none of the 

attendees had ever picked up and disposed of live prairie dogs or their carcasses after a Rozol 

application. At the time of the meeting, Rozol had only been approved for use on prairie dogs 

for one season in North Dakota and South Dakota. Some attendees have since indicated that 

applicators did go back out to search per the label and did not find BTPDs on the surface, 

surmising that above-ground BTPDs had been scavenged or died underground. 

A recent on-farm survey on anticoagulant use in Northern Ireland found that applicators seldom 

followed best practice guidelines designed to maximize efficacy and reduce risk of non-target 

species exposure (Tosh et al. 2011). They found that applicators almost never searched for and 

removed poisoned carcasses and many baited for prolonged periods or permanently. We are not 

aware of any similar anticoagulant use behavior studies conducted in the United States that 

would inform Rozol applicator use behavior. However, we suspect that challenges with label 

restrictions, especially retrieval of live prairie dogs and carcasses, is an issue given the amount of 

effort needed to accomplish this task and the few resources available to ensure compliance. We 

conclude that while most labels are difficult to enforce, the comparatively complex nature of the 

Rozol label renders it particularly vulnerable to noncompliance, and reports from users indicate 

that failure to pick up prairie dogs is a “widespread and commonly recognized practice,” a 

designation outlined in FIFRA as a means for determining registration eligibility. 

Pamphlets produced by Liphatech indicate that little effort is needed to meet the Rozol label 

requirement for carcass searches and disposal of prairie dogs carcasses (Bruesch 2009, Liphatech 

2009). These pamphlets, made available during the time when the Rozol label required two 

return visits for carcass searches, indicated that Rozol was less labor intensive than a competing 
21

rodenticide labeled for use on prairie dogs that did not require carcass searches or in-burrow 

application. Bruesh (2009) makes the recommendation to “allow a little extra time for carcass 

search and recovery” when using anticoagulant rodenticides to control prairie dogs. Both 

pamphlets imply that the requirement to conduct two carcass searches and properly dispose of 

bait and carcasses found above ground is less labor intensive than a single pre-baiting trip and 

the potential need to reapply a competing rodenticide (Bruesch 2009, Liphatech 2009). Quick 

searches that lack systematic protocols are expected to find fewer poisoned carcasses than those 

that include walking transects of specified width (e.g., Lee and Hygnstrom 2007, Vyas 2010a, 

Witmer et al. 1995). Furthermore, Vyas (2010a) observed dying BTPDs on his last search 

29 days after an application. Thus, applicators that cease carcasses searches after 2 weeks if no 

animals are found, as specified on the label, would miss later mortalities as indicated by Yoder 

(2008). We believe that, although Rozol-exposed prairie dogs may be found dead or debilitated 

on the surface of a colony for at least a month following application, searches as described on the 

label are inadequate to consistently locate poisoned prairie dogs above ground and thus unlikely 

to prevent non-target exposure. 

Though we note that follow-up search protocols may not always be followed, the Service 

believes that current Rozol label directions to reduce secondary exposure by collecting and 

disposing of dead and dying prairie dogs at 1- to 2-day intervals late in the day are inadequate to 

protect non-target species. While the label specifies a search frequency, it does not specify 

protocols how to conduct the searches. A random search pattern, which would be the likely 

categorization for the current Rozol label searches, is poor in detecting target and non-target 

animals (Witmer et al.1995). Searcher efficacy in locating dead animals is significantly 

increased if transect patterns are employed to search for animals (Witmer et al. 1995). That same 

study showed that searcher effectiveness when using protocols for walking transects or circular 

subplots ranged from 24.5 – 36.2 percent compared to just 2.6 percent when using a random 

search pattern protocol (Witmer et al. 1995). Systematic searches, such as transect-line searches 

spaced at appropriate intervals, increase detection of poisoned prairie dogs and non-targets (Lee 

and Hyngstrom 2007, Vyas 2010a). 

Many prairie dogs are likely scavenged prior to the opportunity for removal by applicators. 

Carcass retrieval studies, aimed at evaluating pesticide mortality events, have found that as high 

as 92 percent of carcasses are scavenged within 24 hours and that carcass removal by scavengers 

is more rapid in areas of higher carcass density than in lower density kills because clumped food 

sources can attract scavengers (Vyas 1999). Thus, even if the label is followed and applicators 

remove carcasses at 1- to 2-day intervals late in the day, it is unlikely to outpace removal by 

scavengers. Further, poisoned animals are alive for an extended period of time (days to weeks) 

and nontarget animals in particular, may move away from the application area before they die. 

We could locate no information to indicate that the current label requirements in practice prevent 

secondary exposure, mainly because we can locate no information that prairie dogs are being 

collected per the label restrictions. Furthermore, there is no indication that, if carcasses were 

retrieved from the surface, they would be removed from the site since the label allows prairie 

dogs found on the surface to be placed in prairie dog burrows or otherwise buried on site. Such 

carcasses could be targeted by coyotes, foxes, badgers, bears, black-footed ferrets, and other 

carnivores that can dig up prey or carrion. 
22

Based on the information in this section, we conclude that few, if any, poisoned prairie dogs are 

removed from a colony as a result of return visits by applicators. Thus, poisoned BTPDs are 

likely to remain at the colony where they were poisoned and be available for consumption by 

federally listed species and other non-target species that federally listed species prey upon. 

5. Field Study Observations of Secondary Exposure or Toxicity 

As indicated previously, chlorophacinone and diphacinone toxicity share a similar mode of 

action; thus, we consider information on secondary exposure to non-target species from 

diphacinone as relevant in evaluating Rozol exposure. Four studies have evaluated 

chlorophacinone or diphacinone exposure to non-target species following applications to poison 

BTPDs (Bruening 2007, Lee and Hygnstrom 2007, Forgacs 2010, Vyas 2010a). These studies 

are discussed briefly below. 

Field studies sponsored by Liphatech (Lee and Hygnstrom 2007, Forgacs 2010) reported little to 

no evidence of secondary exposure and did not observe any scavenging by avian predators. Lee 

and Hygnstrom (2007) performed a study designed to assess the efficacy of chlorophacinone in 

killing BTPDs that included searches for carcasses only on and immediately around baited plots. 

They found 10 carcasses above ground (9 BTPDs and a cottontail rabbit) at a ratio of 1 carcass 

found per 14 acres searched. Forgacs (2010) quantified the number of dead and dying prairie 

dogs above ground following a field application and included searches on three test plots 

consisting of approximately 24 acres for 21 days after application. They did not find any dead 

prairie dogs or non-target carcasses; however, the study was performed in early February and 

included precipitation and storm events that the researchers believe limited the prairie dog 

activity above ground and the ability of the researchers to return to the sites to search for prairie 

dogs (Forgacs 2010). According to a field study sponsored by Scimetrics, the registrant for 

Kaput Prairie Dog Bait (diphacinone active ingredient), sick and lethargic prairie dogs were 

observed above ground following a field application, and researchers also observed a bald eagle 

flying off the treatment plot with a prairie dog in its talons (Bruening 2007). 

A study sponsored by the Service and performed by the U.S. Geological Survey (Vyas 2010a) 

documented avian and mammalian non-target exposure and effects following a field application 

of Rozol. Signs of exposure reported in this study included mortality, morbidity, discolored 

droppings, scavenging, possible blood stained soil, and a general change in the number of 

BTPDs and other wildlife (Vyas 2010a). Carcass searches were conducted over an area of 

approximately 43 acres for 14 days over a 29-day post-application period and recovered 2 intact 

13-lined ground squirrels (Spermophilus tridecemlineatus), 9 intact BTPDs, 7 scavenged BTPDs, 

and 1 intact western meadowlark (Vyas 2010a). The meadowlark had abundant hemorrhaging in 

the pectoral muscle, one focal hemorrhage in the brain, and chlorophacinone was detected in the 

liver and lower gastrointestinal contents (Vyas, pers. comm., 2010). Meadowlarks are a 

recognized food source for the federally endangered northern aplomado falcon (FWS 2002b). 

Raptors were also seen visiting the poisoned prairie dog colony and foraging on BTPDs (Vyas 

2010a). 
23

A Rozol application in South Dakota on a prairie dog colony in 2005 found approximately 

400-500 dead and dying prairie dogs on the surface when a 160-acre densely populated prairie 

dog town was treated with Rozol (Golden and Gober 2010). The South Dakota incident was 

investigated by the EPA and confirmed to be related to an application of Rozol. At that time, 

Rozol was not authorized for use in South Dakota and a subsequent investigation by the EPA 

ensued, but the outcome is not available at this time. 

In December 2006, a deceased adult female bald eagle was recovered by Service Law 

Enforcement and submitted to the National Fish and Wildlife Forensics Laboratory in Ashland, 

Oregon (FWS 2007a). The necropsy revealed that poisoning with chlorophacinone and physical 

trauma had occurred. The laboratory report concluded that “the observed small hemorrhagic 

skin laceration on the dorsal elbow region of the right wing was caused by trauma from an 

undetermined source. This trauma may have initiated the extensive hemorrhaging caused by the 

presence of the anticoagulant rodenticide in the eagle.” Chlorophacinone was detected in the 

bald eagle’s liver at 0.30 μg/g ww, a concentration similar to that detected in the liver of another 

bald eagle (0.40 μg/g ww, as described below) and considered indicative of chlorophacinone 

poisoning (FWS 2011b). The Service Special Agent working on the Nebraska bald eagle 

mortality case interviewed a licensed applicator regarding the incident. The applicator remarked 

that even when label directions for Rozol applications are followed, BTPDs are often seen above 

ground in a moribund state of stupor that leaves them vulnerable to capture or predation (FWS 

2007a). 

In January 2009, a sub-adult female ferruginous hawk and an adult male great-horned owl (Bubo 

virginianus) were collected by Service Law Enforcement and submitted to the National Fish and 

Wildlife Forensics Laboratory in Ashland, Oregon (FWS 2009c). Both raptors had a liver 

chlorophacinone concentration of 0.25 μg/g ww and were found in an area in Kansas where 

Rozol was being used to control prairie dogs. The ferruginous hawk had prairie dog hair in its 

stomach contents, and the owl’s stomach contents had hairs from rodents and/or insectivores 

(Rodentia; Soricomorpha). 

In March 2011, another bald eagle carcass was opportunistically recovered in Nebraska and 

analyzed by the National Fish and Wildlife Forensics Laboratory. The bald eagle’s cause of 

death was diagnosed as ingestion of chlorophacinone due to a liver chlorophacinone 

concentration of 0.4 μg/g ww and hemorrhage of the subcutaneous tissues, body cavities and 

lungs (FWS). According to the examiner, “no gut contents were available for examination, but 

toxicity was likely incurred through ingestion of one or more poisoned rodents.” Prairie dog 

colonies were in the general vicinity of where the bald eagle was recovered, and the law 

enforcement case is still under investigation. 

Based on the reports described above (Lee and Hygnstrom 2007; FWS 2007a, 2009c; Bruning 

2007; Vyas 2010a), we conclude that chlorophacinone exposure to federally listed species and 

non-target animals following field applications of Rozol has occurred in the past and is likely to 

occur in the future if Rozol is used to poison BTPDs under the current label directions. 
24

D. REVIEW OF THE EPA’S ROZOL EFFECTS DETERMINATION 

We believe that risk calculations in the EPA’s BA likely underestimate risk to non-target species 

(described in detail below). Therefore, the analysis in this section informed the development of 

this BO and serve as feedback to the EPA for consideration in developing future effects 

determinations for listed species. 

a. Underestimated Risk to Avian Species

A Risk Quotient (RQ) is equal to the Estimated Environmental Concentration (EEC), a term used 

to estimate exposure, divided by the relevant toxicological endpoint or Toxicity Reference Value 

(TRV). The BA provides a RQ of 0.104 for avian species, a value that barely exceeds the EPA’s 

Level of Concern (LOC) of 0.1 (EPA 2010b). The TRV used to calculate this RQ is based on 

dietary median Lethal Concentration (LC50) for northern bobwhite (Colinus virginianus) quail. 

Although the EPA’s selection of a sub-acute dietary LC50 test value for the TRV is preferred to a 

single dose LD50 value, this TRV is still likely to underestimate risk to avian species. As dietary 

LC50 results can be highly dependent on a species’ willingness to eat the bait and their ability to 

cope with reduced nutriment, their applicability in quantitative risk assessment has been 

questioned (Hill 1993, Mineau et al. 1994, Hoffman 2003). In addition, data suggest that the 

northern bobwhite quail, which eats primarily insects and vegetation, is not likely to be 

representative of other more sensitive avian species, especially those that prey upon and 

scavenge prairie dogs or other non-target small animals. Though toxicity data are lacking for 

chlorophacinone effects to a wide breadth of species, recent investigations have found that 

sensitivity of raptors to the closely related indandione rodenticide diphacinone is much greater 

than predicted from test species used in pesticide registrations. Acute diphacinone toxicity tests 

indicate that American kestrels (Falco sparverius) are over 20 times more sensitive than northern 

bobwhite quail and over 30 times more sensitive than mallard (Anas platyrhynchos) ducks, 2 test 

species required by the EPA for pesticide registration (Rattner et al. 2010a and 2011b). Golden 

eagles (Aquila chrysaetos) appear to be even more sensitive to diphacinone than kestrels (Savarie 

et al. 1979, Rattner et al. 2011b). Given the similarity of chlorophacinone to diphacinone, we 

conclude that at least raptors (e.g., the northern aplomado falcon), and possibly other groups of 

species, will likely exhibit greater sensitivity than can be estimated from existing mallard or 

northern bobwhite quail studies. 

Furthermore, the LC50-based TRV does not account for potential sub-lethal effects of 

chlorophacinone that can decrease listed species’ survival and/or reproduction. Accounting for 

sub-lethal effects from chlorophacinone exposure such as fatigue, clotting abnormalities, and 

hemorrhaging is important when evaluating risk to federally listed species. This is especially 

true when evaluating cumulative effects that include sub-lethal effects from exposure to 

chlorophacinone as well as other environmental stressors such as adverse weather, food 

shortages, and predation (Vyas et al. 2006). The BA identifies external bleeding, internal 

hemorrhaging, and increased blood coagulation time as sub-lethal effects to avian species from 

secondary exposure to chlorophacinone-poisoned food; however, other sub-lethal effects (e.g., 

fatigue) can occur even prior to gross observation of internal and external bleeding. As 

mentioned previously, chlorophacinone uncouples oxidative phosphorylation, and studies have 

reported that the first observed signs of secondary chlorophacinone toxicity in raptors include 
25

fatigue such as wing-drooping (Radvanyi et al. 1988). Fatigue induced from chlorophacinone 

exposure is expected to substantially reduce a listed species’ ability to capture prey and thus 

negatively affect its reproduction and survival in the wild. 

Sub-lethal effects have been documented in raptors exposed to anticoagulants and those effects 

can occur despite low tissue residue concentrations. For example, American kestrels 

administered diphacinone had liver residues just above the detection limits of 0.263 and 

0.280 μg/g ww diphacinone, but histological evidence revealed hemorrhages in lung and liver 

tissues (Rattner et al. 2011b). Golden eagles fed muscle from diphacinone-treated sheep 

exhibited extreme weakness, ataxia (lack of muscle control), and hemorrhages (Savarie et al. 

1979). These studies indicate that raptors are susceptible to indandione’s multiple modes of 

action. Although some avian species have survived laboratory studies after being fed 

anticoagulant poisoned rodents until time of euthanasia (Savarie et al. 1979, Mendenhall and 

Pank 1980, Radvanyi et al. 1988), sub-lethal effects described in these studies (e.g., fatigue; 

wing-drooping; and lung, heart, and liver hematomas) are expected to result in decreased 

survival or reproduction under field conditions. A comprehensive assessment of potential effects 

of chlorophacinone exposure to sensitive populations of migratory birds has not been completed, 

and reliance on labeled use restrictions does not protect vulnerable species (Golden and Gober 

2010). Thus, in addition to the avian reproduction study that the EPA has required Liphatech to 

complete, we have recommended that the EPA exercise their authority under the FIFRA to 

require additional field assessments that include tracking avian predators and scavengers (e.g., 

ferruginous hawks, eagles) that are expected to be the most susceptible to Rozol use in prairie 

dog towns (Schwarz and Gober 2011). Until such studies are completed to provide data on sublethal effects and subsequent reproduction and survival, it is difficult to evaluate the secondary 

toxicity risk of Rozol exposure to federally listed species such as the northern aplomado falcon. 

An acute exposure to listed species from a one-time feeding of chlorophacinone bait or poisoned 

prey may still result in death or harmful sub-lethal effects because even minor increases in 

fatigue in predators can undermine their ability to acquire prey. However, as the EPA indicated 

in the BA, there is high potential for chronic effects to occur in birds because LD50 and LC50 data 

indicate that acute environmental exposures can result in doses that do not result in immediate 

direct lethality but instead create potential for long-term exposures and chronic toxicity. The 

potential for chronic exposure to birds is further increased by the potential for exposure to other 

anticoagulant rodenticides (e.g., diphacinone) and by repeated exposures to chlorophacinone and 

diphacinone from multiple applications and at multiple locations as the species forage over large 

home ranges and migrates. One of the other diphacinone products to control BTPDs is 

Kaput®-D, which was previously available for use from October 1 to March 15 under a FIFRA 

Section 24c registration in Colorado, Kansas, Nebraska, Texas, and Wyoming and has a pending 

request for registration for use throughout the BTPD’s range (Golden and Gober 2010). 

Previous studies indicate that anticoagulant rodenticides have a wide geographic use and 

detection of one or more of these compounds in the livers of predatory birds is common (Stone 

et al. 2003, Albert et al. 2010). Therefore, it is a reasonable assumption that raptors such as the 

northern aplomado falcon may already be carrying an anticoagulant burden and are thus more 

susceptible to adverse effects from additional exposure. 
26

b. Prairie Dog Chlorophacinone Residues 

In its BA, the EPA uses a maximum carcass whole-body residue value of 2.24 μg/g ww for the 

Environmental Effects Concentration in evaluating secondary risk to species that consume 

poisoned BTPDs; however, this value may underestimate exposure. The prairie dog with a 

carcass concentration of 2.24 μg/g ww had a liver concentration of 6.66 μg/g ww and was 

collected an unknown number of days after bait application. It is also unknown whether this 

prairie dog had recently consumed bait or stopped eating bait days before it died. Currently, data 

exists for BTPD carcasses that were picked up 10 to 25 days after a field application (Lee and 

Hygnstrom 2007, Primus 2007), but it is unclear if they still had bait in their system or if they 

became too sick and stopped eating bait days before they died. Lab data also exists for BTPDs 

that consumed a single dose (53 grams bait) and were euthanized periodically after being 

maintained on a clean diet (Witmer 2011). Prairie dogs in the Witmer (2011) study that had 

most recently consumed bait had the highest liver and carcass concentrations of 

chlorophacinone. However, for field applications, there may be 10 or more lethal doses 

distributed per individual prairie dog (based on 3.9 active burrows per prairie dog as explained 

previously) and a longer lag time between exposure and death. Thus, prairie dogs likely 

continue to eat Rozol after they have consumed a lethal dose. These prairie dogs likely have 

higher chlorophacinone residues, especially in the liver, than those that die several days after 

they stop eating bait (Pitt et al. 2005, Witmer 2011). 

The use of whole-body chlorophacinone residues, as opposed to chlorophacinone residues in 

liver, may underestimate secondary exposure risk to non-target wildlife, particularly scavenging 

and predating birds. The EPA’s BA does not account for concentrations of chlorophacinone in 

internal organs, such as liver, which may be selectively consumed by certain predators or 

scavengers and livers generally much greater concentrations than whole-body samples. Eight 

BTPD carcasses collected after a field application of chlorophacinone bait had a mean 

concentration of chlorophacinone in liver of 5.86 ± 1.88 μg/g ww (maximum of 6.66 μg/g) 

compared to a whole body mean concentration of 1.48 ± 0.46 μg/g ww (maximum of 2.24 μg/g) 

(Primus 2007). Use of a liver concentration instead of a carcass concentration may be more 

appropriate based on feeding behavior of some animals that selectively eat parts of prairie dogs. 

For instance, some predators may only forage on the most readily accessible body cavity organs, 

including the liver (Figure 2). When multiple carcasses or moribund prairie dogs are readily 

available, internal organs may also be preferentially selected over other less accessible or 

digestible prairie dog body parts. A realistic worst-case scenario would include a maximum liver 

concentration for the EEC, as opposed to the maximum whole body residue used in the BA. The 

highest liver known chlorophacinone concentration in a BTPD is 8.4 μg/g ww in a BTPD that 

consumed 52.8 grams of Rozol and was euthanized 2 days later (Witmer 2011). We recognize 

that data for chlorophacinone concentrations in livers from prairie dogs is extremely limited; 

thus, liver concentrations of 8.4 μg/g ww from a euthanized prairie dog and 6.6 μg/g ww from a 

dead field collected prairie dog are unlikely to be the greatest concentrations encountered if more 

than a few dozen prairie dog livers are examined. 

 
27

Figure 2. BTPDs (A and B) scavenged at a prairie dog colony in 2005 after an application 

of Rozol. Note selective feeding by scavengers that target internal body organs.

A

B
28

c. Risk Quotient Calculations and Uncertainty 

A review of the BA by Liphatech (2010) critiqued it for not correctly accounting for a “high 

degree of uncertainty in the resulting Risk Quotient calculations.” We agree with this 

assessment, but for different reasons. Liphatech requested uncertainty be considered given the 

use of what they termed as “extreme” data for non-target species and prairie dog carcass 

residues. We disagree that extreme data was used and, for reasons specified above, believe that 

TRVs selected for non-target species and residue values in prairie dogs used by the EPA are both 

too low to represent a realistic worst case scenario. Contrary to Liphatech’s concern for RQs 

being too high due to unaccounted uncertainty, several lines of evidence regarding Rozol 

exposure and effects suggest that the calculated RQs should be greater to account for uncertainty 

and missing data. For example, as calculated in the BA, the RQ derived from the BTPD 

whole-body concentration of 2.24 μg/g ww does not exceed the LOC for secondary toxicity to 

avian species (EPA 2010b page 80, Table 5.1). Not only are greater exposure estimates 

warranted that increase the EEC, based on consumption of chlorophacinone concentrations in 

liver, but also the TRV is overestimated based on the use of acute toxicity tests rather than 

chronic or sub-acute tests and differences in species’ sensitively as explained above. Both an 

increased EEC and decreased TRV would result in a greater RQ. Further, the EPA’s RQ 

calculations in the BA do not specifically address uncertainty from the influence of 

environmental stressors that can make non-target animals more susceptible to poisoned food 

(e.g., adverse weather conditions, food shortages, migration, and predation). 

Uncertainty factors are recommended for use in risk assessments to protect federally listed 

species as scientifically appropriate or where available data are incomplete or otherwise warrant 

its application (EPA 1995 and 2011d). For Rozol, all three reasons to include uncertainty factors 

are valid. According to the EPA technical guidance, reasonable uncertainty factors may range 

from 1-100 for interspecies uncertainty, 1-10 for intraspecies variability, and 1-10 for sub-acute 

to chronic toxicity (EPA 1995). In the case of chlorophacinone, information from closely related 

pesticides indicate that interspecies sensitivity could be as much as 20 or 30 times greater than 

toxicity values measured in test species (Rattner et al. 2010a, 2011b). Reported mortality 

incidents involving raptors described herein support the likelihood that these taxa can be killed 

from exposure to chlorophacinone through Rozol use. If the BA applied uncertainty factors for 

interspecies sensitivity alone, then RQs based on chlorophacinone concentrations in BTPDs 

would exceed the LOC and be more in accordance with our concerns for secondary exposure to 

birds and mammals that consume Rozol-poisoned prairie dogs. 

In addition, RQs were not calculated for chronic or sub-lethal effects to federally listed birds, 

presumably due to the lack of registrant-submitted reproduction studies. In the absence of data, a 

lack of effects cannot be assumed, but available lines of evidence must be examined to determine 

if effects can be reasonably ruled out. In the case of Rozol, chronic exposure to anticoagulant 

rodenticides is likely for predatory and scavenging species which can cause death or sub-lethal 

effects that may hasten death when combined with other stressors (Stone et al. 1999). These 

effects are likely to occur at concentrations below those which would produce lethality in a 

laboratory setting and therefore must be considered as distinct endpoints. Where data are lacking 

to produce quantitative RQs with much certainty or assign numeric uncertainty factors, a 

preferred option is to express risk in qualitative terms. Professional judgment or other qualitative 
29

evaluation techniques are appropriate for ranking risks into categories such as low, medium, and 

high when exposure and effects data are limited or are not easily expressed in quantitative terms 

(EPA 1998b). For the New Mexican ridge-nosed rattlesnake, for example, the EPA determined 

that adverse effects were likely even though both RQs were below the LOC because chronic 

effects could occur. Thus, the Service agrees with the EPA’s conclusion that chronic effects 

cannot be ruled out based on the available data. The EPA’s decision to ultimately base adverse 

effects determinations not solely on RQs but on the uncertainty surrounding chronic effects that 

could result in growth, survival, and reproductive impairments that are detrimental to species 

recovery we believe was appropriate. 

E. WILDLIFE MORTALITY INCIDENTS

Due to the sensitivity of testing Rozol on listed species, we have no direct information on the 

effects of Rozol to the species under consultation. Therefore, we look to studies of effects of 

Rozol on other non-target species to inform our analysis. We characterize these studies in this 

section. 

Based on sub-lethal effects to non-target species as reported from laboratory studies as well as 

reported mortalities and concerns based on opportunistic field recoveries (Erickson and Urban 

2004, FWS 2007a, EPA 2010b, Ruder et al. 2011), there is a need for field studies that evaluate 

anticoagulant exposure and effects to the many species that consume anticoagulant poisoned 

prairie dogs and other primary consumers. Although a lack of incident reporting is likely a 

factor in addressing risk uncertainty (Erickson and Urban 2004), wildlife mortality incidents 

involving chlorophacinone reported to the EPA include bald eagles, a red-tailed hawk, turkeys, 

coyotes, San Joaquin kit foxes, grey squirrels, and a bobcat (Erickson and Urban 2004, FWS 

2007a). It is noteworthy that the bobcat had a liver concentration of 0.4 μg/g ww 

chlorophacinone (a concentration similar to other non-target species that are believed to have 

died from chlorophacinone exposure (FWS 2007a, 2011b)) and apparently died from tertiary 

exposure to chlorophacinone as it was found dead 1 day after seen feeding on a dead owl that 

contained a rodent carcass in its crop (Erickson and Urban 2004, EPA 2010b). 

 

Ruder et al. (2011) reported three mortality events in Kansas involving several species, including 

wild turkeys (Meleagris gallopavo), a raccoon (Procyon lotor), and an American badger 

(Taxidea taxus). In all three cases, chlorophacinone was detected in the liver of the non-target 

species. The first incident in 2002 included the death of 1 wild turkeys found 2.5 weeks after a 

Rozol application; concentrations of chlorophacinone in their livers were 0.69 and 0.40 μg/g 

(Ruder et al., 2011). The second incident in 2009 included 45 dead turkeys from exposure to 

zinc phosphide as well as a raccoon with liver concentrations of chlorophacinone, brodifacoum, 

bromadiolone, and diphacinone of 1.4 μg/g, 0.5 μg/g, 0.37 μg/g, and trace, respectively. The 

authors suspected that the raccoon exposure to brodifacoum, bromadiolone, and diphacinone was 

from the use of over-the-counter rodenticides against commensal rodents (Ruder et al., 2011). 

The badger was found within an area in western Kansas where Rozol had been used and had a 

high chlorophacinone concentration of 4.4 μg/g ww in its liver (Ruder et al., 2011). The authors 

concluded that their opportunistic findings of non-target species mortalities likely underestimate 

actual non-target species losses. This conclusion seems justified as a 4-year survey of 
30

anticoagulant poisonings of wildlife in France based on a wildlife disease surveillance network 

yielded 59 confirmed diagnoses for bromadiolone and 41 for chlorophacinone, indicating that 

chlorophacinone is frequently detected in non-target species (Berny et al. 1997). 

In addition to the opportunistic wildlife mortality incidents noted above, there are likely many 

more individuals and non-target species poisoned from chlorophacinone that have not been 

found. As mentioned previously, carcass-detection studies have found that even when searches 

are performed in areas known to contain carcasses, a significant percentage will never be found 

due to scavenging, size or coloration that renders the carcass inconspicuous, or field conditions 

such as remote, inaccessible areas, that impede searches (Vyas 1999). In the case of 

anticoagulants, the delayed toxicity can temporally or geographically distance the carcass from 

the application area (Colvin et al. 1988). In addition, exposure to chlorophacinone may result in 

sub-lethal effects that occur at concentrations below a diagnostic threshold for lethality, masking 

their role in mortality incidents where acute lethal hemorrhage is not the proximal cause of death 

and may be attributed to causes such as trauma or disease (Stone et al. 1999). 

Opportunistic recoveries indicate that raptors may be at high risk to secondary toxicity from 

chlorophacinone use to poison BTPDs. As described in the “Rozol Exposure Assessment” 

above, Service Law Enforcement recovered two bald eagles in Nebraska and a great horned owl 

and ferruginous hawk in Kansas which died following chlorophacinone exposure (FWS 2007a, 

2009c, 2011b). More dead raptors were found in that same area of Kansas after Rozol was used 

to control prairie dogs in 2009, including two more ferruginous hawks and a bald eagle that were 

found shot and thus not tested for chlorophacinone (FWS 2009c). Also in that same area of 

Kansas, Audubon of Kansas reported that, in addition to the raptors provided to Service Law 

Enforcement in 2009, they had found an additional 17 dead hawks, mostly ferruginous hawks 

that were not picked up in the field. It is not firmly established whether the raptor mortalities are 

attributed to chlorophacinone or Rozol as no definitive testing for chlorophacinone in body 

tissues was conducted on the raptors; however, the opportunistic finding of the raptors coincided 

with Rozol applications nearby. 

 

Migratory raptors are especially susceptible to secondary poisoning from anticoagulant use due 

to their propensity to feed in prairie dog colonies (Golden and Gober 2010). Raptors are 

believed to be especially susceptible to secondary poisoning from Rozol given the likelihood that 

they can spot dead or dying BTPDs that are more difficult to see from a ground level perspective 

(Vyas 2010b) and raptors have been observed to be attracted to Rozol poisoned BTPD colonies 

(Vyas 2010a). The golden eagle, ferruginous hawk, and burrowing owl are among nine species 

with documented dependence on prairie dog colonies (Kotliar et al. 1999, Seery and Matiatos 

2000). All three of these raptor species have been identified as “Species of Conservation 

Concern,” defined as species that are likely to become candidates for listing under the ESA 

without additional conservation action (FWS 2008a). Further, bald and golden eagles are 

protected under the Bald and Golden Eagle Protection Act. In particular, ferruginous hawks and 

golden eagle populations appear to be experiencing declines throughout most of their range, and 

the availability of poisoned prey, which occurs when anticoagulants are used for prairie dog 

control, are expected to exacerbate population declines. Golden eagle populations may not be 

able to withstand additional loss of individuals (FWS 2009d, Golden and Gober 2010). Bald 

eagles have a kleptoparasitic association with ferruginous hawks (whereby eagles pursue 
31

ferruginous hawks and steal their prey) which are an efficient predator of prairie dogs (Jorde and 

Lingle 1988). Thus, both species may be particularly vulnerable to anticoagulants use to kill 

BTPDs (Golden and Gober 2010). This suspected vulnerability is further supported by the 

opportunistic recovery of two bald eagles killed from chlorophacinone exposure previously 

described and the abundance of dead ferruginous hawks reported by Audubon of Kansas from an 

area where Rozol was being used to poison prairie dogs. Migratory bird deaths attributed to 

chlorophacinone poisoning are not permitted or authorized under the Migratory Bird Treaty Act. 

The Service is gaining a better understanding of the Rozol label requirements regarding multiple 

return visits to retrieve dead and dying prairie dogs and exposed bait. Based on the information 

provided by the EPA and for reasons explained above, we believe the label requirements do not 

prevent exposure to migratory birds or may be impractical or not implementable. Rozol use on 

BTPDs is expected to result in take of migratory birds, including federally listed species such as 

the northern aplomado falcon. 

As noted earlier, Rozol use on BTPDs was determined to have killed a bald eagle in 2006, when 

that species was protected under the ESA, which prohibits unauthorized taking of federally listed 

endangered or threatened species. In accordance with the bald eagle post-delisting monitoring 

plan (FWS 2010b), the bald eagle monitoring team continues to track new and potentially 

significant sources of bald eagle mortality. Since Rozol was authorized for BTPD control in 

2006, there have been two bald eagle deaths attributed to chlorophacinone poisoning in 

Nebraska. We consider Rozol use on BTPDs as a new and potentially significant source of 

mortality to bald eagles from secondary poisoning that can occur when a bald eagle eats dead or 

dying prairie dogs that have been poisoned with Rozol. 

F. SUMMARY OF ROZOL EXPOSURE AND EFFECTS RELEVANT TO ALL LISTED 

SPECIES ADDRESSED IN THIS BIOLOGICAL OPINION 

 Toxic effects from chlorophacinone exposure include fatigue and increased permeability of 

capillaries resulting in systemic internal hemorrhaging prior to death. There is no evidence 

of taste aversion to Rozol; thus, non-target species may continue consumption until they 

receive a lethal dose, or they may suffer from sub-lethal effects. Sub-lethal effects could 

result in death when combined with other stressors (e.g., temperature, predation, trauma, food 

scarcity, migration), or growth and reproductive impairments could be detrimental to species’ 

recovery. 

 Chlorophacinone is most toxic when animals are exposed to multiple doses for multiple days. 

Thus, current required acute standardized toxicity tests for chlorophacinone greatly 

underestimate risk to non-target animals. 

 According to the EPA, mobility from Rozol bait into soil or water is considered a negligible 

exposure pathway to non-target organisms, and that chlorophacinone is expected to remain 

undegraded in bait. Actual consumption of bait and consumption of poisoned animals is the 

primary environmental dissipation pathway for Rozol. We agree with the EPA on those 

points. 
32

 Based on the label application rate, excessive lethal doses per BTPD are likely applied and 

result in increased risk to non-target species. In addition to having excess bait available for 

direct consumption by non-target species, over-application and Rozol’s prolonged toxic 

mode of action may result in a high risk of secondary exposure to non-target species, 

especially those species attracted to poisoned BTPD colonies. A 6-month application season 

for Rozol can result in a long duration and increased opportunity for repeated exposure to 

chlorophacinone and/or diphacinone rodenticides as the species migrates or moves within 

their territory. 

 Despite current label restrictions and requirements, previous studies and observations 

indicate that Rozol is available to non-target species by both primary and secondary exposure 

routes and may even result in tertiary poisoning. A label search protocol that does not 

specify how to conduct carcass searches will likely result in random search methods that are 

far less efficient than standard line-transect search methods. Further, label requirements 

aimed at reducing exposure to non-target species that are based on return site visits for weeks 

after the application to pick up dead and dying prairie dogs and bait may be impractical. 

Burying prairie dogs on the colony may not be effective at preventing exposure to non-target 

species that can dig up carcasses or feed on poisoned prey between carcass searches. 

 RQs derived in the EPA’s BA underestimate non-target species risk to Rozol because they 

are: a) based on study protocols that consider limited (1- to 5-day) exposures in the lab; 

b) do not account for information indicating that raptors may be 20-30 times more sensitive 

than standard avian test species such as quail and ducks; c) do not attempt to quantify known 

sub-lethal effects; and d) do not consider higher concentrations of chlorophacinone in the 

liver, especially for species that may selectively consume internal organs instead of wholebody tissues. 

 Although wildlife mortality incidents are underreported and surveillance efforts are lacking, 

opportunistic recoveries of non-target species exposed to chlorophacinone include: bald 

eagles, hawks, owls, turkeys, meadow lark, pigeons, coyotes, kit foxes, raccoon, badger, 

squirrels, and a bobcat. 

 Opportunistic recoveries have shown that Rozol use on BTPDs has killed non-target species 

protected under the ESA, Migratory Bird Treaty Act, and the Bald and Golden Eagle 

Protection Act. Many of these species (e.g., bald eagles, golden eagles, ferruginous hawks, 

American kestrels, owls) appear to be especially susceptible to Rozol toxicity and are 

expected to continue to die from Rozol exposure given current label use restrictions. 

VI. GENERAL CONSERVATION RECOMMENDATIONS 

Section 7(a)(1) of the ESA directs Federal agencies to utilize their authorities to further the 

purposes of the ESA by carrying out conservation programs for the benefit of endangered and 

threatened species. Conservation recommendations are discretionary agency activities to 

minimize or avoid adverse effects of a proposed action on listed species or critical habitat, to 

help implement recovery plans, or to develop information. Based on the above discussion of 

Rozol’s mode of action, its environmental fate and effects and known exposure routes and risks 

to nontargets animals we believe it is important identify conservation recommendations that 
33

address those concerns. Accordingly, we provide the following conservation recommendations 

for EPA’s consideration that are within your authorities and will further the purposes of the ESA 

and benefit the listed species in this consultation. 

A. If the EPA chooses to continue registration of Rozol and other anticoagulants for use on 

prairie dogs, it should first develop alternative testing protocols to evaluate their toxicity to 

non-target species. The currently required standardized toxicity tests for chlorophacinone 

greatly underestimates risk to non-target species because indandiones are much more lethal 

when multiple doses are consumed over multiple days as opposed to a one-time feeding. We 

recommend future assessments for first generation indandione rodenticides are modified to 

include multiple-day exposures tests that measure individual daily dosage and responses. 

This would complement the current required avian oral test and dietary lethality tests. 

Additionally, protocols should be designed to evaluate sub-lethal effects by including 

observational periods, sensitive blood clotting assays (Rattner et al., 2010b), gross pathology 

and microscopic examination of tissues (histopathology). 

B. If the EPA chooses to continue registration of Rozol or other anticoagulants for use on prairie 

dogs, it should first study how to prevent secondary poisoning of predators and scavengers 

that may feed upon dead and dying prairie dogs. The results of such studies should be used 

to modify the label. 

C. If the EPA chooses to continue registration of Rozol or other anticoagulants for use on prairie 

dogs, it should first study detrimental effects to raptors and other wildlife that consume dead 

and dying prairie dogs. Thus, in addition to the avian reproduction study that the EPA has 

required Liphatech to complete, we recommend that the EPA exercise their authority under 

FIFRA to require additional field assessments that include tracking avian predators and 

scavengers that are expected to be most susceptible (e.g., ferruginous hawks, eagles, canines) 

to Rozol poisoning from applications at prairie dog towns. Such information would benefit 

our evaluation of the endangered northern aplomado falcon, gray wolves, and other predators 

and scavengers if those species were to become federally listed under the ESA. 

D. If the EPA chooses to continue registration of Rozol or other anticoagulants for use on prairie 

dogs, it should not rely on quail and mallards as the test species for development of 

anticoagulant risk assessments. These species do not reflect the risks to raptors which can be 

20 to 30 times more sensitive than these species. Further, raptors are the likely avian species 

that will exposure risk from Rozol applications to BTPDs. We recommend that risk 

assessments for anticoagulants include measures to assess harmful effects to the likely 

affected bird guild. Raptors and scavengers are those likely end-point species, and the Rozol 

risk assessment should reflect that. 

E. If the EPA chooses to continue registration of Rozol or other anticoagulants, the EPA should 

conduct tests to determine the minimum amount of product that should be applied to 

accomplish the intended task. 
34

F. Given our concerns with secondary toxicity, we encourage the EPA and Liphatech, Inc. to 

support Integrated Pest Management (IPM) education and outreach to applicators. An IPM 

approach could prevent unnecessary applications when good alternatives to pesticides exist. 

Guidance on how to perform IPM should be accessible on the EPA’s Bulletins Live! online 

site. 

VII. SPECIES ANALYSES 

A. OVERVIEW 

On September 9, 2011, we agreed with the EPA’s analysis that Rozol use on BTPD towns is 

likely to adversely affect listed species and critical habitats (FWS 2011c). As explained in the 

“Description of the Action” section above, additional coordination during the formal consultation 

process resulted in the EPA’s adoption of conservation measures to avoid or reduce adverse 

effects to some listed species and their critical habitats. However, conservation measures were 

not necessary for all species. Among those species/habitats for which conservation measures 

were not developed, the Service conducted additional review after submitting our September 9, 

2011, letter to the EPA and found that adverse effects are not likely for the American burying 

beetle, black-capped vireo, Canada lynx, Eskimo curlew, golden-cheeked warbler, gulf-coast 

jaguarondi, ocelot, piping plover, and whooping crane (Table 1). This conclusion is generally 

due to lack of overlap in range of the species or critical habitat with the range of the BTPD or 

lack of common use by the species of habitats occupied by the BTPD. For those species, the risk 

of Rozol exposure and effects is considered highly unlikely and therefore adverse effects are not 

expected to occur. 

The adopted conservation measures in the EPA’s December 13, 2011, letter have been agreed to 

by Liphatech, Inc. and will be incorporated into County Bulletins via the EPA’s Bulletins Live!

as part of the Rozol label before October 1, 2012 (EPA 2011c). Those measures are reiterated in 

the “Description of the Action” section above and have removed or reduced the risk of adverse 

impacts to several listed species. The analyses herein for the black-footed ferret, Chiricahua 

leopard frog, grizzly bear, jaguar, (Mexican) gray wolf, Mexican spotted owl, New Mexico 

ridge-nosed rattlesnake, and PMJM are based on these conservation measures. 

We provide more in-depth analysis for the black-footed ferret, gray wolf, and northern aplomado 

falcon because conservation measures were unable to entirely preclude adverse effects to these 

species, although the conservation measures did reduce impacts and, in the case of the 

black-footed ferret, did so significantly. The analyses for black-footed ferret, gray wolf, and 

northern aplomado falcon includes species and habitat information, environmental baseline, 

effects of the action, cumulative effects, conclusions regarding jeopardy or destruction/adverse 

modification, and associated Incidental Take Statements (ITSs) with RPMs and implementing 

terms and conditions. 

Thus, the species/habitats analyzed for this consultation are categorized as falling into one of 

three groups: 1) species for which further review by the Service, after consultation was initiated, 

revealed that adverse effects are not anticipated; 2) species for which the EPA adopted 

conservation measures after initiating formal consultation, removing or reducing the risk of 
35

adverse effects; and 3) species for which adverse effects are anticipated as a result of the 

proposed action, with or without conservation measures. The species and critical habitats that 

fall into each of these categories are listed below (Table 1). 

Table 2. Summary of species determinations and page number for each species’ analysis 

within this BO. 

Species and/or 

Critical Habitat 

Species for which No 

Adverse Effects are 

anticipated, without 

Conservation 

Measures 

Species for which 

Conservation 

Measures Preclude 

Adverse Effects 

Species for which 

Adverse Effects are 

anticipated, with or 

without Conservation 

Measures 

American Burying 

Beetle (Nicrophorus 

americanus) 

■

Black-capped Vireo 

(Vireo atricapilla) ■

Black-footed Ferret 

(Mustela nigripes) ■

Canada Lynx (Lynx 

Canadensis) ■ 

Chiricahua Leopard 

Frog (Lithobates 

[Rana] chiricahuensis) 

■

Eskimo Curlew 

(Numenius borealis) ■ 

Golden-cheeked 

Warbler (Dendroica 

chrysoparia) 

■

Gray Wolf (Canis 

lupus) ■

Grizzly Bear (Ursus 

arctos horribilis) ■

Gulf Coast Jaguarundi 

(Herpailurus (=Felis) 

yagouaroundi 

cacomitli) 

■ 

Jaguar (Panthera onca) ■

Mexican Spotted Owl 

(Strix occidentalis 

lucida) 

■

New Mexico Ridgenosed Rattlensake 

(Crotalus willardi 

obscurus) 

■
36

Species and/or 

Critical Habitat 

Species for which No 

Adverse Effects are 

anticipated, without 

Conservation 

Measures 

Species for which 

Conservation 

Measures Preclude 

Adverse Effects 

Species for which 

Adverse Effects are 

anticipated, with or 

without Conservation 

Measures 

Northern Aplomado 

Falcon (Falco 

femoralis 

septentrionalis) 

 ■

Ocelot (Lepardus 

pardalis) ■

Piping Plover 

(Charadrius melodus) ■ 

PMJM (Zapus 

hudsonius preblei) ■

Whooping Crane (Grus 

americana) ■ 

The details regarding the anticipated effects of the proposed action on each of the species in this 

consultation are provided in the analyses below. 

B. SPECIES FOR WHICH NO ADVERSE EFFECTS ARE ANTICIPATED WITHOUT 

CONSERVATION MEASURES

Conservation measures were not developed for all species in this consultation. We have 

determined that, upon additional biological review, adverse effects as a result of Rozol use on 

BTPDs are not anticipated for nine species that did not have associated conservation measure(s). 

They are: 1) American burying beetle, 2) black-capped vireo, 3) Canada lynx, 4) Eskimo 

curlew, 5) golden-cheeked warbler, 6) Gulf Coast jaguarundi, 7) ocelot, 8) piping plover, and 9) 

whooping crane. 

a. AMERICAN BURYING BEETLE

The EPA concludes in their BA that the use of chlorophacinone to control BTPDs is likely to 

adversely affect the American burying beetle based on direct reproductive effects. 

The reproductive effects are due to lower carcass size in chlorophacinone treated 

carcasses and effects to larvae. An acute toxicity test for the earthworm (MRID 

47383002) and an open literature study (Fisher et al. 2007) indicate that there is 

no risk to invertebrates at exposure levels relevant to this use. Furthermore, the 

second phase of the burying beetle study (MRID 47383001) that showed 

reproductive effects to burying beetles based on lower carcass weights showed 

that there were no direct acute effects to adult burying beetles fed 

chlorophacinone treated ground beef. In fact, those exposed to the 

chlorophacinone faired better than the control group. 
37

Chlorophacinone use is expected to affect reproduction of the American burying 

beetle through effects to emerged beetles. Number of emerged beetles is negatively 

affected by use of chlorophacinone poisoned carcasses in burying beetles (MRID 

47383001). This type of effect is considered to be a direct effect. 

The portion of the action area of concern for the American burying beetle for this consultation 

includes Nebraska and South Dakota where the range of this species overlaps the use of Rozol as 

BTPD bait. The current range known from South Dakota includes portions of Bennett, Gregory, 

Tripp, and Todd Counties. However, a comprehensive status survey has never been completed 

in South Dakota, so American burying beetles may occur in other counties with suitable habitat. 

In Nebraska, two disjunct populations of American burying beetles occur over much of the State. 

Habitats between the two populations are dissimilar with the northern Nebraska/South Dakota 

population occurring in the Sandhills, while the southwest Nebraska population occurs in the 

Loess Hills. These two populations alone contain as much as half of the known Midwest 

American burying beetle population and are a strong-hold for this species. The other Midwest 

populations (Arkansas, Kansas, Missouri, and Oklahoma) are outside of the BTPD range. 

The American burying beetle is an annual species, active in the summer months, inactive during 

the winter months, nocturnal, and typically only reproduce once in their lifetime. They bury 

themselves in the soil for the duration of the winter. The young of the year overwinter as adults 

and comprise the breeding population the following summer (Raithel 1991). Both adults and 

larvae are dependent on carrion for food and reproduction. Reproductive activity commences in 

late May and is completed in mid-August in Nebraska and South Dakota. Per the Rozol label, 

chlorophacinone used on BTPD colonies is limited to October 1 through March 15. Therefore, it 

should not affect the American burying beetle as the species will be underground and inactive 

during the use window for Rozol. 

In summary, we do not anticipate adverse effects to the American burying beetle from the use of 

chlorophacinone to control BTPDs. This conclusion is based primarily on the fact that American 

burying beetles are not active during the period in which the label allows the use of 

chlorophacinone. In addition, prairie dog carrion is not a preferred food source of American 

burying beetles. No critical habitat for the American burying beetle has been designated; 

therefore, none will be affected. 

 

b. BLACK-CAPPED VIREO 

The black-capped vireo is a small (12 centimeters (cm) or 4.5 inches (in.)) insect-eating songbird 

that was once common as far north as Kansas but is now limited largely to western and central 

Texas, north-central Mexico, and the Wichita Mountains of Oklahoma (Gryzbowski 1995). 

Black-capped vireos were federally listed as endangered in 1987. Black-capped vireos arrive in 

Texas from late March to mid-April (late April in dry years). They arrive in Oklahoma from 

mid-April to early May (mid-May in dry years). The black-capped vireo usually migrates 

southward from Oklahoma by late August-September and from Texas by mid-September (FWS 

1991) to winter in Mexico. The black-capped vireo occurs in mixed deciduous/evergreen 

shrubland. Black-capped vireos require broadleaf shrub vegetation in the form of low deciduous 

cover (e.g., juniper and oak sp.) which is a key element in their habitat. Nests are preferentially 
38

located in dense deciduous vegetation. Nests are placed in the fork of a variety of deciduous 

species with blackjack oak being preferred in Oklahoma and shin oak, Texas oak, and sumac 

commonly used in Texas (FWS 1991). 

 

Black-capped vireos are insectivores during the breeding season, gleaning insects off the foliage 

of oaks and other deciduous trees (Graber 1961, Grzybowski 1995). The common prey items 

found in stomach contents include spiders and insects of the orders Lepidoptera (butterflies and 

moths), Coleoptera (beetles), and Hemiptera with suborder Homoptera (cicadas, aphids, 

planthoppers, leafhoppers, shield bugs, and others) (Graber 1961). During winter, black-capped 

vireos switch to an omnivorous diet, and nearly 50 percent of stomach contents sampled from 

western Mexico included seeds (Graber 1961). 

To determine the risk that Rozol may pose to black-capped vireos, we conducted a thorough 

review of their life history to determine to what extent the range, habitat preferences, and diet of 

this species overlaps with areas where BTPD colonies occur and the likelihood that black-capped 

vireos would come into direct or indirect exposure with Rozol bait or dead/dying (poisoned) 

prairie dogs, resulting in adverse effects. Label restrictions that were designed to limit impacts 

to non-target species were also considered, but some were not heavily weighted due to factors 

previously discussed. 

A habitat separation exists between the black-capped vireos and BTPDs. Black-capped vireos 

are a lowland dependent species, preferring mixed evergreen/deciduous shrubland. The BTPDs 

are native to short-grass prairie habitats typical of the southernmost regions of the Great Plains 

that extend into north Texas. The BTPDs tend to avoid areas of heavy brush and tall grass due to 

the reduced visibility that these habitats impose. Therefore, habitats used by black-capped vireos 

do not overlap with the open prairie habitat required by BTPDs. 

While black-capped vireos become omnivorous during winter by adding seeds in their diet, they 

are otherwise exclusively insectivorous. Black-capped vireos do not prey on rodents or small 

mammals such as BTPDs, so risk of Rozol poisoning directly from diet is reduced. The risk 

posed to black-capped vireos from secondary poisoning through consumption of insects 

containing residues of Rozol (i.e., consumption of insects that have come into contact with Rozol 

grain bait or poisoned BTPDs) is possible but highly unlikely when all factors herein are 

considered.

The timing of the black-capped vireos’ migration and arrival at the nesting grounds is also a 

factor. The Rozol label restricts applications to the period between October 1 and March 15 

which somewhat limits potential exposures to non-target wildlife. Black-capped vireos leave 

Texas to migrate south for the winter by mid-September, returning in late March the following 

year, and would therefore be wintering in western Mexico during the majority of the October 1 

to March 15 timeframe when Rozol applications are allowed. 

Although the range for the black-capped vireo historically was larger than today, current overlap 

of the range of the black-capped vireo with BTPDs is geographically limited. Likewise, BTPDs 

historically occurred over most of the western half of Texas but have been extirpated from 

portions of their former range (Davis and Schmidly 1994). The range for the black-capped vireo 

today only marginally overlaps with the range for BTPDs, and different habitat requirements 

preclude the co-existence of these two species in the same location. 
39

We conclude that adverse effects to black-capped vireos from the proposed action are unlikely 

due to: 1) limited geographic overlap between the current ranges of the black-capped vireo and 

BTPD; 2) black-capped vireos migrate to Mexico during the time frame in which Rozol 

application would be permitted; and 3) in the highly unlikely event that black-capped vireos used 

habitat where Rozol was applied, their dietary requirements would minimize the probability of 

primary or secondary exposure. No critical habitat for the black-capped vireo has been 

designated; therefore none will be affected. 

c. CANADA LYNX 

The BA describes that direct effects to Canada lynx are expected to occur based on the potential 

for them to consume prey items that have consumed the chlorophacinone bait. It further 

describes that growth and reproductive effects cannot be precluded due to the absence of chronic 

data; however, growth and reproductive effects are not expected because mortality typically 

occurs as a result of acute exposure. The BA also stated that the range of Canada lynx overlaps 

with BTPD habitat. Therefore, it was determined in the BA that the use of chlorophacinone to 

control BTPDs is likely to adversely affect Canada lynx. 

Within the action area, Canada lynx may occur in Montana, Wyoming, and Colorado. Upon 

further analysis, we have determined that the range of Canada lynx has minimal overlap with 

BTPD habitat. No overlap of Canada lynx habitat with known BTPD colonies occurs in 

Montana, and no overlap of Canada lynx habitat with known BTPD colonies or potential range 

occurs in Wyoming. A very minimal amount of overlap of Canada lynx habitat with the BTPD’s 

overall range in Colorado occurs; however, no overlap with mapped BTPD colonies occurs in 

Colorado. 

Canada lynx are dependent on presence of snowshoe hares and the hare’s preferred habitat 

conditions which include dense understories of young trees, shrubs or overhanging boughs that 

protrude above the snow and mature multistoried stands with conifer boughs touching the snow 

surface. Snowshoe hares are not found in BTPD habitat. Canada lynx have been observed (via 

snow tracking) to avoid open habitats (i.e., prairie dog towns) (Koehler 1990, Staples 1995) 

during daily movements within the home range. Canada Lynx prefer to move through 

continuous forest using the highest terrain available such as ridges and saddles (Koehler 1990, 

Staples 1995). While some Canada lynx may move through open habitats at times during 

transient or dispersal movements, the likelihood of a Canada lynx moving through a BTPD 

colony is small, and the likelihood that they would move through a black tailed prairie dog 

colony that is also being treated with Rozol is so unlikely that it is discountable. Therefore, we 

do not anticipate adverse effects to Canada lynx from the use of Rozol to treat BTPD colonies. 

The BA indicates that adverse effects to Canada lynx critical habitat are expected to occur 

because critical habitat overlaps with the use area or action area (BTPD habitat). Critical habitat 

for Canada lynx is not designated in Colorado, and critical habitat in Wyoming and Montana 

does not overlap with BTPD known occurrences and potential range. Therefore, we conclude 

that the use of Rozol in BTPD colonies would not adversely affect designated critical habitat for 

Canada lynx. 
40

d. ESKIMO CURLEW 

The EPA determined that the use of Rozol to control BTPDs is likely to adversely affect the 

Eskimo curlew. This determination was based on likely exposure to Rozol as indicated by the 

overlapping ranges for the two species and expected direct and indirect effects to the Eskimo 

curlew associated with exposure. The EPA concluded in the BA that direct effects to Eskimo 

curlew could occur due to potential for this species to consume terrestrial invertebrate prey items 

that have consumed Rozol. Additionally, impacts to terrestrial invertebrates from Rozol 

exposure were expected to indirectly affect Eskimo curlews by depleting their prey base. The 

EPA also concluded that potential Rozol exposure to Eskimo curlews would be limited to the 

spring migration and reproductive effects could not be precluded based on an absence of chronic 

exposure and effects data for any species. 

 

The Eskimo curlew was identified as being threatened by extinction under the Endangered 

Species Preservation Act of 1966 (FWS 1967) and, after the ESA was enacted in 1970, was 

listed as endangered (FWS 1970). The species once numbered in the hundreds of thousands, but 

declined rapidly in the 1870s to 1890s and is now most likely extinct. No nests have been 

located in 140 years, and the last specimen was obtained in the 1960s (Environment Canada 

2007). Environment Canada and the Service have both concluded that recovery of the Eskimo 

Curlew is currently not considered feasible as there is very little information on locations of 

habitat necessary for survival or recovery and there are very few, if any, individuals left in 

existence (Environment Canada 2007, FWS 2011e). 

Recent quantitative methods used to evaluate the probability of the Eskimo curlew’s existence 

have estimated extinction dates of 1967 and 1965, respectively, with the upper bounds of 

95 percent confidence intervals in 1977 and 1970 (Elphick et al. 2010, FWS 2011e). These 

estimates are based on the last uncontroversial record of observance, a specimen that was shot in 

Barbados in 1963 (FWS 2011e). From 1963 to the spring of 2009, 39 potential sightings have 

occurred in 22 different years (Committee on the Status of Endangered Wildlife in Canada 

2009); however, the reliability of these sightings is variable, and none have been confirmed by 

physical evidence (FWS 2011e). If controversial records of observance are included, then the 

analysis estimates an extinction date of 2008 with the upper bound of 95 percent confidence 

interval reaching 2013 (FWS 2011e). 

Eskimo curlews were not well studied before their decline; thus, their association with prairie 

dog towns is largely unknown. The related long-billed curlew (Numenius americanus) is 

associated with BTPD colonies in western South Dakota, but that species also uses short- and 

mixed-grass prairies absent of prairie dogs (Sharps and Uresk 1990). In Kansas, where the last 

Eskimo curlew sighting was in 1902, habitat preference purportedly included prairie dog towns 

where they fed on invertebrates (Kansas Department of Wildlife and Parks 2000). Although 

there is some indication that prairie dog towns may provide foraging habitat for Eskimo curlews, 

more relevant habitat factors that have likely contributed to their decline include the wide-scale 

conversion of grassland to agriculture, fire suppression, and the extinction of the Rocky 

Mountain grasshopper (Melanoplus spretus) as an important food source (FWS 2011e). 
41

In conclusion, Eskimo curlews are likely already extinct or at best extremely rare; thus, direct 

and indirect effects from Rozol exposure are so highly unlikely to occur as to be considered 

discountable. Therefore, the Service does not anticipate adverse effects to Eskimo curlew from 

use of Rozol on BTPDs. No critical habitat for the Eskimo curlew has been designated; 

therefore none will be affected. 

e. GOLDEN-CHEEKED WARBLER 

The golden-cheeked warbler is the only breeding bird endemic to the State of Texas. The 

golden-cheeked warbler is a small (12 cm or 4.5 in.) migratory songbird whose nesting range is 

currently confined to habitat in 33 counties in central Texas. Golden-cheeked warblers were 

federally listed as endangered in 1990. The birds are dependent on Ashe juniper (blueberry 

juniper or cedar) for fine bark strips used in nest construction. Although nests may be placed in 

various species of trees, such as Ashe juniper, Texas oak, live oak, and cedar elm, all nests 

contain strips of Ashe juniper bark woven together with spider webs. Golden-cheeked warblers 

feed almost entirely on caterpillars, spiders, beetles, and other insects found in foliage. The 

species winters in southern Mexico and Central America. In the period from July to August, 

golden-cheeked warblers migrate southward from Texas through the pine-oak woodlands of 

eastern Mexico and begin returning to Texas in late February. The earliest arrival date on the 

breeding grounds in Texas is March 2; however, most arrive mid-March (Pulich 1976). 

 

The EPA determined that the golden-cheeked warbler may be adversely affected by Rozol use 

because the species’ range overlaps with that of the BTPD, and they assumed that 

golden-cheeked warblers could ingest toxic levels of Rozol via consumption of invertebrates 

exposed to chlorophacinone. For our assessment of the risk that Rozol may pose to 

golden-cheeked warblers, we reviewed their life history to determine to what extent the range, 

habitat preferences, and diet of this species overlaps with areas where BTPD colonies occur and 

the likelihood that golden-cheeked warblers would come into direct or indirect exposure with 

Rozol bait or poisoned prairie dogs that could result in adverse effects. Label restrictions that 

were designed to limit impacts to non-target species were also considered, but some 

requirements were not heavily weighted due to limitations with the label restrictions previously 

discussed. 

Golden-cheeked warblers use juniper and oak dominated woodlands and prefer canyon or hill 

country. The BTPDs in Texas are native to short-grass prairie habitats typical of the 

southernmost regions of the Great Plains that extend into north Texas and tend to avoid areas of 

heavy brush and tall grass due to the reduced visibility that these habitats impose. Therefore, 

habitats used by golden-cheeked warblers do not overlap with the open prairie habitat used by 

BTPDs. 

 

Golden-cheeked warblers are exclusively insectivorous. Golden-cheeked warblers do not prey 

on rodents or small mammals such as BTPDs, so risk of Rozol poisoning directly from diet is not 

expected. The risk posed to golden-cheeked warblers from secondary poisoning through 

consumption of insects containing residues of Rozol (i.e., consumption of insects that have come 

into contact with Rozol grain bait or poisoned BTPDs) is possible but considered unlikely when 

life histories of both species are considered.
42

The warbler’s migration timing is a factor to consider. The Rozol label restricts applications to 

the period between October 1 and March 15 which somewhat limits potential exposures to 

non-target wildlife. Golden-cheeked warblers leave Texas in August, returning in late February 

the following year and, therefore, would be wintering in Mexico and Central America during the 

majority of the October 1 to March 15 timeframe when Rozol applications are allowed. 

Although the range for the golden-cheeked warbler was historically larger than today, its current 

overlap with BTPDs is limited geographically. Historically, BTPDs occurred over most of the 

western half of Texas, but they have been extirpated from portions of their former range (Natural 

Science Research Laboratory 2012). Although the range for the golden-cheeked warbler 

marginally overlaps with the range for BTPDs, different habitat requirements preclude the 

co-existence of this avian species with the BTPD. 

We conclude that adverse effects to golden cheeked warblers from the proposed action are 

unlikely due to: 1) limited geographic overlap between the current ranges of the golden-cheeked 

warbler and BTPD; 2) in the highly unlikely event that golden-cheeked warblers would use 

habitat where Rozol was applied, their dietary requirements would minimize the probability of 

primary or secondary exposure; and 3) golden-cheeked warblers winter in Mexico during the 

time frame in which Rozol application would be permitted. No critical habitat for the 

golden-cheeked warbler has been designated; therefore none will be affected. 

f. GULF COAST JAGUARUNDI 

The EPA determined that the use of Rozol is likely to adversely affect the Gulf Coast jaguarundi 

based on potential direct effects from prey that may consume chlorophacinone bait, including 

BTPDs and non-target animals. However, the BA indicated that there would be no indirect 

effects from prey-base loss expected because this species’ habitat is distinct from BTPD habitat. 

No map was provided in the BA where the Gulf Coast jaguarundi overlaps with the BTPD, but 

the Service agrees with the EPA that there is no overlap in range between the two species. 

The Gulf Coast jaguarundi is reported from Mexico, southern Arizona, and southern Texas. It is 

not found within the BTPD range. As such, any effects from the action to the Gulf Coast 

jaguarundi are considered to be highly unlikely to occur. Therefore, the Service does not 

anticipate adverse effects to the Gulf Coast jaguarundi from use of Rozol on BTPDs. No critical 

habitat for the Gulf Coast jaguarondi has been designated; therefore none will be affected. 

g. OCELOT 

The EPA determined that the ocelot may be adversely affected by Rozol use based on potential 

direct effects from prey that may consume chlorophacinone bait, including BTPDs and 

non-target animals. However, the BA indicated that there would be no indirect effects from 

prey-base loss expected because this species’ habitat is distinct from the BTPD habitat. 

The ocelot is found in Mexico, southern Arizona, and southern Texas. There is no overlap 

between the BTPD and the ocelot; therefore, we conclude that the proposed action is not likely to 

adversely affect the ocelot. No critical habitat for the ocelot has been designated; therefore none 

will be affected. 
43

h. PIPING PLOVER 

The action area encompasses the entire United States breeding range of the Northern Great 

Plains population of the piping plover. Piping plovers have nested near prairie dog towns (within 

0.10 mile) (USCOE 2011, Kempema et al. 2009, Montana Natural Heritage Program 2011). 

However, our analysis suggests that there is little, if any, overlap between prairie dog towns and 

piping plover critical habitat or known nesting areas. Additionally, piping plovers’ predilection 

to nest and forage in sandy or gravelly areas near water with little vegetation make it unlikely 

that they would extensively use prairie dog towns. In areas where prairie dog towns are in close 

proximity to nesting habitat, it is possible that piping plovers could ingest invertebrates that had 

fed on Rozol or that dying prairie dogs may expire along the shoreline, exposing piping plovers 

to Rozol through maggots. However, because piping plovers are not expected to forage in the 

prairie dog towns directly and the Rozol use season ends before piping plovers are likely to 

encounter prairie dog colonies (see below), the risk of exposure to piping plovers is unlikely. 

Piping plover critical habitat has been designated along Lake Oahe in South Dakota. The 

primary constituent elements on reservoirs are defined as “sparsely vegetated shoreline beaches; 

peninsulas; islands composed of sand, gravel, or shale; and their interface with the water bodies” 

(FWS 2002a). Piping plover breeding habitat is by nature ephemeral and cyclical with 

unvegetated habitat emerging following wet periods, only to become vegetated over time and 

unsuitable until the next flood inundates the habitat again, clearing it of vegetation. Since prairie 

dogs use vegetated areas which are not suitable for piping plovers even after the prairie dogs 

have clipped the grasses in the area, prairie dog towns would not have the primary constituent 

element of “sparsely vegetated shoreline beaches.” Therefore, since Rozol application would 

occur only in prairie dog towns which do not have the primary constituent elements that define 

piping plover critical habitat, we do not anticipate impacts. 

The Rozol label allows treatment only between October 1 and March 15 of the following year. 

During this time period, piping plovers would be on the wintering grounds which do not overlap 

with the BTPD range. Contaminated prairie dog carcasses have been documented on the surface 

up to 29 days post treatment, so some piping plovers arriving on the breeding grounds in April 

and May could overlap temporally when contaminated carcasses are available. There is some 

potential for disturbance by applicators collecting carcasses in April when piping plovers have 

started to arrive, but this disturbance is expected to be minimal since the activity will be 

concentrated in the prairie dog towns, which piping plovers do not use for nesting. 

A number of documented prairie dog towns occur near the designated critical habitat along the 

Missouri River and reservoir system in North Dakota and South Dakota. However, no piping 

plover nests have been documented to occur within the prairie dog towns (USCOE 2011), nor 

have piping plovers been observed to forage within prairie dog towns (Someson 2012, personal 

communication). Piping plovers have not been documented to eat grains, so they would be 

unlikely to feed directly on Rozol. Secondary poisoning is a potential risk if piping plovers were 

to prey on maggots or other insects that had fed on the bait directly or on contaminated prairie 

dogs. In the Great Lakes, maggots were postulated to be the source of Type E botulism that 

infected and killed some piping plovers (FWS 2009e). In the two reported cases where piping 

plovers have been observed foraging on carcasses, the carcasses have been along the shoreline; 
44

plovers were not documented to leave their traditional foraging areas to forage on carcasses 

(Keane 2002, FWS 2009e). We do not anticipate Rozol use along the Missouri River shoreline, 

so exposure of piping plovers to contaminated maggots is not expected. 

Piping plovers have been documented to nest up to one-half mile from the water along the 

reservoirs (Pavelka 2008, personal communication), but this was in low water years and the nests 

were below the elevation at which the reservoirs are considered full in a normal year. Most nests 

are initiated relatively close to the water (Anteau et al. 2011). The average number of piping 

plovers nesting on the Missouri River reservoirs annually from 1994-2010 has been 496 

(USCOE 2011), but only a very small subset (less than a few dozen) of these were near prairie 

dog towns and none were in prairie dog towns. 

The risk of secondary poisoning is unlikely due to the chain of events that would have to occur 

for piping plovers to be exposed. Since piping plovers do not eat grain or carcasses directly, 

poisoning would have to occur via a secondary route. For terrestrial insects to be available for 

piping plover forage, contaminated insects would have to leave the prairie dog town and move to 

unvegetated habitat (most likely along the water’s edge) where piping plovers do most of their 

foraging, and be ingested by piping plovers. It is unlikely that piping plovers would be exposed 

to sufficient Rozol concentrations in this manner. 

In summary, impacts to piping plovers are not anticipated because: 

 The Rozol label only allows application to occur between October 1 and March 15 of the 

following year, when piping plovers are absent from the breeding grounds. 

 The potential Rozol exposure routes are circuitous with both possible transmissions being via 

insects; neither of which is expected to occur. 

o Route 1 – the invertebrates have eaten the bait directly and then move to piping plover 

foraging areas. While this route is possible, the time lag between the last application of 

Rozol and the arrival of piping plovers reduces the likelihood of impact. Further, prairie 

dog colonies are generally well removed from piping plover nesting areas, and 

contaminated invertebrates would have to move from the prairie dog town to piping 

plover habitat to be exposed to ingestion by piping plovers. 

o Route 2 - the invertebrates (most likely maggots) may become contaminated through 

feeding on a contaminated carcass. This route would require a contaminated carcass 

from a Rozol application (that had occurred weeks to months earlier) to be located in 

piping plover foraging habitat on the shoreline, which would be out of the prairie dog 

town, and remain in place long enough to become infested with maggots. The maggots 

would have to be carrying a high enough concentration of Rozol to affect piping plovers 

and/or the piping plovers would have to consume them in sufficient quantity to be 

impacted. 

 Most of the activity associated with poisoning would occur outside of piping plover use 

areas, so disturbance associated with poisoning activities is unlikely. 
45

 By definition, prairie dog habitat does not have the primary constituent elements that define 

piping plover critical habitat. Thus, we do not anticipate that Rozol application would 

adversely affect designated critical habitat. 

Based on the above information, the Service concludes that adverse effects to piping plovers 

from the use of Rozol to poison BTPDs are not likely, and the action is not likely to adversely 

affect designated critical habitat. 

i. WHOOPING CRANE 

In the BA, the EPA concludes that the use of Rozol to control the BTPD is likely to adversely 

affect the whooping crane for the following reasons: 

Direct effects to the whooping crane are expected to occur based on the potential 

for this species to consume the chlorophacinone bait (RQ of 0.89 which exceeds 

the LOC of 0.1) or other prey items that may have consumed the chlorophacinone 

bait (RQ of 0.104 for exposure to non-target animals which exceeds the LOC of 

0.1). Growth and reproductive effects cannot be precluded due to the absence of 

chronic data. 

Indirect effects from the loss of the prey base are expected because effects to 

individuals within populations have been demonstrated in mammals, birds, and 

terrestrial invertebrates. No indirect effects from habitat loss are expected 

because this species does not use BTPD burrows. 

Habitat modification for the whooping crane is expected because the critical 

habitat for the whooping crane overlaps with the use area (BTPD habitat). 

The BA map indicates some overlap between the whooping crane and BTPD in Montana, North 

Dakota, South Dakota, Wyoming, Colorado, Nebraska, Kansas, and Oklahoma. The map does 

not depict any counties in Texas; the Service has sent a map of Texas counties to the EPA 

indicating potential whooping crane presence. 

Three populations of whooping cranes exist in the wild: 1) the Aransas Wood Buffalo 

Population, 2) the Florida Population, and 3) the Eastern Migratory Population. The Aransas 

Wood Buffalo Population nests in the Wood Buffalo National Park in the Northwest Territories 

of Canada and in Alberta, Canada. This population migrates through eastern Montana, North 

Dakota, South Dakota, Nebraska, Kansas, Oklahoma, and Texas between breeding grounds in 

Canada and wintering grounds of Aransas National Wildlife Refuge on the Gulf Coast of Texas. 

This migration route overlaps with the range of BTPDs. The Florida Population is 

non-migratory and is located on the Kissimmee Prairie, south of Orlando in Osceola and Polk 

counties and does not overlap with the range of BTPDs. The Eastern Migratory Population was 

reintroduced to the Necedah National Wildlife Refuge in Wisconsin with captive birds trained to 

migrate to Chassahowitzka National Wildlife Refuge on the Gulf Coast of Florida and does not 

overlap with the range of BTPDs. The Aransas Wood Buffalo Population is the only 

self-sustaining wild population. The Florida Population and Eastern Migratory Population are 

introduced and are designated nonessential experimental by the Service. 
46

As noted in the BA, the whooping crane is a territorial nester and returns to the same area each 

year. Whooping cranes summer in marshes and prairie potholes and winter in coastal marshes 

and prairies. Eggs are laid from April to mid-May. Incubation lasts for a month. At Wood 

Buffalo National Park, whooping cranes migrate southward in the fall from mid-September to 

mid-November to winter at the Aransas National Wildlife Refuge. However, those dates may 

vary. Ten Aransas Wood Buffalo Population whooping cranes were fitted with Global 

Positioning System (GPS) platform transmitters and were tracked by the Service and The Crane 

Trust as they migrated from Wood Buffalo National Park to Aransas National Wildlife Refuge. 

In 2010, whooping cranes left Wood Buffalo National Park as early as August 20 and continued 

until October 31. They arrived at Aransas National Wildlife Refuge between October 28 and 

November 26. Whooping cranes spent most of their time in Saskatchewan followed by North 

Dakota, South Dakota, Nebraska, Kansas, Oklahoma, and Texas. The whooping cranes made 

stopovers on 39 private properties and 15 public land sites and varied between rivers (including 

reservoirs on the Missouri River), lakes, wetlands, and uplands. Upland roost sites consisted of 

corn fields, fields planted in winter wheat, and a harvested rice field. In spring, the migration 

begins between March 25 and April 15, and some may not leave Aransas National Wildlife 

Refuge until May. 

Diet during the summer consists of larval and nymphal insects, frogs, rodents, berries, small 

birds, and minnows. On the wintering grounds at Aransas National Wildlife Refuge, whooping 

cranes feed primarily on blue crabs, razor clams, and wolfberries. During migration, they forage 

on agricultural waste grains like barley, wheat, and corn, along with frogs, fish, insects, tubers, 

and crayfish. 

Whooping cranes are likely to be migrating between October 1 and December 1 from Wood 

Buffalo National Park to Aransas National Wildlife Refuge which is the first half of the Rozol 

application season. During their spring migration from Aransas National Wildlife Refuge to 

Wood Buffalo National Park in late March, it is possible that Rozol will have been applied to 

areas within days prior to their departure and contaminated prairie dog carcasses have been 

documented on the surface up to 29 days post-treatment. While whooping cranes are not known 

to use BTPD colonies during their migration between wintering and breeding areas, it is possible 

to foresee some possible Rozol exposure routes since whooping cranes are known to eat 

agricultural grains, frogs, fish, insects, tubers, rodents, and crayfish during their migration. 

Further, since Rozol is grain-based, it could be consumed in amounts that would exceed the RQ 

for consumption of 0.89 for endangered species. According to the EPA, the whooping cranes 

would have to eat 23 poisoned mice or more than 1 poisoned BTPD every day for 5 days to 

reach the LOC. The BA also states that it may be possible for the whooping cranes to consume 

that many mice in a day but unlikely that it would eat more than one BTPD every day. 

Although whooping cranes use a wide range of environments, they primarily depend on highly 

productive wetlands, marshes, mudflats, wet prairies, rivers, streams, and crop fields for 

migratory stopover habitat. They feed primarily in a variety of croplands and roost in marshy 

wetlands or riverine habitats. Heavily vegetated wetlands are not generally used. During 

migration, whooping cranes are often recorded in riverine habitats such as in the Platte River, 

North and Middle Loup Rivers, and Niobrara River in Nebraska; the Missouri River in North 

Dakota and South Dakota; and the Red River in Texas. They roost on submerged sandbars in 

wide, unobstructed channels that are isolated from human disturbance. 
47

The BTPDs establish colonies near intermittent streams, water impoundments, homestead sites 

and windmills. However, BTPD colonies are typically in upland locations where the Service has 

not documented extensive whooping crane use. The greatly reduced vegetative cover in the 

vicinity of prairie dog colonies may further detract from the possibility of whooping cranes 

foraging in those areas. Service knowledge of whooping cranes does not suggest that, while 

foraging, they would venture into prairie dog burrows where Rozol-treated bait is placed. Where 

both whooping cranes and the BTPD occur, habitat isolation between the whooping cranes and 

BTPD reduces the chance that the whooping cranes would encounter treated grain. 

However, the Service is currently monitoring whooping cranes within the migratory corridor 

with the use of telemetry data from the current whooping crane tracking study. A relatively 

small number of whooping cranes are marked with transmitters, but this study may inform 

whether whooping cranes occur in or near prairie dog colonies. We anticipate that a diagnostic 

necropsy of any dead whooping cranes will occur and should detect chlorophacinone if that is a 

factor in their death. If the tracking study or necropsies reveal significant new information or 

indicate adverse effects are occurring to whooping cranes, we will request that the EPA reinitiate 

consultation (as per the new information clause in the Reinitiation Notice at the end of the BO). 

In summary: a) whooping cranes have not been documented to forage or roost in BTPD 

colonies, b) the occurrence of the species in the proximity of BTPD colonies is not likely to be 

frequent, c) during migration, whooping cranes are not expected to venture into BTPD colonies, 

creating a degree of habitat isolation between the two species, and d) mechanisms are in place to 

further assess whether whooping cranes use BTPD colonies. 

There is some potential for whooping crane disturbance by applicators collecting carcasses, but 

this disturbance is expected to be minimal since the activity will be concentrated in the prairie 

dog towns which whooping cranes are not known to use. The Service is also unaware of any 

incidents involving Rozol and whooping cranes despite Rozol’s ongoing use as a BTPD 

rodenticide in the migratory corridor since the early 1990s (Lee et al. 2005). 

Whooping crane critical habitat occurs in five sites in four States. They are: 

 Cheyenne Bottoms State Waterfowl Management Area and Quivira National Wildlife Refuge 

in Kansas; 

 The Platte River between Lexington and Denman, Nebraska; 

 Salt Plains National Wildlife Refuge in Oklahoma; and 

 Aransas National Wildlife Refuge and vicinity in Texas. 

Each of the five factors normally associated with critical elements pertain to the whooping crane 

(i.e., space for individual and population growth and for normal behavior; food, water, air, light, 

minerals, or other nutritional or physiological requirements; cover or shelter; sites for breeding, 

reproduction, or rearing of offspring; and generally, habitats that are protected from disturbances 

or are representative of the geographical distribution of the listed species). 

With exception of the Platte River in Nebraska, all designated critical habitats are Service 

National Wildlife Refuges or WaterfowlManagement Areas that are unlikely to have Rozol use 

on their properties; doing so would result in a future Section 7 consultation. The BTPD colonies 
48

are not known to occur in the designated critical habitat areas. Burrows are not specified critical 

elements of whooping crane critical habitat. The EPA’s conceptual impact model on page 60 of 

the BA lists “altered plant community composition” as a second indirect effect on habitat 

resulting from BTPD control. Reduction or eradication of BTPD colonies could lead to 

increases in vegetation height and density at sites treated with Rozol. However, some thicker 

vegetation is unlikely to cause adverse effects to the critical habitat for species because there are 

minimal BTPD colonies in whooping crane designated critical habitat. 

 

We conclude that adverse effects to the whooping crane from the proposed action are unlikely. 

Additionally, we believe that adverse effects to whooping crane critical habitat are unlikely. 

C. SPECIES FOR WHICH CONSERVATION MEASURES PRECLUDE ADVERSE 

EFFECTS 

The following species analyses are based on the EPA’s adoption of conservation measures that 

are anticipated to result in the avoidance of adverse effects to federally listed species/critical 

habitats, primarily by identifying areas where the product is prohibited and/or applying timing 

restrictions for the application of Rozol. As a result of the conservation measures incorporated 

into the proposed action by the EPA and the applicant, we conclude that adverse effects are not 

likely for: 1) the Chiricahua leopard frog, 2) grizzly bear, 3) jaguar, 4) New Mexico ridge-nosed 

rattlesnake, 5) Mexican spotted owl, and 6) PMJM. Conservation measures were also developed 

for the black-footed ferret and the gray wolf (Mexican subspecies); see “Species for which 

Adverse Effects are Anticipated” section of this BO for those species analyses. 

1. CHIRICAHUA LEOPARD FROG 

The area of concern for the Chiricahua leopard frog relative to this consultation includes New 

Mexico, the only State where the range of this species overlaps the use of Rozol as BTPD bait. 

In New Mexico, the species occurs in Catron, Hidalgo, Grant, Sierra, and Socorro Counties, 

which is about 16 to 19 percent of its historical localities (FWS 2007b). Fourteen units of critical 

habitat have been designated in New Mexico for the Chiricahua leopard frog (FWS 2012a). 

Chiricahua critical habitat and the BTPD range appear to overlap in New Mexico, at least at a 

landscape-scale level. 

The EPA determined that the proposed action may directly affect the Chiricahua leopard frog 

because the range of the species overlaps with BTPD habitat. Although Catron, Hidalgo, Grant, 

Sierra, and Socorro Counties do not have large colonies of BTPDs (1,541 acres or 2 percent of 

Statewide acres), small scattered colonies may occur adjacent to Chiricahua leopard frog habitat, 

thus creating the possibility that Rozol could be used within or near Chiricahua leopard frog 

habitats (Johnson et al. 2003). The EPA determined that the Chiricahua leopard frog could be 

affected by Rozol applications through consumption of poisoned invertebrates that have ingested 

Rozol or loss of invertebrate prey base. Most likely, we believe such effects would be limited to 

individual Chiricahua leopard frogs and would not result in large scale die-offs or population 

losses. In addition, Chiricahua leopard frogs only eat live prey and would not consume a dead 

organism; they do not scavenge. A large portion of the Chiricahua leopard frog range in New 

Mexico is located on U.S. Forest Service lands, and agency approval would be required before 

Rozol could be deployed. 
49

The EPA has agreed to adopt conservation measures as part of their proposed action to minimize 

potential exposure of Chiricahua leopard frogs to Rozol by precluding its application in Catron, 

Hidalgo, Grant, Sierra, and Socorro Counties. Because designated critical habitat captures a 

large portion of the range of Chiricahua leopard frog in New Mexico, the proposed conservation 

measure of prohibiting Rozol use in Catron, Hidalgo, Grant, Sierra, and Socorro Counties would 

greatly reduce the potential for exposure to Rozol and significantly reduce the potential for 

adverse effects to the Chiricahua leopard frog and its proposed critical habitat. Additionally, 

Rozol would not be applied within critical habitat; thus, no Rozol impacts to critical habitat are 

anticipated. 

Accordingly, implementation of the proposed action and its associated conservation measures is 

not expected to result in adverse effects to the Chiricahua leopard frog or adverse effects to its 

designated critical habitat. 

2. GRIZZLY BEAR 

In the BA, the EPA describes direct effects to grizzly bears that are expected to occur based on 

the potential for the species to consume chlorophacinone bait (primary exposure) or other prey 

items that may have consumed chlorophacinone bait (secondary exposure). The EPA assumed 

chlorophacinone exposure to grizzly bears would occur because the grizzly bear range overlaps 

BTPD habitat and the Rozol application season overlaps periods during which grizzly bears are 

active and not hibernating. The EPA defines the Rozol application period on the label as 

occurring between October 1 and March 15. The BA further describes that “growth and 

reproductive effects cannot be precluded due to the absence of chronic data; however, growth 

and reproductive effects are not expected because mortality typically occurs as a result of acute 

exposure.” The EPA assumes acute exposure apparently based on the assumption that “a grizzly 

bear is most likely to encounter a Rozol application area shortly before or after hibernation at 

which time the bear is engorging itself.” The EPA calculated RQs that greatly exceeded a 

0.1 LOC for grizzly bears (Table 5.3, page 83), especially for primary consumption (RQ = 

75.42). The BA also describes the potential indirect effects due to the loss of prey base. 

Therefore, the EPA concluded in their BA that use of Rozol is likely to adversely affect grizzly 

bears. 

Since the preparation of the BA, the EPA has agreed to impose a timing restriction so use of 

Rozol would only be used during the grizzly bear denning period (use would only occur between 

December 1 and March 1) within those counties in Montana where grizzly bears may occur and 

may overlap with BTPDs (see list below). This measure would greatly reduce the potential for 

overlap of grizzly bears and Rozol-treated BTPD colonies during the period where grizzly bears 

could be exposed to Rozol through primary or secondary exposure (the non-denning period). 

Further, there are very few BTPD colonies that exist in the mountain/prairie transition zone 

where the occasional grizzly bear may encounter BTPD colonies. Based on a map produced by 

the Montana Natural Heritage Tracker website, less than 10 known or documented BTPD 

colonies occur where grizzly bears currently may occur (Montana Natural Heritage Program 

2011). 
50

Counties in Montana with Rozol treatment timing restrictions: 

 Carbon  Lewis and Clark 

 Stillwater, South of I-90  Cascade 

 Sweetgrass, South of I-90  Teton 

 Park, South of I-90  Pondera 

 Gallatin, South of I-90  Glacier 

 Madison  Toole 

 Powell 

With the timing restriction, the likelihood of grizzly bear exposure to chlorophacinone from 

Rozol use to control BTPDs is low enough to be considered discountable. With few BTPD 

colonies in areas where grizzly bears are likely to occur, the likelihood of grizzly bears using 

BTPD habitats as part of their home range is low. The restricted use season for Rozol 

(December 1 to March 1) would further reduce the likelihood that a grizzly bear will encounter 

poisoned prairie dogs or unconsumed bait. By December 1, no grizzly bears are expected to be 

in BTPD habitat as they will have moved to higher elevation mountain slopes to den. On 

average, grizzly bears emerge from dens in the beginning of April. However, grizzly bears 

would not be expected to use grassland/prairie habitat, including BTPD, until 2 to 4 weeks after 

emerging from their dens if they use those areas at all. Therefore, grizzly bears would not be 

expected to overlap with BTPD colonies for approximately 6 to 8 weeks after March 1 (around 

50 days or more post any final application). 

With the timing restriction conservation measure, we conclude that adverse effects to grizzly 

bears from primary exposure to Rozol are highly unlikely to occur. Prevalence of 

chlorophacinone bait visible in or around burrows declined by approximately 87 percent by 

day 7 (Lee and Hygnstrom 2007). Thus, after approximately 50 days post-application when 

grizzly bears may first encounter a Rozol-poisoned BTPD town, essentially all of the bait is 

likely to have been consumed by BTPDs or non-target species. The EPA calculated that a 

grizzly bear needs only to consume 4 grams of bait per day for 5 days to exceed a 0.1 LOC 

(page 99 of the BA), indicating that grizzly bears may not need to eat much Rozol bait to be 

susceptible to adverse effects. However, after 50 days following application, it is likely that an 

insufficient amount of bait would remain for grizzly bears to consume. Therefore, based on the 

timing restriction and the minimal overlap of grizzly bear habitat and BTPD colonies, we 

conclude that the likelihood of a grizzly bear encountering and consuming a sufficient quantity 

of Rozol bait to result in harmful effects is so low that it is discountable. 

The likelihood of detrimental effects to grizzly bears from secondary exposure to Rozol is also 

so low that it is discountable. The die-off of BTPDs and non-target animals following a Rozol 

application would likely reach its conclusion before a grizzly bear would encounter a poisoned 

colony. Fifty or more days following application, few, if any, Rozol-poisoned carcasses or prey 

debilitated by exposure to Rozol would be available for consumption by grizzly bears. While 

moribund BTPDs were detected by 29 days after Rozol application (Vyas 2010a), the prairie dog 

availability is not expected to be high 50 days following application. Most prairie dogs are 

expected to die within days to weeks of application, and predators and scavengers would likely 

remove most prairie dogs by the time grizzly bears may encounter Rozol-poisoned colonies. 
51

Therefore, by the time grizzly bears may use habitat within these areas, the Services concludes 

there will be insufficient quantities of available prey items or bait to cause adverse effects. 

It is also the Service’s conclusion that indirect effects to grizzly bears due to the loss of prey base 

from use of Rozol are insignificant. Few BTPD colonies occur in areas where grizzly bears also 

occur, and prairie dogs are not a significant dietary item for grizzly bears. 

In summary, few BTPD colonies occur in areas accessed by grizzly bears and, with the restricted 

timing of Rozol use in grizzly bear areas (between December 1 and March 1), the Service does 

not anticipate adverse effects to grizzly bears as a result of Rozol use on BTPDs in those areas. 

No critical habitat for the grizzly bear has been designated; therefore none will be affected. 

3. JAGUAR 

The EPA determined that the registration and use of Rozol may affect and is likely to adversely 

affect the jaguar based on potential direct effects from prey that may consume chlorophacinone 

bait, including BTPDs and non-target animals. In addition, the EPA’s BA indicates that there 

could be indirect effects from prey-base loss. 

The jaguar is reported from Mexico, Arizona, and New Mexico. It is rarely found (one report in 

the last 20 years) within the action area in the Peloncillo Mountains of Hidalgo County, New 

Mexico, near the Arizona border. Jaguars are generalist predators typically foraging on diurnal 

mammals (Seymour 1989). The jaguar is a wide-ranging species that might occasionally 

encounter prairie dogs; however, there are few BTPDs in Hidalgo County (Johnson et al. 2003). 

The proposed conservation measure of prohibiting Rozol application in Hidalgo County 

substantially reduces the risk of Rozol exposure to the jaguar. Based on the low BTPD 

abundance, unlikely interaction of the jaguar and BTPD, and prohibition of Rozol application in 

the area occupied by the jaguar, the Service does not anticipate adverse effects to the jaguar. No 

critical habitat for the jaguar has been designated; therefore none will be affected. 

4. MEXICAN SPOTTED OWL 

The EPA determined that the proposed action may directly affect the Mexican spotted owl 

because the range of the species overlaps with BTPD habitat at a large landscape scale. The 

EPA determined that the Mexican spotted owl could be affected by application of Rozol through 

consumption of poisoned prey or loss of prey base, and adverse effects to Mexican spotted owl 

critical habitat may occur. 

Within the action area for this project, the Mexican spotted owl occurs within Colorado, New 

Mexico, and western Texas. In Texas, the Mexican spotted owl is only known from the 

Guadalupe Mountains National Park (FWS 1995). The action area was analyzed for possible 

effects to the Mexican spotted owl that include the BTPD range within the three States listed. 

Effects may extend beyond the use area due to exposure to individuals or via prey items with 

chlorophacinone residues if found outside of their described range. The final Mexican spotted 

owl critical habitat rule (FWS 2004) designated approximately 3.5 million ha (8.6 million acres) 

of critical habitat in Arizona, Colorado, New Mexico, and Utah, mostly on Federal lands (FWS 
52

2004). Within this larger area, critical habitat is limited to areas that contain the primary 

constituent elements (FWS 2004). The primary constituent elements include forest structure for 

nesting and prey maintenance but not the prey base itself (FWS 2004). In summary: 

 Known habitat use by the Mexican spotted owl does not correspond with BTPD habitat; thus, 

the Mexican spot owl is considered extremely unlikely to occur within BTPD habitats where 

Rozol will be applied. The potential for Mexican spotted owls to experience secondary 

exposure to chlorophacinone is considered so unlikely as to be discountable. 

 The proposed action will not result in any effects to the PCEs of designated critical habitat 

for the Mexican spotted owl. PCEs for the Mexican spotted owl include mixed-conifer, 

pine-oak, and riparian forest types that provide for one or more of the owl’s habitat needs for 

nesting, roosting, foraging, and dispersing. These PCEs do not correspond with BTPD 

habitat and are unlikely to occur within the areas ROZOL is applied. Therefore, the potential 

for Mexican spotted owl PCEs to be adversely affected by chlorophacinone is considered so 

unlikely as to be discountable. 

 The prohibition of Rozol application in Catron, Grant, Sierra, and Socorro Counties protect 

important Mexican spotted owl ecological management units and designated critical habitat. 

Based on the above, the Service anticipates that adverse effects to Mexican spotted owls or their 

critical habitat are highly unlikely to occur. 

5. NEW MEXICO RIDGE-NOSED RATTLESNAKE 

The BA indicates that New Mexico ridge-nosed rattlesnakes are unlikely to be killed by bait 

ingestion because the RQ is less than the LOC, but direct effects based on reproduction cannot 

be precluded. Additionally, indirect effects from prey-base loss are expected because effects to 

potential prey species have been demonstrated. No indirect effects from habitat loss are 

expected because this species does not use BTPD burrows. In addition, the BA indicates that 

adverse effects to designated critical habitat are expected because of overlap with BTPD habitat. 

The New Mexico ridge-nosed rattlesnake is reported from Mexico, Arizona, and New Mexico. 

Within the action area, the New Mexico ridge-nosed rattlesnake is only found in Hidalgo 

County, New Mexico. New Mexico ridge-nosed rattlesnakes are found in steep, rocky canyons 

with intermittent streams and on talus slopes in the Animas Mountains. The BTPD habitat does 

not overlap with the New Mexico ridge-nosed rattlesnake, although occasional prairie dogs 

might be found in adjacent habitats where the action might indirectly affect the species. The 

EPA adopted the conservation measure of excluding Hidalgo County from the area where Rozol 

may be applied, substantially reducing the potential impacts of the action to the New Mexico 

ridge-nosed rattlesnake. Because of the low BTPD abundance in Hidalgo County (Johnson et al. 

2003), the low probability of interaction between the New Mexico ridge-nosed rattlesnake and 

BTPD, based on differing habitat use of each species, and Rozol use prohibition in the area 

occupied by the Mexico ridge-nosed rattlesnake, effects from the action are unlikely to occur. 

The Service does not anticipate adverse effects to the New Mexico ridge-nosed rattlesnake. 
53

Designated critical habitat for the New Mexico ridge-nosed rattlesnake occurs only in Hidalgo 

County within the action area. There are no known BTPDs in designated critical habitat. The 

conservation measure of excluding Rozol application in Hidalgo County precludes effects of the 

action on designated critical habitat. Thus, adverse effects to New Mexico ridge-nosed 

rattlesnake designated critical habitat are not anticipated. 

6. PREBLE’S MEADOW JUMPING MOUSE 

In the BA (page 104), the EPA concludes that the use of Rozol to control the BTPD is likely to 

adversely affect the PMJM (Zapus hudsonius preblei) for the following reasons: 

The range of this species overlaps with Black-tailed prairie dog habitat. Rozol 

Prairie Dog bait application season for the control for Black-tailed prairie dogs 

overlaps periods during which the Preble’s meadow jumping mouse is active and 

not hibernating. However, Preble’s meadow jumping mice will be hibernating 

during most of this time. Chlorophacinone can be applied between October 1 and 

March 15 or spring green-up, whichever occurs later. Preble’s meadow jumping 

mice typically enter hibernation between late August and October and come out 

of hibernation in May. Based on the life history information it seems reasonable 

that the Preble’s meadow jumping mouse could be exposed to the 

chlorophacinone bait. A Preble’s meadow jumping mouse would have to eat less 

than one grain of Rozol Prairie Dog bait per day for five days to reach the LOC. 

It is possible that a Preble’s meadow jumping mouse could consume this amount 

of bait. The Preble’s meadow jumping mouse is most likely to encounter a Rozol 

application area shortly before or after hibernation at which time the mouse is 

engorging itself. This only increases the likelihood that the bait would be 

consumed. 

The PMJM is found in Wyoming and Colorado, in both the North Platte River and South Platte 

River basins, from the eastern flank of the Laramie Mountains and the Laramie Plains in 

southeastern Wyoming south along the eastern flank of the Front Range in Colorado and into the 

headwaters of the Arkansas River Basin near Colorado Springs, Colorado. The EPA map for 

this consultation, indicating the overlap of the initial area of concern with the PMJM range, 

erroneously shows that range to be throughout all of Wyoming (the EPA made note of this error 

and committed to correcting it for future analyses). 

The action area defined by the EPA in the BA broadly overlaps the range of the PMJM. 

However, the known distribution of the PMJM and the known distribution of the BTPD within 

Wyoming and Colorado overlap significantly less than depicted in the BA. This inaccuracy 

results from the inclusion of areas in the mapped PMJM range where potential habitat may exist 

but where the PMJM is not known to occur and from the EPA’s defined action area in Wyoming 

and Colorado extending well beyond the actual range of the BTPD. 

In Wyoming, the PMJM is known to occur only in Albany, southern Converse, Laramie, and 

Platte counties. The PMJM is not thought to occur in Wyoming’s Goshen and Niobrara Counties 

to the east or eastern Laramie County (Keinath 2001). Occurrence of the PMJM and BTPD in 
54

Wyoming overlaps primarily in portions of southern Converse County and western Platte County 

(Wyoming Natural Diversity Database [WYNDD] 2011). Known distribution of the PMJM in 

Colorado includes Boulder, Douglas, El Paso, Elbert, Jefferson, Larimer, and Weld Counties. 

The easternmost captures extend to western Weld County, western Elbert County, and 

north-central El Paso County. No recent captures of the PMJM have been documented within its 

potential range in Adams, Arapahoe, Broomfield, Denver, or Morgan Counties, and it is likely 

that the PMJM does not occur in these areas. Occurrence of the PMJM and BTPD in Colorado 

overlaps primarily in west-central Weld County, eastern Boulder County, parts of Jefferson 

County, western Elbert County, eastern Douglas County, and northern El Paso County (Colorado 

Division of Parks and Wildlife (CPW) 2011). 

Less than 30 percent of the PMJM distribution is estimated to fall within the range of the BTPD. 

Within the BTPD range, the species’ colonies occupy only a small percentage of the area, just 

over 1 percent in Wyoming (Grenier et al. 2007, WYNDD 2011) and about 3 percent in 

Colorado (Odell et al. 2008, CPW 2011). While these same percentages may not apply directly 

to areas of PMJM occurrence, it is reasonable to believe that presence of the PMJM in close 

proximity to BTPD colonies is infrequent throughout occupied PMJM range. 

In the BA (page 32), the EPA states: 

For the animal species ingestion is the only significant route of exposure and the 

only exposure route assessed in this document and for that, the species’ diet must 

be that of a granivore or it must be attracted to grain baits to have primary 

exposure to chlorophacinone; it must be a carnivore or scavenger to have 

secondary exposure to chlorophacinone. It was also determined that insects may 

be exposed to the grain bait and may retain residues that are high enough to 

cause direct mortality to invertivores. 

Preble’s meadow jumping mice are omnivores and consume such foods as seeds, fruits, fungi, 

and insects. Studies specific to the PMJM diet are limited, but fecal analyses suggest that PMJM 

diet shifts seasonally; it consists primarily of insects and fungus after emerging from hibernation, 

shifts to fungus, moss, and pollen during mid-summer (July to August), with insects again added 

in September (Shenk and Sivert 1999). The PMJM would probably consume both treated grain 

bait and exposed insects if they were encountered. 

Where both PMJM and the BTPD occur, habitat isolation between the PMJM and BTPD reduces 

the chance that the PMJM would encounter treated grain or exposed insects. Typical habitat for 

the PMJM is comprised of well-developed plains riparian vegetation with adjacent, relatively 

undisturbed grassland communities and a nearby water source. Well-developed plains riparian 

vegetation typically includes a dense combination of grasses, forbs, and shrubs; a taller shrub and 

tree canopy may be present (Bakeman 1997). Areas of highest use by the PMJM tend to be 

along creeks, and in areas with a high percent cover of shrubs (especially wetland shrubs) and 

grasses (Trainor et al. 2007). In contrast, BTPD colonies are typically in uplands, where their 

activities greatly reduce vegetative cover in the vicinity of their burrows. The PMJM 

infrequently enters areas of low, sparse vegetation characteristic of prairie dog colonies. 

Individual prairie dog burrows in proximity to dense riparian vegetation are most likely to be 

encountered by the PMJM. 
55

The PMJM is a true hibernator, usually entering underground hibernacula (hibernation nests) in 

September or October and emerging the following May after a potential hibernation period of 

7 or 8 months. The only direct overlap between the PMJM active season and the Rozol 

treatment period, as reflected in label instructions (October 1 C March 15) is October, when 

some PMJM remain actively foraging above ground. During the consultation process, Liphatech 

and the EPA agreed to timing restrictions on Rozol applications, limiting its use within the 

known range of PMJM occurrence in Wyoming and Colorado to the period November 1 C

March 15. Timing restrictions will be included in County Bulletins via the EPA’s Bulletins Live!

for those counties included. 

By November 1, all PMJM individuals have likely entered hibernation, and the conservation 

measure agreed to above would eliminate the likelihood of the species encountering 

Rozol-treated bait in the fall. Emergence of the mouse from hibernation in spring has not been 

documented prior to the first week in May. Assuming that the earliest date could be May 1, 

emergence would follow the last Rozol application by a minimum of 46 days. The majority of 

individuals are likely to emerge later in May, providing even more temporal separation between 

the final Rozol application and the PMJM active season. Further, data on the diet of the PMJM 

indicates that insects and fungus may be preferred rather than seeds when emerging from 

hibernation (Shenk and Sivert 1999). 

In accordance with label instructions, Rozol-treated bait is placed at least 6 inches down BTPD 

burrows. Our knowledge of the PMJM does not suggest that, while foraging, they would venture 

into prairie dog burrows where Rozol-treated bait is placed. Spillage, improper baiting, or BTPD 

digging activity could result in some bait exposed on the ground surface. By the time PMJM 

emerge from hibernation, bait consumption by various granivores, including insects, would 

reduce remaining bait availability. 

The scenario of the PMJM emerging from hibernation in locations adjacent to BTPD colonies, 

foraging in those colonies, and encountering and consuming Rozol-treated bait or exposed 

insects is considered highly unlikely to occur and therefore discountable. 

Potential reduction of invertebrates in Rozol-treated areas and its possible effect on PMJM food 

resources was noted in the EPA’s “Effects Determination” within the BA as a possible secondary 

impact to the PMJM. As stated above, the species feeds on a variety of items, including insects. 

However, it is unlikely to regularly forage in BTPD colonies, and invertebrate prey from such 

habitat is not known to be a significant food source for the PMJM. The potential for the PMJM 

to be adversely impacted by reduction of the invertebrate populations within BTPD colonies 

appears insignificant. 

In summary, occurrence of the PMJM in the proximity of BTPD colonies is likely infrequent 

within PMJM range. Where it occurs, the PMJM would rarely venture into BTPD colonies, 

creating a degree of habitat isolation between the two species. The PMJM hibernates 

November-April, throughout the period of Rozol application as modified by the agreed upon 

conservation measures (November-March 15), creating a temporal isolation between availability 

of Rozol-treated bait or affected insects and the PMJM active season. Therefore, the Service 

does not anticipate adverse effects as a result of the proposed action. 
56

Regarding potential impacts to PMJM critical habitat, in the BA (page 22), the EPA states: 

Habitat modification for the Preble’s meadow jumping mouse is expected because 

the critical habitat for the Preble’s meadow jumping mouse overlaps with the use 

area (BTPD habitat). 

An estimated 10,200 acres of PMJM critical habitat in Colorado overlaps with the BTPD range, 

which is approximately 35 percent of all PMJM designated critical habitat. For the PMJM, 

primary constituent elements (PCEs) of critical habitat are: 

 

 Riparian corridors: formed and maintained by normal, dynamic, geomorphological, and 

hydrological processes that create and maintain river and stream channels, floodplains, and 

floodplain benches and that promote patterns of vegetation favorable to the PMJM; 

containing dense, riparian vegetation consisting of grasses, forbs, or shrubs, or any 

combination thereof, in areas along rivers and streams that normally provide open water 

through the PMJM active season; and including specific movement corridors that provide 

connectivity between and within populations. This may include river and stream reaches 

with minimal vegetative cover or that are armored for erosion control; travel ways beneath 

bridges, through culverts, along canals and ditches; and other areas that have experienced 

substantial human alteration or disturbance. 

 Additional adjacent floodplain and upland habitat with limited human disturbance (including 

hayed fields, grazed pasture, other agricultural lands that are not plowed or disked regularly, 

areas that have been restored after past aggregate extraction, areas supporting recreational 

trails, and urban–wildland interfaces). 

While the use of Rozol to control the BTPD and subsequent loss of prairie dog colonies is 

unlikely to adversely impact the PCEs of PMJM critical habitat above, it could have indirect 

effects to PMJM critical habitat due to the loss of BTPD burrows and cessation of BTPD 

activities that would otherwise modify vegetation. In the BA (pages 84-85), the EPA states that 

loss of burrows is not expected to have an adverse impact to the PMJM. 

The Service agrees. Burrows of other animals are not specified PCEs of PMJM critical habitat. 

Since the PMJM digs its own burrows and is not known to be dependent on burrows of other 

animals, it is unlikely that the PMJM critical habitat would be adversely affected by the loss of 

prairie dog burrows following Rozol application. In the BA (page 60), the EPA’s conceptual 

impact model lists “altered plant community composition” as a second indirect effect on habitat 

resulting from BTPD control. Reduction or eradication of BTPDs would likely lead to 

vegetation of greater height and density at sites of their former BTPD colonies. Where BTPD 

colonies are abandoned within designated critical habitat or adjacent to other riparian corridors 

occupied by the PMJM, the altered plant community could be of greater habitat value to the 

PMJM than low, sparse vegetation typically found within an active BTPD colony. 
57

The Service initially concurred with the EPA’s determination that the use of Rozol to control the 

BTPD may adversely affect the PMJM. However, with the conservation measures agreed to by 

the EPA and Liphatech as well as further analysis, adverse effects to the PMJM are considered 

so unlikely as to be discountable. The Service does not anticipate adverse effects to the PMJM 

or its critical habitat.

D. SPECIES FOR WHICH ADVERSE EFFECTS ARE ANTICIPATED WITH 

OR WITHOUT CONSERVATION MEASURES 

For those species for which conservation measures did not preclude adverse effects, the full 

analysis of a biological opinion is necessary. Three species are anticipated to experience adverse 

effects, with or without the conservation measures adopted by the EPA: 1) black-footed ferret, 

2) gray wolf and 3) northern aplomado falcon. 

1. BLACK-FOOTED FERRET 

a. Status of the Species/Critical Habitat 

The black-footed ferret was listed as endangered in 1967 and again in 1970 under early 

endangered species legislation and was “grandfathered” into the current ESA in 1973 (FWS 

2008b). Critical habitat has not been designated for this species. The species’ historical range 

includes 12 States (Arizona, Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, 

Oklahoma, South Dakota, Texas, Utah, and Wyoming) and the Canadian provinces of Alberta 

and Saskatchewan (Anderson et al. 1986). 

The black-footed ferret was considered extinct or nearly extinct when a small population was 

located in Mellette County, South Dakota, in 1964 (Henderson et al. 1969). The last wild 

black-footed ferret observed at the Mellette County site was in 1974 (Clark 1989). Attempts at 

captive breeding of a few captured animals from the Mellette County population failed, and 

when the last captive animal died at Patuxent Wildlife Research Center in Laurel, Maryland, in 

1979, the black-footed ferret was again presumed extinct (FWS 1988). 

In 1981, a second population was discovered in Meeteetse, Wyoming (Clark et al. 1986, 

Lockhart et al. 2006). Following disease outbreaks at Meeteetse, all surviving wild black-footed 

ferrets (totaling 18 individuals) were removed from the wild between 1985 and 1987 to initiate a 

captive breeding program (FWS 1988). Seven of the black-footed ferrets captured at Meeteetse 

successfully reared young, leading to a lineage of continuing captive reproduction that provides 

black-footed ferrets to reintroduction sites today (Hutchins et al. 1996, Garelle et al. 2006). 

Reintroductions began in 1991 (Table 2) and all extant populations, both captive and 

reintroduced, descend from these seven “founder” animals (Garelle et al. 2006). 

No wild populations of black-footed ferrets have been found since the capture of the last 

Meeteetse black-footed ferret, despite extensive and intensive range-wide searches. It is unlikely 

that any undiscovered wild populations remain (Lockhart et al. 2006). No known extant wild 

populations of black-footed ferrets exist, except those at reintroduction sites. 
58

(1) Ferret Reintroductions 

Section 10(j) of the ESA allows reintroduced populations to be designated Nonessential 

Experimental Populations (NEPs) to ease concerns about listed species reintroductions and 

facilitate species recovery efforts. To date, 11 black-footed ferret reintroductions have occurred 

through use of Section 10(j) designated NEP areas in the United States (FWS 2008b). There 

have also been six black-footed ferret reintroductions in the United States that used 

Section 10(a)(1)(A) recovery permits. Additionally, there have been black-footed ferret 

reintroductions in Chihuahua, Mexico, and in Saskatchewan, Canada, in compliance with those 

countries’ statutes, for a total of 19 reintroduction attempts (FWS 2008b, Fargey 2010). See 

Table 3 for the location and date of initiation of each of the black-footed ferret reintroduction 

sites. 

Table 3. Black-footed ferret reintroductions in North America locations, year initiated, and 

prairie dog species. 

SITE (YEAR INITIATED) PRAIRIE DOG SPECIES

Shirley Basin, Wyoming (1991) White-tailed 

UL Bend National Wildlife Refuge, Montana (1994) Black-tailed 

Badlands National Park, South Dakota (1994) Black-tailed 

Aubrey Valley, Arizona (1996) Gunnison’s 

Conata Basin, South Dakota (1996) Black-tailed

Ft. Belknap Indian Reservation, Montana (1997) Black-tailed

Coyote Basin, Utah (1999) White-tailed

Cheyenne River Indian Reservation, South Dakota (2000) Black-tailed

Bureau Land Management 40-complex, Montana (2001) Black-tailed

Wolf Creek, Colorado (2001) White-tailed

Janos, Mexico (2001) Black-tailed

Rosebud Indian Reservation, South Dakota (2004) Black-tailed

Lower Brule Indian Reservation, South Dakota (2006) Black-tailed

Wind Cave National Park, South Dakota (2007) Black-tailed

Espee Ranch, Arizona (2007) Gunnison’s

Smoky Valley, Kansas (2007) Black-tailed

Northern Cheyenne Indian Reservation, Montana (2008) Black-tailed

Vermejo Park Ranch, New Mexico (2008) Black-tailed 

Grassland National Park, Canada (2009) Black-tailed

(2) Life History 

The black-footed ferret is a medium-sized mustelid typically weighing 1.4 to 2.5 pounds (lbs) 

(645 to 1,125 grams) and measuring 19 to 24 inches (479 to 600 millimeters) in total length. 

Upper body parts are yellowish buff, occasionally whitish; feet and tail tip are black; and a black 

“mask” occurs across the eyes. It is the only ferret species native to the Americas (there are no 

recognized subspecies). Other ferret species in the genus include the Siberian polecat (Mustela 

eversmanni) and the European ferret (Mustela putorius) (Hillman and Clark 1980, Anderson 
59

et al. 1986). The black-footed ferret was first formally described in 1851 by J.J. Audubon and J. 

Bachman (Clark et al. 1986). The black-footed ferret is endemic to North America. Ferrets 

entered North America from Siberia approximately 1 to 2 million years ago, spread across 

Beringia, and advanced southward through ice-free corridors to the Great Plains approximately 

800,000 years ago (Wisely 2006). Contrary to early characterizations that addressed natural 

history, the species was probably common historically, although its secretive habits (nocturnal 

and often underground) made it difficult to observe (Forrest et al. 1985, Anderson et al. 1986, 

Clark 1989). 

Black-footed ferrets prey primarily on prairie dogs (Cynomys spp.) and use their burrows for 

shelter and denning (Henderson et al. 1969, Hillman and Linder 1973, Forrest et al. 1985). Since 

black-footed ferrets depend almost exclusively on prairie dogs for food and shelter, and the 

species’ range overlaps that of certain prairie dog species (Anderson et al. 1986) with no 

documentation of black-footed ferrets breeding outside of prairie dog colonies, the Service 

believes that black-footed ferrets were historically endemic to the range of three prairie dog 

species. There are records of black-footed ferrets from the ranges of the BTPD (Cynomys 

ludovicianus), white-tailed prairie dog (Cynomys leucurus), and Gunnison’s prairie dog 

(Cynomys gunnisoni) (Anderson et al. 1986) which collectively occupied approximately 

100 million ac (40 million ha) of intermontane and prairie grasslands (Biggins et al. 1997, Clark 

et al. 1986, Ernst et al. 2006). Ernst (2008, pers. comm.) estimates that in the United States, this 

occupied habitat existed within an estimated 562 million ac (228 million ha) of potential habitat. 

Ernst (2008, pers. comm.) used a geographic information system database to predict the 

distribution of prairie dog habitat across the United States and concluded that, historically, 

85 percent of all black-footed ferrets probably occurred in BTPD habitat, 8 percent in 

Gunnison’s prairie dog habitat and 7 percent in white-tailed prairie dog habitat. We conclude 

that most black-footed ferrets likely occurred in BTPD habitat. 

The black-footed ferret breeds at 1 year of age, from mid-March through early April, and 

gestation is about 42-45 days. Litter sizes average about 3.5 (Wilson and Ruff 1999). Juveniles 

disperse in late summer/early fall. The black-footed ferret leads a solitary existence except for 

the period when mother and young are together (Forrest et al. 1985). It is a “searcher” predator 

that is generally nocturnal, appearing above ground at irregular intervals and for irregular 

durations (Clark et al. 1986). 

The black-footed ferret’s close association with prairie dogs was an important factor in its 

decline. From the late 1800s to approximately 1960, both prairie dog habitat and numbers were 

dramatically reduced by the sequential and overlapping effects of habitat loss from conversion of 

native prairie to cropland, poisoning, and habitat modification due to disease (FWS 2008b). The 

North American black-footed ferret population declined precipitously as a result (Biggins 2006), 

and the species was one of the original species listed under early versions of the ESA and was 

grandfathered in as an endangered species with passages of the ESA in 1973 (FWS 2008b). 

Black-footed ferret populations in the BTPD range and other prairie dog species are known to 

exist today only in areas where black-footed ferret reintroductions have occurred (FWS 2008b). 
60

a. Environmental Baseline 

Since the 1960s, occupied BTPD acreage has increased from approximately 365,000 acres to 

approximately 2.4 million acres within the 10 states where Rozol is currently allowed or 

proposed to be used as a rodenticide (EPA 2010b, FWS 2009b). There is an extensive history of 

prairie dog poisoning in these 10 states, and we believe that BTPDs are likely to be poisoned by 

various rodenticides into the future regardless if Rozol is available or not. Current BTPD 

populations do not indicate a downward trend even though Rozol has been used under SLN 

labels for BTPD control since 2004 and as early as 1991 under a pocket gopher formulation (Lee 

et al. 2005, FWS 2009b). 

While current information suggests that the BTPD can withstand the impact of Rozol use, prairie 

dog poisoning is a high magnitude threat to the black-footed ferret (FWS 2008b). Therefore, the 

conservation measure that prevents Rozol use in black-footed ferret reintroduction areas is key to 

maintaining the current reintroduction sites and providing a mechanism to accommodate future 

reintroduction sites. 

Nineteen black-footed ferret reintroductions (Table 2) have been undertaken in North America 

beginning in 1991, and most of these sites continue to have some black-footed ferrets remaining 

(FWS 2008b, Fargey 2010). Thirteen reintroductions are within the range of BTPDs, and 11 of 

those sites are within the 10 states where Rozol is either labeled for use or proposed to be used as 

a prairie dog rodenticide (EPA 2010b). Despite these 19 black-footed ferret reintroductions to 

date, insufficient time has passed at approximately one third of the sites to indicate whether the 

existing reintroduction sites may eventually meet criteria for Black-footed Ferret Recovery Plan 

objectives (FWS 2008b). 

A recent estimate of black-footed ferret populations at reintroduction sites indicates 

approximately 840 black-footed ferrets alive in the wild with approximately half of those located 

in the BTPD range (FWS 2008b). Since that time, plague has reduced black-footed ferret 

numbers at the Conata Basin in South Dakota (Griebel 2010) while existing black-footed ferret 

populations are believed to have expanded in Arizona and Wyoming (Corcoran 2012, Grenier 

2008). The Service believes that approximately 800 black-footed ferrets alive in the fall of 2011 

is a reasonable estimate of the species’ current population numbers in the wild. 

To date, there have been a few instances where black-footed ferrets are known to have left a 

reintroduction site and been located on adjacent property. If a black-footed ferret does disperse 

from a reintroduction site, there are provisions in the reintroduction site permit or the 

reintroduction plans to relocate that individual at the request of the adjacent property owner if the 

owner grants access and permission to do so. This accommodation, while available to adjacent 

landowners, has rarely been used or needed. The Service does not expect that to change with 

Rozol use as a BTPD rodenticide. 

Landowners adjacent to current black-footed ferret reintroduction sites are not required to 

conduct surveys for the species prior to undertaking normal ranching operations, such as the use 

of rodenticides to control prairie dogs. The Service anticipates that future black-footed ferret 

reintroduction sites will similarly not require black-footed ferret surveys on adjacent properties. 
61

Black-footed ferret surveys can be time consuming and expensive to undertake; requiring them 

of adjacent landowners prior to normal ranching operations would undermine support for the 

reintroduction effort. 

The Black-footed Ferret Recovery Plan identifies recovery objectives for downlisting the species 

from endangered to threatened status. The objectives include increasing the captive population 

of black-footed ferrets to 200 breeding adults and establishing at least 1,500 free ranging 

breeding adult black-footed ferrets that are distributed between at least 10 populations with no 

fewer than 30 breeding adults in a population, and those populations shall have the widest 

possible distribution (FWS 1988). The first objective of increasing the captive black-footed 

ferret population has been surpassed. The second objective is approximately 25 percent met 

when fall black-footed ferret numbers of approximately 800 animals are estimated to result in 

400 breeding adults by spring, and four reintroductions sites have successfully established free 

ranging populations and meet recovery objectives (FWS 2008b). This indicates that additional 

successful black-footed ferret reintroduction sites are needed to meet the downlisting objective. 

Recovery objectives for complete delisting of the black-footed ferret have not been finalized but 

are anticipated to include at least 3,000 free ranging breeding adult black-footed ferrets 

distributed between at least 30 populations. The downlisting objectives indicate that there will 

need to be significant continued efforts to establish free ranging black-footed ferret populations 

through the use of reintroductions, and complete delisting of the species will require 

considerably more reintroductions. 

b. Effects of the Action 

Rodenticides used to poison prairie dogs can have multiple effects to black-footed ferrets by 

secondarily poisoning individuals or by destroying the habitat where the species lives or could 

live. A study in the 1980s evaluated the potential secondary poisoning of chlorophacinone, the 

active ingredient in Rozol, and found that 5 of 6 domestic ferrets were killed when each domestic 

ferret was fed 4 poisoned BTPDs over 8 days. The study concluded that chlorophacinone may 

not be an acceptable prairie dog toxicant based on high secondary toxicity to non-target animals 

(Fisher and Timm 1987). The Service believes that black-footed ferrets would be similarly 

killed as the domestic ferrets were, if they consumed prairie dogs poisoned by Rozol. 

Accordingly, the EPA, Liphatech and the Service developed conservation measures that would 

prevent Rozol use at current and future black-footed ferret reintroduction sites. These measures 

were intended to address the secondary poisoning of black-footed ferrets and the loss of prey 

base for black-footed ferrets at reintroduction sites (EPA 2011c). The issue of black-footed 

ferret dispersal away from a reintroduction site that might encounter a Rozol poisoned BTPD 

colony was more difficult to address. 

The key challenge with development of the black-footed ferret conservation measures was to 

ensure that Rozol use would not occur at locations where the species is being reestablished while 

at the same time ensure that adjacent landowners’ ability to manage prairie dogs on their 

properties would not be impacted. There was discussion about banning Rozol use in areas 

surrounding black-footed ferret reintroduction sites (up to a county in size), but it was concluded 

that doing so would increase animosity toward black-footed ferret reintroduction efforts and 

undermine or prevent reintroductions altogether. Accordingly, to avoid creating that backlash, 
62

conservation measures were developed that would restrict Rozol use at reintroduction sites, but 

not impose restrictions on adjacent landowners’ use of legal rodenticides. As indicated above, 

the Service does not believe that black-footed ferret surveys on properties adjacent to or in the 

vicinity of a reintroduction site are needed prior to undertaking otherwise legal activities such as 

rodenticide use on prairie dogs, and the cost and inconvenience of black-footed ferret surveys on 

adjacent lands would generate opposition to, and possibly compromise, the black-footed ferret 

reintroduction effort. If a black-footed ferret disperses from a reintroduction site, and if the 

landowner wants the ferret relocated and grants permission to access the property, then the 

relocation can be done under existing mechanisms. 

The black-footed ferret conservation measures rely upon identification of existing and future 

black-footed ferret reintroduction sites on the Bulletins Live! database maintained by the EPA 

and referenced on the Rozol label which becomes part of the legal requirement for label 

compliance. Prior to Rozol use, applicators are required to consult this database to ensure that 

they are not applying Rozol at an existing black-footed ferret reintroduction site. If additional 

reintroductions are started in the future, we will provide the information for those sites to the 

EPA for inclusion in the EPA’s Bulletins Live! database to reflect the new black-footed ferret 

reintroduction sites. The process to add areas to the Bulletins Live! database takes approximately 

8 months to complete and that timeframe will be factored into the timing of adding new 

reintroduction sites or modifications to that database. 

The Service recognizes that if a black-footed ferret leaves a reintroduction site it could encounter 

prairie dog colonies where Rozol is being used and could consume poisoned prairie dogs and 

perish. That mortality must be balanced with the intent of the reintroduction, which is to 

establish a breeding black-footed ferret population at the reintroduction site. The deaths of 

black-footed ferrets that leave the reintroduction site are not anticipated to materially affect the 

reintroduction site’s ability to meet recovery objectives for the species because the sites are 

reliant upon the amount of black-footed ferret habitat within their boundaries to meet those 

objectives. The Service selects reintroduction sites that have the attributes (i.e., prairie dog 

acreage, densities, locations, partnerships, etc.) to help meet the black-footed ferret recovery 

objectives of establishing widely distributed breeding populations. The Service and our 

reintroduction partners have long understood that dispersing black-footed ferrets from a 

reintroduction site could be lost from many factors and that use of legal rodenticides off the 

reintroduction site is one of those factors (FWS 1988, 1994b). Accordingly, we believe that the 

conservation measure to restrict Rozol use at the reintroduction site, but not on adjacent 

properties is appropriate. 

Another possible effect of Rozol use for BTPD control involves the elimination of possible 

black-footed ferret reintroduction habitat because of Rozol use. In 2009, the Service estimated 

that there were approximately 2.4 million acres of BTPDs in the 10 States where Rozol is used or 

proposed for use as a BTPD rodenticide (FWS 2009b, EPA 2010b). Luce (2006) examined 

opportunities for immediate and near term potential reintroduction sites and concluded that there 

are over 70 potential sites within the black-footed ferret range, most of which are in BTPD 

colonies. The Service believes that rodenticide use (including Rozol), while widespread in the 

BTPD range, in and of itself is not the determinate factor whether a black-footed ferret 

reintroduction can occur. Instead, it is the willingness of partners (private, State, Tribal and 
63

Federal) to consider a reintroduction and then commit to manage a block of prairie dog habitat 

for black-footed ferret conservation. Most recent BTPD surveys indicate that there are many 

biologically suitable and potential reintroduction sites available, but the key to achieving 

black-footed ferret reintroductions and thus recovery is finding interested landowners and 

partners (FWS 2009b, Lockhart et al 2006, Luce 2006). Further, our experience is that 

landowners who are strong proponents of poisoning prairie dogs are not interested in 

participating in black-footed ferret reintroductions and, if Rozol was not available, they would 

likely use a different rodenticide. Therefore, the Service believes that Rozol use on BTPDs, with 

the agreed upon conservation measure to restrict Rozol use on future black-footed ferret 

reintroduction sites, will not eliminate future opportunities for reintroductions. Use of Rozol will 

not preclude black-footed ferret recovery. 

c. Cumulative Effects 

Cumulative effects include the effects of future State, Tribal, local, or private actions that are 

reasonably certain to occur in the action area considered in this BO. Future Federal actions that 

are unrelated to the proposed action are not considered in this section because they require 

separate consultation pursuant to Section 7 of the ESA. 

Future rodenticide use, along with some land conversion from grasslands or rangeland into 

croplands or other development, is likely to continue in the range of the BTPD. With the 

black-footed ferret conservation measures in place, we do not believe that these actions will 

preclude conservation and recovery of the black-footed ferret because recent trends in BTPD 

occupied habitat are stable to increasing over large areas of the species’ range (FWS 2009b). 

While Rozol use is likely increasing, its use may be supplanting some of the previously used 

prairie dog rodenticides. Thus, even though Rozol has been used for prairie dog control for 

nearly 2 decades in one state and for 5 to 10 years in others (Lee et al. 2005, EPA 2010b, 1993), 

it does not appear to be altering the stable to increasing prairie dogs trends found by the Service 

(FWS 2009b). Because the use of Rozol in black-footed ferret reintroduction sites will not be 

allowed, the impacts to current and future black-footed ferret reintroduction sites are not 

expected to be seriously impacted. 

Within the black-footed ferret’s range, which includes three species of prairie dogs, the Service 

believes that the availability of rodenticides will not prevent recovery of the black-footed ferret 

because recent analysis of the three prairie dog species indicates that those prairie dog species 

continue to inhabit millions of acres of habitat (FWS 2010c, 2009b, 2008c). As noted earlier, 

without adequate regulatory mechanisms, poisoning can affect current and future black-footed 

ferret reintroduction sites (FWS 2008b). While the total prairie dog acreage among the three 

species is much greater than is believed necessary to recover the black-footed ferret, much of the 

existing prairie dog acreage is not of a size or in a location to contribute to the black-footed 

ferret’s recovery. The Black-footed Ferret Recovery Plan estimated that an average of 124 acres 

of prairie dog colonies is needed per black-footed ferret or approximately 185,000 acres of 

black-footed ferret occupied prairie dog habitat is needed to meet downlisting objectives for the 

species (FWS 1988). This acreage amount can be distributed between the three species of prairie 

dogs that encompass the black-footed ferrets’ range (FWS 1988). While complete delisting 
64

objectives for the black-footed ferret have not been finalized, it is likely that 500,000 acres of 

managed prairie dogs distributed between the three prairie dogs species would be sufficient to 

support delisting recovery objectives for the black-footed ferret (FWS 1988). 

Another important factor affecting prairie dog populations and therefore black-footed ferret 

recovery is sylvatic plaque and the ongoing outbreaks which can result in widespread prairie dog 

die offs or, in some cases, more subtle deaths (Cully et al. 2010, Matchett et al. 2010). This 

exotic disease can directly kill black-footed ferrets that consume infected prairie dogs or 

eliminate black-footed ferret habitat among the three prairie dog species (Gage and Kosoy 2006, 

Godbey et al. 2006). At this time, the Service does not have information that Rozol use on 

BTPDs, in combination with other rodenticides and sylvatic plague, will prevent black-footed 

ferret recovery, but, in order to make informed decisions in the future, it will be important to 

have an understanding of the extent of Rozol use in each state. 

d. Conclusion Regarding Jeopardy 

After reviewing the current status of the black-footed ferret, the environmental baseline for the 

action area, the effects of the proposed action, and the cumulative effects, it is the Service’s 

biological opinion that the use of Rozol as a BTPD rodenticide, which includes the black-footed 

ferret conservation measures, is not likely to jeopardize the continued existence of the 

black-footed ferret. No critical habitat for the black-footed ferret has been designated; therefore 

none will be affected. At this time, the Service believes that Rozol use on BTPDs, as modified 

through the agreed upon conservation measures will not preclude the conservation and recovery 

of the black-footed ferret even when combined with the use of other currently available legal 

rodenticides and our understanding of sylvatic plague. 

In summary, this conclusion is based on the following: 

 The modifications to the project description via the black-footed ferret conservation 

measures included in the EPA’s letter of December 13, 2011 (EPA 2011c) and additional 

agreed upon conservation measures in April 2012, which ensure that: 

o Rozol use is prohibited in current and future black-footed ferret reintroduction sites; thus, 

we anticipate that survival of the species in the wild will not be compromised by this 

product. 

o Rozol use is prohibited in an area if an unknown wild black-footed ferret population is 

discovered. 

o Rozol restrictions on properties adjacent to reintroductions are minimized which lessens 

opposition to black-footed ferret reintroductions. 

o Rozol production quantities and distribution to locations within states will be provided to 

the Service which will allow an assessment whether the level of use could preclude 

recovery of the black-footed ferret. 

 Sufficient prairie dog acreage exists among the three species of prairie dogs to support 

current Black-footed Ferret Recovery Plan downlisting objectives and likely future delisting 

objectives when those become finalized in the revised Recovery Plan. 
65

2. GRAY WOLF 

a. Status of the Species/Critical Habitat 

Gray wolves from three separate populations are relevant to this consultation: 1) the Northern 

Rocky Mountains Distinct Population Segment (DPS) which encompasses the eastern one-third 

of Washington and Oregon, a small part of north-central Utah, and all of Montana, Idaho, and 

Wyoming; 2) the Western Great Lakes DPS which has a core area occurring in Michigan, 

Wisconsin, and Minnesota and a peripheral zone including eastern North Dakota, eastern South 

Dakota, northern Iowa, and a small portion of northern Illinois; and 3) the Mexican gray wolf 

which has been considered a subspecies and reintroduced into a NEP (under Section 10j of the 

ESA) area that includes portions of central Arizona, central and southern New Mexico, and a 

minute portion of western Texas, south of New Mexico. 

In 1974-1976, the Service listed three subspecies of gray wolf (Northern Rocky Mountain gray 

wolf (Canis lupus irremotus), eastern timber wolf (Canis lupus lycaon) (FWS 1974), and 

Mexican wolf (Canis lupus baileyi)) (FWS 1976)) under the ESA, but in 1978 revised those 

regulations to list the entire gray wolf species as endangered, except in Minnesota where it was 

listed as threatened, in the coterminous United States (FWS 1978). At that time, the Service also 

designated critical habitat in Isle Royale, Michigan, and parts of northern Minnesota (FWS 

1978). Since then, the Service has implemented numerous actions relative to the gray wolf, 

including development of recovery plans, identification of DPSs and NEPs, initiation of 

reintroductions and other recovery actions, and development of regulatory changes that have 

been subject to litigation in numerous Federal courts. For additional details and maps of these 

wolf recovery areas see: 1) Final Rule To Identify the Northern Rocky Mountain Population of 

Gray Wolf as a Distinct Population Segment and To Revise the List of Endangered and 

Threatened Wildlife (FWS 2009f), 2) Endangered and Threatened Wildlife and Plants; Revising 

the Listing of the Gray Wolf (Canis lupus) in the Western Great Lakes (FWS 2011f), 3) Final 

Rule; Establishment of a Nonessential Experimental Population of the Mexican Gray Wolf in 

Arizona and New Mexico (FWS 1998), and 4) Lower 48-State and Mexico Gray wolf (Canis 

lupus) listing, as revised, 5-Year Review: Summary and Evaluation (FWS 2012b). 

Currently, gray wolves in the Northern Rocky Mountain DPS (including Montana and Idaho, as 

well as portions of eastern Oregon, eastern Washington, and north-central Utah, but excluding 

Wyoming) are removed from the List of Endangered and Threatened Wildlife and no longer 

receive protections under the ESA (FWS 2011g). Management of wolf populations in Montana 

and Idaho has been transferred to State authority. The Service has proposed to delist wolves in 

Wyoming (FWS 2011h). Wyoming has a management plan contingent upon necessary 

additional changes to Wyoming State law; Wyoming is anticipated to adopt the necessary 

statutory and regulatory changes within the next several months (FWS 2011h). Until then, 

wolves in Wyoming are protected by the ESA and considered a NEP designated under 

Section 10(j) which has increased the Service’s flexibility and discretion in managing the gray 

wolf reintroduced population. 
66

A final rule to remove wolves in the Western Great Lakes DPS from the list of Endangered and 

Threatened Wildlife was published in the Federal Register on December 28, 2011 (FWS 2011f), 

effective January 27, 2012. Management of wolf populations in Minnesota, Wisconsin and 

Michigan is now under the purview of those States. 

Mexican gray wolves currently retain their original NEP, Section 10(j) status, and are protected 

by the ESA within the parameters established for that reintroduction effort (FWS 1998). 

Mexican gray wolves have been released annually into this population, and this practice will 

likely continue until natural reproduction sustains wild population growth. 

While the open rangeland habitat of the BTPD does not coincide with the typical habitats 

(forested landscapes) used by gray wolf populations in the United States today, the ranges of the 

two species overlap when individual gray wolves disperse from their core populations. Those 

dispersing individuals are most relevant to this analysis. When wolves disperse from their packs 

and occur in other areas outside the boundaries of any DPS or Nonessential Experimental 

reintroduction area, their status under the ESA changes; they take on the listing status of the gray 

wolf in that area (wolves occurring in western North Dakota and South Dakota, Nebraska, 

Colorado, and other areas are considered endangered). Those wolves will remain protected by 

the ESA regardless of recent delisting actions in the Northern Rocky Mountain and Western 

Great Lakes DPSs, unless the Service makes additional regulatory changes in the future. Those 

wolves within Nonessential Experimental area boundaries (Wyoming and Arizona/New Mexico) 

retain ESA protections but with the management parameters established with the Section 10(j) 

rulemaking. 

Critical habitat has been designated for the gray wolf but not within the action area. Due to a 

lack of overlap with the BTPD range, the Service agrees with the EPA that no critical habitat will 

be impacted by the proposed action; therefore, gray wolf designated critical habitat is not 

described herein. 

(1) Species description 

Gray wolves (Canis lupus) are the largest wild members of the dog family (Canidae). Adult gray

wolves range from 18–80 kilograms (40–175 pounds) depending upon sex and region (Mech 

1974). Smaller sizes tend to be found in the southern portion of wolf range (the Mexican wolf is 

the smallest extant wolf in North America) and larger sizes in the northern portion. Females 

weigh slightly less than males. Wolves reach adult size by 1 year of age. Wolves’ fur color is 

frequently a grizzled gray, but it can vary from pure white to coal black. Mexican wolves are 

typically a patchy black, brown to cinnamon, and cream color, with primarily light underparts 

(Brown 1988). Solid black or white Mexican wolves do not exist as seen in other North 

American gray wolves. 
67

(2) Life history 

Elements considered relevant to this consultation are described below. Additional detailed 

information on the biology of this species is available in numerous documents within the 

literature cited of this document (e.g.,“Biology and Ecology of Gray Wolves” section of the 

April 1, 2003, final rule to reclassify and remove the gray wolf from the list of endangered and 

threatened wildlife in portions of the conterminous United States (FWS 2003). 

(a) Range and habitat 

Within North America, gray wolves formerly ranged from coast to coast with the exception of 

the mid-Atlantic states, the Southeast (areas occupied by the red wolf), and perhaps parts of 

California. They have historically been found in almost all habitat types, including the prairie 

and rangelands of the central United States where, coinciding with human settlement, most 

populations of wolves were extirpated by the early 1900s. In the coterminous 48 states today, 

they are found in the mostly forested lands of Minnesota, Wisconsin, Michigan, Montana, Idaho, 

and Wyoming, with the addition of the Mexican wolf reintroduction area in New Mexico, 

Arizona and a small part of western Texas. The Mexican wolf is endemic to the southwestern 

United States and Mexico. Once thought to need wilderness areas to survive, wolves can 

successfully occupy a wide range of habitats, though they tend to more readily occupy heavily 

forested areas and landscapes with low road densities (Mladenoff et al. 1995). The BTPD 

habitat is generally not considered preferred habitat by the gray wolf today; it offers little 

protective cover, and though individuals may traverse it quickly, they often do not survive 

human encounters in such areas. In Minnesota and Wisconsin, wolves are proving themselves 

more tolerant of human disturbance than previously thought and their range has expanded to 

include areas that are a mix of forest and agriculture. Essentially, wolves can live almost 

anywhere if they have abundant wild prey and if excessive numbers are not taken by humans. 

(b) Prey items 

Wolves are predators of primarily medium and large mammals. They may not eat for a week or 

more but are capable of eating 20 pounds of meat in a single meal. Wild prey species in North 

America include animals such as white-tailed deer (Odocoileus virginianus), mule deer 

(O. hemionus), moose (Alces alces), elk (Cervus canadensis), and other large ungulates. Wolves 

will also prey on mid-sized mammals, such as snowshoe hare (Lepus americanus) and beaver 

(Castor canadensis), with small mammals, birds, and large invertebrates sometimes being taken 

(Mech 1974, Stebler 1944, Wisconsin Department of Natural Resources 1999). 

 

(c) Social nature and territory size 

Wolves are social animals, normally living in packs of 2 to 12 wolves (but that number can vary 

considerably; pack sizes ranging into the 30s have been documented). The pack defends a 

territory that can be as large as 50 square miles or even extend up to 1,000 square miles in areas 

where prey is scarce. The pack consists of a breeding (top-ranking or alpha) pair, their pups 

from the current year, offspring from the previous year, and occasionally an unrelated wolf. 

Unrelated wolves are typically individuals dispersing from other packs. 
68

(d) Dispersal 

As indicated by the territory size described above, wolves often cover large areas and may travel 

as far as 30 miles a day. Although they trot at approximately 5 miles per hour (mph), wolves can 

attain speeds as high as 40 mph. By 3 years of age, many wolves disperse from the pack that 

they were born into to find mates and to expand into new areas. The animals have extraordinary 

dispersing ability, traveling over 600 miles, sometimes over large areas of inhospitable terrain. 

A wolf in Sweden with a Global Postitioning System (GPS) collar travelled a straight line 

distance of >1,092 kilometers (682 miles) with an actual travel distance of over 

>10,000 kilometers (6,000 miles) in just under a year (Wabakken et al. 2007). A wolf that 

dispersed from Gardiner, Montana, to western Colorado, where she was illegally killed by 

1080 Compound poison in March 2009, travelled a straight line distance of 400 miles in 6 

months, but daily GPS locations showed she actually walked over 3,000 miles (FWS et al. 2011).

Considerable information on wolf dispersal was obtained during 1993-2008, when 

1,681 radio-collared wolves (858 males and 823 females) in the Northern Rocky Mountain DPS 

were tracked (Jimenez et al. 2011). The large sample size distinguishes that study; however, 

most of what was documented mirrored that already found by others (Fritts and Mech 1981, 

Boyd and Pletscher 1999, Mech 1987, Gese and Mech 1991, Boyd et al. 1995). Ten percent of 

the Northern Rocky Mountain wolf population dispersed annually; 297 known dispersals by 

281 wolves were documented (some wolves dispersed and returned to their original pack up to 

three times). Many other dispersal events likely occurred during the Northern Rocky Mountain 

dispersal study but were undetected because only about 30 percent of the Northern Rocky 

Mountain wolf population was radio-collared by 2008 and it is difficult to detect lone dispersing 

wolves. Most wolves tended to move southward, but 55 dispersals occurred in an easterly 

direction. The dispersals could occur anytime during the year, but increases were noted in the 

fall with the peak occurring in January, and 58 percent (n=153) of all dispersals occurred 

between October and February (i.e., during the timeframe that Rozol may be applied) (Jimenez 

et al. 2011, unpublished data). Licht and Fritts (1994) studied 10 wolf mortality records in North 

Dakota and South Dakota between 1981 and 1992 and found that nine occurred in winter. 

 

Dispersal distance by individual wolves in the Northern Rocky Mountain wolves study (Jimenez 

et al. 2011, unpublished data) was not as great as the species’ potential, described above; mean 

dispersal distance for males was 98.1 kilometers (61 miles) and was not significantly different 

(P=0.11) than female dispersal distance at 87.7 kilometers (54.5 miles). However, in 

10 instances, the wolves moved more than 186 miles which were considered to be unusually long 

distances (Jimenez et al. 2011, unpublished data). About 20 confirmed Northern Rocky 

Mountain wolf dispersal events from 1992-2010 have been over 190 miles with 4 wolves 

travelling beyond the Northern Rocky Mountain DPS border (FWS et al. 2011). The eastern 

edge of the Northern Rocky Mountain DPS is about 400 miles from the western edge (eastern 

Minnesota) of the Western Great Lakes DPS core area and is separated from it by hundreds of 

miles of unsuitable habitat in those Great Plains States (FWS 2009g). This propensity to 

disperse and the distances that have been recorded are the factors that lead the Service to believe 

that gray wolves could encounter and be exposed to Rozol-poisoned prairie dogs. 
69

Dispersing wolves can have a lower survival rate than individuals that do not leave their packs 

(Jimenez et al. 2011, unpublished data), and those that disperse often die in proportionately 

higher numbers from human causes than those that do not disperse (Boyd and Pletscher 1999). 

Of 281 dispersing wolves in the Northern Rocky Mountain study, 166 (59 percent) survived 

dispersal to pair with another dispersing wolf to form new packs or to join new packs (Jimenez 

et al. 2011, unpublished data). The unusually long-distance dispersers typically do not find 

mates or survive long enough to form packs or to breed in the United States (FWS 2009f). 

Human causes of mortality among dispersing wolves include illegal shootings, trapping, 

poisonings (e.g., M-44s intended for coyotes), and vehicle collisions. Dispersing wolves have 

been noted by the Service in Colorado in recent years with a likely vehicle collision mortality of 

an individual in 2004 and an illegal poisoning of another wolf in 2009 (via banned substance: 

Compound 1080). Of the 10 wolf mortalities documented in North Dakota and South Dakota 

from 1981-1992, 8 were mistakenly shot as coyotes, 1 was beaten to death after being chased by 

dogs, and another was shot by a hunter after the wolf allegedly attacked the man’s horse as he 

was riding it (Licht and Fritts 1994). A wolf killed by a car near Sturgis, South Dakota, in 2006 

was determined to have been from the Northern Rocky Mountain DPS. A wolf from the 

Western Great Lakes DPS was shot in Nebraska in 2003. A wolf (Minnesota origin) killed via a 

cyanide gun (M-44) intended for coyotes was documented in Harding County, South Dakota, in 

2001. Other instances of mortality were noted in the Service’s May 5, 2011, Proposed Rule To 

Revise the List of Endangered and Threatened Wildlife for the Gray Wolf (Canis lupus) in the 

Eastern United States, Initiation of Status Reviews for the Gray Wolf and for the Eastern Wolf 

(Canis lycaon) (FWS 2011j):

 An adult male shot near Devil’s Lake, North Dakota, in 2002. 

 Another adult male shot in Richland County in extreme southeastern North Dakota in 2003. 

 A wolf was shot in Roberts County, South Dakota, in January 2009. 

 Another wolf was found dead in a foothold trap that was set as part of an ongoing USDA 

Wildlife Service’s coyote control operation in southeastern Eddy County, North Dakota. 

Despite human-caused mortalities, populations have continued to increase in both numbers and 

range in both the Northern Rocky Mountain and Western Great Lakes DPSs. However, the 

Mexican wolf population has struggled to overcome this issue; 66 percent of all documented 

mortalities as of December 31, 2010, were human-caused, and these high mortality rates may 

reduce dispersing wolves below levels noted for other studied wolf populations (FWS 2011i). 

(3) Population dynamics 

Gray wolves are known to live up to 13 years in the wild and 15 years in captivity. Wolves 

typically breed as 2-year olds and may annually produce young until they are over 10 years old. 

Litter sizes range between 1-11 pups but generally include 4-6 pups (FWS 2003). Normally a 

pack has a single litter annually, but producing 2 or 3 litters in 1 year has been documented in 

Yellowstone National Park (FWS et al. 2002). The breeding season for wolves is from late 

January through March. 
70

Breeding members of wolf packs can be quickly replaced either from within or outside the pack. 

Pups can be reared by another pack member should their parents die (Packard 2003, Brainerd 

et al. 2008, Mech 2006). Consequently, wolf populations can rapidly recover from severe 

disruptions, such as very high levels of human-caused mortality or disease. After severe 

declines, wolf populations can more than double in just 2 years if mortality is reduced; increases 

of nearly 100 percent per year have been documented in low-density suitable habitat (Fuller et al. 

2003, Service et al. 2008, 2009f). Additionally, their extraordinary dispersal ability helps 

explain why wolves can recolonize even distant vacant suitable habitat relatively quickly and 

why their populations are resistant to extirpation (Mech and Boitani 2003, Adams et al. 2008). 

Starting with an estimated 55 individuals that naturally colonized northwestern Montana in 1993, 

the Northern Rocky Mountain population grew an average of 25 percent annually between 1993 

and 2008, with the assistance of reintroduction efforts in Wyoming and Idaho. At the end of 

2009, the population estimate had grown to at least 1,706 wolves in 242 wolf packs and 

115 breeding pairs (Bangs 2010). In 2010, that number was slightly down to 1,651 (FWS et al. 

2011). 

The Western Great Lakes DPS today is estimated to contain over 4,000 wolves, with the 

majority occurring in Minnesota. The Minnesota wolf population increased from an estimated 

1,000 individuals in 1976 to 2,921 as of 2007-2008, and the estimated wolf range in the State has 

expanded by approximately 225 percent (FWS 2011j). Wolves were considered extirpated from 

Wisconsin in 1960 but began to recolonize in the 1970s, and an increase in the late 1980s has 

continued into 2011; the current population estimate there is 782 wolves (FWS 2011k, 2011f). 

With the exception of Isle Royale, wolves were extirpated from Michigan prior to the gray wolf 

listing, but wolves began to return in the late 1980s (Beyer et al. 2009), and wolf packs have 

continued to spread throughout Michigan’s Upper Peninsula. Wolves are now found in nearly 

every county of Michigan’s Upper Peninsula (Huntzinger et al. 2005), and 87 individuals were 

estimated to occur in Michigan in 2010-2011 (FWS 2011f). 

The Mexican wolf reintroduction began in 1998 with the release of 11 individuals in the Blue 

Range Wolf Recovery Area of New Mexico and Arizona. The population has increased with a 

minimum end-of-year count peak of 59 wolves in 2006, via natural reproduction, translocations, 

and initial releases. At the end of 2010, the wild population totaled a minimum of 50 individuals 

(FWS 2012c). 

With a minimum of 1,651 wolves in the Northern Rocky Mountain DPS in 2010 (FWS et al. 

2011), an estimated 4,390 in the Western Great Lakes DPS (assuming the number of wolves in 

Minnesota has not changed substantially since 2007-2008, the date of the most recent estimate 

available for this analysis) (FWS 2011f) and a 2010 estimate of the Mexican wolf population at 

50 (FWS 2012c), the total minimum estimate of wolves in these areas combined is 

approximately 6,091. Wolf population levels in the range of the BTPD are limited to dispersing 

wolves. 
71

(4) Status, trends, and distribution 

The decline and near extirpation of wolves from the lower 48 states in the early part of the 

20th century was caused by a number of factors, including extreme control programs designed to 

eliminate the species. Factors in the eastern timber wolfs’ decline included intensive human 

settlement, direct conflict with domestic livestock, lack of understanding of the animal’s ecology 

and habits, and fears and superstitions regarding wolves and extreme control programs designed 

to eradicate it (Young and Goldman 1944, Mech 1970). These were a common thread among 

wolf populations in other areas of the United States as well. Land development (loss of habitat), 

impacts to prey base, poisoning, trapping, and hunting were also factors identified in the decline 

(FWS 1987). Mech (1995) indicates that primarily inadequate prey density and a high level of 

human persecution limit wolf distribution. In short, human-caused mortality is identified as the 

most significant issue to the long-term conservation status of wolves. Managing this source of 

mortality (i.e., overutilization of wolves for commercial, recreational, scientific and educational 

purposes and human predation) remains the primary challenge to maintaining a recovered wolf 

population into the foreseeable future (FWS 2009f). 

In both the Northern Rocky Mountain and Western Great Lakes DPSs today, wolf numbers are 

trending upward but at slower rates than has been documented in the recent past. Available 

habitat appears to be reaching carrying capacity. The total population in the Northern Rocky 

Mountain DPS today is about five times higher than the minimum population recovery goal and 

three times higher than the minimum breeding pair recovery goal (FWS 2009f); the population 

has exceeded numeric and distributional recovery goals for about a decade. The Northern Rocky 

Mountain wolf population occupies nearly 100 percent of the recovery areas recommended in the 

1987 recovery plan (FWS 1987) and nearly 100 percent of the primary analysis areas (the areas 

where suitable habitat was predicted to exist and the wolf population would live) analyzed for 

wolf reintroduction in central Idaho and the greater Yellowstone area (FWS 1994a). As 

mentioned above, wolves in the Northern Rocky Mountain DPS have been delisted in Montana, 

Idaho, Eastern Oregon, and Eastern Washington and are proposed to be delisted in Wyoming. 

Relatively slow growth to stable populations in Minnesota, Wisconsin, and Michigan in recent 

years is indicative that available habitat is being filled in the Western Great Lakes DPS. Wolves 

in the Western Great Lakes DPS greatly exceed the recovery criteria (FWS 1992) for 1) a secure 

wolf population in Minnesota, and 2) a second population outside Minnesota and Isle Royale 

consisting of 100 wolves for 5 successive years. Based on the criteria set by the Eastern Wolf 

Recovery Team in 1992 and reaffirmed in 1997 and 1998 (FWS 2011j), the proposed DPS 

contains sufficient wolf numbers and distribution to ensure their long-term survival within the 

DPS, and this population has been delisted (FWS 2011f). 

As mentioned above, the Mexican gray wolf population in New Mexico and Arizona has 

struggled to remain viable, and numbers remain very low. The NEP is currently not 

self-sustaining. A captive breeding program has been the source of Mexican wolves for 

reintroduction efforts to date. Currently, dispersing Mexican wolves are stringently managed. 

Individuals known to be from the reintroduced population are not allowed to establish territories 

outside the recovery area boundaries; they are captured and may be returned to the recovery area, 

put into the captive population, or otherwise managed according to existing provisions (FWS 
72

1998). Mexico has recently initiated reintroductions of the Mexican wolf; in 2011, officials 

released five captive-bred Mexican wolves into the San Luis Mountains in Sonora just south of 

the United States-Mexico border (Bryan 2011). As of February 2012, four of the five released 

animals were confirmed dead due to poison (Albuquerque Journal 2012). Despite the initial 

setback, Mexico continues plan additional releases. If wolves from Mexico disperse into the 

United States, they will be considered endangered under the ESA, unless they establish 

themselves within the boundaries of the United States Mexican wolf experimental area, where 

they would be subject to the existing management provisions (FWS 1998). 

The number of dispersing wolves from recovered wolf populations may currently be at its peak 

due to high wolf recovery numbers. As states take over wolf management, they will likely seek 

to achieve lower, but still viable, wolf population levels; thus, the number of dispersing wolves 

may decrease under state management plans. However, the Service believes there will still be 

some dispersing wolves from existing populations into areas where Rozol may be applied for 

prairie dog control. Areas within the BTPD range where the wolf remains protected are the 

locations where exposure to Rozol may occur that results in take of gray wolves. 

(5) Analysis of the species likely to be affected 

Any gray wolves protected by the ESA that disperse from known populations in existing 

(typically forested) occupied habitats into open rangelands where the BTPD exists (within the 

10 States where Rozol may be applied) are the individuals of concern with the potential to be 

adversely affected by the proposed action. This may include reintroduced Mexican gray wolves 

that enter the United States from Mexico. Wolves in NEPs receive protections of the ESA per 

their specific rulemaking parameters. Wolves occurring outside of existing DPSs or NEPs take 

on the ESA status of the area that they are in. 

As mentioned previously under the “Conservation Measures” section, in order to provide some 

protections for the Mexican gray wolf, the EPA and Liphatech agreed to preclude Rozol use 

from Catron, Grant, Hidalgo, and Sierra Counties of New Mexico which are part of the Blue 

Range Wolf Recovery Area. Prairie dogs occur in these counties but are primarily Gunnison’s 

prairie dog (Cynomys gunnisoni); the BTPD is not common in these areas (Johnson et al. 2003), 

and prohibiting Rozol use on BTPDs will further reduce possible impacts to those reintroduction 

efforts. Dispersing wolves from the Mexican gray wolf reintroduced population are few, and 

individuals are typically translocated or killed. Thus, while Rozol use may still occur within the 

greater NEP area boundary, key areas of the reintroduction area will not have Rozol use. This 

conservation measure is anticipated to reduce the risk of adverse effects from Rozol use to the 

Mexican gray wolf. 

Some level of wolf dispersal is expected from other recovered wolf populations, and the 

potential for endangered wolves to encounter Rozol in the proposed 10-state area of application 

exits. Documented gray wolf mortalities in the action area since 1981 (20 records were located 

for this analysis over a span of 31 years in the states of North Dakota and South Dakota (17), 

Colorado (2) and Nebraska (1)) have averaged approximately 0.65 wolves per year. These are 

documented wolf mortalities, but it is unknown how many gray wolves may disperse into the 

action area and not be reported. 
73

(a) Environmental Baseline 

(1) Status of the species within the action area 

Gray wolves are not uniformly protected under the ESA throughout the range of the BTPD. 

Some wolf populations have been delisted, and wolves in Wyoming are proposed to be delisted. 

The exact number of dispersing wolves that may occur in the range of the BTPD where Rozol is 

proposed for use cannot be determined with certainty. The Service does not know of wolf 

populations in the range of the BTPD except for the reintroduction efforts in southwestern New 

Mexico. The Service recognizes that dispersing wolves can occur throughout the BTPD range 

and could be exposed to Rozol use. 

(2) Factors Affecting Species Environment within the Action Area 

Throughout the range of the wolf, generally three factors dominate wolf population dynamics: 

food, people, and source populations (Fuller et al. 2003). Among those three factors and within 

the BTPD range, people likely have the greatest influence on dispersing wolves. Traveling 

wolves must cross numerous stretches of roads and may be struck by vehicles. In addition to 

such vehicle-caused mortality, road access to wolf habitat generally increases the risk of other 

human-related mortality of wolves, including shooting and trapping (Mech et al. 1988; Fuller 

1989). When individual wolves appear in areas not known to harbor packs, they are often 

mistaken for coyotes and shot. Wolves become particularly vulnerable to this type of mortality 

when they occur in open rangelands, far from the protective cover of forested areas they usually 

inhabit. Cases of livestock depredation by dispersing wolves have also been documented, and 

those wolves are often killed as well. Ongoing animal damage control activities by the United 

States Department of Agriculture and/or state agencies in the action area that target coyotes may 

instead kill wolves in accordance with established wolf depredation plans. While these factors 

affecting dispersing wolves are not expected to influence the existing healthy wolf populations 

from which they came, in the dispersal areas, wolves may not survive long due to human-caused 

mortality. Dispersing wolves are likely to encounter many forms of threats when they leave their 

core areas, and high wolf mortality rates in the BTPD range are likely irrespective if Rozol is 

being used. We currently have no documented Rozol-related mortalities of gray wolves. 

(b) Effects of the Action 

(1) Factors to be considered 

According to the BA (page 107), chlorophacinone exposure to the gray wolf is expected as the 

wolf range overlaps BTPD and gray wolf prey items may include animals poisoned by Rozol, 

including small mammals, birds and large invertebrates. The EPA determined that adverse direct 

effects to the gray wolf are likely based on calculated RQs that included 24.82 for exposure to 

non-target animals and 9.59 for exposure to BTPDs (Table 1.1, page 21, of the BA). In their 

Risk Quotient Methods and Levels of Concern submitted for this consultation, the EPA further 

estimates that the gray wolf would only need to consume less than 1 poisoned mouse or less than 

1 poisoned BTPD every day for 5 days to exceed a 0.1 LOC for endangered species. On page 21 

of the BA (Table 1.1), the EPA states that “growth and reproductive effects cannot be precluded 

due to the absence of chronic data; however, growth and reproductive effects are not expected 
74

because mortality typically occurs as a result of acute exposure.” Table 1.1 of the BA also 

describes potential indirect effects due to the loss of prey base. The Service agrees that Rozol 

use on BTPDs could adversely affect dispersing wolves. 

(2) Analyses for the effects of the action 

The effects to dispersing gray wolves in the action area are most likely to be indirect, i.e., 

secondary poisoning via consumption of Rozol-poisoned live animals or carcasses. It is 

suspected that wolves would consume dead or dying prairie dogs if they are encountered above 

ground and may also excavate and consume prairie dogs that are buried or die underground. The 

frequency at which a dispersing wolf might encounter a Rozol-poisoned area is unknown and 

would depend on a variety of factors such as the prevalence of Rozol use in the area, the type of 

habitat traveled by the wolf, the distance traversed, and the availability of other prey items. 

Although there are no previous reports of gray wolf exposure to chlorophacinone rodenticides, 

other canines (including kit foxes and coyotes), in addition to an American badger, have been 

found dead in association with Rozol applications (Ruder et al. 2011). Although these animals 

are smaller than a wolf, they are all opportunistic predators and scavengers like wolves. If 

multiple dead and dying prairie dogs and other non-target small mammals were available for 

consumption, a wolf would likely take advantage of that situation. Effects of chlorophacinone 

exposure to the gray wolf when individuals do encounter a Rozol-poisoned prairie dog colony 

would likely be similar to those seen in domestic dogs suffering from anticoagulant rodenticide 

toxicosis which include shortness of breath, hemoptysis (i.e., the spitting up of blood from the 

lungs), pallor (i.e., reduced amount of oxyhaemoglobin in skin), and lethargy (Sheafor and Couto 

1999, Murray and Tseng 2008). The EPA’s use of an adjusted LD 50 of 0.03 mg/kg to evaluate 

risk to gray wolves is much more conservative than using the chlorophacinone LD50 range of 

50-100 mg/kg for dogs (EPA 2010b). 

The Service agrees with the EPA that a wolf that encounters a Rozol-poisoned BTPD colony 

could receive a lethal dose from consuming poisoned prairie dogs. The extent of effects and 

severity of response by a gray wolf to consumption of Rozol-poisoned animals would depend in 

part on the amount of Rozol ingested over time because most animals experience greater adverse 

effects from multiple doses of chlorophacinone. Repeat exposure could occur if a dispersing 

wolf remains near a Rozol-poisoned prairie dog colony and obtains multiple meals from it. 

Receiving a lethal dose may take more than one poisoned prairie dog. Sub-lethal effects may 

occur if a wolf leaves a prairie dog town before consuming a lethal dose or if timing is such that 

it does not find enough Rozol-poisoned animals to consume. However, little information is 

available regarding sub-lethal effects, and Rozol is known to be an effective anticoagulant. It 

seems likely that death would be the likely result for a gray wolf that ingests Rozol, either 

directly through hemorrhaging or sub-lethal impairment of behavior (e.g., breeding, feeding and 

sheltering), that eventually leads to its demise. 

It is the Service’s opinion that indirect effects to the gray wolf due to the loss of prey base from 

use of Rozol are not cause for concern regarding effects to wolves because prairie dogs are not 

known to be a significant dietary item for the gray wolf which normally does not inhabit BTPD 

areas. Dispersing individuals are anticipated to come upon BTPD colonies only 

opportunistically as they travel. 
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(3) Species’ Response to the Action 

Because the number of wolves dispersing into the action area is anticipated to be very low (as 

indicated above, we are aware of 20 gray wolf mortalities over 31 years in the action area), 

population-level effects are not anticipated. Most of the habitat within the action area is not 

important for wolf recovery, and we do not expect populations to become established in these 

areas. Lethal control of wolves in North Dakota and South Dakota has been determined to have 

no adverse effects on the long-term viability of wolf populations in the delisted Western Great 

Lakes DPS because the existence of a wolf or a wolf population in the Dakotas would not make a 

meaningful contribution to the maintenance of the current viable, self-sustaining, and 

representative metapopulation of wolves in the Western Great Lakes DPS (FWS 2011j). The 

same may be said for wolves dispersing from the Northern Rocky Mountain DPS. The potential 

impact to the Mexican gray wolf population within the area occupied by wolves is not expected 

to be great, given the EPA’s adopted conservation measure to prohibit Rozol use in counties 

within the core reintroduction area, the ongoing intensive management (capture and return of 

dispersing wolves to reintroduction area) that inhibits dispersal of Mexican gray wolves, relative 

lack of preference by wolves for the open country typical of BTPD colonies, and risk posed to 

wolves that occur in such habitats where they are highly visible and vulnerable to more direct 

forms of human mortality (i.e., shooting). However, within the 15-year timeframe for which this 

BO is applicable, it is possible for reintroduced Mexican gray wolves to enter the United States 

via Mexico’s reintroduction efforts, and Mexican gray wolves in New Mexico may expand their 

populations beyond the current 10(j) boundaries. If Rozol use is determined to result in wolf 

mortality beyond the low levels anticipated herein, such mortality could impede recovery of the 

Mexican gray wolf (FWS 1982). With the exception of the Mexican gray wolf population, 

individual gray wolves lost to Rozol poisoning are not anticipated to incur population level 

effects to the species. In the absence of human-induced mortalities and presence of adequate 

prey, gray wolves are a resilient species demonstrating relatively fast recovery rates after 

population declines. However, due to the diminished status of the Mexican gray wolf 

population, take of any wolves in New Mexico due to Rozol is of increased concern and could 

affect the ability of wolves to expand their populations. 

(a) Cumulative Effects 

Cumulative effects include the effects of future state, tribal, local or private actions that are 

reasonably certain to occur in the action area considered in this BO. Future Federal actions that 

are unrelated to the proposed action are not considered in this section because they require 

separate consultation pursuant to Section 7 of the ESA. 

The level of human activities in the action area today is anticipated to continue and perhaps 

increase as human populations continue to expand. Farming and ranching is prevalent in the 

range of the BTPD and will continue into the foreseeable future. The Service anticipates high 

mortality rates for gray wolves that disperse in the BTPD range. Such wolves occurring outside 

of their current cores ranges are likely to be intentionally or unintentionally killed via such 

mechanisms as vehicle collisions, poisoning, and shooting which will likely prevent 

recolonization of significant areas of the BTPD range. Cumulatively, wolf populations have 

continued to rise in the face of these factors, except for the Mexican gray wolf population. For 
76

Mexican gray wolves, any additional mortality, when combined with the effects of the proposed 

action, is a cause for concern. However, we do not believe that it is to the level that would 

preclude recovery of the Mexican gray wolf, due to the low value of the open habitats preferred 

by BTPDs for the wolf. 

(b) Conclusion Regarding Jeopardy 

After reviewing the current status of the gray wolf, the environmental baseline for the action 

area, the effects of the proposed use of Rozol to control BTPDs in 10 western states, and the 

cumulative effects, it is the Service’s biological opinion that the action, as proposed, is not likely 

to jeopardize the continued existence of the gray wolf. Critical habitat has been designated but 

does not occur in or near the action area; therefore, none will be affected. Our conclusion was 

based primarily on the following factors: 

 Gray wolves dispersing into the action area are a very small portion of existing gray wolf 

populations, and such individuals are typically precluded from establishing packs and 

territories due partly to high mortality rates. 

 Dispersing wolves in the BTPD range are not considered critical to the recovery of wolf 

populations in the United States and, cumulatively, gray wolf populations have continued to 

increase despite losses of dispersing individuals. 

 The BTPD colonies are not typical habitat for the gray wolf, dispersing individuals are not 

anticipated to remain in such areas for long, and lack of cover for gray wolves within BTPD 

habitat often results in increased vulnerability to other mortality factors such as shooting. 

 Gray wolf populations are considered recovered by the Service in the Northern Rocky 

Mountain and Western Great Lakes DPSs; delisting has occurred, and future delisting in 

Wyoming is proposed. 

 The conservation measure by the EPA to preclude Catron, Grant, Hidalgo, and Sierra 

Counties in New Mexico from Rozol use is protective of the Mexican gray wolf. 

Impediments to recovery may be possible in the future if Mexican wolf populations expand 

into new areas and Rozol-related mortalities are determined to exceed currently anticipated 

levels for the Mexican gray wolf, but a low number of Mexican gray wolves are expected to 

be affected by the action at this time. 

3. NORTHERN APLOMADO FALCON 

a. Status of the Species/Critical Habitat 

The northern aplomado falcon (Falco femoralis septentrionalis) is one of three subspecies of the 

aplomado falcon and is the only one of those recorded in the United States. This subspecies was 

listed by the Service as an endangered species on February 25, 1986 (FWS 1986). It once 

extended from Trans-Pecos Texas, southern New Mexico and southeastern Arizona, to Chiapas 

and the northern Yucatan along the Gulf of Mexico and along the Pacific slope of Central 

America north of Nicaragua (FWS 1990). Northern aplomado falcons were fairly common in 

suitable habitat throughout these areas until the 1940s. However, they subsequently declined 
77

rapidly and became extirpated from the United States after 1952. The last documented nesting 

pair of wild northern aplomado falcons in the United States was in Luna County, New Mexico, 

in 1952. 

The decline of the northern aplomado falcon was caused by widespread shrub encroachment 

resulting from control of range fires and intense overgrazing (FWS 1986, Burnham et al. 2002), 

and large-scale agricultural development in grassland habitats used by the northern aplomado 

falcon (Heady 1994, Keddy-Hector 2000). Pesticide exposure was likely a significant cause of 

the subspecies’ extirpation from the United States with the initiation of widespread use of 

organochlorine pesticides, such as DDT (dichlorodiphenyltrichloroethane) and DDE 

(dichlorodiphenyldichloroethylene), after World War II which coincided with the northern 

aplomado falcon’s disappearance (FWS 1986). Northern aplomado falcons in Mexico in the 

1950s were heavily contaminated with DDT residue, and these levels caused a 25 percent 

decrease in eggshell thickness (Kiff et al. 1980). Such high residue levels can often result in 

reproductive failure from egg breakage (FWS 1990). Use of organophosphate insecticides may 

also threaten northern aplomado falcons because insects and small, insectivorous birds are the 

species’ preferred prey items (Keddy-Hector 2000). Collection of northern aplomado falcons 

and their eggs may have also been detrimental to the subspecies in some localities. However, 

populations of birds of prey are generally resilient to localized collection pressure (FWS 1990). 

Little is known about the migratory behavior or seasonal movements of northern aplomado 

falcons (Service 1990). Nesting chronology is somewhat variable with egg-laying recorded from 

January to September, although eggs are usually laid during the months of March to May. 

Northern aplomado falcons do not build their own nests, but use nest sites constructed by corvids 

such as Chihuahuan ravens (Corvus cryptoleucus) or by large raptors. Thus, northern aplomado 

falcons are dependent on nesting activities of other stick nest-building birds and their habitat 

requirements. Nest sites are found in structures such as multi-stemmed yuccas (Yucca torreyi 

and Yucca elata) and large mesquite trees (Prosopis spp.) as well as other trees. 

Northern aplomado falcons feed on a variety of prey, including birds, insects, rodents, small 

snakes, and lizards. Ligon (1961) suggested that the food habits of northern aplomado falcons 

“consisted almost wholly of small reptiles, lizards, mice, other rodents, grasshoppers, and 

various other kinds of insects, rarely small birds except in winter when other food is lacking.” 

Therefore, in winter, factors affecting habitat suitability for migratory bird species may also 

affect the suitability of the habitat for northern aplomado falcons which in turn can affect the 

potential for survival of northern aplomado falcons (FWS 2002b). In eastern Mexico, small 

birds accounted for 97 percent of total prey biomass, but insects represented 65 percent of prey 

individuals (Hector 1985). In one study, 82 bird species were found in prey remains; of these, 

the most common were meadowlarks (Sturnella spp.), common nighthawks (Chordeiles minor), 

northern mockingbirds (Mimus polyglottos), western kingbirds (Tyrannus verticalis), brownheaded cowbirds (Molothrus ater), Scott’s oriole (Icterus parisorum), mourning doves (Zenaida 

macroura), cactus wrens (Campylorhynchus brunneicapillus), and pyrrhuloxia (Cardinalis 

sinuatus), suggesting a preference for medium-sized songbirds (FWS 2002b). Documented 

invertebrate prey includes grasshoppers, beetles, dragonflies, cicadas, crickets, butterflies, moths, 

wasps, and bees (FWS 1990). Differences in prey abundance and nest site availability can cause 

differences in home range size. Based on several studies, the Service estimates the northern 
78

aplomado falcon home range size to be approximately 34 square km2 (8,401 acres) (FWS 1990, 

2002b). For management purposes, this area can be described by a circle with a radius of 3.2 km 

(2 mi) around a particular habitat feature (e.g., a nest site). 

Northern aplomado falcon habitat is variable throughout its range and includes palm and oak 

savannahs, various desert grassland associations, and open pine woodlands. Within these 

variations, the essential habitat elements appear to be open terrain with scattered trees, relatively 

low ground cover, an abundance of insects and small to medium-sized birds, and a supply of nest 

sites (FWS 1990). In Mexico, reported habitat includes palm and oak savannas, open tropical 

deciduous woodlands, wooded fringes of extensive marshes, various desert grassland 

associations, and upland pine parklands (FWS 1990). The historical range of the northern 

aplomado falcon in Texas, New Mexico and Arizona occurs within the Chihuahuan Desert which 

is comprised of three basic community types: desert scrub, desert grasslands, and woodlands. 

The species’ historical range also occurs in the coastal prairies of southern Texas. 

Northern aplomado falcons are primarily associated with open grasslands that include scattered 

mesquite and/or yuccas, although small patches of scrub and woodlands may be used (FWS 

2006f). Existing data suggest that the ecological status of Chihuahuan Desert grasslands 

currently occupied by northern aplomado falcons is high seral to potential natural community or 

climax with significant basal cover of grass species. Montoya et al. (1997) reported the occupied 

nesting habitat as having basal ground cover ranging from 29 to 70 percent with a mean of 

46 percent. Woody plant density ranged from 5 to 56 plants per acre with a mean of 31 plants 

per acre. Dominant woody plant species, comprising 74 percent of this community, were 

Mormon tea (Ephedra viridis), soaptree yucca (Yucca elata), sacahuista (Nolina microcarpa), 

mesquite, senecio (Senecio spp.), creosotebush (Larrea tridentata), and baccharis (Baccharis

spp.). Site-specific habitat assessments should be conducted to further define whether the site of 

a given project or activity occurs within suitable habitat for this species. 

In recent times, the intense overgrazing that resulted in shrub encroachment into grasslands has 

moderated, and improved range management techniques have been developed, including 

decreased stocking rates, stock rotation, prescribed burning, and other brush control methods 

(Archer 1994, Heady 1994, Burnham et al. 2002). Furthermore, the use of DDT was banned in 

the United States in 1972 and in Mexico in 2000. Present threats to the northern aplomado 

falcon including long-term drought and continued replacement of grassland communities with 

shrubs in Chihuahuan Desert grasslands. Additionally, large-scale conversion of grasslands to 

agriculture and the increased presence of the great-horned owl (Bubo virginianus), which preys 

upon the northern aplomado falcon, may be limiting recovery of this subspecies (Macías-Duarte 

et al. 2004, FWS 2006g). In contrast to these current threats, northern aplomado falcons appear 

to be relatively tolerant of human presence. They have been observed to tolerate approach to 

within 100 m (328 ft) of their nests by researchers, have nested within 100 m (328 ft) of 

highways in eastern Mexico (Keddy-Hector 2000), and are frequently found nesting in 

association with well-managed livestock grazing operations in Mexico and Texas (Burnham 

et al. 2002). Burnham et al. (2002) concluded that northern aplomado falcons would be able to 

coexist with most current land-use practices in the United States on the broad scale. 

A recovery plan for the northern aplomado falcon was finalized by the Service in 1990 (FWS 

1990). The objective of the Aplomado Falcon Recovery Plan is to ensure that the northern 
79

aplomado falcon is no longer threatened by habitat loss, pesticide contamination, or human 

persecution. Implementation of the steps outlined in the Aplomado Falcon Recovery Plan could 

lead to downlisting the northern aplomado falcon from endangered to threatened by 2030. 

To address reestablishment of northern aplomado falcons in the United States, reintroduction of 

nestling northern aplomado falcons was identified by the Aplomado Falcon Recovery Plan as a 

recommended methodology. To further aid reestablishment, reintroduction sites are carefully 

selected to optimize habitat suitability. Northern aplomado falcon reintroductions have been 

ongoing in southern Texas since 1985 on National Wildlife Refuges and private land under Safe 

Harbor Agreements. Consequently, by 2005, reintroductions had resulted in at least 44 pairs of 

northern aplomado falcons in southern Texas and adjacent Tamaulipas, Mexico, where no pairs 

had been recorded since 1942 (Jenny et al. 2004). The first nesting pair of northern aplomado 

falcons in south Texas subsequent to releases did not occur until 1995; however, by 2005, the 

Texas pairs had successfully fledged more than 244 young (Juergens and Heinrich 2005). In 

2008, The Peregrine Fund found that 31 out of 38 territories surveyed in southern Texas were 

occupied (The Peregrine Fund 2009). There are likely more breeding pairs present in this area 

than what has been documented, considering areas of habitat that are inaccessible for surveys. 

Reintroduction of captive-bred northern aplomado falcons began in west Texas in 2002. The 

Peregrine Fund reported up to 10 breeding pairs were found in west Texas in 2009, including 

pairs that successfully reproduced (Heinrich 2010). 

 

Reintroduction of captive-bred northern aplomado falcons began in New Mexico with the release 

of 11 birds in 2006 on the privately-owned Armendaris Ranch near Truth or Consequences. In 

2007, a pair of northern aplomado falcons from this first year of reintroductions produced two 

fledglings on the ranch. In 2007, a total of 41 birds were released in New Mexico on private, 

State, Bureau of Land Management, and Department of Defense lands. Releases are planned to 

continue through 2015 with up to 150 northern aplomado falcons released in New Mexico each 

year. 

To date, 686 young falcons have been released in west Texas and 305 falcons in southern New 

Mexico in unfragmented native grasslands on private, State, and federally-managed areas. 

Northern aplomado falcons in New Mexico and Arizona are included in a NEP designation under 

Section 10(j) of the ESA (Service 2006f). When NEPs are located outside a National Wildlife 

Refuge or unit of National Parks, they are treated as proposed for listing and only two provisions 

of Section 7 apply: Section 7(a)(1) and Section 7(a)(4). Section 7(a)(4) requires Federal 

agencies to confer, rather than consult, with the Service on actions that are likely to jeopardize 

the continued existence of a proposed species. The results of a conference are advisory in nature 

and do not restrict agencies from carrying out, funding, or authorizing activities. Northern 

aplomado falcons have been reintroduced in Texas on private lands using Safe Harbor 

Agreements, and their regulatory status under the ESA is endangered. Therefore, Section 7(a)(2) 

consultation by Federal agencies applies to aplomado falcons in Texas. 
80

Currently, there are approximately 36 aplomado falcon pairs in the United States, which 

constitute less than two-thirds of the minimum number of 60 self-sustaining breeding pairs in 

suitable parts of the southwestern United States recommended by the 1990 Recovery Plan for 

reclassification of the subspecies to threatened status. The great majority of these breeding pairs 

currently occur outside the action area of this project in south Texas due to higher prey 

availability in the coastal region. Over the course of this 15-year project, the Service expects 

more breeding pairs to establish in New Mexico and west Texas. 

b. Environmental Baseline 

Formal surveys and reliable sightings submitted to the Service show that a small number of 

northern aplomado falcons have been sighted in the United States during every decade since the 

1960s (FWS 2006f). In addition, a resident pair of northern aplomado falcons in Luna County, 

New Mexico, bred successfully in 2002, fledging three young. These were the first known 

northern aplomado falcons produced in either New Mexico or Arizona since the subspecies' 

extirpation as a breeding species in the 1950s. Another pair was reported near this site in 2002, 

but no nest was located and only one of the pair was present 2 days later (Meyer and Williams 

2005). The 2002 nest represented the first successful reproduction by naturally occurring 

northern aplomado falcons in the United States in 50 years. Meyers and Williams (2005) 

reported at least eight individual northern aplomado falcons in Luna County between 2000 and 

2004. The species occurred historically in Hidalgo County, and there have been five reports of 

northern aplomado falcons in or near the Animas Valley from the 1990s through the early 2000s 

(Meyer and Williams 2005). 

(1) Status of the species within the action area 

The action area for this consultation includes the historic range of the BTPD in the United States 

and counties adjacent to that range. The northern aplomado falcon is currently found in Texas 

and New Mexico as well as Guatemala and Mexico. Therefore, the portion of the action area of 

concern for the northern aplomado falcon includes only New Mexico and Texas where the range 

of this species coincides with the proposed use of Rozol to control BTPDs in the United States. 

Northern aplomado falcons in New Mexico were designated a 10(j) NEP to encourage 

landowners to support the reintroduction of northern aplomado falcons in the state. Several 

landowners have supported reintroduction and manage the introduction areas to promote 

northern aplomado falcons. Under the 10(j) rule, northern aplomado falcons do not have 

incidental take restrictions on private lands. In Texas, private landowners that have allowed 

releases of northern aplomado falcons on their property are party to a Safe Harbor Agreement 

(FWS 1996 and 2000a) that covers the entire area within 30 miles of each release site. Under the 

Safe Harbor Agreement program, participating landowners are permitted to take northern 

aplomado falcons incidental to future lawful land-use actions (such as prairie dog control), 

provided that the landowner maintains any established baseline responsibilities (FWS 2000b). 

All northern aplomado falcon release sites and all recorded nests and northern aplomado falcon 

pairs within the action area in Texas occur on lands covered by the Safe Harbor Agreement 

(Montoya 2011, personal communication). 
81

(2) Factors affecting species environment within the action area 

The loss of or physical degradation of conditions in occupied habitat or in potential 

reintroduction sites would compromise the reintroduction program and recovery of the northern 

aplomado falcon. While the NEP in New Mexico and Arizona is not necessary for the continued 

survival of the species, it provides the benefit of an additional population in the event of a 

catastrophic loss of populations in Texas.

 

Sources of loss and degradation of nesting and roosting sites may include land use and human 

activities. The activities described below are common sources of stressors that affect the 

conservation of the northern aplomado falcon. 

(a) Land use 

Land use activities affect the distribution, density, and species composition of the native 

vegetation communities on the landscape. Land clearing (including for facilities, roads, trails 

and utility corridors) eliminates the vegetation, livestock grazing reduces the biomass of desired 

species and promotes others (that may have differing densities on the ground as well), ground or 

surface water depletion eliminates riparian and marsh vegetation communities, and erosion can 

eliminate plants along the paths of gullies.

(b) Livestock grazing 

There has been considerable literature produced on the effects of livestock grazing on natural 

vegetation communities in the desert Southwest. Desert shrublands, grasslands, and woodlands 

in arid areas face certain threats from any land use that affects the surface and vegetation 

community. 

Currently, the intense overgrazing that resulted in shrub encroachment in the Chihuahuan Desert 

grasslands in New Mexico and Arizona has moderated, and improved range management 

techniques have been developed and implemented, including decreased stocking rates and stock 

rotation. Techniques to increase the incidence of beneficial fire, to restore and increase 

vegetative productivity, to control erosion, and to suppress brush encroachment have been 

widely implemented in this planning unit. Among these are managed fire (including prescribed 

burns), various types of erosion control structures, and various types of brush control measures 

(Archer 1994, Heady 1994, Burnham et al. 2002). In addition, livestock management on Federal 

lands must now also consider other public resources. Within this planning unit, many private 

landowners and public land managers maintain well-managed livestock grazing programs that 

are compatible with northern aplomado falcon nesting and roosting and maintenance of 

reintroduction habitat suitability. 

(c) Road construction, maintenance, and use

Construction and maintenance of access roads has a significant effect on the landscape. Roads 

and trails provide for foot or vehicle access to the landscape for a variety of purposes that often 

have other effects on soils, water features, vegetation communities, and wildlife.
82

(d) Communications towers and power lines

Although the effect of communication towers and power lines on the northern aplomado falcon 

is not well documented, these structures can have an adverse effect on bird species in general, 

and raptors in particular, due to collision or electrocution. Although birds can collide with any 

part of a communication tower, causing injury or death, they are most likely to collide with 

unmarked guy wires, which can be difficult to see. Northern aplomado falcons may also collide 

with power lines, especially if the power lines are unmarked. Power lines that are uninsulated 

may electrocute northern aplomado falcons if they try to use them to perch on or collide with 

them. Northern aplomado falcons may be particularly vulnerable to collision with such objects 

as they tend to “engage in high-speed, low-level, reckless pursuits of swift avian prey” (KeddyHector 2000).

(e) Organochlorine and organophosphate pesticide contamination 

In the past, organochlorine compounds (DDE/DDT) were heavily used in pesticide applications 

in the agricultural areas surrounding northern aplomado falcon habitat in south Texas. It is 

unclear to what degree residual chemicals may still be present in the species’ prey base, although 

some evidence indicates that this may be a lingering threat (Mora et al. 1997, Keddy-Hector 

2000). In addition, organophosphate insecticides may threaten the species through adverse 

effects on its primary prey base of insects and small insectivorous birds, particularly in 

agricultural areas of south Texas. 

c. Effects of the Action

The RQ calculated by the EPA for the northern aplomado falcon, based on the LC50 value of 

56 mg active ingredient per kilogram diet, was 0.104 for consumption of non-target animals. A 

LOC of 0.1 for the RQ is set for listed species (EPA 2010b). Because the RQ of 0.104 exceeds 

the LOC, the EPA determined that there is potential for risk of acute adverse effects to northern 

aplomado falcons from exposure to Rozol (EPA 2010b). The BA states that the northern 

aplomado falcon would have to consume 5 poisoned mice or less than 1 poisoned BTPD to reach 

the LOC and are more likely to consume mice than BTPDs. The BA also states that, because no 

avian reproduction studies have been conducted, risk cannot be precluded at any level. 

While there is no avian reproductive study to help estimate risk, external bleeding, fatigue, 

internal hemorrhaging, and increased blood coagulation has been reported in studies of 

secondary exposure to birds (see section on “Indandione Mode of Action and Toxicity” above). 

Additionally, chlorophacinone is a first generation rodenticide, and consecutive intake over 

multiple days tends to reduce the amount that results in lethal dose. Thus, BTPDs and non-target 

species such as mice can accumulate a “super dose” prior to expiring or becoming intoxicated 

and predated upon by birds such as the northern aplomado falcon. It could take less than 5 mice 

or 1 BTPD to intoxicate a northern aplomado falcon. However, due to its relatively small size, 

the northern aplomado falcon is not likely to take prey as large as a BTPD, and the northern 

aplomado falcon is not known to scavenge. 

As described in the “General Background” section above, raptors such as the northern aplomado 

falcon may be especially sensitive to Rozol per our previous discussion in the “Rozol Exposure 

and Effects Assessment” section. Although toxicity data for chlorophacinone effects to raptors 
83

are lacking, toxicity tests with diphacinone indicate that some raptors are 20-30 times more 

sensitive than the two test species, northern bobwhite quail and mallard duck, required by the 

EPA for pesticide registration (Rattner et al. 2010a, 2011a, 2011b). Given the similarity of 

chlorophacinone to diphacinone, we believe that the northern aplomado falcon is more sensitive 

to Rozol than was estimated in the BA using bobwhite quail LC50 data. Therefore, acute and 

sub-acute risks to the northern aplomado falcon are likely higher than assessed in the BA. 

If individual northern aplomado falcons were to enter a BTPD colony, exposure to 

chlorophacinone via consumption of primary consumers of Rozol bait may occur. The falcons 

are not known to consume carrion, but Rozol poisoning of this species is possible via 

consumption of live mammals and birds that have fed on Rozol bait. As mentioned previously, 

the evidence of Rozol exposure to horned larks and a meadowlark from a field application of 

Rozol (Vyas 2010a) indicate that predation of songbirds that have consumed Rozol bait is a 

likely route of exposure to northern aplomado falcons. In addition to small birds, which the 

falcon may prey on preferentially in the winter when other food is lacking, the food habits of the 

northern aplomado falcon consist of small reptiles, lizards, mice, other rodents, grasshoppers and 

other insect species. In eastern Mexico, small birds accounted for 97 percent of total prey 

biomass, but insects represented 65 percent of prey individuals (Hector 1985). In one study, 

82 bird species were found in prey remains suggesting a preference for medium-sized songbirds, 

although birds over 500 g have been recorded (FWS 2002b). 

Following treatment with Rozol, northern aplomado falcons may experience repeated doses of 

Rozol-exposed prey. During a Rozol treatment, dead and dying primary consumers (i.e., 

BTPDs, other small mammals, and birds) were visible in colonies 9 days after treatment and 

were still present when the study ended at day 29 post-treatment (Vyas 2010a). Additionally, 

raptors may preferentially fed at prairie dog colonies treated with Rozol compared to untreated 

colonies (Vyas 2010a). This effect has been observed in predators previously. Kestrels 

preferentially catch prey displaying aberrant behavior following pesticide exposure compared to 

healthy prey (Hunt et al. 1992). The northern aplomado falcon may also be attracted to 

Rozol-treated prairie dog colonies if they provide a source of easy meals of either rodents or 

birds species. 

Northern aplomado falcons experiencing secondary exposure to chlorophacinone are likely to 

experience mortality or sub-lethal effects which may result in behavioral changes affecting 

feeding, breeding, or sheltering activities of individuals. The effects of toxicity could be 

influenced by other stressors, such as previous exposure and retention of pesticides, including 

other anticoagulants. 

Because raptors may be highly sensitive to Rozol, non-target exposure is also likely to reduce the 

availability of large raptor nests that northern aplomado falcons require for nesting. As 

described above, northern aplomado falcons do not build their own nests but use nests 

constructed by corvids or large raptors. These large predators can successfully predate or 

scavenge prairie dogs that have eaten Rozol-contaminated bait. When these predators are killed 

by exposure to Rozol, the number of stick nests available to northern aplomado falcons for 

nesting is also reduced. This may cause northern aplomado falcons to expend more time, energy, 

and risk to locate suitable nesting substrate, or they may find no suitable nests and forego 

breeding altogether. 
84

Actual exposure is expected to be minimal due to the low density of BTPD colonies within the 

northern aplomado falcon’s range. In addition, in areas where the northern aplomado falcon has 

been reintroduced in Texas, landowners have signed cooperative agreements with the Service 

and The Peregrine Fund to maintain northern aplomado falcon habitat at or above baseline levels 

and are responsible to notify these organizations before performing land use practices that may 

adversely affect the northern aplomado falcon. For these reasons, we expect the frequency of 

northern aplomado falcons encountering Rozol-treated BTPD colonies to be low, and few 

northern aplomado falcons would experience sub-lethal effects or mortality from consuming 

Rozol-exposed prey. 

However, we also anticipate that detection of Rozol-poisoned northern aplomado falcons will be 

rare. The birds are highly mobile; debilitated, dying, or dead falcons, particularly when they 

move away from Rozol-poisoned prairie dog colonies, are likely to go unreported. Rozol has 

been used for BTPD control in Texas since 2006 under a SLN label. While we are unaware of 

any incidents involving Rozol and the northern aplomado falcon, we recognize the vastness of 

the area involved and the difficulty in locating Rozol-affected raptors such as northern aplomado 

falcon. 

d. Cumulative Effects

Cumulative effects include the effects of future State, tribal, local or private actions that are 

reasonably certain to occur in the action area considered in this BO. Future Federal actions that 

are unrelated to the proposed action are not considered in this section because they require 

separate consultation pursuant to Section 7 of the ESA. 

Human activities may affect the northern aplomado falcon and result in direct and indirect 

mortality, habitat loss, or reduction of habitat suitability. Anthropogenic uses of northern 

aplomado falcon habitat include ungulate grazing, recreation, fuels reduction treatments, 

resource extraction (e.g., timber, oil and gas), and development (e.g., roads and power lines). 

These activities can potentially reduce the quality of northern aplomado falcon nesting, roosting, 

and foraging habitat, and may cause disturbance during the breeding season. 

e. Conclusion Regarding Jeopardy 

After reviewing the current status of the northern aplomado falcon, the environmental baseline 

for the action area, the effects from the use of Rozol, and the cumulative effects, it is the 

Service’s biological opinion that the use of Rozol, as proposed, is not likely to jeopardize the 

continued existence of the northern aplomado falcon. No critical habitat has been designated for 

this species; therefore, none will be affected. 

The reasons for this determination are: 

 The northern aplomado falcon may prey on non-target organisms that feed on Rozol grain 

bait, but it is unlikely that this would occur regularly or predictably. Because the aplomado 

falcon does not feed upon dead animals, exposure to individuals would only occur from 

moribund animals on the surface. Moribund animals are expected to be a small proportion of 

Rozol-poisoned animals available on the surface. 
85

 In areas where the northern aplomado falcon has been reestablished in Texas, landowners 

have signed cooperative agreements with the Service and The Peregrine Fund to maintain 

northern aplomado falcon habitat at or above baseline levels, and are responsible to notify 

these entities before performing land use practices that may adversely affect the northern 

aplomado falcon. 

 As BTPD colonies are not known to be highly important habitat for northern aplomado 

falcon foraging, it is not anticipated that Rozol use as proposed in this action will preclude 

recovery of this species even when combined with other potential anthropogenic threats. In 

addition, cooperative agreements with landowners in reintroduction areas allows for the 

monitoring and potential avoidance of take within reintroduction areas. 

 Most breeding aplomado falcons are outside the action area of this project in south Texas. 

This greater proportion is expected to persist for the duration of this project due to higher 

prey availability in the coastal region. Therefore, the survival of the northern aplomado 

falcon is not anticipated to be jeopardized by Rozol use in New Mexico and west Texas. 

 Reintroduction of captively bred northern aplomado falcons is expected to continue within 

the range of the species during some years of this project. 

 
86

INCIDENTAL TAKE STATEMENT 

I. INTRODUCTION

Section 9 of the ESA and Federal regulation pursuant to Section 4(d) of the ESA prohibit the 

take of endangered and threatened species, respectively, without special exemption. Take means 

to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture or collect, or to attempt to engage 

in any such conduct. Harm is further defined by the Service to include significant habitat 

modification or degradation that results in death or injury to listed species by significantly 

impairing essential behavioral patterns, including breeding, feeding, or sheltering. Harass is 

defined by the Service as intentional or negligent actions that create the likelihood of injury to 

listed species to such an extent as to significantly disrupt normal behavior patterns which 

include, but are not limited to, breeding, feeding or sheltering. Incidental take is defined as take 

that is incidental to, and not the purpose of, the carrying out of an otherwise lawful activity. 

Under the terms of Section 7(b)(4) and Section 7(o)(2), taking that is incidental to and not 

intended as part of the agency action is not considered to be prohibited taking under the ESA, 

provided that such taking is in compliance with the terms and conditions of the ITS. 

The measures described below are non-discretionary and must be undertaken by the EPA so that 

they become binding conditions of any grant or permit issued to Liphatech, Inc., as appropriate, 

for the exemption in Section 7(o)(2) to apply. The EPA has a continuing duty to regulate the 

activity covered by this ITS. If the EPA 1) fails to assume and implement the terms and 

conditions, or 2) fails to require Liphatech, Inc. to adhere to the terms and conditions of the ITS 

through enforceable terms that are added to the permit document, the protective coverage of 

Section 7(o)(2) may lapse. In order to monitor the impact of incidental take, the EPA must 

report the progress of the action and its impact on the species to the Service as specified in the 

ITS (50 CFR § 402.14(i)(3)). For the northern aplomado falcon, this applies to Texas 

populations. 

For northern aplomado falcons in New Mexico, the prohibitions against taking this species found 

in Section 9 of the ESA have been modified by the nonessential experimental designation. The 

results of this conference are advisory in nature and do not restrict agencies from carrying out, 

funding, or authorizing activities. However, the Service advises EPA to consider implementing 

the RPMs for northern aplomado falcons in New Mexico. 

Under the Safe Harbor Agreement program, for northern aplomado falcons participating 

landowners are permitted to take aplomado falcons incidental to future lawful land-use actions 

(such as prairie dog control), provided that the landowner maintains any established baseline 

responsibilities (Service 2000b). 

This ITS exempts take of black-footed ferrets, gray wolves, and northern aplomado falcons 

protected by the ESA that may be incurred by the proposed action, provided the September 10, 

2010, Rozol label, with modifications specified herein, is followed. 

Noncompliance with the Rozol label that results in take of gray wolves is not covered by this 

ITS; end users who do not comply with label requirements are not afforded take coverage and 

are subject to prosecution under Section 9 of the ESA. 
87

II. AMOUNT OR EXTENT OF TAKE ANTICIPATED

A. Black-footed ferret 

The Service has developed this ITS based on the premise that the EPA and Liphatech will 

implement the label measures that include black-footed ferret conservation measures as 

previously described. The conservation measures prohibit application of Rozol within current 

black-footed ferret reintroduction sites (12 sites in the 10 states) and future reintroduction areas 

to reduce the level of impact to the black-footed ferret. This information is to be located in the 

EPA’s Bulletin Live! database. Changes to this database take approximately 8 months to enact; 

therefore, the Service will provide information to the EPA accordingly.

Take of black-footed ferrets is expected in the form of mortality when individuals disperse from 

a reintroduction area and encounter a BTPD colony that has been poisoned with Rozol within the 

previous 2 months, or if the black-footed ferret is residing on a colony when Rozol is applied. 

While black-footed ferrets can leave reintroduction sites, those departures are unlikely to be 

documented, and the Service is unable to accurately predict the number of black-footed ferrets 

that may encounter Rozol-poisoned BTPD colonies. Most black-footed ferrets that leave a 

reintroduction area are likely to die because of natural causes (predation/starvation) or other 

activities (vehicle collisions) unrelated to Rozol. Further, due to black-footed ferrets’ nocturnal 

behavior and tendency to spend much of their time underground in prairie dog burrows, it is 

unlikely that many, if any, black-footed ferret mortalities due to Rozol will be reported to further 

inform this issue. Therefore, while dispersing black-footed ferrets may die from consuming 

Rozol-poisoned prairie dogs, this number is not anticipated to be large and will rarely be 

detected.

At previous black-footed ferret reintroduction sites, there are very few reports of dispersing 

animals outside the reintroduction site, and the reports received are typically associated with 

mortalities such as vehicle collisions or possible sightings that are followed up with concerted 

nighttime surveys (Hanebury and Biggins 2006). Black-footed ferret reintroduction site 

managers are authorized to retrieve dispersing black-footed ferrets if that information is available 

and if the landowner wants the black-footed ferrets removed from their property. Requests to 

relocate black-footed ferrets that have left a reintroduction area are very rare. 

The Service anticipates that take of dispersing black-footed ferrets that leave a reintroduction 

area and encounter a Rozol poisoned BTPD colony will result in two or fewer black-footed ferret 

mortalities per year because the number of dispersing individuals is not believed to be high and 

most dispersing black-footed ferrets are expected to die of natural causes or other forms of 

incidental take. Black-footed ferrets that are captured alive from an area proposed for Rozol use 

and relocated to suitable habitat where Rozol will not be applied will not be counted against the 

lethal take of two black-footed ferrets per calendar year. The relocation of live black-footed 

ferrets from proposed Rozol use areas, while considered take, is authorized under each 

reintroduction sites’ existing management plan and through a Service issued permit to the 

recovery partners at that site. That permit authorizes activities including black-footed ferret 

relocation, if needed, at each of the reintroduction sites through coordination with the 

Black-footed Ferret Recovery Coordinator. Therefore, this Rozol ITS is not intended to cover 
88

relocation activities because such actions have been already been authorized under the ESA, or 

will be authorized by another means in the future. Black-footed ferret mortalities from those 

relocation efforts are not anticipated. 

The Service does not anticipate take in the form of harm through habitat loss because the 

conservation measures prohibit Rozol use in existing and future black-footed ferret 

reintroduction sites. Current information does not indicate that Rozol use is limiting potential 

black-footed ferret reintroduction sites. 

B. Gray wolf 

The Service anticipates that dispersing wolves from source populations may occur in the BTPD 

range at an average rate of 0.65 wolves per year (essentially 1 or 2 every other year), based on 

documented mortalities outside of existing DPSs and the 10(j) area for the Mexican gray wolf. 

This is considered a conservative number as additional dispersers have likely occurred and have 

gone undetected. Other forms of mortality can affect these wolves before any exposure to Rozol 

occurs. However, if wolves ingest poisoned prey, evidence suggests that the wolves are likely to 

die. The exact number of wolves that may encounter a Rozol-poisoned prairie dog town with 

dead and dying prey is not determinable; however, we conclude that the number would be low. 

The Service anticipates that one ESA-protected gray wolf every 3 years could be taken as a result 

of this proposed action. Due to the long-distance dispersal capabilities of gray wolves, this take 

could conceivably occur in Rozol-poisoned prairie dog towns throughout the action area, but the 

risk is likely greatest in those states within proximity to the source populations of the recovered 

Northern Rocky Mountain and Western Great Lakes DPSs (e.g., North Dakota, South Dakota, 

Nebraska, and Colorado). Due to the low number of gray wolves in the Mexican gray wolf 

population, we anticipate take of gray wolves from the Mexican gray wolf to be lower. We 

anticipate that only one gray wolf from the Mexican gray wolf population will be taken over the 

course of the 15-year term of this biological opinion. 

D. Northern aplomado falcon 

Take of the northern aplomado falcon is expected in the form of mortality or sub-lethal effects 

such as changes in behavior when they consume prey from a BTPD colony that has been 

poisoned with Rozol. The Service is unlikely to know when that might occur nor be able to 

accurately predict the number of northern aplomado falcons that may encounter BTPD colonies 

or non-target prey that have been exposed to Rozol. It is unlikely that northern aplomado falcons 

will be found; therefore, it is unlikely that many, if any, northern aplomado falcon mortalities 

due to Rozol will be reported to further inform the EPA and the Service on this issue. 

We anticipate that northern aplomado falcons in Texas that encounter Rozol-exposed BTPD 

colonies or non-target prey will result in one or fewer mortalities over 5 years. We further 

anticipate that one or fewer northern aplomado falcons in Texas over 5 years will be harassed to 

a level that results in take through a reduction in available nest sites caused by Rozol mortality to 

large raptors and ravens. However, since this take is unlikely to be easily detected, 2 falcon 

mortalities or injuries attributable to Rozol use will be considered to be representative of the total 

amount of take exempted for each 5 years of this 15-year project. 
89

III. EFFECT OF TAKE

A. Black-footed ferret

The Service has determined that two mortalities per year of dispersing black-footed ferrets due to 

Rozol use is not likely to jeopardize the continued existence of the species or materially affect 

black-footed ferret recovery because individuals dispersing from reintroduction sites are not 

known to regularly return and contribute further to ferret recovery. It is acknowledged that if a 

Rozol-caused black-footed ferret mortality that is reported, there could be multiple black-footed 

ferret mortalities not found or reported. Because the expected mortalities are likely to be 

dispersing black-footed ferrets that are unlikely to contribute to the success of the reintroduction 

site, such losses are not anticipated to compromise the survival and recovery of the black-footed 

ferret. 

B. Gray wolf

The Service determines that the level of anticipated take is not likely to result in jeopardy to the 

species or destruction or adverse modification of critical habitat. Gray wolf critical habitat does 

not occur within the action area. Few gray wolves are anticipated to disperse into the action area 

from established populations. The BTPD habitat is generally not preferred habitat for this 

species. Take is expected to be relatively low and not anticipated to have any population-level 

effects to recovered source populations of gray wolves that disperse into the action area. The 

low number of Mexican wolves (one over 15-year timeframe) that may be taken is not currently 

a threat to its recovery. Rozol use on BTPD towns, and any resulting take of gray wolves will 

likely not substantially change the mortality rates of long-distance dispersing wolves, as these 

individuals are already at high risk of encountering other known factors of wolf mortality during 

their travels. Rozol poisoning is likely a compensatory form of mortality (whereby any 

individuals lost to Rozol poisoning would have been likely to succumb to another form of 

mortality in the absence of Rozol) not resulting in an overall increase in total mortality of gray 

wolves. 

C. Northern aplomado falcon

The Service has determined that two northern aplomado falcons, in the form of one mortality and 

one harassment per 5 years in the 15-year timeframe, due to Rozol use are not likely to 

jeopardize the continued existence of the northern aplomado falcon. This amount of take is not 

likely to result in population level effects to the species nor reduce its chances for recovery. This 

is due to the fact that the core of the northern aplomado falcon population is expected to persist 

at current or greater levels in southern Texas, outside the action area of this project. In addition, 

reintroduction of captively bred northern aplomado falcons is expected to continue within the 

range of the species during some years of this project. 
90

IV. REASONABLE AND PRUDENT MEASURES

The Service believes the following RPMs are necessary and appropriate to minimize the impacts 

of incidental take of black-footed ferrets, gray wolves, and/or northern aplomado falcons 

resulting from the proposed action. The RPMs below apply to all three species unless specified 

otherwise within the RPM.

RPM 1: 

 The EPA shall ensure that proper information regarding listed species and secondary 

poisoning risks is provided to Rozol users. 

RPM 2: 

 The EPA shall ensure that the best available information is applied to the Rozol label in the 

future. 

RPM 3: 

 The EPA, in cooperation with Liphatech, Inc. shall develop and maintain a system to track 

Rozol used for BTPD control and report to the Service the amounts distributed in each of the 

10 States.

RPM 4: 

 If an applicator or the EPA becomes aware that a black-footed ferret is known to occupy a 

BTPD colony outside of a reintroduction area, Rozol cannot be used on that colony until the 

individual or individuals have been relocated. The EPA will ensure that if a previously 

unknown wild black-footed ferret population is discovered, Rozol use will not be used on 

that population.

RPM 5: 

 Within the range of the northern aplomado falcon, the EPA shall maintain its County Bulletin 

(Bulletins Live!) website so that a current listing of counties with habitat for northern 

aplomado falcons is available to the public for educational purposes. We are aware that an 

8-month timeframe exists for incorporating any new information into Bulletins Live!.

RPM 6: 

 Within the range of the northern aplomado falcon, the EPA shall inform public users about 

the risks of Rozol to non-target organisms and how risks can be minimized.

The EPA has adopted Conservation Measures intended to reduce the adverse impacts of 

Rozol use on federally listed species via prohibition of Rozol use in some areas and/or timing 

restrictions; new Rozol label language requiring systematic search protocols to improve 

above-ground detection and disposal of above-ground target and non-target animals, 

reporting of federally listed species as well as reporting of any non-targets; and new 

education, training, and outreach efforts intended to improve applicator compliance with the 

Rozol label. The above RPMs with their implementing terms and conditions below include 

additional items not addressed by EPA’s Conservation Measures. Some aspects of the 

education, training and outreach Conservation Measure requires additional coordination with 
91

the Service to ensure content meets the intended purpose. Information regarding the most 

appropriate search protocol is currently lacking at this time, thus in the event improved 

methods are developed in the future, it is appropriate for EPA to consider that information 

and adjust the Rozol label accordingly to lower the risk of take. Information regarding the 

amount of Rozol produced, used, and sold is not currently available to the Service and 

constraints exist to obtaining it; thus gross production data will be evaluated over time as to 

whether it provides useful information relative to species’ recovery prospects. Relocation of 

black-footed ferrets that have moved beyond reintroduction site boundaries and protection of 

currently unknown wild ferret population are appropriate steps to reduce take to that species. 

Education and outreach are deemed valuable to reduce the risk of take to northern aplomado 

falcons, particularly with the current level of ongoing coordination with private landowners. 

V. TERMS AND CONDITIONS 

Compliance with the following terms and conditions must be achieved in order to be exempt 

from the prohibitions of section 9 of the ESA. These terms and conditions implement the RPMs 

described above. These terms and conditions are nondiscretionary. 

To implement RPM 1: 

 The EPA shall submit to the Service, for review and approval prior to their use, materials to 

be used relative to the Conservation Measure for the EPA’s additional training during annual 

pesticide applicator recertification programs and Liphatech’s Rozol Prairie Dog Bait Product 

Stewardship Program. At a minimum, the training materials shall include (in addition to the 

information provided by EPA as a conservation measure) a description of the listed species 

and their habitats; the general provisions of the Endangered Species Act; the necessity for 

adhering to the provisions of the Act; the penalties associated with violating the provisions of 

the Act; the specific measures that are being implemented to use Rozol in a manner 

compatible with the conservation of listed species; and the boundaries in which Rozol can be 

lawfully applied. 

 The EPA and Liphatech shall provide the Service with the opportunity to attend and 

participate in any education, outreach, and training sessions conducted as part of the EPA’s 

efforts relative to the annual pesticide applicator recertification program and Liphatech’s 

Rozol Prairie Dog Bait Product Stewardship Program.

To implement RPM 2: 

 If information becomes available on more effective methods for search and removal 

protocols than the line-transect protocol specified on the label (as described in the 

Conservation Measures portion of the Description of the Proposed Action section above), the 

EPA shall incorporate the best available information on the Rozol label to reduce the 

availability of Rozol-poisoned target and non-target animals on the surface after coordinating 

with the Service. 
92

To implement RPM 3: 

 Liphatech and the EPA will provide information to the FWS regarding the amount of Rozol 

produced for BTPD control and the gross distribution per state for a period of 5 years. When 

Liphatech and the EPA provide such information to FWS, it will be marked, if appropriate, 

as Confidential Business or Commercial Information. After 5 years, the EPA, Liphatech and 

the Service will determine the need for continued reporting. The decision of whether to 

continue this reporting will be based upon the confidence that the available information 

provides the Service with an acceptable understanding of Rozol sales for future projection 

over the course of the Biological Opinion for the registration of Rozol. The factors that may 

be considered shall include (but shall not be limited to): 

o Measures of the statistical confidence in the sales trend derived from the 5 years of 

reported data, and 

o The nature of the trend function fitted to the available sales data. 

For example, if the data suggest that the sales trend has reached some asymptote, the 

continuation of additional reporting may be unnecessary as the market has matured (other 

factors may be considered in this event). If the sales trend shows a logarithmic increase 

in sales, there may be a need to continue reporting to determine if this trend estimate is 

accurate. If the trend line shows a stable linear growth, the registrant my elect to 

terminate or continue reporting with the understanding that the trend line information up 

to that point would serve as the predictor of sales and treated acres for the remainder of 

the registration decision. 

To implement RPM 4: 

 In the event live/dead black-footed ferrets are found outside reintroduction sites, before, 

during, or after Rozol application, the Black-footed Ferret Coordinator must be contacted 

immediately at (970) 897-2730, extension 224. Sufficient time must be allowed to capture 

and relocate black-footed ferrets before Rozol application. Additional contact information 

for the Black-footed Ferret Coordinator is provided below under “Disposition of federally 

listed species.” 

 The EPA shall modify the EPA Bulletins Live! website to include the location of wild extant 

black-footed ferret populations if discovered in the future. 

To implement RPM 5: 

 By November 26, 2012, within the range of the northern aplomado falcon, the EPA shall 

include the following language in the EPA’s County Bulletins (Bulletins Live!) for counties 

with falcon habitat to increase landowner awareness in these areas: 

Prairie dog colonies in this county may be occupied by the federally endangered 

northern aplomado falcon. Rozol application may be harmful to the northern 

aplomado falcon. Please contact the U.S. Fish and Wildlife Service in New 

Mexico at 505-346-2525, and in Texas at 817-277-1100 to find out where 

northern aplomado falcons occur in the county before application.
93

To implement RPM 6: 

 Prior to Rozol application in the range of the falcon, the EPA will include content on its 

Endangered Species Protection Program (ESPP) website about the risks of Rozol to 

non-target organisms, such as the aplomado falcon and its prey, and how risks can be 

minimized. This information will be developed in coordination with the Service, and will be 

in a format that can be printed as a hand-out for distribution to landowners with suitable 

habitat for the northern aplomado falcon.

 This information will also be electronically provided to states that include the northern 

aplomado falcon range for their use and dissemination during certified applicator training.

Reporting requirement 

When incidental take is anticipated, provisions for monitoring activities of the action are required 

to determine actual effects on federally listed species. Monitoring and reporting is essential for 

the Service to assess the action effects, track incidental take levels, and refine the BO, RPMs, 

and terms and conditions. Thus, the EPA shall provide a written annual report to the Service 

each year this biological opinion is in effect. The report shall be submitted to the Service by 

May 15 of each year. The report shall include: 

 The number of, and species of, any non-target species reported to the National Pesticide 

Information Center, with associated relevant incident information; 

 The number and locations of applicator training sessions, including the number of attendees 

at each training. 

 The number and circumstances surrounding any federally listed species killed or injured as a 

result of Rozol poisoning; 

 A discussion of progress in implementing the RPMs and terms and conditions contained in 

the BO, including: 

o Any problems encountered in implementing them; 

o Recommendations for modifying the stipulations to enhance the conservation of the 

covered species; 

o Any new information, study results, or other relevant information that EPA receives 

regarding the proposed action and it's likely effects to listed species; 

o A description of activities planned for the coming reporting year; and 

o Any other pertinent information. 

This document will assist the Service, the EPA, and the Liphatech evaluating future measures for 

the conservation of the black-footed ferret, gray wolf, and aplomado falcon. 
94

Disposition of dead or injured federally listed species

Upon locating dead, injured, or sick federally listed species, the animals shall be left in place, 

photographed if possible, and immediately reported to one of the Service Law Enforcement 

numbers provided on the label (via EPA’s Conservation Measure to change the label), or a local 

Service Law Enforcement Agent, along with any information related to Rozol use in the area 

where the animals were found. The date, time, location, and any other relevant details shall be 

conveyed. Specimens (collected by authorized individuals) shall be kept cool or frozen to 

facilitate later examination for Rozol poisoning. Sick or injured animals shall be picked up and 

transported by authorized individuals to a permitted local wildlife rehabilitation or veterinary 

facility for treatment. Care must be taken in handling sick or injured animals to ensure effective 

treatment. 

For federally listed species located in the States of Montana, North Dakota, South Dakota, 

Wyoming, Nebraska, Colorado and Kansas, the local Service Ecological Services Office within 

the state the animal is detected shall be notified as soon as possible and informed of the incident 

and local Rozol use, if known. Office contact information may be found on the internet at 

www.fws.gov.

The National Black-Footed Ferret Coordinator must also be notified at U.S. Fish and Wildlife 

Service, P.O. Box 190, Wellington, CO 80549. Phone: 970-897-2730 x 224, Fax: 970-897-2943 

Mobile: 720-626-5260. 

For gray wolves located in Oklahoma, New Mexico, or Texas (potentially Mexican gray wolves 

from a reintroduced population) the Mexican Wolf Recovery Coordinator must be notified as 

soon as possible and informed of any Rozol use, if known. Contact: U.S. Fish and Wildlife 

Service, New Mexico Ecological Services Field Office, 2105 Osuna Road NE, Albuquerque, 

NM 87113, Office Phone: (505) 761-4748, Office Fax: (505) 346-2542. 

The Service’s Northern Aplomado Falcon Coordinator must also be notified of sick, injured, or 

dead northern aplomado falcons within 24 hours by calling (505) 346-2525 at the New Mexico 

Ecological Services Field Office, 2105 Osuna Road NE, Albuquerque, NM 87113; Fax: (505) 

346-2542. 

The Service believes that no more than two black-footed ferrets per year; one wolf every 3 years 

with only one being from the Mexican wolf population; and two northern aplomado falcons for 

each 5-year period within this 15-year project will be incidentally taken as a result of the 

proposed action. The Service expects that the RPMs, with their implementing terms and 

conditions, are designed to minimize the impact of incidental take that might otherwise result 

from the proposed action. If, during the course of the action, this level of incidental take is 

exceeded, such incidental take represents new information requiring reinitiation of consultation 

and review of the RPM provided. The EPA must immediately provide an explanation of the 

causes of the taking and review with the Service the need for possible modification of the RPM. 
95

VI. CONSERVATION RECOMMENDATIONS 

Section 7(a)(1) of the ESA directs Federal agencies to use their existing authorities to further the 

purposes of the ESA by carrying out programs or activities to conserve endangered or threatened 

species. Conservation recommendations are discretionary activities to minimize or avoid 

adverse effects of a proposed action on listed species or critical habitat, to help implement 

recovery plans, or to develop biological information. The Service recommends the following 

conservation activities that are within the EPA’s authorities and can benefit northern aplomado 

falcon recovery. We believe implementation of these will assist EPA in demonstrating that it is 

meeting the requirements of 7(a)(1) of the ESA. 

 A voluntary reporting form shall be developed and made available at training or education 

sessions and on the internet in association with Rozol information that identifies the time and 

date of return visits, which wildlife species were located, disposition of wildlife found (i.e., 

whether the prairie dogs were removed from the colony, if Rozol was found on the surface 

and other information that can be used to assess the routes of exposure to nontarget wildlife). 

Completed forms shall be sent directly to the Service. 

 The EPA should work in coordination with the Service to evaluate methods to prevent 

secondary poisoning of federally listed species by performing a field study that allows for an 

evaluation of efficacy of the newly implemented line-transect animal search and removal 

protocol as well as other feasible methods to prevent secondary poisoning. Although other 

research entities may be acceptable, the Service recommends the EPA contact a university to 

develop a graduate-level research study with the objective of determining appropriate search 

methodology/protocols to reduce the above-ground availability of Rozol-poisoned BTPDs 

and non-target animals. 

 The EPA should become a member of the Black-footed Ferret Recovery Implementation 

Team due to its congressionally delegated responsibilities for regulating rodenticides and 

recovering federally threatened and endangered species. Prairie dog rodenticide registrations 

under FIFRA are significant actions that can adversely affect black-footed ferrets and other 

listed species. The EPA participation on the Black-footed Ferret Recovery Implementation 

Team would provide an avenue for the agency to understand the ramifications of rodenticide 

use on black-footed ferret habitat along with an opportunity to work with recovery partners to 

ensure EPA actions avoid working at cross purposes with black-footed ferret recovery. 

 The EPA should monitor the registered rodenticides used on the three species of prairie dogs 

in the black-footed ferrets’ range and report the amounts of prairie dog rodenticides sold, 

used, and the expected prairie dog acreage poisoned per state per year. 

 The EPA should initiate or require studies to evaluate secondary toxicity of the EPA 

registered prairie dog rodenticides to black-footed ferrets. 

 The EPA should implement the above listed RPMs and Terms and Conditions throughout the 

nonessential experimental range of the northern aplomado falcon in New Mexico where 

Rozol may be used. 
96

 The EPA should coordinate with the New Mexico Ecological Services Field Office to assist 

in recovery efforts for the northern aplomado falcon by contributing to research, monitoring, 

and/or falcon reintroductions.

 The EPA should initiate or require studies to evaluate secondary toxicity of the EPA 

registered prairie dog rodenticides to northern aplomado falcons, other raptors, and ravens. 

In order for the Service to be kept informed of actions minimizing or avoiding adverse effects or 

benefiting listed species or their habitats, the Service requests notification of the implementation 

of any conservation recommendations. 

VII. REINITIATION NOTICE 

This concludes formal consultation on the action outlined in the EPA’s September 30, 2010, 

request for formal consultation regarding federally listed species and critical habitat impacts 

relative to the registration and application of Rozol to control BTPDs in 10 western States. As 

provided in 50 CFR § 402.16, reinitiation of formal consultation is required where discretionary 

Federal agency involvement or control over the action has been retained (or is authorized by law) 

and if: 1) the amount or extent of incidental take is exceeded (or take occurs of species for 

which the Service currently does not anticipate adverse effects from the proposed action); 2) new 

information reveals effects of the agency action that may impact listed species or critical habitat 

in a manner or extent not considered in this BO (for example, this BO does not cover Rozol use 

on any other prairie dog species; thus, expansion of Rozol use to prairie dog species other than 

the BTPD would necessitate reinitiation of formal consultation; changes to the September 10, 

2010, Rozol label altering the application of the product may also represent new information not 

considered herein); 3) the agency action is subsequently modified in a manner that causes an 

effect to the listed species or critical habitat that was not considered in this BO; 4) future 

information indicates that Rozol use by itself or in combination with other factors is precluding 

black-footed ferret recovery, then the EPA and the Service shall reinitiate consultation to 

determine appropriate measures to allow black-footed ferret recovery to proceed; or 5) a new 

species is listed or critical habitat is designated that may be affected by the action. In instances 

where the amount or extent of incidental take is exceeded, any activities causing such take must 

cease pending reinitiation. 

 
97

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U.S. Fish and Wildlife Service. 2011e. Eskimo curlew (Numenius borealis) 5-year review: 

summary and evaluation. Fairbanks Fish and Wildlife Field Office; Fairbanks, AK. 

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U.S. Fish and Wildlife Service. 2011f. Endangered and threatened wildlife and plants; revising 

the listing of the gray wolf (Canis lupus) in the Western Great Lakes. Federal Register 

76(249):81666 - 81726. 

U.S. Fish and Wildlife Service. 2011g. Endangered and threatened wildlife and plants; 

reissuance of final rule to identify the Northern Rocky Mountain population of gray wolf 

as a distinct population segment and to revise the list of endangered and threatened 

wildlife. Federal Register 76(87):25590-25592. 

U.S. Fish and Wildlife Service. 2011h. Endangered and threatened wildlife and plants; removal 

of the gray wolf in Wyoming from the federal list of endangered and threatened wildlife 

and removal of the Wyoming wolf population’s status as an experimental population. 

Federal Register 76(193): 61782-61823. 

U.S. Fish and Wildlife Service. 2011i. Mexican wolf Blue Range reintroduction project 

statistics, causes of documented Mexican wolf mortalities in the Blue Range wolf 

recovery area, Arizona and New Mexico, 1998-2010. Accessed online December, 2011, 

at: <http://www.fws.gov/southwest/es/mexicanwolf/pdf/MW_mortality.pdf.> 

U.S. Fish and Wildlife Service. 2011j. Endangered and threatened wildlife and plants; proposed 

rule to revise the list of endangered and threatened wildlife for the gray wolf (Canis 

lupus) in the eastern United States, initiation of status reviews for the gray wolf and for 

the eastern wolf (Canis lycaon). Federal Register 76(87):26086-26145. 
113

U.S. Fish and Wildlife Service. 2011k. Fact sheet: gray wolf recovery in Minnesota, 

Wisconsin, and Michigan. December 2011. Accessed online January 5, 2010 at: 

<http://www.fws.gov/midwest/wolf/aboutwolves/pdf/R3wolfrec.pdf.> 

U.S. Fish and Wildlife Service. 2010a. September 23 letter from Jeffrey Towner to Debbie 

Edwards, U.S. Environmental Protection Agency, Office of Pesticide Programs. 

Unrealistic and impractical label requirements as characterized by North Dakota field 

tour of black-tailed prairie dog towns and meetings with applicators. 2 pp. 

U.S. Fish and Wildlife Service. 2010b. Post-delisting monitoring plan for the bald eagle 

(Haliaeetus leucocephalus) in the contiguous 48 states. U.S. Fish and Wildlife Service, 

Divisions of Endangered Species and Migratory Birds and State Programs, Midwest 

Regional Office; Twin Cities, MN. 75 pp. 

U.S. Fish and Wildlife Service. 2010c. Endangered and threatened wildlife and plants; 

12-month finding on a petition to list the white-tailed prairie dog as threatened or 

endangered. Federal Register 75(104):30338-30363. 

U.S. Fish and Wildlife Service. 2009a. September 8 letter from Bryan Arroyo to Debbie 

Edwards, U.S. Environmental Protection Agency, Office of Pesticide Programs. 

Recommendation to EPA to withdraw Rozol registration and not issue registration for 

Kaput prairie dog bait. Washington, D.C. 9 pp. 

U.S. Fish and Wildlife Service. 2009b. Endangered and threatened wildlife and plants; 

12-month finding on a petition to list the black-tailed prairie dog as threatened or 

endangered. Federal Register 74(231):63343-63366. 

U.S. Fish and Wildlife Service. 2009c. Veterinary medical examination report. Lab Case 

#09-000049. National Fish and Wildlife Forensics Laboratory; Ashland, OR. 11 pp. 

U.S. Fish and Wildlife Service. 2009d. Final environmental assessment: proposal to permit 

take as provided under the Bald and Golden Eagle Protection Act. Division of 

Migratory Bird Management. Washington, D.C. 199 pp. 

U.S. Fish and Wildlife Service. 2009e. Piping plover (Charadrius melodus) 5-year review: 

summary and evaluation. U.S. Fish and Wildlife Service, Ecological Services, Northeast 

Region; Hadley, Massachusetts, and Midwest Region, East Lansing Field Office, MI. 

214 pp. 

U.S. Fish and Wildlife Service. 2009f. Endangered and threatened wildlife and plants; final rule 

to identify the Northern Rocky Mountain population of gray wolf as a distinct population 

segment and to revise the list of endangered and threatened wildlife. Federal Register 

74(62):15123-15188. 
114

U.S. Fish and Wildlife Service. 2009g. Endangered and threatened wildlife and plants; final 

rule to identify the Western Great Lakes populations of gray wolves as a distinct 

population segment and to revise the list of endangered and threatened wildlife. Federal 

Register 74(62):15070-15123. 

U.S. Fish and Wildlife Service. 2009h. Letter dated July 6 to William Even, South Dakota 

Department of Agriculture. Request to not to issue registration for Rozol use as a prairie 

dog rodenticide. Ecological Services, South Dakota Field Office, Pierre, SD. 

U.S. Fish and Wildlife Service. 2008a. Birds of conservation concern 2008. U.S. Department 

of the Interior, Fish and Wildlife Service, Division of Migratory Bird Management; 

Arlington, VA. 85 pp. 

<http://www.fws.gov/migratorybirds/NewReportsPublications/SpecialTopics/ 

BCC2008/BCC2008.pdf> 

U.S. Fish and Wildlife Service. 2008b. Black-footed ferret (Mustela nigripes) 5-year status 

review: summary and evaluation. 38 pp. 

U.S. Fish and Wildlife Service. 2008c. Endangered and threatened wildlife and plants; 

12-month finding on a petition to list the gunnison’s prairie dog as threatened or 

endangered. Federal Register 73(24):6660-6684. 

U.S. Fish and Wildlife Service. 2007a. Veterinary medical examination report. Lab Case 

#07-000015. National Fish and Wildlife Forensics Laboratory; Ashland, OR. 11 pp. 

U.S. Fish and Wildlife Service. 2007b. Chiricahua leopard frog (Rana chiricahuensis) recovery 

plan. Region 2, U.S. Fish and Wildlife Service; Albuquerque, NM. 

U.S. Fish and Wildlife Service. 2007c. Letter dated December 21 to Debbie Edwards, Office of 

Pesticide Programs, U.S. Environmental Protection Agency. Request to disapprove 

Section 24(c) Special Local Needs registration for use of Kaput Prairie Dog Bait for 

control of black-tailed prairie dogs. Mountain-Prairie Region; Denver, CO. 

U.S. Fish and Wildlife Service. 2006a. January 13 letter to Greg Ibach, Nebraska Department of 

Agriculture. Request to not issue a section 24(c) Special Local Needs registration for use 

of Rozol Pocket Gopher Bait for control of black-tailed prairie dogs. U.S. Fish and 

Wildlife Service, Ecological Services, Nebraska Field Office; Grand Island, NE. 

U.S. Fish and Wildlife Service. 2006b. January 24 letter to Larry Gabriel, South Dakota 

Department of Agriculture. Request to not issue a section 24(c) Special Local Needs 

registration for use of Rozol Pocket Gopher Bait for control of black-tailed prairie dogs. 

U.S. Fish and Wildlife Service, Ecological Services, South Dakota Field Office; Pierre, 

SD. 
115

U.S. Fish and Wildlife Service. 2006c. February 10 letter to Greg Ibach, Nebraska Department 

of Agriculture. Response and second request to not issue a section 24(c) Special Local 

Needs registration for use of Rozol Pocket Gopher Bait for control of black-tailed prairie 

dogs. U.S. Fish and Wildlife Service, Ecological Services, Nebraska Field Office; Grand 

Island, NE. 

U.S. Fish and Wildlife Service. 2006d. October 10 letter to Laura Quakenbush, Colorado 

Department of Agriculture. Request to not issue a section 24(c) Special Local Needs 

registration for use of Rozol Pocket Gopher Bait for control of black-tailed prairie dogs. 

U.S. Fish and Wildlife Service, Ecological Services, Colorado Field Office; Grand 

Junction, CO. 

U.S. Fish and Wildlife Service. 2006e. May 5 letter to Anne Lindsay, Office of Pesticide 

Programs, U.S. Environmental Protection Agency. Request to disapprove section 24(c) 

Special Local Needs registration for use of Rozol Pocket Gopher Bait for control of 

black-tailed prairie dogs. U.S. Fish and Wildlife Service, Mountain-Prairie Region; 

Denver, CO. 

U.S. Fish and Wildlife Service. 2006f. Endangered and threatened wildlife and plants; 

establishment of a nonessential experimental population of northern aplomado falcons in 

New Mexico and Arizona. Federal Register 71(143):42298-42315. 

U.S. Fish and Wildlife Service. 2006g. Biological opinion for the implementation of the fire 

management plan at the San Bernardino and Leslie Canyon National Wildlife Refuges, 

January 23, 2006. U.S. Fish and Wildlife Service Arizona Ecological Services Field 

Office; Phoenix, AZ. 46 pp. 

U.S. Fish and Wildlife Service. 2004. Endangered and threatened wildlife and plants; final 

designation of critical habitat for the Mexican spotted owl; final rule. August 31, 2004. 

Federal Register 69(168):53182-53297. 

U.S. Fish and Wildlife Service. 2003. Endangered and threatened wildlife and plants; final rule 

to reclassify and remove the gray wolf from the list of endangered and threatened wildlife 

in portions of the conterminous United States; establishment of two special regulations 

for threatened gray wolves. Federal Register 68(62):15804-15875. 

U.S. Fish and Wildlife Service. 2002a. Endangered and threatened wildlife and plants; 

designation of critical habitat for the Northern Great Plains breeding population of the 

piping plover. Federal Register 67(176):57637-57717. 

U.S. Fish and Wildlife Service. 2002b. Biological opinion for the continuation of livestock 

grazing on the Coronado National Forest. Dated October 24, 2002. U.S. Fish and 

Wildlife Service, Arizona Ecological Services Field Office; Phoenix, AZ. 228 pp. 
116

U.S. Fish and Wildlife Service. 2000a. Notice of availability to review the peregrine fund 

request to amendment its incidental take permit for aplomado falcons. Federal Register 

65(54): 14999. <http://www.fws.gov/policy/library/2000/00fr14999.html> 

U.S. Fish and Wildlife Service. 2000b. Amended biological opinion: habitat conservation plan 

for the reintroduction of the aplomado falcon into south Texas. June 1, 2000. Clear Lake 

Ecological Services Office; Clear Lake, TX. 

U.S. Fish and Wildlife Service. 1998. Endangered and threatened wildlife and plants; 

establishment of a nonessential experimental population of the Mexican gray wolf in 

Arizona and New Mexico. Federal Register 63(7):1752-1772. 

U.S. Fish and Wildlife Service. 1996. Availability of an environmental assessment and receipt 

of application for incidental take permit for the peregrine fund’s aplomado falcon 

reintroduction program in Texas. Federal Register 61(139):37488-37489. 

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608 pp. 

U.S. Fish and Wildlife Service. 1994b. Endangered and threatened wildlife and plants; 

Establishment of a nonessential experimental population of black-footed ferrets in 

southwestern South Dakota. Federal Register 59(159):42682-42694. 

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the effects of 16 vertebrate control agents on threatened and endangered species. 

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117

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have the U.S. Environmental Protection Agency suspend use of Rozol use on black-tailed 

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Personal Communications 

Ernst, A. 2008. Email exchange between Andrea Ernst and Pete Gober, Field Supervisor, U.S. 

Fish and Wildlife Service, Ecological Services, South Dakota Field Office. August 4, 

2008. Habitat suitability and availability relative to black-footed ferrets. 

Jones, D.R. 2011. Email exchange and telephone conversation between David R. Jones, Senior 

Scientist, Environmental Fate and Effects Division, Office of Pesticide Programs, U.S. 

EPA, Washington, D.C., and Matt Schwarz, Environmental Contaminants Biologist, U.S. 

Fish and Wildlife Service, Ecological Services, South Dakota Field Office, Pierre, South 

Dakota. November 4, 2011. Discussed environmental fate of chlorophacinone as Rozol. 

Montoya, A. 2011. Email between Angel Montoya, Partners Program biologist, and Pat 

Zenone, Ecological Services Biologist, U.S. Fish and Wildlife Service, New Mexico 

Ecological Services Field Office, Albuquerque, New Mexico. November 30, 2011. 

Status of northern aplomado falcons outside of Safe Harbor area in Texas. 

Pavelka, G. 2008. Email exchange between Gregory A. Pavelka, Wildlife Biologist, U.S. Army 

Corps of Engineers, Yankton, South Dakota , and Carol Aron, Fish and Wildlife 

Biologist, U.S. Fish and Wildlife Service, Ecological Services, North Dakota Field 

Office, Bismarck, North Dakota. December 8, 2008. Inquiry regarding the distance that 

piping plovers will nest from water on Missouri River Reservoirs. 
120

Someson, R. 2012. Email between Russell A. Someson, Natural Resource Specialist, Lake 

Oahe Project, U.S. Army Corps of Engineers, Pierre, South Dakota, and Carol Aron, Fish 

and Wildlife Biologist, U.S. Fish and Wildlife Service, Ecological Services, North 

Dakota Field Office, Bismarck, North Dakota. Confirmation of 2011 verbal exchange 

regarding lack of piping plover use of black-tailed prairie dog colonies. 

Vyas, N. 2011a. Email exchange and telephone conversation between Nimish B. Vyas, 

Research Biologist, U.S. Geological Survey Patuxent Wildlife Research Center, 

Beltsville, Maryland, and Matt Schwarz, Fish and Wildlife Biologist (Environmental 

Contaminants), U.S. Fish and Wildlife Service, Ecological Services, South Dakota Field 

Office, Pierre, South Dakota. June 13, 2011. Discussed shortfalls of the EPA’s required 

5-day LC-50. 

Vyas, N. 2011b. Email exchange and telephone conversation between Nimish B. Vyas, 

Research Biologist, U.S. Geological Survey Patuxent Wildlife Research Center, 

Beltsville, Maryland, and Matt Schwarz, Fish and Wildlife Biologist (Environmental 

Contaminants), U.S. Fish and Wildlife Service, Ecological Services, South Dakota Field 

Office, Pierre, South Dakota. October 3, 2011. Discussed unpublished data on 

chlorophacinone concentrations in samples collected for Vyas (2010) study. 

Vyas, N. 2010. Email exchange and telephone conversation between Nimish B. Vyas, Research 

Biologist, U.S. Geological Survey Patuxent Wildlife Research Center, Beltsville, 

Maryland, and Matt Schwarz, Fish and Wildlife Biologist (Environmental Contaminants), 

U.S. Fish and Wildlife Service, Ecological Services, South Dakota Field Office, Pierre, 

South Dakota. September 30, 2010. Discussed meadowlark histopathology results from 

Vyas (2010) study. 

 
121

APPENDIX A 

September 10, 2010, Label for Rozol® Prairie Dog Bait 

 
122