UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

 WASHINGTON, D.C. 20460

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION 

DRAFT BIOLOGICAL OPINION ISSUED UNDER THE ENDANGERED SPECIES ACT, 

BY THE U.S. FISH AND WILDLIFE SERVICE, RELATED TO THE POTENTIAL EFFECTS 

OF ROZOL PRAIRIE DOG BAIT, FOR THE CONTROL OF BLACK-TAILED PRAIRIE 

DOGS, ON THREATENED AND ENDANGERED WILDLIFE SPECIES

COMMENTS ACCEPTED THROUGH FEBRUARY 17, 2012

EPA has initiated formal consultation with the U.S. Fish and Wildlife Service on the potential 

effects of Rozol Prairie Dog Bait, for the control of black-tailed prairie dogs, on wildlife 

species listed under the Endangered Species Act (ESA) as either threatened or 

endangered. The Biological Opinion relative to this consultation is posted here at

www.epa.gov/espp and included in public docket EPA-HQ-OPP-2011-0909 at 

Regulations.gov so EPA may receive public input on any changes to this pesticide’s 

registration recommended by the U.S. Fish and Wildlife Service. 

The ESA requires that federal agencies assess their “actions” to determine whether species 

listed as threatened or endangered under the ESA may be affected by those actions and/or 

whether critical habitat may be adversely modified. The registered uses of a pesticide 

constitute an EPA "action" under the ESA. 

BACKGROUND

If EPA determines a pesticide's registered uses are likely to adversely affect a federally 

listed threatened or endangered species (listed species) and/or modify its critical habitat, 

EPA initiates "formal consultation" with the U.S. Fish and Wildlife Service or the National 

Marine Fisheries Service (the Service(s)), as appropriate. 

In response to a federal agency initiating formal consultation, the Service develops a 

Biological Opinion (BO) in which it provides its opinion on whether the "action" is likely to 

jeopardize the continued existence of a listed species and/or is likely to adversely modify 

designated critical habitat and, if so, describes reasonable and prudent alternatives to avoid 

jeopardy. The Service(s) may also find that an action adversely affects a species but does 

not jeopardize its continued existence. In these cases, the Service includes an incidental 

take statement in the BO. An incidental take statement typically includes the extent of the 

anticipated take, reasonable and prudent measures to minimize the take and terms and 

conditions that must be observed when implementing those measures. 

In 2005, EPA published in the Federal Register (FR 70 No. 211 pp. 66392-66402), a 

document titled Endangered Species Protection Program Field Implementation. That notice 

of how EPA intends to implement its responsibilities under the ESA, states (p 66401):

PUBLIC INPUT
If EPA must formally consult with the Services, after the Services issue a draft 

Biological Opinion, EPA will welcome input from State, Tribal and local 

governments on draft reasonable and prudent measures and alternatives

[emphasis added] The purpose of this review would be to determine whether 

the alternatives or measures can be reasonably implemented and whether 

there are different measures that may provide adequate protection but result 

in less impact to pesticide users. The Agency will consider this input in 

developing its response to draft Biological Opinions. 

EPA also is seeking input from the public in general, pesticide users and public interest 

organizations on whether the alternatives or measures can be reasonably implemented and 

whether there are different measures that may provide adequate protection but result in less 

impact to pesticide users. The agency will also consider this input in developing its 

response to draft Biological Opinions. 

Further, the Services’ 

APPLICANT INPUT

Consultation Handbook (pp. 2-13), supports their consultation 

regulations and states: 

... the Service and the action agency meet their obligations to [the applicant 

or pesticide registrant] as outlined in 50 CFR section 402 through the 

following: The applicant is entitled to review draft Biological Opinions 

obtained through the action agency and to provide comments through 

the action agency. The Service will discuss the basis of their biological 

determination with the applicant and seek the applicant’s expertise in 

identifying reasonable and prudent alternatives [emphasis added] .... 

The Draft Biological Opinion is included under public docket number EPA-HQ-OPP-2011-

0909 at regulations.gov and is posted here on EPA’s website at 

COMMENTS

www.epa.gov/espp to seek 

input on the Service’s recommended reasonable and prudent measures and alternatives, as 

noted above. Such input should be submitted by February 17, 2012, in order to be 

considered in EPA’s response to the Draft Biological Opinion. Comments received by EPA 

on other aspects of the Draft Biological Opinion will be forwarded to the Service for its 

consideration. 

As stated in the Services’ regulations (50 CFR 402.14(g)(5)):

All comments on the draft Biological Opinion must be submitted to the 

Service through the Federal agency, although the applicant may send a copy 

of its comments directly to the Service. 

You may submit your comments, identified by the docket identification (ID) number 

SUBMITTING YOUR COMMENTS

EPA-HQ-OPP-2011-0909, by one of the following methods: 

Federal eRulemaking Portal: http://www.regulations.gov. Follow the online instructions for 

submitting comments. 
Mail: Office of Pesticide Programs (OPP) Regulatory Public Docket (7502P), Environmental 

Protection Agency, 1200 Pennsylvania Ave., NW, Washington, DC 20460-0001. 

Delivery: OPP Regulatory Public Docket (7502P), Environmental Protection Agency, Rm. 

S-4400, One Potomac Yard (South Bldg.), 2777 S. Crystal Dr., Arlington, VA. Deliveries are 

only accepted during the Docket's normal hours of operation (8:30 a.m. to 4 p.m., Monday 

through Friday, excluding legal holidays). Special arrangements should be made for 

deliveries of boxed information. The Docket Facility telephone number is (703) 305-5805. 

Instructions: EPA's policy is that all comments received will be included in the docket 

without change and may be made available online at http://www.regulations.gov, including 

any personal information provided, unless the comment includes information claimed to be 

Confidential Business Information (CBI) or other information whose disclosure is restricted 

by statute. Do not submit information that you consider to be CBI or otherwise protected 

through regulations.gov or e-mail. The regulations.gov website is an ''anonymous access'' 

system, which means EPA will not know your identity or contact information unless you 

provide it in the body of your comment. If you send an e-mail comment directly to EPA 

without going through regulations.gov, your e-mail address will be automatically captured 

and included as part of the comment that is placed in the docket and made available on the 

Internet. If you submit an electronic comment, EPA recommends that you include your 

name and other contact information in the body of your comment and with any disk or CDROM you submit. If EPA cannot read your comment due to technical difficulties and cannot 

contact you for clarification, EPA may not be able to consider your comment. Electronic files 

should avoid the use of special characters, any form of encryption, and be free of any 

defects or viruses. 

Docket: All documents in the docket are listed in the docket index available in 

regulations.gov. To access the electronic docket, go to http://www.regulations.gov, select 

''Advanced Search,'' then ''Docket Search.'' Insert the docket ID number where indicated 

and select the ''Submit'' button. Follow the instructions on the regulations.gov website to 

view the docket index or access available documents. Although listed in the index, some 

information is not publicly available, e.g., CBI or other information whose disclosure is 

restricted by statute. Certain other material, such as copyrighted material, is not placed on 

the Internet and will be publicly available only in hard copy form. Publicly available docket 

materials are available either in the electronic docket at http://www.regulations.gov or, if 

only available in hard copy, at the OPP Regulatory Public Docket in Rm. S-4400, One 

Potomac Yard (South Bldg.), 2777 S. Crystal Dr., Arlington, VA. The hours of operation of 

this Docket Facility are from 8:30 a.m. to 4 p.m., Monday through Friday, excluding legal 

holidays. The Docket Facility telephone number is (703) 305-5805. 

Draft Biological Opinion

For Rozol Use on Black-tailed Prairie Dogs

Registered under Section 3 of the 

Federal Insecticide, Fungicide and Rodenticide Act 

Photo courtesy of K. Tamkun U.S. Fish and Wildlife Service 

Prepared by:

U.S. Fish and Wildlife Service

Ecological Services Region 6 and Region 2

January 16, 2012
ii

TABLE OF CONTENTS

INTRODUCTION 1

CONSULTATION HISTORY 1

DESCRIPTION OF THE ACTION 6

CONSERVATION MEASURES 6

ROZOL PRAIRIE DOG BAIT REGISTERED USE 8

ACTION AREA 9

GENERAL BACKGROUND AND EFFECTS OF THE ACTION

RELEVANT TO ALL SPECIES IN CONSULTATION 11

INDANDIONE MODE OF ACTION AND TOXICITY 11

CHLOROPHACINONE ENVIRONMENTAL FATE 12

ROZOL EXPOSURE AND EFFECTS ASSESSMENT 13

Primary Exposure 13

Secondary Exposure 14

Surface Presence of Poisoned Black-tailed Prairie Dogs 16

Removal of Poisoned Black-tailed Prairie Dogs 17

Field Study Observations of Secondary Exposure or Toxicity 18

REVIEW OF THE EPA’S ROZOL EFFECTS DETERMINATION 20

Underestimated Risk to Avian Species 21

Prairie Dog Chlorophacinone Residues 22

Risk Quotient Calculations and Uncertainty 25

WILDLIFE MORTALITY INCIDENTS 26

SUMMARY OF ROZOL EXPSOURE AND EFFECTS RELEVANT TO 

ALL LISTED SPEICES ADDRESSED IN THIS BO 28
iii

GENERAL CONSERVATION RECOMMENDATIONS 30

SPECIES ANALYSES

OVERVIEW 32

SPECIES FOR WHICH CONSERVATION MEASURES PRECLUDE 

ADVERSE EFFECTS 34

CHIRICAHUA LEOPARD FROG 34

GRIZZLY BEAR 35

JAGUAR 37

NEW MEXICO RIDGE-NOSED RATTLESNAKE 38

MEXICAN SPOTTED OWL 38

PREBLE’S MEADOW JUMPING MOUSE 39

SPECIES FOR WHICH NO ADVERSE EFFECTS ARE 

ANTICIPATED, WITHOUT CONSERVATION MEASURES

AMERICAN BURYING BEETLE 44

BLACK-CAPPED VIREO 45

CANADA LYNX 47

ESKIMO CURLEW 48

GOLDEN-CHEEKED WARBLER 49

GULF COAST JAGUARUNDI 51

OCELOT 51

PIPING PLOVER 51

WHOOPING CRANE 54

SPECIES FOR WHICH ADVERSE EFFECTS ARE ANTICIPATED

WITH OR WITHOUT CONSERVATION MEASURES

BLACK-FOOTED FERRET

Status of the Species/Critical Habitat 59

Environmental Baseline 62

Effects of the Action 64

Cumulative Effects 66

Conclusion Regarding Jeopardy 67

Incidental Take Statement 67
iv

GRAY WOLF 

Status of the Species/Critical Habitat 73

Environmental Baseline 81

Effects of the Action 82

Cumulative Effects 83

Conclusion Regarding Jeopardy 84

Incidental Take Statement 84

NORTHERN APLOMADO FALCON

Status of the Species/Critical Habitat 87

Environmental Baseline 90

Effects of the Action 93

Cumulative Effects 95

Conclusion Regarding Jeopardy 95

Incidental Take Statement 96

REINITIATION NOTICE 100

REFERENCES CITED 101

APPENDIX 124
v

ACRONYMS AND ABBREVIATIONS

§ Section

μg/g micrograms per gram

Act Endangered Species Act

AOK Audubon of Kansas

BA Biological Assessment

BGEPA Bald and Golden Eagle Protection act

BO Biological Opinion 

BTPD Black-tailed Prairie Dog

CPW Colorado Division of Parks and Wildlife

CFR Code of Federal Regulations 

cm Centimeters

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

et al. and others

Ferret Black-footed Ferret

FIFRA Federal Insecticide, Fungicide and Rodenticide Act

FWS U.S. Fish and Wildlife Service

g gram

GPS Global Positioning System 

ha Hectares 

i.e. in explanation 

in Inches

IPM Integrated Pest Management

ITS Incidental Take Statement 

lbs. Pounds

LC Lethal Concentration 

LD Lethal Dose

LOC Level of Concern

m Meter

mg milligram

MBTA Migratory Bird Treaty Act

MRID Master Record Identification 

NDA Nebraska Department of Agricultural 

NGPC Nebraska Game and Parks Commission

PCE Primary Constituent Element

pH measure of acidity in aqueous solution 

RPA Reasonable and Prudent Alternative
vi

RMP Reasonable and Prudent Measure

RQ Risk Quotient

Service U.S. Fish and Wildlife Service

SLN Special Local Needs

spp. Species 

TRV Toxicity Reference Value

USCOE U.S. Corps of Engineers

USDC U.S. District Court of Columbia 

USDOI U.S. Department of the Interior

USEPA U.S. Environmental Protection Agency

USFWS U.S. Fish and Wildlife Service

USGS U.S. Geological Services 

WAFWA Western Association of Fish and Wildlife Agencies

WWF World Wildlife Fund

ww West Weight

WYNDD Wyoming Natural Diversity Database
1

BIOLOGICAL OPINION

INTRODUCTION

Section 7(a)(2) of the Endangered Species Act (ESA) 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 & Wildlife Service 

(Service). 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.

CONSULTATION HISTORY

Prior to initiation of the current formal section 7 consultation, there was an extensive history 

regarding the use of Rozol® Prairie Dog Bait (Rozol) for black-tailed prairie dog (Cynomys 

ludovicianus) control. The list below is not intended to be all inclusive, but represents the 
2

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/individuals and are relevant to understanding the issues 

associated with Rozol use on black-tailed prairie dogs. Pertinent items are provided below.

Date Activity

Feb 26, 1991 The U.S. Environmental Protection Agency (EPA) requests formal consultation 

with the Service on chlorophacinone (the active ingredient in Rozol) for use as 

a rodent control agent in specific geographic areas and specific rodent species in 

the United States (EPA 1991). This chemical was part of a larger suite of 

chemicals for which EPA initiated formal consultation with the Service. 

March 1993 The 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 (Service 1993). The BO included Reasonable and Prudent 

Alternatives to avoid jeopardy along with Reasonable and Prudent Measures to 

avoid and minimize impacts to listed species from the proposed uses of 

chlorophacinone. Chlorophacinone or Rozol use on black-tailed prairie dogs 

was not a described use at that time and therefore not analyzed in the 1993 BO.

1990’s Rozol Pocket Gopher Bait made with chlorophacinone is used off-label on 

prairie dogs with the EPA’s authorization and begins to generate interest as a 

prairie dog rodenticide (Lee et al. 2005). 

2000’s Six States develop Special Local Needs (SLN) labels to use Rozol on blacktailed prairie dogs (EPA 2010a). The Service provides multiple letters to State

Agricultural Departments discouraging use of Rozol on black-tailed prairie 

dogs because of secondary poisoning and impacts to non-target animals 

including listed species (Service 2006a, 2006b, 2006c and 2006d). 

May 5, 2006 The Service provides a letter to the EPA on a pending proposal for a SLN label 

that would allow Rozol use in Nebraska on black-tailed prairie dogs (Service 

2006e). The Service informs the EPA of expected secondary poisoning to nontarget animals, including then-listed bald eagles and requests the EPA initiate 

section 7 consultation under the ESA.

Oct. 1, 2006 The Nebraska SLN label allows Rozol use on black-tailed prairie dogs to begin 

October 1 (NDA 2006).

Nov. 8, 2006 Rozol is applied to a black-tailed prairie dog town near McCook, Nebraska 

(Service 2007a).
3

Dec. 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 black-tailed prairie dog 

colony (Service 2007a).

Jan. 19, 2007 The EPA, the Service, and other interested parties meet in Topeka, Kansas to 

discuss issues related to Rozol use on black-tailed prairie dogs, including how 

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

May 19, 2008 The EPA and the Service have a multi-region conference call to discuss 

secondary poisoning of non-target animals from Rozol use on black-tailed 

prairie dogs (EPA 2008). 

May 13, 2009 The EPA registers Rozol under section 3 of FIFRA for use on black-tailed 

prairie dogs in ten states with an application date of October 1 through March 

15 (EPA 2009a).

June 5, 2009 The 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 black-tailed prairie dogs (WWF 2009). The EPA chooses to 

treat this letter as a petition to consider suspension of Rozol as a black-tailed 

prairie dog rodenticide (EPA 2009b).

July 10, 2009 Environmental groups Defenders of Wildlife (DOW) and Audubon of Kansas 

(AOK) file a petition in the District of Columbia for judicial review of EPA’s 

May 13, 2009 decision to register Rozol for black-tailed prairie dogs noting the 

lack of ESA section 7 consultation (DOW and AOK 2009a).

July 15, 2009 Defenders of Wildlife submit a Notice of Intent to sue EPA for use of Rozol on 

black-tailed prairie dogs without ESA section 7 consultation and other issues 

(DOW 2009).

July 30, 2009 The Western Association of Fish and Wildlife Agencies (WAFWA) provides a 

letter to Department of Interior (DOI) Secretary Salazar on Rozol use on blacktailed prairie dogs and requests 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). 

Sept. 8, 2009 The Service provides a letter to the EPA on the FIFRA section 3 registration for 

Rozol use on black-tailed prairie dogs and requests that ESA section 7 

consultation be completed prior to use of Rozol on black-tailed prairie dogs and 

Rozol use for that purpose be withdrawn until completion of the section 7 

consultation (Service 2009a).
4

Sept. 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 

ferrets.

Sept. 23, 2009 Two environmental groups file a complaint in the U.S. District Court of 

Columbia (USDC) alleging that the EPA failed to conduct ESA section 7 

consultation for the use of Rozol on black-tailed prairie dogs (DOW and AOK

2009b).

Sept. 30, 2010 The EPA submits a letter to the Service requesting formal ESA section 7 

consultation on Rozol use on black-tailed prairie dogs (EPA 2010b). 

Nov. 16, 2010 The EPA rejects suspension of Rozol as a black-tailed prairie dog rodenticide in 

response to the WWF letter of June 5, 2009 that the EPA considered a petition 

(EPA 2010c).

June 14, 2011 The USDC issues a ruling on the environmental groups’ 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 enjoin use of Rozol until section 7 is completed.

July 13, 2011 The Service provides a signed declaration to the USDC indicating we will 

provide a draft BO to the EPA by December 10, 2011 (Service 2011a). 

Aug. 8, 2011 In response to the litigation outcome, the EPA issues a cancellation order and 

modifies the Rozol label to indicate Rozol is not a labeled use in Montana, 

North Dakota, New Mexico, or South Dakota (EPA 2011a). Upon completion 

of the BO, the EPA anticipates a label modification to add those states back 

onto the label.

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

died of chlorophacinone poisoning (Service 2011b). 

Sept. 9, 2011 The Service responds to the EPA’s request for formal ESA section 7 

consultation for Rozol use on black-tailed prairie dogs and acknowledges there 

is sufficient information to begin formal consultation (Service 2011c). The 

Service also requests information on the status of Reasonable and Prudent 

Measures and suggested studies from the 1993 BO to help inform the current 

section 7 consultation. 

Sept. 2011 The EPA and the Service discuss conservation measures that could be 

developed and instituted to avoid and minimize adverse effects to listed species 

and agree to include the registrant and applicant, Liphatech, Inc., in those 

discussions. 
5

Sept. 28, 2011 A conference call between Liphatech, Inc., the EPA and the Service discussed 

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 black-tailed prairie dogs. All parties were receptive to 

development of conservation measures that could be integrated into the 

proposed action. 

Oct. 2011 Due to interest in the conservation measures, the Service inquires of Liphatech, 

Inc., 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 is expected to significantly modify the 

anticipated impacts to listed species and the parties agree that additional time 

can be afforded.

Oct. 2011 The Service begins providing maps of listed species areas where Rozol use 

would be prohibited or where the use dates of October 1 through March 15 

would be restricted to avoid listed species interaction with black-tailed prairie 

dog colonies that have had Rozol applications. The EPA provides this

information to Liphatech, Inc. 

Oct. 17, 2011 The EPA sends a response to the Service’s September 9, 2011, letter that had 

requested additional information from the 1993 chlorophacinone BO (EPA 

2011b). The EPA letter indicates that no additional information is available;

Reasonable and Prudent Alternatives, Reasonable and Prudent Measures, and 

suggested animal studies from the 1993 BO were either not implemented or 

information is not available on the implementation.

Nov. 8, 2011 Conference call between the EPA and the Service to further discuss 

conservation measures and confirm the information that will be provided to 

Liphatech, Inc. 

Nov. 22, 2011 The Service provides a signed declaration to the District of Columbia Court 

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

per the understanding with the EPA that with the development of the 

conservation measures, additional time for drafting the BO is warranted 

(Service 2011d).

Dec. 13, 2011 The EPA provides a letter to the Service and Liphatech, Inc., that formalizes the 

agreed upon conservation measures which avoided and minimized 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.

Jan. 16, 2012 The Service provides a draft Rozol BO to the EPA.
6

DESCRIPTION OF THE ACTION

On December 12, 2007, the EPA, the National Marine Fisheries Service, and the Service agreed 

that the federal action for EPA’s Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) 

registration actions will be defined as the “authorization for use or uses described in labeling of a 

pesticide product containing a particular pesticide ingredient.” For this consultation, the 

proposed action by the EPA is the administration of the FIFRA section 3 registration of the 

single product label for Rozol (registration number 7173-286) to poison black-tailed prairie dogs 

in ten states. Rozol (active ingredient: chlorophacinone) is manufactured by Liphatech, Inc. 

(Liphatech, the registrant) as a loose-grain bait used to poison black-tailed prairie dogs in the ten 

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/Liphatech have indicated the intent to resume 

application in those states upon section 7 consultation completion; thus, all ten states listed on 

the September 10, 2010, Rozol label (see Appendix) are considered herein. 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; those measures are listed below (EPA 2011c). 

The action area is described and items relevant to use of the product as directed by its label were 

described in the EPA formal consultation initiation package (EPA 2010b). Additionally, 

information regarding direct and indirect effects of the proposed action and potential exposure 

routes to Federal trust species, as well as a review of the EPA’s biological assessment (BA), 

Risks of Chlorophacinone Use on Black Tailed Prairie Dogs to federally Endangered and 

Threatened Species (EPA 2010b), are provided herein. This information provides the context in 

which the subsequent individual species analyses were conducted. 

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 and incorporated into the effects analysis in this BO. The Service identified these 

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

acceptability of the measures as well as the best means to implement them. The measures below

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

County Bulletins, considered to be an extension of the Rozol label thereby legally requiring 

applicators to adhere to them (EPA 2011c). Conservation measures developed for eight federally 

listed species are provided below. Maps of each of the excluded areas described in the 

Conservation Measures will be included in the EPA County Bulletin database and label 

requirements will make clear that Rozol use in these areas is restricted or prohibited. Any use of 

Rozol in these locations will be a violation of federal law.
7

1. Black-footed Ferret Conservation Measure

• Prohibit application of Rozol within current (13 sites) and future black-footed ferret 

reintroduction areas to reduce the level of impact to the black-footed ferret. This 

information will be located in the EPA County Bulletin 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 proposed critical habitat. 

3. Grizzly Bear Conservation Measure

• Delay application of Rozol in the fall by two 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 black-tailed prairie dog to reduce the 

risk of impacts to the grizzly bear. 

• The timing delay applies only in Montana, within the counties 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

• 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 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. 
8

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 one month, until November 1, in areas where the 

range of the Preble’s meadow jumping mouse overlaps with the range of the black-tailed 

prairie dog to reduce the risk of impacts to the Preble’s meadow jumping mouse. 

• 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. 

ROZOL PRAIRIE DOG BAIT REGISTERED USE

The chlorophacinone concentration in Rozol is 0.005% or 50 milligrams per kilogram (mg/kg). 

According to Rozol label instructions (Appendix), the product is to be applied to black-tailed 

prairie dog 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 between October 1 and March 

15 of the following year, when the prairie dogs most readily consume grain bait (Appendix). 

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 the applicator must return to the site within 4 days after bait 

application and at 1 to 2 day intervals thereafter for at least two 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.
9

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 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 black-tailed prairie dog range from 

NatureServe (www.natureserve.org) (Figure 2.2 on pg 55 of 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 black-tailed prairie dog range. Range maps from 

NatureServe for federally listed species and/or their critical habitats were overlaid on that 

historic black-tailed prairie dog 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 black-tailed 

prairie dog 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 black-tailed prairie dog has contracted from its historic range, so in some areas the 

species’ current range overlap with federally listed species has been reduced (Service 2009b). 

The historic range map includes portions of the state of Arizona and small areas within Mexico 

and Canada; however, this consultation applies only to the United States and is limited to Rozol 

use within the ten 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. However, for the purpose of this consultation, the 

Service agrees with the EPA’s definition of the broad action area as it encompasses the potential 

areas where indirect effects may occur. 
10

Figure 1. The historic range of the black-tailed prairie dog by NatureServe as presented in the 

EPA’s BA (EPA 2010b).
11

GENERAL BACKGROUND AND EFFECTS OF THE ACTION 

RELEVANT TO ALL SPECIES IN CONSULTATION

Prairie dogs 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 black-tailed prairie dog colonies (Sharps and Uresk 1990). 

Presence of mountain plover (Charadrius montanus) and burrowing owl (Athene cunicularia), 

two species of conservation concern (Service 2008a), are also considerably higher on blacktailed prairie dog 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 will result in cascading effects through the grassland ecosystem 

that extend beyond the poisoned prairie dog towns. 

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. Both have been registered for use to control black-tailed prairie dogs under FIFRA 

section 24(c) for Special Local Needs and Rozol has been registered under FIFRA section 3. 

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). 
12

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

exposed to daily doses for multiple days (Vyas et al. 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). 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 seven days increased diphacinone toxicity by more than 

an order of magnitude compared to an acute oral toxicity test (Rattner et al. 2011a; Vyas, 

personal communication, 2011a). 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, which have 

their greatest toxicity from repeated daily exposures. We believe 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 one 

time feeding.

When black-tailed prairie dogs are exposed to chlorophacinone, there is 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 two peaks in the 

number of black-tailed prairie deaths, a larger peak that occurs 9 to14 days after exposure and a 

second smaller peak that occurs 17 to 20 days after exposure (Yoder 2008). Black-tailed prairie 

dogs exposed to chlorophacinone may not exhibit any symptoms prior to death but most are

symptomatic for at least 24 hours before death (Yoder 2008). Black-tailed prairie dog 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 (Yoder 

2008). There is no apparent taste aversion to Rozol as black-tailed prairie dogs readily consume 

Rozol bait (Witmer 2011).

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 classified by the EPA as invalid 

(Jones, personal communication, 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). 
13

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, personal 

communication, 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 personal communication, 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 personal communication,

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 nontarget organisms. We assume chlorophacinone remains undegraded in bait after annual 

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

through its consumption.

ROZOL EXPOSURE AND EFFECTS ASSESSMENT

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 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 black-tailed prairie dog holes. Rozol 

was visible in many black-tailed prairie dog burrows that contained angled entrances (as opposed 

to vertical entrances) and that 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, personal communication, 2011b). 
14

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 

system (Vyas 2010a). It would have been helpful if there was some documentation to indicate 

applicator willingness to cease operations and collect misplaced bait or return to the colony days 

to weeks later to collect and disposed of bait found on the surface. Absent that information, it 

appears 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 indicate 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 black-tailed 

prairie dog, 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 likely provides at least 10 lethal doses. Furthermore, 

there are on average 3.9 active burrows entrances for each black-tailed prairie dog (Biggins et al.

2006). If inactive burrows are mistakenly baited then even further bait availability 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 black-tailed prairie dogs 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 levels of death 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 black-tailed prairie dogs. Sullins (1990) reported a 96 

percent reduction in the visible count of black-tailed prairie dogs after providing 0.01 percent 

chlorophacinone product in two applications of 9 grams per active burrow for a total of 18 grams 

within 48 hours. 

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 
15

below). The study noted above (Fisher and Timm 1987) found that five of six domestic ferrets 

were killed after feeding on four poisoned black-tailed prairie dogs over eight days and 

concluded that chlorophacinone may not be an acceptable prairie dog toxicant based on high 

secondary toxicity. As described further in the “Field Study Observations of Secondary 

Toxicity” section below, field observations indicate that the availability of black-tailed prairie 

dogs to secondary consumers is facilitated by a prairie dogs spending time above ground after 

ingesting Rozol (Service 2007a, Golden and Gober 2010, Vyas 2010a). When subjected to 

poisoning, black-tailed prairie dogs can return to the surface of the colony, becoming 

increasingly debilitated until death. Prairie dogs in this debilitated state can be more susceptible 

to predation due to changes in behavior that render them more conspicuous and/or 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). Some avian predators such as ferruginous hawks are attracted to Rozoltreated prairie dog colonies, likely due to the increased presence of morbid 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. 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 

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, 

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. An 

assessment of wildlife anticoagulant rodenticide poisonings in New York from 1971 to 1997 

(Stone et al. 1999) found that pulmonary hemorrhage is far more common in mammals than 

birds but about one-third of birds examined had excessive external bleeding from minor 

superficial wounds, a condition not reported in mammals. Also, studies have reported that the 

first observed signs of secondary chlorophacinone toxicity in raptors include fatigue such as 

wing-drooping (Radvanyi et al., 1988). For species that rely upon speed and stamina, such as 

raptors to attain prey species chlorophacinone induced fatigue can result in decreased survival. 

Because of difference 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 
16

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. 

Surface Presence of Poisoned Black-tailed Prairie Dogs

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

retrun 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 above-ground prairie dogs following application have also been reported to the 

Service’s Law Enforcement Division (Service 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 (Service 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 Special 

Local Needs 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 (Service 2007a), we believe Rozol-poisoned prairie dogs and other rodents 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. 
17

Removal of Poisoned Black-tailed Prairie Dogs

Although the Rozol label requires the search and removal of dead and dying prairie dogs 

following application, the limited information on applicator behavior indicates that few if any 

moribund or dead prairie dogs found on the surface are collected and disposed of in a manner 

that substantially reduces secondary exposure (Service 2010a, Tosh et al. 2011). This 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 are 

not available (Service 2010a). During a prairie dog 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 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 (Service 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 in August 2010 to potentially many more visits. The EPA prefaced their 

inquiry to the ranchers in attendance, that additional returns 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 and thus requiring even more return visits would likely meet a similar fate. 

Of particular note from that meeting was that none of the attendees had ever picked up and 

disposed of live prairie dogs or their carcasses after Rozol application. 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). 

The Service believes that 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. Many prairie dogs are likely scavenged prior to 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 one to two 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 can be difficult to find without systematic searches. We could locate 

no information to indicate 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 

that they would be removed from the site, as 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, ferrets, and other carnivores that can dig up prey or carrion.
18

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. 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 

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 methods are expected to find fewer poisoned carcasses than those 

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

Furthermore, Vyas (2010a) observed dying black-tailed prairie dogs on his last search 29 days 

after application. Thus, searchers that stop finding carcasses after two weeks and end, as 

specified on the label, would likely miss any second peak in deaths 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 in finding poisoned prairie dogs above ground and thus unlikely to prevent nontarget exposure.

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 black-tailed 

prairie dogs are likely to remain at the colony where they were poisoned and are available for 

consumption by federally listed species and other non-target predators and scavengers. 

Field Study Observations of Secondary Exposure or Toxicity

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

action thus we consider study observations of secondary exposure to non-target species from 

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

chlorophacinone or diphacinone exposure to non-target species following applications to poison 
19

black-tailed prairie dogs (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 black-tailed prairie dogs and that study included searches for carcasses on and 

immediately around baited plots. They found 10 carcasses above ground (nine black-tailed 

prairie dogs and a cottontail rabbit) at a ratio of one 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 post 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 blacktailed prairie dogs and other wildlife (Vyas 2010a). Carcass searches were conducted over an 

area of approximately 43 acres for 14 days over the 29-day post application period and recovered 

two intact thirteen-lined ground squirrels (Spermophilus tridecemlineatus), nine intact blacktailed prairie dogs, seven scavenged black-tailed prairie dogs and one 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, personal communication, 2010). Meadowlarks are a recognized food source for 

the federally endangered northern aplomado falcon (Service 2002b). Raptors were also seen 

visiting the poisoned prairie dog colony and foraging on black-tailed prairie dogs (Vyas 2010a). 

A Rozol application in South Dakota on a prairie dog colony in 2005 found approximately 400 to 

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). At that time, Rozol was not authorized 

for use in South Dakota and a subsequent investigation by 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 (Service 2007a). The eagle carcass was in good condition when received by the 

laboratory and was x-rayed, dissected, and examined for gross pathological lesions. Liver 

samples were analyzed for lead and anticoagulant rodenticides. The laboratory diagnosis 
20

revealed that poisoning with chlorophacinone and physical trauma had occurred. The lab 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 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 (Service 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, black-tailed prairie dogs are often seen above ground in a moribund state of stupor that 

leaves them vulnerable to capture or predation (Service 2007a). 

In January of 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 (Service 2009c). Both raptors were 

found in an area where Rozol was being used to control prairie dogs and had a liver 

chlorophacinone concentration of 0.25 μg/g ww. 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 of 2011, another bald eagle carcass was opportunistically recovered 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 (Service 2011b). 

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 eagle was recovered, and the law enforcement case is still under 

investigation.

Based on the reports described above (Lee and Hygnstrom 2007, Service 2007a, Service 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 black-tailed prairie dogs under the 

current label directions. 

REVIEW OF THE EPA’S ROZOL EFFECTS DETERMINATION 

We believe risk calculations in EPA’s BA likely underestimate risk to non-target species. 

Therefore, the comments in this section informed the development of the BO and serve as 

feedback to the EPA for consideration in developing future effects determinations.
21

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. The BA provides a RQ of 0.104 for avian species, a value that barely exceeds the EPA’s 

Level of Concern of 0.1 (EPA 2010b). The Toxicity Reference Value (TRV) used to calculate 

this RQ is based on dietary median Lethal Concentration (LC50) for northern bobwhite (Colinus 

virginianus). 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, 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. 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 and over 30 times more 

sensitive than mallards (Anas platyrhynchos), two 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 exhibit greater 

sensitivity than can be estimated from existing mallard or northern bobwhite 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 

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 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 
22

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 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 sub-lethal 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 black-tailed prairie dogs 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 blacktailed prairie dog’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.

Prairie Dog Chlorophacinone Residues

In its BA, 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 black-tailed prairie dogs; however, this value may underestimate exposure. The prairie 
23

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 black-tailed prairie dog 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 (Witmer 2011) for black-tailed prairie dogs that consumed a single dose (53 grams bait) 

and were euthanized periodically after being maintained on a clean diet. 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 ten 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, that may be selectively consumed by predators or scavengers, and 

are generally much greater than whole-body concentrations. Eight black-tailed prairie dog 

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 black-tailed prairie dog is 8.4 μg/g ww in a black-tailed 

prairie dog that consumed 52.8 grams of Rozol and was euthanized two 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. 
24

Figure 2. Black-tailed prairie dogs (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
25

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 use 

for 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 black-tailed prairie dog 

whole-body concentration of 2.24 μg/g ww does not exceed the Level of Concern 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, EPA’s RQ 

calculations in the BA do not specifically address uncertainty from the influence of 

environmental stressors that can make them 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, 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 and 2011b). Reported mortality 

incidents involving raptors described herein support the likelihood that these taxa can be killed 

from exposure through Rozol use in prairie dogs. If the BA applied uncertainty factors for 

interspecies sensitivity alone, then RQs based on chlorophacinone concentrations in black-tailed 

prairie dogs would exceed the Level of Concern 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 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 
26

option is to express risk in qualitative terms. Professional judgment or other qualitative 

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 

adverse effects were likely even though both RQs were below the Level of Concern 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 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. 

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, Service 2007a, EPA 2010, 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, Service

2007a). It is noteworthy that the bobcat had a liver concentration of 0.4 μg/g ww and apparently 

died from tertiary exposure to chlorophacinone as it was found dead one day after seen feeding 

on a dead owl that contained a rodent carcass in its crop (Eriskson and Urban 2004, EPA 2010). 

 

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 and there were known chlorophacinone applications in the area. The badger was found 

within an area in western Kansas where Rozol had been used and had a 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 four-year survey of 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 
27

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, or size or coloration that renders the carcass inconspicuous, or filed 

conditions such as remote, inaccessible areas, 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 black-tailed prairie dogs. 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 

(Service 2007a, 2009c, and 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 (Service 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. 

Migratory raptors are especially susceptible to secondary poisoning from anticoagulant use due 

to their propensity to feed in prairie dog colonies (Golden and Gober 2011). Raptors are 

believed to be especially susceptible to secondary poisoning from Rozol given the likelihood that 

they can spot dead or dying black-tailed prairie dogs that are more difficult to see from a ground 

level perspective (Vyas 2010b) and raptors have been observed to be attracted to Rozol poisoned 

black-tailed prairie dog 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 (Service 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 (Service

2009d, Golden and Gober 2010). Bald eagles have a kleptoparasitic association with ferruginous 

hawks (whereby eagles pursue 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 black-tailed prairie dogs (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 
28

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 are practical or implementable. While the Migratory Bird Treaty Act has no provision 

for allowing unauthorized take, there is an expectation that reasonable and effective measures to 

prevent poisoning of migratory birds will be implemented. Our Office of Law Enforcement 

carries out its mission to protect migratory birds through investigations and enforcement, as well 

as by fostering relationships with agencies, individuals, companies, and industries that have 

taken effective steps to avoid take of migratory birds and by encouraging others to implement 

measures to avoid take of migratory birds. It is not possible to absolve individuals, companies, 

or agencies from liability even if they implement bird mortality avoidance or other similar 

protective measures. However, the Office of Law Enforcement focuses its resources on 

investigating and prosecuting individuals and companies that take migratory birds without 

identifying and implementing all reasonable, prudent and effective measures to avoid that take. 

Companies and agencies are encouraged to work closely with us to identify available protective 

measures when seeking authorization for actions that are expected to take migratory birds. 

Rozol use on black-tailed prairie dogs is expected to result in take of migratory birds including 

federally listed species such as northern aplomado falcon.

As noted earlier, Rozol use on black-tailed prairie dogs was determined to have killed a bald 

eagle in 2006 when that species was protected under ESA, which prohibits unauthorized taking 

of federally listed endangered or threatened species. In accordance with the bald eagle postdelisting monitoring plan (Service 2010b), the bald eagle monitoring team continues to track new 

and potentially significant sources of bald eagle mortality. Since Rozol was authorized for 

black-tailed prairie dog control in 2006, there have been two bald eagle deaths attributed to 

chlorophacinone poisoning in Nebraska. We consider Rozol use on black-tailed prairie dogs 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. 

SUMMARY OF ROZOL EXPSOURE AND EFFECTS RELEVANT TO ALL LISTED 

SPEICES ADDRESSED IN THIS BO 

• 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-targets animals. 
29

• 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.

• Based on the label application rate, excessive lethal doses per black-tailed prairie dog 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 result in a high risk of secondary exposure to 

non-target species, especially those species attracted to poisoned black-tailed prairie dog 

colonies. A six 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. Label requirements aimed at 

reducing non-target species exposure based on return site visits for weeks after the 

application to pick up dead and dying prairie dogs and bait are impractical, and not 

effective at protecting non-target species that may dig up carcasses or feed on poisoned 

prey during periods between required carcass searches.

• Risk quotients derived in the EPA’s BA underestimate non-target species risk to Rozol 

because they are: a) based on study protocols that consider limited (one to five 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; 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 whole-body 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. 
30

• Opportunistic recoveries have shown that Rozol use on black-tailed prairie dogs 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 especially susceptible to 

Rozol toxicity and are expected to continue to die from Rozol exposure given current 

label use restrictions. 

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. We believe the following 

conservation recommendations are within the EPA’s authorities and can benefit the listed species 

in this consultation. These recommendations are based on the information described in the 

previous section and are intended to reduce Rozol exposure and effects to listed species and nontarget species.

1. If 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 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 one time feeding. We recommend future assessments for first generation indandione 

rodenticides are modified to include multiple day exposures that measure individual daily 

dosage and responses to compliment 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).

2. If 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 current label language 

does not accomplish the intended result. 
31

3. If 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 EPA 

has required Liphatech to complete, we recommended that 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) 

to Rozol poisoning from applications at prairie dog towns. Such information would 

benefit our evaluation of the endangered northern aplomado falcon and other raptors if 

they were to become federally listed under ESA. 

4. If 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. 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.

5. If 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. 

6. Given our concerns with secondary toxicity, we encourage the EPA to include language 

on the Rozol label county bulletin that recommends an Integrated Pest Management 

(IPM) approach for use of Rozol to prevent unnecessary applications when good 

alternatives to pesticides exist. Guidance on how to perform IPM should also be 

provided on the county bulletin. 

7. We recommend that EPA require applicator monitoring and reporting as part of the Rozol 

label. This requirement should be aimed at obtaining standardized data that identifies the 

number of poisoned black-tailed prairie dogs above ground and the number of individual 

and non-target species injured from Rozol. Such information would benefit the 

development of successful strategies to reduce non-target species exposure. 
32

SPECIES ANALYSES

OVERVIEW

On September 9, 2011 we agreed with the EPA’s analysis that Rozol use on black-tailed prairie 

dog towns is likely to adversely affect 18 listed species and critical habitat for six species

(Service 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 listed species and their critical 

habitats. The adopted conservation measures in the EPA’s December 13, 2011, letter have been 

agreed to by Liphatech, and will be incorporated into County Bulletins as part of the Rozol label 

before October 1, 2012 (EPA 2011c). The analysis herein for the black-footed ferret, Chiricahua 

leopard frog, grizzly bear, jaguar, Mexican spotted owl, New Mexican ridge-nosed rattlesnake, 

and Preble’s meadow jumping mouse is based on this new information. 

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 was typically due to lack of overlap in range of the species or 

critical habitat with the range of the black-tailed prairie dog or lack of common use by the 

species of habitats occupied by the black-tailed prairie dog. For those species, the risk of Rozol 

exposure and effects is considered highly unlikely, thus adverse effects are not expected to occur. 

A full analysis is provided herein for the black-footed ferret, gray wolf, and northern aplomado 

falcon, because the 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 with reasonable and prudent measures 

and implementing terms and conditions. 

Thus, the species/habitats analyzed for this formal consultation are categorized as falling into one 

of three groups: 1) species for which the EPA adopted conservation measures after initiating 

formal consultation, removing or reducing the risk of adverse effects; 2) species for which 

further review by the Service, after consultation was initiated, revealed that adverse effects are 

not anticipated; 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).
33

Table 1. Summary of species determinations and page number for each species’ analysis within 

this biological opinion. 

Species and/or 

Critical Habitat

Species for 

Which 

Conservation 

Measures 

Preclude 

Adverse Effects

Species for 

which No 

Adverse Effects 

are anticipated, 

without 

Conservation 

Measures.

Species for 

which Adverse 

Effects are 

anticipated, 

with or without 

Conservation 

Measures

Page

American Burying Beetle

(Nicrophorus americanus) ■ 44

Black-capped Vireo (Vireo 

atricapilla) ■ 45

Black-footed Ferret

(Mustela nigripes) ■ 59

Canada Lynx (Lynx 

Canadensis) ■ 47

Chiricahua Leopard Frog

(Lithobates [Rana] 

chiricahuensis)

■ 34

Eskimo Curlew (Numenius 

borealis) ■ 48

Golden-cheeked Warbler

(Dendroica chrysoparia) ■ 49

Gray Wolf (Canis lupus) ■ 73

Grizzly Bear (Ursus arctos 

horribilis) ■ 35

Gulf Coast Jaguarundi

(Herpailurus (=Felis) 

yagouaroundi cacomitli)

■ 51

Jaguar (Panthera onca) ■ 37

Mexican Spotted Owl

(Strix occidentalis lucida) ■ 38

New Mexican Ridge-nosed 

Rattlensake (Crotalus 

willardi obscurus)

■ 38

Northern Aplomado Falcon

(Falco femoralis 

septentrionalis)

■ 87
34

Ocelot (Lepardus pardalis) ■ 51

Piping Plover (Charadrius 

melodus) ■ 51

Preble’s Meadow Jumping 

Mouse (Zapus hudsonius 

preblei)

■ 39

Whooping Crane (Grus 

americana) ■ 54

The details regarding the anticipated effects of the proposed action on each of the species in this 

consultation are provided in the analyses below. 

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 implementing exclusion zones and/or timing restrictions for the application 

of Rozol. As a result of the conservation measures incorporated into the proposed action by 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) Preble’s meadow jumping mouse. 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 black-tailed 

prairie dog bait. In New Mexico, the species occurs in Catron, Hidalgo, Grant, Sierra, and 

Socorro Counties, in about 16 to 19 percent of its historical localities (Service 2007b). Fifteen 

units of critical habitat have been proposed in New Mexico for the Chiricahua leopard frog

(Service 2011m). Proposed critical habitat and the black-tailed prairie dog range appear to 

overlap in New Mexico, at least at a landscape-scale level.

The EPA determined the proposed action may directly affect the Chiricahua leopard frog 

because the range of the species overlaps with black-tailed prairie dog habitat. Although Catron, 

Hidalgo, Grant, Sierra, and Socorro Counties do not have large colonies of black-tailed prairie 

dogs (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 BA determined that Chiricahua 
35

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, leopard frogs only eat live prey and would 

not consume a dead organism; they do not scavenge. A large portion of 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.

The EPA has agreed to adopt conservation measures to minimize potential exposure of 

Chiricahua leopard frogs to Rozol by precluding its application in Catron, Hidalgo, Grant, Sierra, 

and Socorro Counties. Because proposed critical habitat captures a large portion of the range of 

Chiricahua leopard frog in New Mexico, the proposed conservation measure of excluding 

Catron, Hidalgo, Grant, Sierra, and Socorro Counties would greatly reduce the potential for 

exposure to Rozol and significantly reduce potential for adverse effects to the Chiricahua leopard 

frog and its proposed critical habitat. Additionally, Rozol would not be applied within proposed 

critical habitat, thus no Rozol impacts to critical habitat are anticipated.

Accordingly, implementation of the proposed action, and its associated conservation measures, is 

not anticipated to result in adverse effects to the Chiricahua leopard frog, nor adverse 

modifications of its proposed critical habitat. 

2. GRIZZLY BEAR

In the BA, the EPA describes direct effects to grizzly bears that are expected to occur based on 

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 

black-tailed prairie dog 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 Risk Quotients that

greatly exceeded a 0.1 Level of Concern for grizzly bears (Table 5.3, page 83), especially for 

primary consumption (Risk Quotient = 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 black-tailed prairie dogs (see list below). This measure would greatly reduce 
36

the potential for overlap of grizzly bears and Rozol treated black-tailed prairie dog 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 black-tailed prairie dog colonies 

that exist in the mountain/prairie transition zone where the occasional grizzly bear may 

encounter black-tailed prairie dog colonies. Based on a map produced by the Montana Natural 

Heritage Tracker website, less than 10 known or documented black-tailed prairie dog colonies 

occur where grizzly bears currently may occur (Montana Natural Heritage Program 2011).

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 black-tailed prairie dogs is low enough to be considered discountable. With 

few black-tailed prairie dog colonies in areas where grizzly bears are likely to occur, the 

likelihood of grizzly bears using black-tailed prairie dog habitats as part of their home range is 

low. The restricted use season for Rozol (December 1 – 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 black-tailed prairie dog 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 black-tailed prairie dog colonies, until two to four weeks after 

emerging from their dens if they use those areas at all. Therefore, grizzly bears would not be 

expected to overlap with black-tailed prairie dog colonies for approximately six to eight weeks 

after March 1 (around 50 days or more post any final application). 

With the timing restriction conservation measure, we conclude that detrimental 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 

seven (Lee and Hygnstrom 2007). Thus after approximately 50 days post application, when 

grizzly bears may first encounter a Rozol-poisoned black-tailed prairie dog town, essentially all 

of the bait is likely to have been consumed by black-tailed prairie dogs or non-target species. 

The EPA calculated that a grizzly bear needs only to consume four grams of bait per day for five 

days to exceed a 0.1 Level of Concern (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 black-tailed prairie dog 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. 
37

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 black-tailed prairie dogs 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, Rozolpoisoned carcasses or prey debilitated by exposure to Rozol would be available for consumption 

by grizzly bears. While moribund black-tailed prairie dogs were detected by 29 days after Rozol 

application (Vyas 2010a), the prairie dog availability is not expected to be high 50 days 

following application because 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. Therefore, by the time grizzly bears may 

use habitat within a these areas the Services believes there will be insufficient quantities of 

available prey items or bait to cause adverse effects. 

It is also the Service’s belief that indirect effects to grizzly bears due to the loss of prey base 

from use of Rozol are “insignificant” as defined under the ESA. Few black-tailed prairie dog 

colonies occur in areas where grizzly bears also occur, and prairie dogs are not known to be a 

significant dietary item for grizzly bears. 

In summary, few black-tailed prairie dog 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 blacktailed prairie dogs in those areas. 

3. JAGUAR

The EPA determined 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 black-tailed prairie dogs 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 (one report in last 20 

years) found 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 black-tailed prairie dogs in Hidalgo County (Johnson et al. 2003). 

The proposed conservation measure of Rozol application exclusion in Hidalgo County 

substantially reduces the risk of Rozol exposure to the jaguar. Based on the low black-tailed 

prairie dog abundance, unlikely interaction of the jaguar and black-tailed prairie dog, and Rozol 

application exclusion in the area occupied by the jaguar, Service does not anticipate adverse 

effects to the jaguar.
38

4. NEW MEXICO RIDGE-NOSED RATTLESNAKE

The BA indicates that New Mexico ridge-nosed rattlesnakes are unlikely to be killed by bait 

ingestion because the Risk Quotient is less than the Level of Concern, 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 black-tailed prairie dog burrows. 

In addition, the BA indicates that adverse effects to designated critical habitat are expected 

because of overlap with black-tailed prairie dog 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. Black-tailed prairie dog 

habitat does not overlap with the New Mexico ridge-nosed rattlesnake, though 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 black-tailed prairie dog abundance in 

Hidalgo County (Johnson et al. 2003), the low probability of interaction between the New 

Mexico ridge-nosed rattlesnake and black-tailed prairie dog based on differing habitat use of 

each species, and Rozol use prohibition in the area occupied by the snake, effects from the action 

are unlikely to occur. The Service does not anticipate adverse effects to the New Mexico ridgenosed rattlesnake. 

Designated critical habitat for the New Mexico ridge-nosed rattlesnake occurs only in Hidalgo 

County within the action area. There are no known black-tailed prairie dogs 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. 

5. 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 black-tailed prairie dog 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 (Service 1995). The action area was analyzed for possible 

effects to Mexican spotted owl that includes the black-tailed prairie dog range within the three 

states listed. Effects may extend beyond the use area due to exposure to individuals or via prey 
39

items with chlorophacinone residues if found outside of their described range. The final 

Mexican spotted owl critical habitat rule (Service 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 (Service 2004). Within this larger area, critical habitat is limited to areas that 

contain the primary constituent elements (Service 2004). The primary constituent elements 

include forest structure for nesting and prey maintenance, but not the prey base itself (Service

2004). In summary:

• Known habitat use by the Mexican spotted owl does not correspond with black-tailed 

prairie dog habitat, thus the owl is considered extremely unlikely to occur within blacktailed prairie dog 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 primary constituent elements of 

designated critical habitat for the Mexican spotted owl.

• The proposed Rozol application exclusion 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:

6. PREBLE’S MEADOW JUMPING MOUSE

In the BA (p. 104), the EPA concludes that the use of Rozol to control the black-tailed prairie 

dog is likely to adversely affect the Preble’s meadow jumping mouse (Zapus hudsonius preblei) 

for the following reasons:

The range of this species overlaps with BTPD habitat. Rozol Prairie Dog bait application 

season for the control for BTPDs 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.
40

The Preble’s meadow jumping mouse 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 BA (Appendix A, p. 20) erroneously shows the Preble’s meadow jumping mouse’s

range to be throughout all of Wyoming. 

The action area defined by the EPA in the BA broadly overlaps the range of the Preble’s 

meadow jumping mouse. However, the known distribution of the Preble’s meadow jumping 

mouse and the known distribution of the black-tailed prairie dog within Wyoming and Colorado 

overlap significantly less than depicted in the BA. This inaccuracy results from the inclusion of 

areas in the mapped Preble’s meadow jumping mouse range where potential habitat may exist, 

but where the Preble’s meadow jumping mouse 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 

black-tailed prairie dog. 

In Wyoming, the Preble’s meadow jumping mouse is known to occur only in Albany, southern

Converse, Laramie, and Platte counties. The Preble’s meadow jumping mouse is not thought to 

occur in Wyoming’s Goshen and Niobrara counties to the east, or eastern Laramie County 

(Keinath 2001). Occurrence of the Preble’s meadow jumping mouse and black-tailed prairie dog

in Wyoming overlaps primarily in portions of southern Converse County and western Platte 

County (Wyoming Natural Diversity Database (WYNDD) 2011). Known distribution of the 

Preble’s meadow jumping mouse in Colorado includes Boulder, Douglas, El Paso, Elbert, 

Jefferson, Larimer, Teller, 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

Preble’s meadow jumping mouse have been documented within its potential range in Adams, 

Arapahoe, Broomfield, Denver, or Morgan counties, and it is likely that the Preble’s meadow 

jumping mouse does not occur in these areas. Occurrence of the Preble’s meadow jumping 

mouse and black-tailed prairie dog 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). 

An estimated < 30 percent of the Preble’s meadow jumping mouse distribution falls within the 

range of the black-tailed prairie dog. Within the black-tailed prairie dog 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 Preble’s meadow jumping 

mouse occurrence, it is reasonable to believe that presence of the mouse in close proximity to 

black-tailed prairie dog colonies is infrequent throughout occupied Preble’s meadow jumping 

mouse range. 
41

In the BA (p. 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.

Meadow jumping mice are omnivores and consume such foods as seeds, fruits, fungi, and 

insects. Studies specific to the Preble’s meadow jumping mouse diet are limited, but fecal 

analyses suggest that Preble’s meadow jumping mouse diet shifts seasonally; it consists 

primarily of insects and fungus after emerging from hibernation, shifts to fungus, moss, and 

pollen during mid-summer (July-August), with insects again added in September (Shenk and 

Sivert 1999). The Preble’s meadow jumping mouse would probably consume both treated grain 

bait and exposed insects if they were encountered.

Where both Preble’s meadow jumping mouse and the black-tailed prairie dog occur, habitat 

isolation between the Preble’s meadow jumping mouse and black-tailed prairie dog reduces the 

chance that the Preble’s meadow jumping mouse would encounter treated grain or exposed 

insects. Typical habitat for the Preble’s meadow jumping mouse 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 Preble’s meadow jumping mouse 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, black-tailed prairie dog colonies are typically in uplands, 

where their activities greatly reduce vegetative cover in the vicinity of their burrows. The 

Preble’s meadow jumping mouse 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 Preble’s meadow jumping mouse. 

The Preble’s meadow jumping mouse 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 seven or eight months. The only direct overlap between the 

Preble’s meadow jumping mouse active season and the Rozol treatment period, as reflected in 

label instructions (October 1 through March 15) is October, when some Preble’s meadow 

jumping mouse 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 Preble’s meadow jumping mouse occurrence in Wyoming and 

Colorado to the period November 1 through March 15. Timing restrictions will be included in 

County Bulletins for those counties included.
42

By November 1, all Preble’s meadow jumping mouse 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 Preble’s meadow jumping mouse active 

season. Further, data on the diet of the Preble’s meadow jumping mouse 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 blacktailed prairie dog burrows. Our knowledge of the Preble’s meadow jumping mouse does not 

suggest that, while foraging, they would venture into prairie dog burrows where Rozol-treated 

bait is placed. Spillage, improper baiting, or black-tailed prairie dog digging activity could result 

in some bait exposed on the ground surface. By the time Preble’s meadow jumping mouse

emerge from hibernation, bait consumption by various granivores, including insects, would 

reduce remaining bait availability. 

The scenario of the Preble’s meadow jumping mouse emerging from hibernation in locations 

adjacent to black-tailed prairie dog 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 Preble’s 

meadow jumping mouse food resources was noted in the EPA’s Effects Determination within the 

BA as a possible secondary impact to the mouse. As stated above, the species feeds on a variety 

of items including insects. However, it is unlikely to regularly forage in black-tailed prairie dog

colonies and invertebrate prey from such habitat is not known to be a significant food source for 

the Preble’s meadow jumping mouse. The potential for the mouse to be adversely impacted by 

reduction of the invertebrate populations within prairie dog colonies appears insignificant. 

In summary, occurrence of the Preble’s meadow jumping mouse in the proximity of black-tailed 

prairie dog colonies is likely infrequent within Preble’s meadow jumping mouse range. Where it 

occurs, the Preble’s meadow jumping mouse would rarely venture into black-tailed prairie dog

colonies, creating a degree of habitat isolation between the two species. The Preble’s meadow 

jumping mouse hibernates November through April, throughout the period of Rozol application

as modified by the agreed upon conservation measures (November through March 15), creating a 

temporal isolation between availability of Rozol-treated bait or effected insects and the Preble’s 

meadow jumping mouse active season. Therefore, the Service does not anticipate adverse 

effects as a result of the proposed action. 
43

Regarding potential impact to Preble’s meadow jumping mouse critical habitat, in the BA (p. 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 Preble’s meadow jumping mouse critical habitat in Colorado 

overlaps with the black-tailed prairie dog range, which is approximately 35 percent of all 

Preble’s meadow jumping mouse designated critical habitat. For the Preble’s meadow jumping 

mouse, 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 Preble’s 

meadow jumping mouse; 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 Preble’s meadow jumping mouse 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 black-tailed prairie dog and subsequent loss of prairie dog 

colonies is unlikely to adversely impact the PCEs of Preble’s meadow jumping mouse critical 

habitat above, it could have indirect effects to Preble’s meadow jumping mouse habitat due to 

the loss of black-tailed prairie dog burrows and cessation of black-tailed prairie dog activities 

that would otherwise modify vegetation. In the BA (pp. 84-85), the EPA states that loss of 

burrows is not expected to have an adverse impact to the Preble’s meadow jumping mouse.

The Service agrees. Burrows of other animals are not specified PCEs of Preble’s meadow 

jumping mouse critical habitat. Since the Preble’s meadow jumping mouse digs its own burrows 

and is not known to be dependent on burrows of other animals, it is unlikely that the Preble’s 

meadow jumping mouse critical habitat would be adversely affected by the loss of prairie dog 

burrows following Rozol application. In the BA (p. 60), the EPA’s conceptual impact model 

lists “altered plant community composition” as a second indirect effect on habitat resulting from 

black-tailed prairie dog control. Reduction or eradication of black-tailed prairie dogs would 

likely lead to vegetation of greater height and density at sites of their former black-tailed prairie 
44

dog colonies. Where black-tailed prairie dog colonies are abandoned within designated critical 

habitat or adjacent to other riparian corridors occupied by the Preble’s meadow jumping mouse, 

the altered plant community could be of greater habitat value to the Preble’s meadow jumping 

mouse than low, sparse vegetation typically found within an active black-tailed prairie dog

colony. 

The Service initially concurred with the EPA’s determination that the use of Rozol to control the 

black-tailed prairie dog may adversely affect the Preble’s meadow jumping mouse. However, 

with the conservation measures agreed to by the EPA and Liphatech as well as further analysis, 

adverse effects to the Preble’s meadow jumping mouse are considered so unlikely as to be 

discountable. The Service does not anticipate adverse effects to the Preble’s meadow jumping 

mouse or its critical habitat.

SPECIES FOR WHICH NO ADVERSE EFFECTS ARE ANTICIPATED WITHOUT

CONSERVATION MEASURES

In the previous section, the species analyses indicated adverse effects were not anticipated with 

the application of the EPA’s conservation measures. In this section, adverse effects are also not 

anticipated for nine species, but the Service’s conclusion was not made as a result of 

conservation measures, but rather additional review of the biology of each species. The nine 

species 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. 

1. AMERICAN BURYING BEETLE

The EPA concludes in their BA that the use of chlorophacinone to control black-tailed prairie 

dogs 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. 

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.
45

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 

black-tailed prairie dog 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, Oklahoma) are outside of black-tailed 

prairie dog 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 (Kozol 1990). 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 black-tailed prairie dog colonies is limited to October 1 through March 

15 and therefore should not affect the American burying beetle. 

In summary, we do not anticipate adverse effects to the American burying beetle from the use of 

chlorophacinone to control black-tailed prairie dogs. 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. 

2. 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 vireo usually migrates southward from 

Oklahoma by late August-September and from Texas by mid-September (Service 1991) to 

winter in Mexico. The black-capped vireo occurs in mixed deciduous/evergreen shrubland. 

Vireos require broadleaf shrub vegetation in the form of low deciduous cover (e.g., juniper and 

oak sp.), which is a key element in vireo habitat. Nests are preferentially 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 (Service 1991). 
46

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 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 black-tailed prairie dog 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. 

 

Habitat Use

Black-capped vireos are a lowland dependent species, preferring mixed evergreen/deciduous 

shrubland. Black-tailed prairie dogs are native to short-grass prairie habitats typical of the 

southernmost regions of the Great Plains that extend into north Texas. Black-tailed prairie dogs 

tend to avoid areas of heavy brush and tall grass due to the reduced visibility these habitats 

impose. Therefore, habitats used by black-capped vireos do not overlap with the open prairie 

habitat required by black-tailed prairie dogs. 

Diet

Black-capped vireos become omnivorous during winter by adding seeds in their diet, but are 

otherwise exclusively insectivorous. Black-capped vireos do not prey on rodents or small 

mammals such as black-tailed prairie dogs, 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 black-tailed prairie dogs) is possible but highly unlikely when 

all factors herein are considered.

Migration / Arrival at Nesting Grounds

The Rozol label restricts applications to the period between October 1 and March 15, which 

further 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 - March 15 

timeframe when Rozol applications are allowed.
47

Limited Range Overlap

Although the range for the black-capped vireo historically was larger than today, current overlap 

of the range of the vireo with black-tailed prairie dogs is geographically limited. Likewise, 

black-tailed prairie dogs historically occurred over most of the western half of Texas, but have 

been extirpated from portions of their former range (Davis and Schmidly 1994). Although the 

range for the black-capped vireo today only marginally overlaps with the range for black-tailed 

prairie dogs, different habitat requirements preclude the co-existence of these two species in the 

same location.

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 

black-tailed prairie dog; 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 blackcapped vireos used habitat where Rozol was applied, their dietary requirements would minimize 

the probability of primary or secondary exposure. 

3. 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 black-tailed prairie dog habitat. Therefore, it was determined in the BA that the use of 

chlorophacinone to control black-tailed prairie dogs 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 

black-tailed prairie dog habitat. No overlap of lynx habitat with known black-tailed prairie dog 

colonies occurs in Montana, and no overlap of lynx habitat with known black-tailed prairie dog 

colonies or potential range occurs in Wyoming. A very minimal amount of overlap of lynx 

habitat with the black-tailed prairie dog’s overall range in Colorado occurs; however, no overlap 

with mapped black-tailed prairie dog colonies occurs in Colorado. 

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 black-tailed prairie dog habitat. 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. Lynx prefer to move through continuous forest, 

using the highest terrain available such as ridges and saddles (Koehler 1990, Staples 1995). 

While some lynx may move through open habitats at times during transient or dispersal 

movements, the likelihood of a lynx moving through a black-tailed prairie dog colony is small 
48

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 black-tailed prairie dog 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 (black-tailed prairie dog habitat). 

Critical habitat for Canada lynx is not designated in Colorado and critical habitat in Wyoming 

and Montana does not overlap with black-tailed prairie dog known occurrence and potential 

range. Therefore, we conclude that the use of Rozol in black-tailed prairie dog colonies would 

not adversely affect designated critical habitat for Canada lynx.

4. ESKIMO CURLEW

The EPA determined that the use of Rozol to control black-tailed prairie dogs 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 (Service 1967) and, after the ESA was enacted in 1970, was 

listed as endangered (Service 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, Service 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, Service 2011e). These 

estimates are based on the last uncontroversial record of observance, a specimen that was shot in 

Barbados in 1963 (Service 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 (Service 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 (Service 2011e). 
49

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 black-tailed prairie dog 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 widescale conversion of grassland to agriculture, fire suppression, and the extinction 

of the Rocky Mountain grasshopper (Melanoplus spretus) as an important food source (Service

2011e). 

In conclusion, Eskimo curlews are likely already extinct or at best extremely rare and 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 black-tailed prairie dogs. 

5. GOLDEN-CHEEKED WARBLER

The golden-cheeked warbler is the only breeding bird endemic to the state of Texas. The goldencheeked 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 black-tailed prairie dog, and they assumed 

that warblers could ingest toxic levels of Rozol via consumption of invertebrates exposed to 

chlorophacinone. For our assessment of the risk 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 black-tailed prairie dog 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. 

 
50

Habitat Use

Golden-cheeked warblers use juniper and oak dominated woodlands and prefer canyon or hill 

country. Black-tailed prairie dogs 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 these habitats impose. Therefore, habitats 

used by golden-cheeked warblers do not overlap with the open prairie habitat used by blacktailed prairie dogs. 

 

Diet

Golden-cheeked warblers are exclusively insectivorous. Golden-cheeked warblers do not prey 

on rodents or small mammals such as black-tailed prairie dogs, 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 black-tailed prairie dogs) is 

possible but considered unlikely when life histories of both species are considered.

Migration / Arrival at Nesting Grounds

The Rozol label restricts applications to the period between October 1 and March 15, which 

further limits potential exposures to non-target wildlife. Golden-cheeked warbler leave Texas in 

August, returning in late February the following year, and would therefore be wintering in 

Mexico and Central America during the majority of the October 1 - March 15 timeframe when 

Rozol applications are allowed. 

Limited Range Overlap

Although the range for the golden-cheeked warbler was historically larger than today, its current 

overlap with black-tailed prairie dogs is limited geographically. Historically black-tailed prairie 

dogs occurred over most of the western half of Texas, but they have been extirpated from 

portions of their former range (source: http://www.nsrl.ttu.edu/tmot1/cynoludo.htm). Although 

the range for the golden-cheeked warbler marginally overlaps with the range for black-tailed 

prairie dogs, different habitat requirements preclude the co-existence of this avian species with 

the black-tailed prairie dog.

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 

black-tailed prairie dog; 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. 
51

6. GULF COAST JAGUARUNDI

The EPA determined 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 

black-tailed prairie dogs 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 

black-tailed prairie dog habitat. No map was provided in the BA where the Gulf Coast 

jaguarundi overlaps with the black-tailed prairie dog, 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 black-tailed prairie dog 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 black-tailed 

prairie dogs. 

7. OCELOT

The EPA determined the ocelot may be adversely affected by Rozol use based on potential direct 

effects from prey that may consume chlorophacinone bait including black-tailed prairie dogs 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 black-tailed prairie dog 

habitat. 

The ocelot is found in Mexico, southern Arizona, and southern Texas. There is no overlap 

between the black-tailed prairie dog and the ocelot; therefore, we conclude that the proposed 

action is not likely to adversely affect the ocelot. 

8. PIPING PLOVER

The action area encompasses the entire U.S. 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, 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 plovers to Rozol 

through maggots. However, because plovers are not expected to forage in the prairie dog towns 

directly, and the Rozol use season ends before plovers are likely to encounter prairie dog 

colonies (see below), the risk of exposure to piping plovers is unlikely. 
52

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”

(Service 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 black-tailed prairie dog 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 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 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 plovers (Service 2009e). In the two reported cases where plovers have been 

observed foraging on carcasses, the carcasses have been along the shoreline; plovers were not 

documented to leave their traditional foraging areas to forage on carcasses (Keane 2002, Service

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 

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. 
53

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 

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 plovers do most of their foraging, 

and be ingested by plovers. It is unlikely that piping plovers would be exposed to sufficient 

Rozol concentrations in this manner to cause impacts 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 route is circuitous with both possible transmissions through 

insects that are not expected to occur.

• By definition, prairie dog habitat does not have the primary constituent elements that 

define piping plover critical habitat. Therefore, we do not anticipate that Rozol 

application would adversely affect designated critical habitat. 

o Route 1 – the invertebrates have eaten the bait directly and then move to 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 plovers and/or the 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.

Therefore, the Service concludes that adverse effects to piping plovers from the use of Rozol to 

poison black-tailed prairie dogs are not likely, and the action is not likely to adversely affect 

designated critical habitat for the above reasons.
54

9. WHOOPING CRANE

In the BA, the EPA concludes that the use of Rozol to control the black-tailed prairie dog 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 black-tailed prairie dog in 

Montana, North and South Dakota, Wyoming, Colorado, Nebraska, Kansas and Oklahoma. The 

map does not depict any counties in Texas and should be corrected to indicate the overlap in 

Texas counties. 

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 black-tailed prairie dogs. The Florida Population 

is non-migratory and located on the Kissimmee Prairie, south of Orlando in Osceola and Polk 

counties and does not overlap with the range of black-tailed prairie dogs. 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 black-tailed prairie dogs. The Aransas Wood 

Buffalo Population is the only self-sustaining wild population. The Florida Population and 

Eastern Migratory Population are introduced and are designated experimental non-essential by 

the Service.

As noted in the BA, the whooping crane is a territorial nester and returns to the same area each 

year. 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 
55

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 as they migrated from Wood Buffalo National Park to 

Aransas National Wildlife Refuge by the Service and The Crane Trust. In 2010, whooping 

cranes left Wood Buffalo National Park as early as August 20 and continued until October 31

(Wehtje 2011). 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, 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 black-tailed prairie dog 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 Risk Quotient 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 one poisoned blacktailed prairie dog every day for five days to reach the Level of Concern. The BA also states that 

it may be possible for the whooping cranes to consume that many mice in a day, but unlikely it 

would eat more than one black-tailed prairie dog 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, 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. 
56

Black-tailed prairie dogs establish colonies near intermittent streams, water impoundments, 

homestead sites and windmills. However, black-tailed prairie dog 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 black-tailed prairie dog occur, 

habitat isolation between the whooping cranes and black-tailed prairie dog reduces the chance 

that the whooping cranes would encounter treated grain.

In summary: a) whooping cranes have not been documented to forage or roost in black-tailed 

prairie dog colonies, b) the occurrence of the species in the proximity of black-tailed prairie dog 

colonies is not likely to be frequent, and c) during migration whooping cranes are not expected to 

venture into black-tailed prairie dog colonies, creating a degree of habitat isolation between the 

two species. 

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 black-tailed 

prairie dog rodenticide in the migratory corridor since the early 1990s (Lee et al. 2005). 

Critical habitat

Whooping crane critical habitat occurs in five sites in four states. They are:

• Cheyenne Bottoms State Waterfowl Management Area and Quivira National Wildlife 

Refuge, Kansas; 

• the Platte River bottoms between Lexington and Denman, Nebraska; 

• Salt Plains National Wildlife Refuge, Oklahoma; and 

• Aransas National Wildlife Refuge and vicinity, 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, and habitats that are protected from 

disturbances or are representative of the geographical distribution of the listed species).

With exception of the Platte River Bottoms in Nebraska, all designated critical habitats are 

Service National Wildlife Refuges or Management Areas that are unlikely to have Rozol use on 

their properties; doing so would result in a future section 7 consultation. Black-tailed prairie dog 

colonies 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 
57

effect on habitat resulting from black-tailed prairie dog control. Reduction or eradication of 

black-tailed prairie dog 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 black-tailed prairie dog 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. 

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 was necessary, which includes species/habitat information;

environmental baseline; direct, indirect, and cumulative effects; conclusions regarding jeopardy 

or destruction/adverse modification; and associated incidental take statements with reasonable 

and prudent measures and implementing terms and conditions, as appropriate. Three species fit 

within this category: 1) black-footed ferret, 2) gray wolf and 3) northern aplomado falcon.

Background information is provided below regarding the components of species analysis within 

a BO. This information is presented to further the understanding of the three species analyses 

that follow. 

Species Analysis Components:

Status of the Species/Critical Habitat. This is an analysis of information on species life history, 

habitat and distribution, and other data on factors related to survival and recovery. This analysis 

considers the effects of past human and natural activities or events that have led to the current 

condition of species. This information is usually presented in listing documents and refined in 

recovery plans. Some species/critical habitat information not directly relevant to the consultation 

is not included herein, but rather is referenced for the reader to obtain additional information, if 

needed, from other documents. 

Environmental Baseline. Environmental Baseline is the past and present impacts of all federal, 

state, or private actions and other human activities in the action area, the anticipated impacts of 

all proposed federal projects in the action area that have already undergone formal or early 

section 7 consultation, and the impact of state or private actions which are contemporaneous with 

the consultation in process. [50 CFR § 402.02]. The environmental baseline is a “snapshot” of a 

species’ health at a specified point in time. It does not include the effects of the action under 

review in the consultation.
58

Effects of the Action. This section describes the direct and indirect effects of an action on the 

species and/or critical habitat and its interrelated or interdependent activities, as well as the 

species’ anticipated response to the action.

Cumulative Effects. Cumulative Effects are the effects of future state, tribal, local, or private 

activities that are reasonably certain to occur within 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. This definition 

applies only to section 7 analyses and should not be confused with the broader use of this term in 

the National Environmental Policy Act or other environmental laws. 

Conclusion Regarding Jeopardy. The jeopardy determination is the Service’s opinion after 

review of the current status of the species, the environmental baseline for the action area, the 

effects of the proposed action, and the cumulative effects, as to whether the as proposed action 

is/is not likely to jeopardize the continued existence of the species and is/is not likely to destroy 

or adversely modify designated critical habitat. We evaluate whether the action will directly or 

indirectly appreciably reduce the likelihood of both the survival and recovery of a listed species 

in the wild, or will directly or indirectly alter critical habitat in a manner that appreciably 

diminishes the value of that habitat for both the survival and recovery of a listed species. 

Reasonable and Prudent Alternatives. If the Service determines that a proposed action will 

jeopardize a species or adversely modify critical habitat, we then identify any reasonable and 

prudent alternative actions that the agency or applicant may take to avoid the likelihood of 

jeopardy to the species or destruction or adverse modification of designated critical habitat. 

These alternatives must be implemented in a manner consistent with the intended purpose of the 

action, fall within the scope of the action agency’s legal authority and jurisdiction, and be 

economically and technologically feasible. 

Incidental Take Statement Components

An Incidental Take Statement is provided (where appropriate) following the analysis for each 

species and/or critical habitat, to exempt take that may occur. The Incidental Take Statement 

describes the take and lists means to minimize that take by implementing reasonable and prudent 

measures with implementing terms and conditions. In order to be considered in an incidental 

take statement, any taking associated with an agency’s action must meet the following three 

criteria: 

1. not likely to jeopardize the continued existence of listed species or destroy or 

adversely modify designated critical habitat,

2. result from an otherwise lawful activity, and

3. be incidental to the purpose of the action
59

The components of an incidental take statement include the anticipated amount and extent of the 

take, effects of the take, and reasonable and prudent measures with implementing terms and 

conditions along with conservation recommendations intended to assist the EPA in achieving 

7(a)(1) obligations under the ESA. 

Amount or Extent of Take Anticipated. The amount of take anticipated may be the number of 

individuals expected to be taken or the extent of habitat likely to be destroyed or disturbed. If 

the take would not occur but for the proposed action, then the Service must describe the amount 

or extent of such anticipated incidental take. In instances where take may be difficult to detect, 

some detectable surrogate measure of take is provided. The time period over which the take is 

anticipated should also be presented here. 

Effect of the Take. This segment provides a statement of impact regarding the incidental take 

described in the above segment.

Reasonable and Prudent Measures. These are nondiscretionary measures that are necessary 

and appropriate to minimize the impact of incidental take. Reasonable and prudent measures 

include actions that occur within the action area, involve only minor changes to the project, and 

reduce the level of take associated with project activities. These should minimize the impacts of 

incidental take to the extent reasonable and prudent, meaning they are consistent with the 

proposed action’s basic design, location, scope, duration and timing. 

Terms and Conditions. Terms and conditions implement the reasonable and prudent measures 

by describing the specific methods by which the reasonable and prudent measures are to be 

accomplished. They must include reporting and monitoring requirements to assure adequate 

action agency oversight of any incidental take [50 CFR §402.14(i)(1)(iv) and (i)(3)]. They also 

include a discussion on the “disposition of individuals taken”. In order to be exempt from the 

prohibitions of section 9 of the Act, the EPA must comply with the terms and conditions, which 

implement the reasonable and prudent measures and outline required reporting/monitoring 

requirements. Terms and conditions are non-discretionary. 

Conservation Recommendations. Conservation recommendations are suggestions of the Service 

regarding discretionary measures to minimize or avoid adverse effects of a proposed action on 

listed species or critical habitat or regarding the development of information. [50 CFR §402.02] 

1. BLACK-FOOTED FERRET

Status of the Species/Critical Habitat

The black-footed ferret (ferret) was listed as endangered in 1967 and again in 1970 under early 

endangered species legislation and was “grandfathered” into the ESA in 1973 (Service 2008b). 

Critical habitat has not been designated for this species. The ferret’s historical range includes 12 
60

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 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 ferret observed at 

the Mellette County site was in 1974 (Clark 1989). Attempts at captive breeding ferrets with 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 ferret was 

again presumed extinct (Service 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 ferrets, 

totaling 18 individuals, were removed from the wild between 1985 and 1987 to initiate a captive 

breeding program (Service 1988). Seven of the ferrets captured at Meeteetse successfully reared 

young, leading to a lineage of continuing captive reproduction that provides ferrets to 

reintroduction sites (Hutchins et al. 1996, Garelle et al. 2006). Extant populations, both captive 

and reintroduced, descend from these seven “founder” animals that were part of the original 18 

ferrets brought into captivity (Garelle et al. 2006). Ferret reintroductions began in 1991 with 

animals produced from the captive breeding ferret population that are descendants of ferrets 

captured at Meeteetse from 1985-87 (Table 2).

No wild populations of black-footed ferrets have been found since the capture of the last 

Meeteetse 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 ferrets exist, except those at ferret reintroduction sites. 

Ferret Reintroductions

Section 10(j) of the ESA allows reintroduced populations to be designated non-essential 

experimental populations to ease concerns about listed species reintroductions and facilitate 

species recovery efforts. To date, eleven ferret reintroductions have occurred through use of 

section 10(j) designated experimental population areas in the United States (Service 2008b). 

There have also been six ferret reintroductions that used section 10(a)(1)(A) recovery permits 

along with one ferret reintroduction in Chihuahua, Mexico and one reintroduction in 

Saskatchewan, Canada for a total of 19 reintroduction attempts (Service 2008b, Fargey 2010). 

See Table 2 for the location and date of initiation of each of the ferret reintroduction sites.
61

Table 2. 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 Prairie Dog

UL Bend National Wildlife Refuge, Montana (1994) Black-tailed Prairie Dog

Badlands National Park, South Dakota (1994) Black-tailed Prairie Dog

Aubrey Valley, Arizona (1996) Gunnison’s Prairie Dog

Conata Basin, South Dakota (1996) Black-tailed Prairie Dog

Ft. Belknap Indian Reservation, Montana (1997) Black-tailed Prairie Dog

Coyote Basin, Utah (1999) White-tailed Prairie Dog

Cheyenne River Indian Reservation, South Dakota (2000) Black-tailed Prairie Dog

Bureau Land Management 40-complex, Montana (2001) Black-tailed Prairie Dog

Wolf Creek, Colorado, (2001) White-tailed Prairie Dog

Janos, Mexico (2001) Black-tailed Prairie Dog

Rosebud Indian Reservation, South Dakota (2004) Black-tailed Prairie Dog

Lower Brule Indian Reservation, South Dakota (2006) Black-tailed Prairie Dog

Wind Cave National Park, South Dakota (2007) Black-tailed Prairie Dog

Espee Ranch, Arizona (2007) Gunnison’s Prairie Dog

Smoky Hill, Kansas (2007) Black-tailed Prairie Dog

Northern Cheyenne Indian Reservation, Montana (2008) Black-tailed Prairie Dog

Grassland National Park, Canada (2009) Black-tailed Prairie Dog

Life History

The 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 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).
62

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 ferrets 

depend almost exclusively on prairie dogs for food and shelter, and ferret range overlaps that of 

certain prairie dog species (Anderson et al. 1986) with no documentation of ferrets breeding 

outside of prairie dog colonies, the Service believes that ferrets were historically endemic to the 

range of three prairie dog species. There are records of ferrets from the ranges of black tailed 

prairie dog (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 acres (40 million hectares) of intermontane and prairie 

grasslands (Biggins et al. 1997, Clark et al. 1986, Ernst et al. 2006). Ernst (2008, personal 

communication) estimates that in the United States, this occupied habitat existed within an 

estimated 562 million ac (228 million ha) of potential habitat. Ernst (2008, personal 

communication) used a geographic information system database to predict the distribution of 

prairie dog habitat across the United States and concluded that historically 85% of all ferrets 

probably occurred in black-tailed prairie dog habitat, 8% in Gunnison’s prairie dog habitat and 

7% in white-tailed prairie dog habitat. We conclude that most ferrets likely occurred in blacktailed prairie dog habitat.

The ferret breeds at one 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 ferret leads a solitary existence; except for the period when mother and 

young are together (Forrest et al. 1985). It is a “searcher” predator and is generally nocturnal, 

appearing above ground at irregular intervals and for irregular durations (Clark et al. 1986). 

The 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 (Service 2008b). The 

North American ferret population declined precipitously as a result (Biggins 2006) and the 

species was one of the original species listed under early versions of the Endangered Species Act 

and was grandfathered in as an endangered species with passages of the ESA in 1973 (Service 

2008b). Ferret populations in the black-tailed prairie dog range and other prairie dog species are 

only known to exist where ferret reintroductions have occurred (Service 2008b).

Environmental Baseline

Since the 1960s, occupied black-tailed prairie dog acreage has increased from approximately 

365,000 acres to approximately 2.4 million acres within the ten states where Rozol is currently 

allowed or proposed to be used as a rodenticide (EPA 2010b, Service 2009b). There is an 

extensive history of prairie dog poisoning in these ten states, and we believe that black-tailed 

prairie dogs are likely to be poisoned by various rodenticides into the future regardless if Rozol 

is available or not. In 2009, the Service and concluded that rodenticide use was a threat to the 

species that could warrant listing of the species under the ESA (Service 2009b). Current blacktailed prairie dog populations do not indicate a downward trend even though Rozol has been 
63

used under Special Local Needs labels for black-tailed prairie dog control since 2004 and as 

early as 1991 under a pocket gopher formulation (Lee et al. 2005).

While current information suggests the black-tailed prairie dog species can withstand the impact 

of Rozol use prairie dog poisoning is a high magnitude threat to the black-footed ferret (Service 

2008b). Therefore, the conservation measure that prevents Rozol use in ferret reintroduction 

areas is key to maintaining the current reintroduction sites and providing a mechanism to 

accommodate future reintroduction sites. 

Nineteen ferret reintroductions (Table 2) have been undertaken in North America beginning in 

1991, and most of these sites continue to have some ferrets remaining (Service 2008b, Fargey 

2010). Thirteen reintroductions are within the range of black-tailed prairie, and 11 of those sites 

are within the ten states where Rozol is either labeled for use or proposed to be used as a prairie 

dog rodenticide (EPA 2010b). While there have been 19 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 Ferret Recovery Plan objectives 

(Service 2008b). 

A recent estimate of ferret populations at reintroduction sites indicates approximately 840 ferrets 

alive in the wild with approximately half of those located in the black-tailed prairie dog range 

(Service 2008b). Since that time, plague has reduced ferret numbers at Conata Basin in South 

Dakota (Griebel 2010) while ferret populations are believed to have expanded in Arizona and 

Wyoming (Corcoran 2011, Grenier 2011). The Service believes that approximately 800 ferrets 

alive in the fall of 2011 is a reasonable estimate of current ferret population numbers in the wild.

To date, there have been a few instances where ferrets are known to have left a ferret 

reintroduction site and been located on adjacent property. If a ferret does disperse from a 

reintroduction site, there are provisions in the reintroduction site permit, or the reintroduction 

plans, to relocate that ferret at the request of the adjacent property owner if they grant 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 blacktailed prairie dog rodenticide.

Landowners adjacent to current ferret reintroduction sites are not required to conduct ferret 

surveys prior to undertaking normal ranching operations, such as the use of rodenticides to 

control prairie dogs. The Service anticipates that future ferret reintroduction sites will similarly 

not require ferret surveys on adjacent properties. 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 ferret 

from endangered to threatened status. The objectives include increasing the captive population 

of ferrets to 200 breeding adults, establishing at least 1,500 free ranging breeding adult ferrets 

that are distributed between at least 10 populations with no fewer than 30 breeding adults in a 
64

population and those populations shall have the widest possible distribution (Service 1988). The 

first objective of increasing the captive ferret population has been surpassed. The second 

objective is approximately 25% met when fall 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 (Service 2008b). 

This indicates additional successful ferret reintroduction sites will be needed to meet the 

downlisting objective for ferrets. Recovery objectives for complete delisting of the ferret have 

not been finalized but are anticipated to be at least 3,000 free ranging breeding adult ferrets 

distributed between at least 30 populations. The downlisting objectives indicate there will need 

to be significant continued efforts to establish free ranging ferret populations through the use of 

reintroductions and complete delisting of the ferret will require considerably more ferret 

reintroductions. 

Effects of the Action

Rodenticides used to poison prairie dogs can have multiple effects to ferrets by secondarily 

poisoning the ferret or by destroying the habitat where ferrets live 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 after feeding on four poisoned blacktailed prairie dogs 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 black-footed ferrets would be similarly killed as the 

domestic ferrets were, if they consumed prairie dogs poisoned by Rozol. Accordingly, the 

Service, the EPA and the registrant developed conservation measures that would prevent Rozol 

use at current and future ferret reintroduction sites. These measures were intended to address the 

secondary poisoning of ferrets and the loss of the ferrets’ prey base at reintroduction sites (EPA 

2011c). The issue of ferret dispersal away from a reintroduction site that might encounter a 

Rozol poisoned black-tailed prairie dog colony was more difficult to address.

The key challenge with development of the ferret conservation measures was to ensure that 

Rozol use would not occur at locations where ferrets are being reestablished, while at the same 

time ensure that adjacent landowners’ ability to manage prairie dogs on their properties would 

not be impacted. The parties involved discussed banning Rozol use in areas surrounding ferret 

reintroduction sites (up to a county in size) but concluded that doing so would increase animosity 

towards ferret reintroduction efforts and could undermine or prevent reintroductions altogether. 

Accordingly, to avoid creating a backlash against ferret reintroduction sites, conservation 

measures were developed that would restrict Rozol use at the reintroduction site but not impose 

restrictions on adjacent landowners’ use of legal rodenticides. As indicated above, the Service 

does not believe ferret surveys on properties adjacent to or in the vicinity of a ferret 

reintroduction are needed prior to undertaking otherwise legal activities such as rodenticide use 

on prairie dogs, and the cost and inconvenience of ferret surveys on adjacent lands would 

generate opposition to, and possibly compromise, the ferret reintroduction effort. If a ferret 

disperses from a reintroduction site and the landowner wants the ferret relocated, and grants 

permission to access the property, then the relocation can be done under the existing permits. 
65

The ferret conservation measures rely upon identification of existing and future ferret 

reintroduction sites on the County Bulletin database maintained by the EPA and referenced on 

the Rozol label that then becomes part of the legal requirement for label compliance. Prior to 

Rozol use, applicators are to consult this database to ensure they are not applying Rozol at an 

existing ferret reintroduction site. If new ferret reintroductions are started in the future, we will 

provide the information for those sites to the EPA for inclusion on the County Bulletin database 

to reflect new ferret reintroduction sites.

The Service recognizes that a ferret that leaves a reintroduction site could encounter prairie dog 

colonies where Rozol is being used and consume poisoned prairie dogs and perish. That 

mortality must be balanced with the intent of the reintroduction, which is to establish a breeding 

ferret population at the reintroduction site. These ferret deaths are not anticipated to materially 

affect the reintroduction site’s ability to meet ferret recovery objectives because the sites are 

reliant upon the ferret habitat within their boundaries to meet those objectives. The Service 

selects reintroduction sites because they have the attributes (i.e. prairie dog acreage, densities, 

locations, partnerships) to help meet ferret recovery objectives of establishing widely distributed 

breeding ferret populations. The Service and our reintroduction partners have long understood 

that dispersing 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. Accordingly, we believe the 

conservation measures to restrict Rozol use at the reintroduction site but not on adjacent 

properties are appropriate. 

The Service also acknowledges there could be incidental take of ferrets when Rozol is used 

outside the reintroduction site if dispersing ferrets encounter prairie dog colonies where Rozol is 

used to poison prairie dogs. We recognize that ferrets leaving reintroduction sites may feed upon 

Rozol poisoned prairie dogs outside the reintroduction site and in doing so are expected to die. 

However, those ferret deaths are not anticipated to materially affect the reintroduction site’s 

ability to meet ferret recovery objectives because reintroduction sites are reliant upon the ferret 

habitat within their boundaries to meet recovery objectives.

Another possible effect of Rozol use for black-tailed prairie dog control involves the elimination 

of possible ferret reintroduction habitat because of Rozol use. In 2009, the Service estimated 

there were approximately 2.4 million acres of black-tailed prairie dog in the 10 States where 

Rozol is used or proposed for use as a black-tailed prairie dog rodenticide (Service 2009b, EPA 

2010b). Luce (2006) examined opportunities for immediate and near term potential ferret 

reintroduction sites and concluded there are over 70 potential sites within the ferret range, most 

in the black-tailed prairie dog species. The Service believes that rodenticide use, including 

Rozol, while widespread in the black-tailed prairie dog range, in and of itself is not the 

determinate factor whether a ferret reintroduction can occur. Instead, it is the willingness of 

partners (private, state, tribal and federal) to consider a ferret reintroduction and then commit to 

manage a block of prairie dog habitat for ferret conservation. Most recent black-tailed prairie 

dog surveys indicate there are many biologically suitable and potential ferret reintroduction sites 

available, but the key to achieving ferret reintroductions and thus recovery, is finding interested 

landowners and partners (Service 2009b, Lockhart et al 2006, Luce 2006). Further, our 

experience is that landowners who are strong proponents of poisoning prairie dogs are not 
66

interested in participating in ferret reintroductions and if Rozol was not available, they would 

likely use a different rodenticide. Therefore, the Service believes that Rozol use on black-tailed 

prairie dogs with the agreed upon conservation measures to restrict Rozol use on future ferret 

reintroduction sites, will not eliminate enough future opportunities for ferret reintroductions to 

preclude ferret recovery. At this time, the Service does not believe additional restrictions on 

Rozol use on behalf of ferrets are warranted.

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 biological opinion. 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 Service believes that future rodenticide use along with some land conversion from 

grasslands or rangeland into croplands or other development will continue in the range of the 

black-tailed prairie dog. With the black-footed ferret conservation measures in place we do not 

believe these actions will preclude conservation and recovery of the black-footed ferret because 

recent trends in black-tailed prairie dog occupied habitat are stable to increasing over large areas 

of the species’ range (Service 2009b). While Rozol use is likely increasing, its use may be 

supplanting some of the previously used prairie dog rodenticides and this would explain the 

stable to increasing prairie dogs trends found in Service (2009b) even though Rozol has been 

used for prairie dog control for nearly two decades in one state and five to ten years in others 

(Lee et al, 2005, EPA 2010b). Further, we believe with the agreed upon Rozol conservation 

measures, where use of Rozol in ferret reintroduction sites will not be allowed, the impacts to 

current and future ferret reintroduction sites will not be seriously impacted. 

Within the ferrets’ range, which includes three species of prairie dogs, the Service believes that 

the availability of rodenticides will not prevent recovery of the ferret because recent analysis of 

the three prairie dog species indicates those prairie dog species continue to inhabit millions of 

acres of habitat (Service 2010c, 2009b, 2008c). But as noted earlier, without adequate regulatory 

mechanisms, poisoning can affect current and future ferret reintroduction sites (Service 2008b). 

While the total prairie dog acreage among the three species is much greater than is believed 

necessary to recover the ferret, much of the existing prairie dog acreage is not of a size or in a 

location to contribute to ferret recovery. The Ferret Recovery Plan estimated an average of 124 

acres of prairie dog colonies is needed per ferret or approximately 185,000 acres of ferret 

occupied prairie dog habitat needed to meet downlisting objectives for ferrets (Service 1988). 

This acreage amount can be distributed between the three species of prairie dogs that encompass 

the ferrets’ range (Service 1988). While complete delisting objectives for the 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 

ferret (Service 1988).
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Another important factor affecting prairie dog populations and therefore ferret recovery is 

sylvatic plaque and the ongoing outbreaks which can result in widespread prairie dog die offs or 

in some cases or more subtle deaths (Cully et al. 2010, Matchett et al. 2010). This exotic disease 

can directly kill ferrets that consume infected prairie dogs or eliminate 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 black-tailed prairie dogs in combination with other 

rodenticides and sylvatic plague will prevent 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. 

At this time, the Service believes that Rozol use on black-tailed prairie dogs, as modified through 

the agreed upon conservation measures will not preclude the conservation and recovery of the 

ferret even when combined with the use of other currently available legal rodenticides and our 

understanding of sylvatic plague. 

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 black-tailed prairie dog rodenticide, which includes 

the ferret conservation measures, is not likely to jeopardize the continued existence of the ferret. 

This conclusion is based on the following:

• Rozol use will be prohibited in current and future ferret reintroduction sites. Survival of 

the species will not be compromised.

• The ferret conservation measures are designed to avoid Rozol restrictions on adjacent 

properties to minimize opposition to ferret reintroductions.

• There is sufficient prairie dog acreage between the three species of prairie dogs to support 

current ferret Recovery Plan downlisting objectives and likely future delisting objectives.

This conclusion is based in part on the project description as modified by the ferret conservation 

measures included in the EPA’s letter of December 13, 2011 (EPA 2011c).

Incidental Take Statement

Section 9 of the Act and federal regulations pursuant to section 4(d) of the Act prohibit the take 

of endangered and threatened species, respectively, without special exemption. “Take” is 

defined as 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 (50 CFR 17.3) 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 (50 CFR 17.3) 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 
68

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 Act 

provided that such taking is in compliance with the terms and conditions of this Incidental Take 

Statement.

The measures described below are non-discretionary, and must be undertaken by the EPA so that 

they become binding conditions of any grant, permit or registration that may be issued, for the 

exemption in section 7(o)(2) to apply. The EPA has a continuing duty to regulate the use of 

Rozol for black-tailed prairie dog control to receive coverage by this incidental take statement. 

If the EPA (1) fails to assume and implement the terms and conditions or (2) fails to require 

adherence to the terms and conditions of the incidental take statement through enforceable terms 

that are added to the label and County Bulletins 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 Incidental Take Statement 

(50 CFR § 402.14(i)(3)). 

Amount or Extent of Take Anticipated

The Service has developed this incidental take statement based on the premise that the

EPA and the Registrant will implement the ferret conservation measures as proposed. Take of 

black-footed ferrets is expected in the form of mortality when ferrets disperse from a 

reintroduction area and encounter a black-tailed prairie dog colony that has been poisoned with 

Rozol within the previous two months or if the ferret is residing on a colony when Rozol is 

applied. While ferrets can leave reintroduction sites, the Service is very unlikely to know when 

that occurs nor be able to accurately predict the number of ferrets that may encounter Rozol 

poisoned black-tailed prairie dog colonies. Most 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 ferrets’ nocturnal behavior and tendency to spend 

much of their time underground in prairie dog burrows, it is unlikely that many if any ferret 

mortalities due to Rozol will be reported to further inform this issue. Therefore, while dispersing 

ferrets may die from consuming Rozol-poisoned prairie dogs, this number is not anticipated to be 

large and will rarely be detected.

At previous 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). Ferret reintroduction site managers are authorized to retrieve 

dispersing ferrets if that information is available and the adjacent landowner wants the ferrets 

removed from their property. Requests to relocate ferrets that have left a reintroduction area are 

very rare.

The Service anticipates that take of dispersing ferrets that leave a reintroduction area and 

encounter a Rozol poisoned black-tailed prairie dog colony will result in two or fewer ferret 
69

mortalities per year because the number of dispersing ferrets is not believed to be high and most 

dispersing ferrets are expected to die of natural causes or other forms of incidental take. 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 ferrets per 

calendar year. The relocation of live ferrets from proposed Rozol use areas, while considered 

take is authorized under each ferret sites’ existing management plan and authorized through a 

Service issued permit to the recovery partners at that site. That Service issued reintroduction site 

permit, authorizes activities, including ferret relocation if needed, at each of the reintroduction 

sites through coordination with the Black-footed Ferret Recovery Coordinator. Therefore this 

Rozol Incidental Take Statement is not intended cover relocation activities because such actions 

have been previously authorized. Ferret mortalities from those relocation efforts are not 

anticipated. If two ferret mortalities in a calendar year are attributed to Rozol use then the EPA 

and the Service shall reinitiate consultation to determine if there is additional conservation 

measures that can be incorporated to reduce take of ferrets. This incidental take statement 

exempts take of black-footed ferrets protected by the ESA that may be incurred by the proposed 

action, provided the September 10, 2010, Rozol label is followed. Noncompliance with the 

Rozol label that results in take of black-footed ferrets is not covered by this incidental take

statement; 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.

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 ferret reintroduction sites. 

Current information does not indicate Rozol use is limiting potential ferret reintroduction sites. 

Effect of Take

The Service has determined that two mortalities per year of dispersing ferrets due to Rozol use is 

not likely to jeopardize the continued existence of the black-footed ferret or materially affect 

ferret reintroduction sites because dispersing ferrets are not known to regularly return to the 

reintroduction site. It is acknowledged that for every Rozol ferret mortality reported, there are 

likely to be multiple ferret mortalities not found or reported. Because the ferret mortalities are 

expected to occur to dispersing ferrets unlikely to contribute to the success of the reintroduction 

site, such losses are not anticipated to compromise the survival and recovery of the ferret.

Reasonable and Prudent Measures

The Service believes the following reasonable and prudent measures are necessary and 

appropriate to minimize the impacts of incidental take of the ferret resulting from the proposed 

action:

1. The EPA will ensure Rozol will not be used in current and future ferret reintroduction 

areas.
70

2. If an applicator or the EPA becomes aware that a ferret is known to occupy a black-tailed 

prairie dog colony outside of a reintroduction area, Rozol cannot be used on that colony 

until the ferret or ferrets have been relocated. The reintroduction site manager should be 

contacted 

3. The EPA or an applicator must notify the Service if ferrets or carcasses thereof are found 

during any Rozol use related activities.

4. The EPA in cooperation with Liphatech shall develop and maintain a system to track 

Rozol used for black-tailed prairie dog control and report to the Service the amounts 

sold/used in each of the ten states. 

5. The EPA will ensure that if a previously unknown wild ferret population is discovered, 

Rozol use will not be used on that population.

6. The EPA shall initiate or require studies to evaluate secondary toxicity of the EPA 

registered prairie dog rodenticides to ferrets. 

7. The EPA shall initiate or require studies to demonstrate whether the label requirements 

that are intended to prevent secondary poisoning of non-target animals is preventing 

routes of secondary exposure. 

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 

Reasonable and Prudent Measures described above. These terms and conditions are 

nondiscretionary. The EPA must report to the Service's South Dakota Ecological Services Field 

Office on the implementation of these terms and conditions.

To implement RPM 1:

• The EPA shall modify the existing Rozol label to require that Rozol applicators access 

the EPA County Bulletin website to find out the location of black-footed ferret 

reintroduction sites before dispersing Rozol. The South Dakota Ecological Services Field 

Office shall be given an opportunity to review and approve changes that are intended to 

minimize take of black-footed ferrets.

• The EPA shall maintain and update the EPA County Bulletin website so that a current 

listing of ferret reintroduction sites and Rozol prohibited use areas are available to the 

public. 

• The EPA shall ensure that the ferret conservation measures described in this biological 

opinion are implemented and adhered to.
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To implement RPM 2 and 3:

• The EPA shall develop and implement a reporting system to notify the Service in the 

event of a ferret or other listed species found during Rozol use related activities. If the

reporting system involves a label change, the South Dakota Ecological Services Field 

Office shall be given an opportunity review and approve changes.

• The EPA shall ensure sufficient time (three weeks minimum) is allocated for relocating 

ferrets prior to use of Rozol on black-tailed prairie dog colonies that are known to have 

ferrets.

To implement RPM 4:

• The EPA shall develop and implement a system of reporting for distributors and 

applicators that tracks the amounts of Rozol sold and used in each state and project the 

amount of black-tailed prairie dog acres poisoned.

• The EPA shall report that information to the Service by January 31 after the end of each 

calendar year. 

To implement RPM 5:

1. The EPA shall modify the EPA County Bulletin website to include the location of wild 

extant black-footed ferret populations if discovered in the future.

To implement RPM 6:

1. The EPA shall initiate and complete studies within three years that evaluate secondary 

toxicity of the FIFRA registered prairie dog rodenticides to black-footed ferrets.

To implement RPM 7:

1. The EPA shall initiate and complete studies within three years to determine measures 

necessary to prevent exposure to ferrets and other nontarget wildlife evaluates whether 

the label restrictions intended to prevent secondary are successful.

2. The EPA shall initiate and complete studies within three years that evaluates the 

effectiveness of anticoagulant labels that require multiple return visits to anticoagulant 

poisoned prairie dog towns to retrieve dead and dying prairie dogs. 

3. The EPA shall develop a reporting form for applicators and landowners to use that can be 

return to the EPA and identify 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.
72

4. The EPA shall modify the Rozol label to reflect study results that may prevent Rozol 

exposure to nontarget species.

This incidental take statement exempts take of ferrets protected by the ESA that may be incurred 

by the proposed action, provided the September 10, 2010, Rozol label is followed. 

Noncompliance with the Rozol label that results in take of ferrets is not covered by this 

incidental take statement; 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. 

The Service believes that no more than two ferrets per year will be incidentally taken as a result 

of the proposed action. The reasonable and prudent measures, 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 reasonable and prudent measures 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 reasonable and prudent measures. 

Disposition of Dead or Injured Ferrets 

Upon locating a dead, injured or sick ferret or other listed species initial notification must be 

made to the Service’s Law Enforcement Offices located in the state where the animal is found 

within three working days of its finding. 

The National Black-Footed Ferret Coordinator must also be notified within three working days 

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 

Written notification must be made within five calendar days of locating a dead ferret and include 

the date, time, and location of the animal, a photograph if possible, and any other pertinent 

information. The notification shall be sent to the Law Enforcement Office and a copy to the 

Ferret Coordinator Office above. Care must be taken in handling sick or injured animals to 

ensure effective treatment or in the case of dead specimens, it can be frozen to aid in 

preservation. 

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. The Service recommends the 

following conservation activities that are within the EPA’s authorities and can benefit ferret

recovery:
73

1. The EPA should become a member of the Black-footed Ferret Recovery Implementation 

Team due to 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 ferrets and 

other listed species. The EPA participation on the Black-footed Ferret Recovery 

Implementation Team would provide an avenue to understand the ramifications of 

rodenticide use on ferret habitat along with an opportunity to work with recovery partners 

to ensure EPA actions avoid working at cross purposes with ferret recovery.

2. The EPA should monitor the registered rodenticides used on the three species of prairie 

dogs in the ferrets’ range and report the amounts of prairie dog rodenticides sold, used, 

and the expected prairie dog acreage poisoned per state per year. 

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.

3. GRAY WOLF 

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 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 Distinct Population Segment 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 

reintroduced Mexican gray wolf, a subspecies, reintroduced into an experimental population 

(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) (Service 1974), and 

Mexican wolf (Canis lupus baileyi)) (Service 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 (Service 1978). At that time the Service 

also designated critical habitat in Isle Royale, Michigan, and parts of northern Minnesota 

(Service 1978). Since then the Service has implemented numerous actions relative to the gray 

wolf including development of recovery plans, identification of Distinct Population Segments 

and Nonessential Experimental Populations, 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 (Service 2009f), 2) 
74

Endangered and Threatened Wildlife and Plants; Revising the Listing of the Gray Wolf (Canis 

lupus) in the Western Great Lakes (Service 2011f), and 3) Final Rule; Establishment of a 

Nonessential Experimental Population of the Mexican Gray Wolf in Arizona and New Mexico 

(Service 1998).

Currently, gray wolves in the Northern Rocky Mountain Distinct Population Segment (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 (Service 2011g). Management of wolf 

populations in Montana and Idaho has been transferred to state authority. 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, at which point wolves in Wyoming may be removed from the List of 

Endangered and Threatened Wildlife under the ESA after rulemaking has occurred (Service

2011h). Until then, wolves in Wyoming are protected by the ESA and considered a Nonessential 

Experimental Population designated under section 10(j) which has increased the Service's 

flexibility and discretion in managing the gray wolf reintroduced population. These wolves are 

treated as threatened, allowing for special regulations providing exceptions to the take 

prohibitions under section 9 of the ESA. 

A final rule to remove wolves in the Western Great Lakes Distinct Population Segment from the 

list of Endangered and Threatened Wildlife was published in the Federal Register on December 

28, 2011 (Service 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 Nonessential Experimental Population,

section 10(j) status, and are protected by the ESA within the parameters established for that 

reintroduction effort (Service 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 black-tailed prairie dog 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 Distinct 

Population Segment 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 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 Distinct Population Segments, 

unless the Service makes additional regulatory changes in the future. Those wolves within 

Nonessential Experimental area boundaries (Wyoming, Arizona/New Mexico) retain ESA 

protections, but with the management parameters established with the section 10(j) rulemaking. 
75

Critical habitat has been designated for the gray wolf, but not within the action area. Due to a 

lack of overlap with the black-tailed prairie dog range, the Service agrees with the EPA no 

critical habitat will be impacted by the proposed action; therefore gray wolf designated critical 

habitat is not described herein. 

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 and larger 

sizes in the northern portion. Females weigh slightly less than males. Wolves reach adult size 

by one year of age. Wolves’ fur color is frequently a grizzled gray, but it can vary from pure

white to coal black. 

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 (Service 2003). 

Range and habitat. Within North America, gray wolves formerly ranged from coast to coast with 

the exception of the mid-Atlantic states and 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 1900’s. 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 subspecies reintroduction area in New Mexico, Arizona 

and a small part of western Texas. 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). 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 excessive numbers 

are not taken by humans. 

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). 
76

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 30’s 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 (topranking 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.

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 

(m.p.h.), wolves can attain speeds as high as 40 m.p.h. By three years of age, many wolves 

disperse from the pack they were born into to find mates and 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. 2008). 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 six months but 

daily GPS locations showed she actually walked over 3,000 miles (Service et al. 2011).

Considerable information on wolf dispersal was obtained during 1993-2008, when 1,681 

radiocollared wolves (858 males and 823 females) in the Northern Rocky Mountain Distinct 

Population Segment 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 Rozol may be applied) (Jimenez et al.

2011, unpublished data). Light and Fritts (1999) studied 10 wolf mortality records in North 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 > 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 through 2010 have been over 190 miles with four wolves travelling 

beyond the Northern Rocky Mountain Distinct Population Segment border (Service et al. 2011). 
77

The eastern edge of the Northern Rocky Mountain Distinct Population Segment is about 400 

miles from the western edge (eastern Minnesota) of the Western Great Lakes Distinct Population 

Segment core area and is separated from it by hundreds of miles of unsuitable habitat in those 

Great Plains states (Service 2009g). This propensity to disperse and the distances that have been 

recorded are the factors that lead the Service to believe gray wolves could encounter Rozolpoisoned prairie dogs and be exposed.

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 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 breed in the United States (Service 2009f). Human 

causes of mortality among dispersing wolves include illegal shootings, trapping, poisonings (e.g. 

M-44’s intended for coyotes), and vehicle collisions. Despite human-caused mortalities, 

populations have continued to increase in both numbers and range in both the Northern Rocky 

Mountain and Western Great Lakes Distinct Population Segments. 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 (Service 2011i). 

Of the 10 wolf mortalities documented in North and South Dakota from 1981-1992, eight were 

mistakenly shot as coyotes, one 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 (Light and 

Fritts 1999). 

Dispersing wolves have been noted in Colorado in recent years with mortalities in 2004 and 

2009. A wolf killed by a car in Sturgis, South Dakota in 2006 was determined to have been from 

the Northern Rocky Mountain Distinct Population Segment. A wolf from the Western Great 

Lakes Distinct Population Segment was killed in Nebraska in 2003. A wolf (origin unknown) 

killed via 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) (Service 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.
78

Relatively high road and human densities in the black-tailed prairie dog range and the absence of 

forested cover and high likelihood of conflicts with livestock make wolves highly vulnerable to 

human-caused mortality, precluding recolonization in these areas (Light and Fritts 1999). 

Dispersing wolves are likely to encounter many forms of threats when they leave their core areas 

and high wolf mortality rates in the black-tailed prairie dog range are likely irrespective if Rozol 

is being used. We currently have no documented Rozol-related mortalities of gray wolves. 

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 one to 11 pups, but generally include four to six pups (Service 2003). 

Normally a pack has a single litter annually, but producing two or three litters in one year has 

been documented in Yellowstone National Park (Service et al. 2002). The breeding season for 

wolves is from late January through March; the further south, the earlier the breeding season. 

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 two 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 (Service et al. 2011).

The Western Great Lakes Distinct Population Segment 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 (Service 2011j). Wolves were 

considered extirpated from Wisconsin in 1960, but began to recolonize in the 1970s and an 

increase in the late 1980’s has continued into 2011; the current population estimate there is 782 

wolves (Service 2011k, 2011f). With exception of Isle Royale, wolves were extirpated from 

Michigan prior to the gray wolf listing, but wolves began to return in the late 1980’s (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, Service 2011j), and 87 individuals were estimated to occur in Michigan in 2010-11

(Service 2011f). 
79

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 2009, the wild population totaled a minimum of 42 individuals 

(Service 2010d).

With a minimum of 1,651 wolves in the Northern Rocky Mountain Distinct Population Segment 

in 2010 (Service et al. 2011), an estimated 4,390 in the Western Great Lakes Distinct Population 

Segment (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) (Service 2011f), and a 

2009 estimate of the Mexican wolf population at 42 (Service 2010d), the total minimum estimate 

of wolves in these areas combined is approximately 6,083. Wolf population levels in the range 

of the black-tailed prairie dogs are limited to dispersing wolves. 

Status, Trends, and Distribution

In both the Northern Rocky Mountain and Western Great Lakes Distinct Population Segments, 

wolf numbers are trending upward, but at slower rates than has been documented in the past. 

Available habitat appears to be reaching carrying capacity. The total population in the Northern 

Rocky Mountain Distinct Population Segment today is about five times higher than the minimum 

population recovery goal and three times higher than the minimum breeding pair recovery goal 

(Service 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 (Service 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 (Service 1994). As mentioned above, wolves in the Northern Rocky Mountain 

Distinct Population Segment have been delisted in Montana, Idaho, Wyoming, Eastern Oregon, 

and Eastern Washington, and are proposed to be delisted in Wyoming in the near future. 

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 Distinct 

Population Segment. Wolves in the Western Great Lakes Distinct Population Segment greatly 

exceed the recovery criteria (Service 1992) for (1) a secure wolf population in Minnesota, and 

(2) a second population outside Minnesota and Isle Royale consisting of 100 wolves for five 

successive years. Based on the criteria set by the Eastern Wolf Recovery Team in 1992 and 

reaffirmed in 1997 and 1998 (Service 2011j), the proposed Distinct Population Segment contains 

sufficient wolf numbers and distribution to ensure their long-term survival within the Distinct 

Population Segment and this population has been delisted (Service 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 Nonessential Experimental 

Population is currently not self-sustaining. 
80

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 wolf 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 black-tailed prairie dog range where the wolf remains protected 

are the locations where exposure to Rozol may occur that results in take of gray wolves. 

Reasons for Listing. 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 (Mech 1970, Service 1987) 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 (Service 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 (Service 2009f). 

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 black-tailed prairie dog 

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. Wolves in Nonessential Experimental 

Populations receive protections of the ESA per their specific rulemaking parameters. Wolves 

occurring outside of existing Distinct Population Segments, delisted areas, or Nonessential 

Experimental Populations take on the ESA status of the area they are in, and will remain so until 

future regulatory changes are made. 

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 black-tailed prairie dog is not common in these areas 

(Johnson et al. 2003), and prohibiting Rozol use on black-tailed prairie dog 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 Nonessential Experimental Population area 
81

boundary, key areas of the reintroduction area will not have Rozol use. This conservation 

measure is anticipated to greatly minimize the risk of Rozol use on 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 & South Dakota (17), Colorado (2) and 

Nebraska(1)) have averaged approximately 0.65 wolves/year. These are documented wolf 

mortalities, but it is unknown how many gray wolves may disperse into the action area and not 

be reported. 

Environmental Baseline

Status of the Species within the Action Area

Gray wolves are not uniformly protected under the ESA throughout the range of the black-tailed 

prairie dog. Some wolf populations have already been, or soon may be, delisted. The exact 

number of dispersing wolves that may occur in the range of the black-tailed prairie dog where 

Rozol is proposed for use cannot be determined with certainty. The Service does not know of 

wolf populations in the range of the black-tailed prairie dog except for the reintroduction efforts 

in southwestern New Mexico. The Service recognizes dispersing wolves can occur in the blacktailed prairie dog range and could be exposed to Rozol use. 

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 black-tailed prairie dog 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. 
82

Effects of the Action

According to the BA (page 107), chlorophacinone exposure to the gray wolf is expected as the 

wolf range overlaps black-tailed prairie dog 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 Risk 

Quotients that included 24.82 for exposure to non-target animals and 9.59 for exposure to blacktailed prairie dogs (Table 1.1, page 21 of the BA). The EPA further estimates that the gray wolf 

would only have to consume less than one poisoned mouse or less than one poisoned black-tailed 

prairie dog every day for five days to exceed a 0.1 Level of Concern for endangered species 

(EPA 2010b, Appendix B). 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 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 black-tailed prairie dogs could adversely affect 

dispersing wolves.

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 a Rozol application (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 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 1993, 

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 black-tailed 

prairie dog 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 
83

multiple meals from it. Receiving a lethal dose may take more than one poisoned prairie dog. 

Sublethal 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 sublethal 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, 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 significant as defined under the ESA because prairie dogs are not known to 

be a significant dietary item for the gray wolf, which normally does not inhabit black-tailed 

prairie dog areas. Dispersing individuals are anticipated to come upon black-tailed prairie dog 

colonies only opportunistically as they travel. 

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. Lethal control of wolves in North 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 Distinct Population Segment, 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 Distinct Population Segment (Service 2011j). The same may be said 

for wolves dispersing from the Northern Rocky Mountain Distinct Population Segment. The 

potential impact to the Mexican gray wolf population is not expected to be great, given the 

EPA’s adopted conservation measure to exclude counties within the core reintroduction area and 

the ongoing intensive management that essentially inhibits dispersal of Mexican gray wolves. 

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. 

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 biological opinion. 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 black-tailed prairie dog and will continue into the foreseeable future. The Service 

anticipates high mortality rates for gray wolves that disperse in the black-tailed prairie dog range. 

Such wolves occurring outside of their current cores ranges are likely to be intentionally or 
84

unintentionally killed via such mechanisms as vehicle collisions, poisoning, and shooting which 

will likely prevent recolonization of significant areas of the black-tailed prairie dog range. 

Cumulatively, wolf populations have continued to rise in the face of these factors. 

Conclusion Regarding Jeopardy

After reviewing the current status of gray wolf, the environmental baseline for the action area, 

the effects of the proposed use of Rozol to control black-tailed prairie dogs 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.

• Dispersing wolves are not considered critical to recovery of wolf populations in the 

United States and cumulatively, gray wolf populations have continued to increase despite 

losses of dispersing individuals.

• Gray wolf populations are considered recovered by the Service in the Northern Rocky 

Mountain and Western Great Lakes Distinct Population Segments; 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 are protective of the Mexican gray wolf.

Incidental Take Statement

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 incidental take 

statement.
85

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, 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 incidental take statement. If the EPA (1) fails to assume and implement the 

terms and conditions, or (2) fails to require Liphatech to adhere to the terms and conditions of the 

incidental take statement 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 Incidental Take Statement (50 CFR § 402.14(i)(3)). 

Amount or Extent of Take Anticipated

The Service anticipates dispersing wolves from source populations may occur in the black-tailed 

prairie dog range at an average rate of 0.65 wolves/year (essentially one or two every other year), 

based on documented mortalities outside of existing Distinct Population Segments. This is 

considered a conservative number as additional dispersers have likely occurred and gone 

undetected. Other forms of mortality can affect these wolves before any exposure to Rozol 

occurs. However, if wolves ingest poisoned prey, evidence suggests 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 very low. 

The Service anticipates that one ESA-protected gray wolf every three 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 Distinct Population Segments 

(e.g. North and South Dakota, Nebraska, Colorado). 

Effect of the Take

In the accompanying biological opinion, the Service determined that this level of anticipated take 

is not likely to result in jeopardy to the species or destruction or adverse modification of critical 

habitat. The take is also not anticipated to have any population level effects to recovered source 

populations of gray wolves that disperse into the action area. Rozol use on black-tailed prairie 

dog 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. Thus, Rozol-poisoning 

is likely a compensatory form of mortality, not resulting in an overall increase in total mortality 

of gray wolves. 

Reasonable and Prudent Measures

The Service believes the following reasonable and prudent measure is necessary and appropriate 

to minimize impacts of incidental take of gray wolves:
86

• The EPA shall report, or require applicators to report, all sickened, dying, or dead gray 

wolves (regardless of their status under the ESA) poisoned as a result of Rozol use on 

black-tailed prairie dog colonies.

• The EPA shall develop means to reduce the amount of Rozol-poisoned black-tailed 

prairie dogs and non-target species available for gray wolf consumption.

Little information is available regarding the use of black-tailed prairie dog colonies by dispersing 

gray wolves. The analysis herein presumes gray wolves could and would consume Rozolpoisoned dead and dying prairie dogs if they happen upon them, as well as available non-target 

species, but additional information on such instances would better inform the risks to individuals 

of this species. The Service anticipates this would necessitate a reporting requirement for Rozol 

end-users that is currently not specified, but would be a reasonable expectation given the existing 

requirements of the Rozol label to return post-application to collect above-ground bait and 

dispose of dead or dying animals. 

Terms and Conditions

In order to be exempt from the prohibitions of section 9 of the ESA, the EPA must comply with 

the following terms and conditions, which implement the reasonable and prudent measures 

described above and outline required reporting/monitoring requirements. These terms and 

conditions are non-discretionary. 

To implement RPM 1:

• The EPA shall modify the Rozol label to require that applicators report all 

dead/dying/impaired listed species including gray wolves located on, or in the vicinity 

of, Rozol-poisoned black-tailed prairie dog towns, post-application for as long as the 

product remains effective. This includes development of means to collect that 

information. Any wolves found shall be left in place, photographed if possible, and 

reported to local U.S. Fish and Wildlife Service Law Enforcement personnel 

immediately. Specimens should be collected by authorized individuals as soon as 

possible when located, and kept cool or frozen to facilitate later examination for Rozol 

poisoning. These requirements shall be added to the Rozol label upon the 2012 

proposed use of Rozol to control black-tailed prairie dogs in the ten states covered by 

this consultation.

To implement RPM 2:

• The EPA shall work with the Service to develop a search protocol that would be 

adequate to reduce the risk of secondary poisoning to gray wolves by improving 

detection of black-tailed prairie dogs and non-target species on the surface. Compliance 

with the current September 10, 2010 label (Appendix) does not preclude the risk of 

secondary poisoning of non-targets like the gray wolf. The Service does not know of a 

practicable method to ensure poisoned animals are removed from a colony before 
87

secondary poisoning can occur. The Service recommends EPA engage research 

institutions and evaluate methods to prevent secondary poisoning of non-target animals 

when Rozol is used on black-tailed prairie dogs. 

This incidental take statement exempts take of gray wolves protected by the ESA that may be 

incurred by the proposed action, provided the September 10, 2010, Rozol label is followed. 

Noncompliance with the Rozol label that results in take of gray wolves is not covered by this 

incidental take statement; 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. 

The Service believes that no more than one wolf every three years will be incidentally taken as a 

result of the proposed action. The reasonable and prudent measures, 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 reasonable and prudent measures 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 reasonable and prudent measures. 

2. NORTHERN APLOMADO FALCON

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 (Service 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 (Service 1990). Northern aplomado falcons were fairly common in 

suitable habitat throughout these areas until the 1940s. However, they subsequently declined 

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 (Service 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 (Service 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 
88

reproductive failure from egg breakage (Service 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 (Service

1990).

The species appears to be non-migratory throughout its range. 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 (e.g., Chihuahuan ravens (Corvus cryptoleucus)) or 

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 (Service 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 (Service 2002b). Documented 

invertebrate prey includes grasshoppers, beetles, dragonflies, cicadas, crickets, butterflies, moths, 

wasps, and bees (Service 1990). Differences in prey abundance and nest site availability can 

cause differences in home range size. Based on several studies, the Service estimates northern 

aplomado falcon home range size to be approximately 34 square km2 (8,401 acres) (Service 

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 (Service 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 (Service 1990). The historical range of the northern 

aplomado falcon in Texas, New Mexico and Arizona occurs within the Chihuahuan Desert, 
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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 (Service 

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 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.). Sitespecific 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, Service 2006b). 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 (Service 

1990). The objective of the Aplomado Falcon Recovery Plan is to ensure that the northern 

aplomado falcon is no longer threatened by habitat loss, pesticide contamination, or human 

persecution. Implementation of the steps outlined in the 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 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 
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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 2007, The 

Peregrine Fund found that 29 out of 32 territories surveyed in southern Texas were occupied 

(Heinrich 2010). 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. Northern aplomado falcons in New Mexico and 

Arizona are included in a non-essential experimental population designation under section 10(j) 

of the Act (Service 2006f). Northern aplomado falcons have been reintroduced in Texas on 

private lands using Safe Harbor Agreements, and their regulatory status under the Act is 

endangered. 

Currently, there are approximately 36 aplomado falcon pairs in the U.S., which constitute less 

than two-thirds of the minimum number of 60 self-sustaining breeding pairs in suitable parts of 

the southwestern U.S. recommended by the 1990 Recovery Plan for reclassification of the 

subspecies to threatened status. 

Environmental Baseline

Formal surveys and reliable sightings submitted to USFWS show that a small number of falcons 

have been sighted in the United States during every decade since the 1960s (Service 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 aplomado falcons 

produced in either New Mexico or Arizona since the subspecies' extirpation as a breeding species

in the 1950's. Another pair was reported near this site in 2002, but no nest was located and only 

one of the pair was present two 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 

falcons in Luna County between 2000 and 2004. The species occurred historically in Hidalgo 
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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). 

Status of the Species within the Action Area

The action area for this consultation includes the historic range of the black-tailed prairie dog 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 blacktailed prairie dogs in the United States. 

Northern aplomado falcons in New Mexico were designated a 10(j) nonessential experimental 

population to encourage landowners to support the reintroduction of falcons in the state. Several 

landowners have supported reintroduction and manage the introduction areas to promote falcons. 

Under the 10(j) rule, 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 (Service 1996, Service 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 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). All northern aplomado falcon release sites and all recorded 

nests and falcon pairs within the action area in Texas occur on lands covered by the Safe Harbor 

Agreement (Montoya 2011, personal communication).

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 aplomado 

falcon. While the Nonessential Experimental Population 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.

 

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.
92

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 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.

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.

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, which is also more likely 

if they 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” (Keddy-Hector 2000). 

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 this may be a lingering threat (Mora et al. 1997, Hector-Keddy 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.
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Effects of the Action

The Risk Quotient 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 Level of Concern of 0.1 for the Risk Quotient is set for listed species. Because the 

Risk Quotient of 0.104 exceeds the Level of Concern, the EPA determined 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 five poisoned mice or 

less than one poisoned black-tailed prairie dog to reach the Level of Concern, and are more 

likely to consume mice than black-tailed prairie dog. 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 Inandione 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, black-tailed prairie 

dog 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 five mice or one black-tailed prairie dog to intoxicate a northern aplomado falcon. 

However, due to its relatively small size, the aplomado falcon is not likely to take prey as large 

as a black-tailed prairie do, and the 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 

are lacking, toxicity tests with diphacinone indicate that some raptors are 20-30 times more 

sensitive than the two test species, bobwhite and mallard, 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 black-tailed prairie dog colony, exposure 

to chlorophacinone via consumption of primary consumers of Rozol bait may occur. Northern 

aplomado falcons may potentially consume both 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, though birds over 500 g have been recorded (Service 2002b). 
94

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., blacktailed prairie dogs, other small mammals, birds) were visible in colonies nine days after 

treatment and were still present when the study ended at day 29 post-treatment (Vyas 2010a). 

Additionally, Vyas (2011c, personal communication) reported that raptors preferentially fed at 

prairie dog colonies treated 1499with Rozol compared to untreated colonies. This effect has 

been observed in predators previously. Hunt et al. (1992) reported that kestrels preferentially 

caught prey displaying aberrant behavior following pesticide exposure compared to healthy prey. 

The northern aplomado falcon may also be attracted to Rozol-treated prairie 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 sublethal 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 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. 

Actual exposure is expected to be minimal due to the low density of black-tailed prairie dog 

colonies within the falcon’s range. In addition, in areas where the falcon has been reintroduced 

in Texas, landowners have signed cooperative agreements with the Service and The Peregrine 

Fund to maintain falcon habitat at or above baseline levels and are responsible to notify these 

organizations before performing land use practices that may adversely affect the falcon. For 

these reasons, we expect the frequency of northern aplomado falcons encountering Rozol-treated 

black-tailed prairie dog colonies to be low, and few falcons would experience sublethal effects or 

mortality from consuming Rozol-exposed prey. 

However, we also anticipate that detection of Rozol-poisoned 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 blacktailed prairie dog control in Texas since 2006 under a Special Local Needs 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. 
95

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 biological opinion. 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, gas), and development (e.g., roads, power lines). These 

activities have the potential to reduce the quality of northern aplomado falcon nesting, roosting, 

and foraging habitat, and may cause disturbance during the breeding season. As black-tailed 

prairie dog colonies are not considered to be 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 anthropogenic threats. In addition, cooperative 

agreements with landowners in reintroduction areas allows for the monitoring and potential 

avoidance of take within reintroduction areas.

Conclusion Regarding Jeopardy

After reviewing the current status of 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 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.

• In areas where the falcon has been reestablished in Texas, landowners have signed 

cooperative agreements with the Service and The Peregrine Fund to maintain falcon 

habitat at or above baseline levels, and are responsible to notify these entities before 

performing land use practices that may adversely affect the falcon.

• At this time, the Service does not have information to indicate Rozol-use in blacktailed prairie dog colonies will preclude survival or recovery of the northern 

aplomado falcon. 
96

Incidental Take Statement

Section 9 of the Act and federal regulations pursuant to section 4(d) of the Act prohibit the take 

of endangered and threatened species, respectively, without special exemption. “Take” is 

defined as 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 (50 CFR 17.3) 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 (50 CFR 17.3) 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 Act 

provided that such taking is in compliance with the terms and conditions of this Incidental Take 

Statement.

The measures described below are non-discretionary, and must be undertaken by the EPA so that 

they become binding conditions of any grant, permit or registration that may be issued, for the 

exemption in section 7( o )(2) to apply. The EPA has a continuing duty to regulate the use of 

Rozol for black-tailed prairie dog control to receive coverage by this incidental take statement. 

If the EPA (1) fails to assume and implement the terms and conditions or (2) fails to require 

adherence to the terms and conditions of the incidental take statement through enforceable terms 

that are added to the label and County Bulletins the protective coverage of section 7( o )(2) may 

lapse. In order to monitor the impact of incidental take to northern aplomado falcon, the EPA 

must report the amount of Rozol sold, black-tailed prairie dog acreage estimated to be poisoned 

per state, the numbers and species of non-target animals reported and its impact on the species to 

the Service as specified in the incidental take statement (50 CFR §402.14(i)(3)).

Amount or Extent of Take Anticipated

Take of the falcon is expected in the form of mortality or sub-lethal effects such as changes in 

behavior when falcons consume prey from a black-tailed prairie dog 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 falcons that may encounter black-tailed prairie dog colonies or 

non-target prey that have been exposed to Rozol. It is unlikely that falcons will be found, 

therefore it is unlikely that many, if any, falcon mortalities due to Rozol will be reported to 

further inform the EPA and the Service on this issue. 
97

We anticipate that falcons in Texas that encounter Rozol-exposed black-tailed prairie dog 

colonies or non-target prey will result in one or fewer falcon mortality per year. We further 

anticipate that one or fewer falcons in Texas 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, two falcon mortalities or injuries 

attributable to Rozol use will be considered to be representative of the total amount of take 

exempted annually.

Effects of the Take

The Service has determined that two falcons in the form of one falcon mortality and one falcon 

harassed per year due to Rozol use are not likely to jeopardize the continued existence of the 

falcon. This amount of take is not likely to result in population level effects to the falcon nor 

reduce its chances for recovery.

Reasonable and Prudent measures

The Service believes the following reasonable and prudent measures are necessary and 

appropriate to minimize the impacts of incidental take of the northern aplomado falcon in Texas 

resulting from the proposed action. Landowners covered by Safe Harbor Agreements for the 

northern aplomado falcon are exempt from use restrictions identified in these reasonable and 

prudent measures.

The prohibitions against taking the northern aplomado falcon found in section 9 of the Act do not 

apply to the 10(j) non essential experimental population in New Mexico. However, the Service 

advises the EPA to consider implementing the reasonable and prudent measures, as described

above, for this population.

The prohibitions against taking the northern aplomado falcon found in section 9 of the Act do not 

apply to the 10(j) non essential experimental population in New Mexico. However, the Service 

advises the EPA to consider implementing the reasonable and prudent measures, as described 

above, for this population.

1. Notify the Service if northern aplomado falcons or carcasses thereof are found during any 

Rozol use activities.

2. Maintain a system to track Rozol used for black-tailed prairie dog control and report to 

the Service the amounts sold/used in each of the ten states. 

3. Within the range of the northern aplomado falcon, maintain the EPA County Bulletin 

website so that a current listing of counties with habitat for northern aplomado falcons is 

available to the public.
98

4. Within the range of the northern aplomado falcon, inform public users about the risks of 

Rozol to non-target organisms and how risks can be minimized.

5. Contribute to efforts to re-establish the northern aplomado falcon within its range in the 

U.S.

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 

Reasonable and Prudent Measures described above. These terms and conditions are 

nondiscretionary.

The EPA must report to the Service's Species Lead for the falcon in the Texas and New Mexico 

Ecological Services Field Offices on the implementation of these terms and conditions.

To implement RPM 1:

• The EPA shall develop and implement a monitoring and reporting system to notify the 

Service in the event of a northern aplomado falcon or other listed species found during 

Rozol use activities. 

To implement RPM 2:

• The EPA shall develop and implement a system of reporting for distributors and 

applicators that tracks the amounts of Rozol sold and used in each State and project the 

amount of black-tailed prairie dog acres poisoned.

• The EPA shall report the above information to the Service by January 31 after the end of 

each calendar year. 

To implement RPM 3:

• Prior to Rozol application in the range of the falcon, the EPA shall include the following 

language in the EPA County Bulletins for counties with falcon habitat: Prairie dog 

colonies in this county may be occupied by the 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.
99

To implement RPM 4:

• Prior to Rozol application in the range of the falcon, the EPA shall develop a brochure, 

reviewed by the Service, about the risks of Rozol to non-target organisms and how risks 

can be minimized.

• When the above brochure is finalized, the EPA shall immediately disseminate the 

brochure and provide expert assistance about this information to landowners with 

suitable habitat for the northern aplomado falcon.

To implement RPM 5, the EPA shall:

• Prior to Rozol application in the range of the falcon, 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.

This incidental take statement exempts take of northern aplomado falcons protected by the ESA 

that may be incurred by the proposed action, provided the September 10, 2010, Rozol label is 

followed. Noncompliance with the Rozol label that results in take of northern aplomado falcons 

is not covered by this incidental take statement; 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. 

The Service believes that no more than two aplomado falcon per year in Texas will be 

incidentally taken as a result of the proposed action. The reasonable and prudent measures, 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 reasonable and prudent measures 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 reasonable and prudent measures. 

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:

1. 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. 
100

2. The EPA should initiate or require studies to evaluate the effectiveness of anticoagulant 

labels that require multiple return visits to anticoagulant-poisoned prairie dog towns to 

retrieve dead and dying prairie dogs. The Service was unable to locate any information, 

and the EPA provided none to indicate this label requirement is accomplishing its 

intended task of reducing secondary poisoning of non-target animals. There is 

information to indicate it is not preventing secondary poisoning of non-target animals. 

3. The EPA should initiate or require studies to evaluate what conditions or methods would 

prevent anticoagulant poisoned prairie dogs from secondarily poisoning non-target 

animals. 

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.

___________________________________________________________

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 black-tailed prairie dogs in ten 

western states. This BO does not cover Rozol use on any other prairie dog species. Expansion 

of Rozol use to prairie dog species other than the black-tailed would necessitate reinitiation of 

formal consultation. 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; 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 ferret recovery, then the EPA and the

Service shall reinitiate consultation to determine appropriate measures to allow 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. If none of these reinitiation triggers are met 

within the next 15 years, then reinitiation will be required in 2027 because the Opinion only 

covers the action for 15 years. 
101

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Biologist, USGS Patuxent Wildlife Research Center, Beltsville, Maryland, and Matt 

Schwarz, Fish and Wildlife Biologist (Contaminants), U.S. Fish and Wildlife Service, 

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Schwarz, Fish and Wildlife Biologist (Contaminants), U.S. Fish and Wildlife Service, 

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2010. Discussed meadowlark histopathology results from Vyas (2010) study. 
124

APPENDIX

September 10, 2010, Label for Rozol® Prairie Dog Bait
125