[Federal Register Volume 83, Number 111 (Friday, June 8, 2018)]
[Proposed Rules]
[Pages 26623-26640]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2018-12409]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R6-ES-2018-0008; FXES11130900000-189-FF09E42000]
RIN 1018-BC02


Endangered and Threatened Wildlife and Plants; Removing Oenothera 
coloradensis (Colorado Butterfly Plant) From the Federal List of 
Endangered and Threatened Plants

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
remove the Colorado butterfly plant (Oenothera coloradensis, currently 
listed as Gaura neomexicana ssp. coloradensis) from the Federal List of 
Endangered and Threatened Plants (List) due to recovery. This 
determination is based on a thorough review of the best available 
scientific and commercial data, which indicate that the threats to the 
Colorado butterfly plant have been eliminated or reduced to the point 
that it has recovered, and that this plant is no longer likely to 
become endangered in the foreseeable future and, therefore, no longer 
meets the definition of a threatened species under the Endangered 
Species Act of 1973, as amended (Act). This proposed rule, if made 
final, would also remove the currently designated critical habitat for 
the Colorado butterfly plant. We are seeking information, data, and 
comments from the public on the proposed rule to remove the Colorado 
butterfly plant from the List (i.e., ``delist'' the species). In 
addition, we are also seeking input on considerations for post-
delisting monitoring of the Colorado butterfly plant.

DATES: We will accept comments received or postmarked on or before 
August 7, 2018. Comments submitted electronically using the Federal 
eRulemaking Portal (see ADDRESSES, below), must be received by 11:59 
p.m. Eastern Time on the closing date. We must receive requests for 
public hearings, in writing, at the address shown in FOR FURTHER 
INFORMATION CONTACT by July 23, 2018.

ADDRESSES: Written comments: You may submit written comments by one of 
the following methods:
    <bullet> Electronically: Go to the Federal eRulemaking Portal: 
http://www.regulations.gov. In the Search box, enter Docket No. FWS-R6-
ES-2018-0008, which is the docket number for this rulemaking. Then, 
click on the Search button. On the resulting page, in the Search panel 
on the left side of the screen, under the Document Type heading, click 
on the Proposed Rules link to locate this document. You may submit a 
comment by clicking on the blue ``Comment Now!'' box. If your comments 
will fit in the provided comment box, please use this feature of http://www.regulations.gov, as it is most compatible with our comment review 
procedures. If you attach your comments as a separate document, our 
preferred file format is Microsoft Word. If you attach multiple 
comments (such as form letters), our preferred formation is a 
spreadsheet in Microsoft Excel.
    <bullet> By hard copy: Submit by U.S. mail or hand-delivery to: 
Public Comments Processing, Attn: FWS-R6-ES-2018-0008; U.S. Fish and 
Wildlife Service; MS: BPHC; 5275 Leesburg Pike, Falls Church, VA 22041-
3803.
    We request that you submit written comments only by the methods 
described above. We will post all comments on http://www.regulations.gov. This generally means that we will post any 
personal information you provide us (see Public Comments, below, for 
more details).
    Document availability: This proposed rule and supporting documents, 
including a copy of the draft post-delisting monitoring plan referenced 
in this document, are available on http://www.regulations.gov at Docket 
No. FWS-R6-ES-2018-0008. In addition, the supporting file for this 
proposed rule will be available for public inspection, by appointment, 
during normal business hours at the Wyoming Ecological Services Field 
Office; 5353 Yellowstone Road, Suite 308A, Cheyenne, WY 82009; 
telephone: 307-772-2374. Persons who use a telecommunications device 
for the deaf (TDD) may call the Federal Relay Service at 800-877-8339.

FOR FURTHER INFORMATION CONTACT: Tyler A. Abbott, Field Supervisor, 
telephone: 307-772-2374. Direct all questions or requests for 
additional information to: COLORADO BUTTERFLY PLANT QUESTIONS, U.S. 
Fish and Wildlife Service; Wyoming Ecological Services Field Office; 
5353 Yellowstone Road, Suite 308A, Cheyenne, WY 82009. Individuals who 
are hearing-impaired or speech-impaired may call the Federal Relay 
Service at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Information Requested

Public Comments

    We want any final action resulting from this proposal to be as 
accurate as possible. Therefore, we invite tribal and governmental 
agencies, the scientific community, industry, and other interested 
parties to submit comments or recommendations concerning any aspect of 
this proposed rule. Comments should be as specific as possible. We 
particularly seek comments and new information concerning:
    (1) Our analyses of the Colorado butterfly plant's abundance, 
distribution, and population trends;
    (2) Potential impacts from disturbances, such as grazing and 
residential, urban, and energy development;
    (3) Conservation activities within the plant's range;
    (4) Potential impacts from the effects of climate change; and
    (5) Input on considerations for post-delisting monitoring of the 
Colorado butterfly plant.
    Please include sufficient supporting information with your 
submission (such as scientific journal articles or other publications) 
to allow us to verify any scientific or commercial information you 
include. Please note that submissions merely stating support for or 
opposition to the action under consideration without providing 
supporting information, although noted, may not meet the standard of 
information required by section 4(b)(1)(A) of the Act (16 U.S.C. 1531 
et seq.), which directs that determinations as to whether any species 
is an endangered or threatened species must be made ``solely on the 
basis of the best scientific and commercial data available.''
    To issue a final rule to implement this proposed action, we will 
take into consideration all comments and any additional information we 
receive. Such communications may lead to a final rule that differs from 
this proposal. All comments, including commenters' names and addresses, 
if provided to us, will become part of the supporting record.

[[Page 26624]]

    You may submit your comments and materials concerning the proposed 
rule by one of the methods listed in ADDRESSES. Comments must be 
submitted to http://www.regulations.gov before 11:59 p.m. (Eastern 
Time) on the date specified in DATES. We will not consider hand-
delivered comments that we do not receive, or mailed comments that are 
not postmarked, by the date specified in DATES.
    We will post your entire comment--including your personal 
identifying information--on http://www.regulations.gov. If you provide 
personal identifying information in your comment, you may request at 
the top of your document that we withhold this information from public 
review. However, we cannot guarantee that we will be able to do so.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on http://www.regulations.gov, or by 
appointment, during normal business hours at the U.S. Fish and Wildlife 
Service, Wyoming Ecological Services Field Office (see Document 
availability under ADDRESSES, above).

Public Hearing

    Section 4(b)(5) of the Act provides for one or more public hearings 
on this proposal, if requested. Requests must be received within 45 
days after the date of publication of this proposed rule in the Federal 
Register (see DATES, above). Such requests must be sent to the address 
shown in FOR FURTHER INFORMATION CONTACT. We will schedule a public 
hearing on this proposal, if any is requested, and announce the date, 
time, and place of the hearing, as well as how to obtain reasonable 
accommodations, in the Federal Register and local newspapers at least 
15 days before the hearing.

Peer Review

    In accordance with our policy, ``Notice of Interagency Cooperative 
Policy for Peer Review in Endangered Species Act Activities,'' 
published on July 1, 1994 (59 FR 34270), we will seek the expert 
opinion of at least three appropriate and independent specialists 
regarding scientific data and interpretations contained in this 
proposed rule. We will send copies of this proposed rule to the peer 
reviewers immediately following its publication in the Federal 
Register. We will ensure that the opinions of peer reviewers are 
objective and unbiased by following the guidelines set forth in the 
Director's Memo that updates and clarifies Service policy on peer 
review (USFWS 2016a). The purpose of such review is to ensure that our 
decisions are based on scientifically sound data, assumptions, and 
analysis. Accordingly, our final decision may differ from that 
described in this proposal.

Previous Federal Actions

    On October 18, 2000, we published a rule in the Federal Register 
(65 FR 62302) listing the Colorado butterfly plant, with the scientific 
name Gaura neomexicana ssp. coloradensis, as a federally threatened 
species. On January 11, 2005, we designated critical habitat for the 
Colorado butterfly plant (70 FR 1940).
    On May 25, 2010, we developed a recovery outline that laid out a 
preliminary course of action for the recovery of the Colorado butterfly 
plant. This recovery outline identified residential and urban 
development as the most immediate and severe threat to the species, 
with mowing and haying as an additional potential threat. A recovery 
plan has not been developed for this species, although a draft was 
assembled prior to the species' listing by the Service, the Nature 
Conservancy, and the Wyoming Natural Diversity Database in 1987 (USFWS 
1987, entire).
    On December 17, 2012, we completed a 5-year review of the Colorado 
butterfly plant. The review was revised in June 2016, to remove private 
information protected under wildlife extension agreements (WEAs) from 
the document. The 5-year review concluded that the species should 
remain listed as threatened but also stated that threats currently 
affecting the species were occurring at low levels overall for Colorado 
butterfly plant populations and recommended further actions and 
analyses prior to the next 5-year review to assist in determining 
whether the species could be delisted.

Species Description and Life History

    Detailed information regarding the Colorado butterfly plant's 
biology and life history can be found in the Species Biological Report 
for Colorado butterfly plant (USFWS 2017a, pp. 6-7), which was reviewed 
by recovery partners. The Species Biological Report is an in-depth 
review of the species' biology and threats, an evaluation of its 
biological status, and an assessment of the resources and conditions 
needed to maintain long-term viability. The Species Biological Report 
is an interim approach taken as we transition to using a Species Status 
Assessment (SSA) framework as the standard format that the Service uses 
to analyze species as we make decisions under the Act, and includes 
similar analyses of the species' viability in terms of its resiliency, 
redundancy, and representation (USFWS 2016b, entire). We summarize 
relevant information below.
    The Colorado butterfly plant is a short-lived perennial herb that 
is monocarpic or semelparous, meaning that it flowers once, sets seed, 
and then dies. Flowering plants may, on rare occasions, flower a second 
year or become vegetative the year after flowering (Floyd 1995, pp. 10-
15, 32). Pollinators for related species of Gaura and Colyphus 
(Onagraceae, tribe Onagreae) consist of noctuid moths (Noctuidae) and 
halictid bees (Lasioglossum; Clinebell et al. 2004, p. 378); both moths 
and bees have been identified visiting Colorado butterfly plant flowers 
during annual surveys (USFWS 2016c, entire). Additionally, one study 
found that the Colorado butterfly plant does not exhibit a bimodal (day 
and night) pollination system that is seen in other Gaura species, 
since the majority of pollination occurs at night by noctuid moths 
(Krakos et al. 2013, entire).
    The Colorado butterfly plant is self-compatible; plants produce 
flowers capable of forming viable seed with pollen from the same plant 
(Floyd 1995, p. 4). During dispersal, many seeds fall to the ground 
around parent plants (Floyd and Ranker 1998, p. 854). Because the seed 
floats, it also may be dispersed downstream. Livestock and native 
ungulates could provide an important dispersal mechanism as well, 
through ingestion of the seeds (USFWS 2012, p. 27). Populations of this 
species show evidence of a seedbank, an adaptation that enables the 
species to take advantage of favorable growing seasons, particularly in 
flood-prone areas (Holzel and Otte 2004, p. 279).
    The number of individuals in a population of Colorado butterfly 
plants appears to be influenced by rates of seedling establishment and 
survival of vegetative rosettes to reproductive maturity. These factors 
may be influenced by summer precipitation (Floyd and Ranker 1998, p. 
858; Fertig 2000, p. 13). The combination of cool and moist spring 
months is important in germination, and germination levels influence 
the outcome of flowering plant population census in subsequent years. 
Additionally, summer conditions, and temperature in particular, appear 
to be an important mortality factor rather than influencing germination 
(Laursen and Heidel 2003, p. 6). Differences in soil moisture and 
vegetation cover may also influence recruitment success (Munk et al. 
2002, p. 123).
    The vegetative rosettes within a population may provide an 
important

[[Page 26625]]

and particularly resilient stage of the life history of this species. 
Individual vegetative rosettes appear to be capable of surviving 
adverse stochastic events such as flooding (Mountain West Environmental 
Services 1985, pp. 2-3) and adverse climatic years when new seedling 
establishment is low. Therefore, episodic establishment of large 
seedling recruitment classes may be important for the long-term growth, 
replenishment, and survival of populations (Floyd and Ranker 1998, 
entire).

Taxonomy

    The Colorado butterfly plant, a member of the evening primrose 
family (Onagraceae), was listed as Gaura neomexicana ssp. coloradensis 
in 2000 (65 FR 62302; October 18, 2000). Molecular studies by Hoggard 
et al. (2004, p. 143) and Levin et al. (2004, pp. 151-152) and 
subsequent revisions of the classification of the family Onagraceae 
(Wagner et al. 2007, p. 211) transferred the taxon previously known as 
Gaura neomexicana Wooton to Oenothera as Oenothera coloradensis ssp. 
neomexicana (Wooton) W.L. Wagner & Hoch. More recent analyses showed 
that there are no infraspecific entities (any taxa below the rank of 
species) within the taxon; the listed entity is now recognized as 
Oenothera coloradensis (Wagner et al. 2013, p. 67). A more detailed 
assessment of the taxonomy of the Colorado butterfly plant is available 
in the species Biological Report (USFWS 2017a, pp. 4-6). The taxonomic 
and nomenclatural changes do not alter the description, range, or 
threat status of the listed entity.
    Throughout this proposed rule, we will use the current scientific 
name and rank, Oenothera coloradensis, for the Colorado butterfly 
plant. We acknowledge, however, that the listing of the Colorado 
butterfly plant in the Code of Federal Regulations (CFR) will continue 
to be identified as Gaura neomexicana ssp. coloradensis until such time 
as we publish a correction or a final delisting rule in the Federal 
Register.

Species Abundance, Habitat, and Distribution

    The Colorado butterfly plant is a regional endemic riparian species 
known from 34 12-digit hydrologic unit code watersheds (watersheds) (28 
extant and 6 extirpated), found from Boulder, Douglas, Larimer, and 
Weld Counties in Colorado, Laramie and Platte Counties in Wyoming, and 
western Kimball County in Nebraska (see figure below). Prior to 1984, 
few extensive searches for the plant had been conducted, and data taken 
from herbarium specimens were the primary basis of understanding the 
extent of the species' historical distribution. At that time, the plant 
was known from a few historical and presumably extirpated locations in 
southeastern Wyoming and several locations in northern Colorado, as 
well as from three extant occurrences in Laramie County in Wyoming and 
Weld County in Colorado. Prior to listing, extensive surveys were 
conducted in 1998, to document the status of the known occurrences, and 
all still contained Colorado butterfly plants (Fertig 1998a, entire).
 BILLING CODE 4333-15-P

[[Page 26626]]

[GRAPHIC] [TIFF OMITTED] TP08JN18.007

 BILLING CODE 4333-15-C

Habitat Description

    The Colorado butterfly plant occurs on subirrigated (water reaches 
plant root zone from below the soil surface), alluvial soils derived 
from conglomerates, sandstones, and tuffaceous mudstones and siltstones 
of the Tertiary White River, Arikaree, and Oglalla Formations (Love and 
Christiansen 1985 in Fertig 2000, p. 6) on level or slightly sloping 
floodplains and drainage bottoms at elevations of 1,524-1,951 meters 
(m) (5,000-6,400 feet (ft)). Populations are typically found in 
habitats created and maintained by streams active within their 
floodplains, with vegetation that is relatively open and not overly 
dense or overgrown (65 FR 62302; October 18, 2000). Populations occur 
in a range of ecological settings, including streamside, outside of the 
stream channel but within the floodplain, and spring-fed wet meadows. 
The plant is often found in but not restricted to early- to mid-
succession riparian habitat. Historically, flooding was probably the 
main cause of disturbances in the plant's habitat, although wildfire 
and grazing by native herbivores also may have been important. Although 
flowering and fruiting stems may exhibit increased dieback because of 
the abovementioned events, vegetative rosettes appear to be little 
affected (Mountain West Environmental Services 1985, pp. 2-3).
    It commonly occurs in communities dominated by nonnative and 
disturbance-tolerant native species including: Agrostis stolonifera 
(creeping bentgrass), Poa pratensis (Kentucky bluegrass), Glycyrrhiza 
lepidota (American licorice), Cirsium flodmanii (Flodman's thistle), 
Grindelia squarrosa (curlytop gumweed), and Equisetum laevigatum 
(smooth scouring rush). Its habitat on Warren Air Force Base (AFB) 
includes wet meadow zones dominated by Panicum virgatum (switchgrass), 
Muhlenbergia richadrsonis (mat muhly), Schizachyrium scoparium (little 
bluestem), Spartina pectinata (prairie cordgrass), and other native 
grasses. All of these habitat types are usually intermediate in 
moisture ranging from wet, streamside communities dominated by sedges, 
rushes, and cattails to dry, upland prairie habitats (Fertig 1998a, pp. 
2-4).
    Typically, Colorado butterfly plant habitat is open, without dense 
or woody vegetation. The establishment and survival of seedlings 
appears to be enhanced at sites where tall and dense vegetation has 
been removed by some form of disturbance. In the absence of occasional 
disturbance, the plant's habitat can become choked by dense growth of 
willows, grasses, and exotic plants (Fertig 1996, p. 12). This prevents 
new seedlings from becoming established and replacing plants that have 
died (Fertig 1996, pp. 12-14).
    For the purposes of this analysis, we consider all occurrences of 
the Colorado

[[Page 26627]]

butterfly plant within the same watershed to be one population. There 
are no data (e.g., genetic relatedness) available to more precisely 
define populations, and although distance of 1 km (0.6 mi) or greater 
may exceed the distance traveled by pollinators, it is possible that 
seeds may disperse over much greater distances (Heidel 2016, pers. 
comm.). Therefore, because these gaps are probably too small to prevent 
the dispersal of pollinators and/or seeds between subpopulations, 
colonies along the same stream reach should be considered part of the 
same population. This varies from the characterization of populations 
in both the listing decision (65 FR 62302; October 18, 2000) and 
critical habitat designation (70 FR 1940; January 11, 2005), where 
populations were defined by landowner and/or proximity within a 
drainage. We find organizing populations by watershed more accurately 
describes components of population ecology (genetic exchange within a 
geographic area), and stressors affecting the species tend to vary by 
watershed. Because of this new organization of population structure, 
some populations considered distinct and separate during the 2000 
listing decision are now combined and vice versa, although many 
populations are the same in this proposed rule as they were presented 
in the 2000 listing rule.

Population Abundance and Trends

    The Colorado butterfly plant occurred historically and persists in 
various ecological settings described above under Habitat Description 
including wet meadows, stream channels, stream floodplains, and spring-
fed wetlands. A detailed summary of the status of the species between 
1979 and 2016 is provided in the species' Biological Report (USFWS 
2017a, pp. 13-22).
    In 1998 and 1999, in preparation for listing the species, the 
rangewide census of flowering individuals was estimated at 47,300 to 
50,300, with the majority of these occurring in Wyoming (Fertig 1998a, 
p. 5; Fertig 2000, pp. 8-13). However, a population was discovered in 
Colorado in 2005 that had a peak census of 26,000 plants in 2011, 
bringing the total rangewide population to approximately 73,300 to 
76,300 plants over time. Another population was discovered upstream of 
known populations on Horse Creek in Laramie County, Wyoming, in 2016 
with only 17 individuals, although the area had just been hayed and was 
likely an incomplete representation of the total number of plants in 
this population (USFWS 2016c, entire).
    Average numbers may be a more appropriate way to represent 
populations than the minimum and maximum values, although all provide 
insight into the population's resiliency, or the ability to withstand 
stochastic events. The number of reproductive individuals in a 
population is somewhat driven by environmental factors and varies 
considerably, so understanding the variability in the number of 
individuals present in any given year is meaningful in assessing 
population resiliency. Population numbers have fluctuated five-fold 
over the course of the longest-running monitoring study (28 years) 
conducted on Warren AFB. There, the population peaked at over 11,000 
flowering plants in 1999 and 2011, making it one of the largest 
populations rangewide, and then dropped to 1,916 plants in 2008 (Heidel 
et al. 2016, p. 1). The Warren AFB population numbers provide some 
indication of how population numbers can vary in landscapes not managed 
for agricultural purposes, and it is likely that numbers vary even more 
dramatically on managed landscapes. If this fluctuation was applied to 
the rangewide population estimates above, then total rangewide numbers 
for average years might be less than 50 percent of rangewide estimates 
in favorable years (Handwerk 2016, pers. comm.; Heidel 2016, pers. 
comm.).
    The final listing rule (65 FR 62302; October 18, 2000) defined 
large populations as those containing more than 3,000 reproductive 
individuals; moderate populations as those containing 500 to 2,500 
reproductive individuals; and small populations having fewer than 500 
reproductive individuals. At the time, the species was represented by 
10 stable or increasing populations, 4 extant but declining 
populations, 3 likely small populations, and 9 likely extirpated 
populations. However, after monitoring roughly half the known 
populations annually for the past 13 years, we understand that 
population size fluctuates significantly from year to year; therefore, 
population size in any given year is not a good indicator of 
resiliency. Therefore, our estimates of resiliency are now based on 
averages of population censuses over multiple years and trends of 
populations in response to management and stressors. Based on this, we 
now have 15 highly resilient populations, 2 moderately resilient 
populations, 6 low resiliency populations, 2 populations with unknown 
resiliency, 3 introduced populations, and records of 6 extirpated 
populations.

Colorado

    In 2005, when critical habitat was designated for the Colorado 
butterfly plant, only a single population was known from Colorado. That 
population was not designated as critical habitat because it was 
protected under a WEA. Currently, the species is known to occur in 
Adams, Boulder, Douglas, Jefferson, Larimer, and Weld Counties in 
northern Colorado, spanning 12 watersheds (see figure above). Six 
historical occurrences have not been documented since 1984, and are 
presumed extirpated. Three of the eight records in Colorado are 
introduced and do not represent indigenous populations, and are either 
seeded into the wild or into a garden. These introduced sites were not 
designed specifically for species' conservation, and therefore are not 
the focus of this species status evaluation in Colorado.
    The majority of Colorado butterfly plants in Colorado are located 
on lands managed by the City of Fort Collins Natural Areas Department 
(Ft. Collins or CFCNAD) in Weld and Larimer Counties. The plants are 
distributed among three distinct habitats on either side of Interstate 
25 and have numbered between 3 to more than 26,000 reproductive 
individuals. These areas are being managed to maintain suitable habitat 
for the species (CFCNAD 2008, p. 1; CFCNAD 2010, p. 1; CFCNAD 2011a, 
entire; CFCNAD 2011b, entire; CFCNAD 2014, entire). Annual census 
information on flowering individuals at the Meadow Springs Ranch in 
Weld County indicates that the large fluctuations in population numbers 
are actually around a stable mean (434 flowering plant average, median 
of 205, range of 45-1,432 flowering plants). Other populations in 
Colorado have not been routinely monitored; consequently, no trend 
information is available (USFWS 2016c, entire). In summary, the species 
is represented in Colorado by two highly resilient, three low 
resiliency, and three introduced populations.

Nebraska

    Populations of the Colorado butterfly plant in Nebraska are 
considered at the edge of the species' range and exist at higher 
elevations than we knew at the time we listed the species. Surveys 
conducted in 1985, along Lodgepole Creek near the Nebraska/Wyoming 
border in Kimball County, found just over 2,000 flowering plants (Rabbe 
2016, pers. comm). A survey in 1992 found two populations of Colorado 
butterfly plant: One population (547 plants) along Lodgepole Creek and 
one population (43 plants) at Oliver Reservoir State Recreation Area 
(SRA) in the southwest panhandle of Nebraska in Kimball County (Fertig 
2000a, p. 12).

[[Page 26628]]

Survey results from 2004 suggested the species was extirpated from the 
State. In 2005, no critical habitat was designated in Nebraska. 
However, a 2008 survey along historically occupied habitat and the 
Oliver Reservoir SRA, located 12 plants in four locations on private 
lands along Lodgepole Creek: 5 plants in areas where the species had 
been located before and 7 plants in areas newly watered by a landowner 
piping water into Lodgepole Creek from a cattle stock tank. No plants 
were found at the Oliver Reservoir SRA (Wooten 2008, p. 4). These areas 
have not been surveyed since 2008. Outside of these occurrences, no 
other populations of the species are known to occur in Nebraska (Rabbe 
2016, pers. comm.).

Wyoming

    Extant populations of Colorado butterfly plant in Wyoming occur 
throughout most of Laramie County and extend northward into Platte 
County (USFWS 2012, pp. 11-21), spanning 17 watersheds (see figure 
above). Over 90 percent of known occurrences in Wyoming are on private 
lands, with parts of two occurrences on State school trust lands, one 
occurrence on State lands, and one occurrence on Federal lands. 
Populations in Wyoming that are found partly or fully on State school 
trust lands are managed for agricultural uses. The population on 
Federal lands occurs on Warren AFB located adjacent to Cheyenne, 
provides information on species trends as it may have occurred prior to 
human settlement of the area (with wild grazers and natural 
streamflow), and represents the level of hydrological complexity of 
three different sizes of streams. The highest census numbers at Warren 
AFB totaled over 11,000 plants in 1998 and 2011, and the mean census 
numbers for all other years have remained at or above 50 percent of 
that peak, based on 1988-2016 numbers (Heidel et al. 2016, pp. 11-14).
    In terms of genetic representation, a study conducted on Colorado 
butterfly plants occupying three drainages at Warren AFB found that one 
of the drainages was genetically unique and more diverse than the other 
two drainages (Floyd 1995, pp. 73-81). Another study at Warren AFB 
found that plants in one of the drainages contained unique alleles, 
sharing genetic composition with only a small number of individuals 
from the second and no individuals of the third drainage, indicating 
fine-scale genetic variability within that portion of the species' 
range (Tuthill and Brown 2003, p. 251). Assuming similar genetic 
structure across the species' range, this result suggests a high degree 
of genetic representation at the species' level. This genetic 
information, however, does not provide sufficient strength in terms of 
sample size in discerning populations from each other.
    The Service has agreements with 11 private landowners within six 
watersheds in Laramie County, Wyoming, and one watershed in Weld 
County, Colorado (described in detail under Conservation Efforts, 
below), since 2004 to conduct annual monitoring of the Colorado 
butterfly plant. We also provide management recommendations to help 
landowners maintain habitat for the species. Many of the landowners 
graze cattle or horses where the species occurs; others use the areas 
for haying operations. Populations at these locations may fluctuate by 
as much as 100-fold annually (USFWS 2012, pp. 11-21; USFWS 2016c, 
entire). For example, one population was heavily grazed for over a 
decade, leading to counts of fewer than 30 reproductive individuals for 
several years, but when the grazing pressure was relieved, the 
population rebounded within 1 year to more than 600 reproductive 
individuals (USFWS 2016c, entire). This may indicate that either a 
robust seedbank was present or vegetative rosettes avoided the intense 
grazing pressure and bolted after grazing diminished. The total number 
of plants counted in Wyoming under these agreements has varied from 
approximately 1,000 to over 21,000 reproductive individuals since 2004. 
Combining annual census numbers from all monitored populations in 
Wyoming, we have observed small to extreme population fluctuations 
(USFWS 2012, pp. 11-21; USFWS 2016c, entire). Wyoming is represented by 
13 highly resilient populations, 2 moderately resilient populations, 
and 2 populations with unknown resiliency due to lack of information.
    The listing decision (65 FR 62302, October 18, 2000, see p. 62308) 
stated that ``[i]n order for a population to sustain itself, there must 
be enough reproducing individuals and sufficient habitat to ensure 
survival of the population. It is not known if the scattered 
populations of [the Colorado butterfly plant] contain sufficient 
individuals and diversity to ensure their continued existence over the 
long term.'' Today, we understand that, regarding ecological 
representation, the species is characterized by having at least one 
population within each ecological setting and within all but the 
southern-most portions of the historical range. Furthermore, most 
extant populations have high resiliency (with more than 100 
reproductive individuals in most years). Additionally, most populations 
contain individuals in more than one ecological setting, such as 
individuals along the creek bank and individuals outside of the creek 
bank and in the floodplain of the creek. While surveyors typically 
census the number of flowering individuals during surveys due to 
relative ease in counting, the number of flowering plants in a survey 
location in any given year does not represent the resiliency of the 
population. Resiliency is determined through a combination of number of 
flowering individuals, trends in this number, and response of the 
population to stochastic events.

Conservation Efforts

    The Service has worked with partners to protect existing 
populations. Much of this work has been accomplished through voluntary 
cooperative agreements. For example, beginning in 2004, the Service has 
entered into 11 WEAs with private landowners, representing six 
watersheds, to manage riparian habitat for Colorado butterfly plant (70 
FR 1940; January 11, 2005). These 15-year WEAs cover a total of 1,038 
hectares (ha) (2,564 acres (ac)) of the species' habitat along 59 km 
(37 mi) of stream. These agreements represent approximately one-third 
of the known populations of Colorado butterfly plant in Wyoming and 
Colorado, including some of the largest populations on private lands. 
All of the landowners have agreed to the following:
    (1) Allow Service representatives or their designee access to the 
property for monitoring or fence installation;
    (2) Coordinate hay cutting activities in areas managed primarily 
for hay production to consider the Colorado butterfly plant's seed 
production needs;
    (3) Prevent application of herbicides closer than 30.5 m (100 ft) 
from known subpopulations of the Colorado butterfly plant; and
    (4) Manage livestock grazing activities in conjunction with 
conservation needs of the Colorado butterfly plant.
    One of the landowners signed a 10-year agreement instead of a 15-
year agreement that was renewed for an additional 10 years in 2015. The 
remaining agreements expire in late 2019. We anticipate that 
participating landowners will continue to support the work being 
performed under the WEAs and will seek renewal of these agreements if 
the species remains listed under the Act. Based on the ongoing 
relationship that the Service has with these participating landowners, 
we anticipate that they would support the inclusions of their 
properties under the

[[Page 26629]]

post-delisting monitoring program should the Colorado butterfly plant 
be delisted.
    One of the benefits of the WEAs for both the Service and private 
landowners is that we can review the population numbers annually and 
together develop management recommendations to improve growing 
conditions for the species. Populations occurring within designated 
critical habitat (see figure, above) have not been surveyed since 2004, 
and their trends, threats, and viabilities are uncertain. However, no 
projects potentially impacting critical habitat for this species have 
occurred. Additionally, we reviewed aerial imagery of the critical 
habitat units and found only two minimal changes between 2004 and 2015 
(reflecting habitat conditions at the time of designation and the most 
recent aerial imagery available) throughout all critical habitat units; 
these changes affect only a few acres of designated critical habitat 
(USFWS 2017b, entire). Consequently, we determine that activities 
occurring on critical habitat are likely the same as they were at the 
time of designation. Furthermore, because many of the private lands 
included in the critical habitat designation are adjacent to lands 
under WEAs, we determine that the populations occurring within 
designated critical habitat are likely stable, and fluctuating 
similarly to populations on lands that we monitor under WEAs. We have 
no reason to believe that populations occurring on designated critical 
habitat are responding to stressors differently than those populations 
we monitor. Therefore, populations throughout the species' range on 
private, local, and Federal lands either have been observed to be, or 
are highly likely to be, fluctuating around a stable population size.
    The Service and the U.S. Air Force signed a memorandum of agreement 
(MOA) on January 18, 1982 (updated in 1999 and 2004) to facilitate the 
preservation, conservation, and management of the Colorado butterfly 
plant (USFWS 1982, entire; USFWS 1999, entire; USFWS 2004, entire). In 
2004, Warren AFB developed a conservation and management plan for the 
species (Warren AFB 2004, entire) that was added to their integrated 
natural resources management plan in 2014 (Warren AFB 2014, entire). 
Through these plans, the Service partners with the U.S. Air Force and 
Wyoming Natural Diversity Database to monitor and protect the 
population of the Colorado butterfly plant on the Warren AFB. This 
includes annual monitoring; nonnative, invasive species control and 
eradication; and maintenance of appropriate floodplain characteristics 
for the species. Based on 29 years of monitoring and management, the 
population of the Colorado butterfly plant on the Warren AFB is doing 
well, with some areas declining while others are increasing (Heidel et 
al. 2016, entire).
    Three populations in Larimer and Weld Counties, Colorado, occur on 
properties owned by the City of Fort Collins, and two are among the 
largest across the species' range. The City of Fort Collins developed a 
10-year master plan for the Natural Areas Department in 2014, which 
provides a framework for the conservation and preservation of natural 
areas, including the populations of the Colorado butterfly plant. The 
master plan prescribes conservation actions that allow for the 
persistence of the Colorado butterfly plant on the landscape (CFCNAD 
2016a, entire), including prescribed burns to eliminate competition, 
managed grazing, and improved security of water flow to the species' 
habitat.
    In summary, these agreements and plans have provided useful data, 
facilitated good management of nine of the largest and most resilient 
populations, and resulted in stable or increasing population trends. 
Because of the information we obtained through these agreements and 
plans, we are able to understand the resilience of individual plants 
and populations, the representation of the species within its 
ecological settings, and the redundancy of the plant population's 
numbers and potential for connectivity.

Summary of Factors Affecting the Species

    Section 4 of the Act and its implementing regulations (50 CFR part 
424) set forth the procedures for listing species, reclassifying 
species, or removing species from listed status. ``Species'' is defined 
by the Act as including any species or subspecies of fish or wildlife 
or plants, and any distinct vertebrate population segment of fish or 
wildlife that interbreeds when mature (16 U.S.C. 1532(16)). A species 
may be determined to be an endangered or threatened species due to one 
or more of the five factors described in section 4(a)(1) of the Act: 
(A) The present or threatened destruction, modification, or curtailment 
of its habitat or range; (B) overutilization for commercial, 
recreational, scientific, or educational purposes; (C) disease or 
predation; (D) the inadequacy of existing regulatory mechanisms; or (E) 
other natural or manmade factors affecting its continued existence.
    Determining whether the status of a species has improved to the 
point that it can be downlisted (i.e., reclassified from endangered to 
threatened) or delisted requires consideration of whether the species 
meets the definitions of either an endangered species or threatened 
species contained in the Act. For species that are already listed as 
endangered species or threatened species, this analysis of threats is 
an evaluation of both the threats currently facing the species and the 
threats that are reasonably likely to affect the species in the 
foreseeable future following the delisting or downlisting and the 
removal or reduction of the Act's protections.
    A species is an ``endangered species'' for purposes of the Act if 
it is in danger of extinction throughout all or a significant portion 
of its range and is a ``threatened species'' if it is likely to become 
an endangered species within the foreseeable future throughout all or a 
significant portion of its range. The word ``range'' in the significant 
portion of its range phrase refers to the range in which the species 
currently exists, and the word ``significant'' refers to the value of 
that portion of the range being considered to the conservation of the 
species. We consider ``foreseeable future'' as that period of time 
within which a reliable prediction can be reasonably relied upon in 
making a determination about the future conservation status of a 
species, as described in the Solicitor's opinion dated January 16, 
2009. We consider 15 to 20 years to be a reasonable period of time 
within which reliable predictions can be made for the Colorado 
butterfly plant. This time period includes at least five generations of 
the species, coincides with the duration of one renewal of the WEAs 
expiring in 2019, and aligns with the timeframes for predictions 
regarding municipal development and growth in the area. For the 
purposes of this analysis, we first evaluate the status of the species 
throughout all of its range, then consider whether the species is in 
danger of extinction or likely to become so in any significant portion 
of its range.
    In considering what factors might constitute threats, we must look 
beyond the exposure of the species to a particular factor to evaluate 
whether the species may respond to the factor in a way that causes 
actual impacts to the species. If there is exposure to a factor, but no 
response, or only a positive response, that factor is not a threat. If 
there is exposure to a factor and the species responds negatively, the 
factor

[[Page 26630]]

may be a threat, and we attempt to determine how significant a threat 
it is. If the threat is significant it may drive, or contribute to, the 
risk of extinction of the species such that the species warrants 
listing as an endangered species or a threatened species as those terms 
are defined by the Act. This does not necessarily require empirical 
proof of a threat. The combination of exposure and some corroborating 
evidence of how the species is likely impacted could suffice. The mere 
identification of factors that could impact a species negatively is not 
sufficient to compel a finding that listing is appropriate; we require 
evidence that these factors individually or cumulatively are operative 
threats that act on the species to the point that the species meets the 
definition of an endangered species or threatened species under the 
Act.
    The Colorado butterfly plant is federally listed as threatened. 
Below, we present a summary of threats affecting the species and its 
habitats in the past, present, and predicted into the future. A 
detailed evaluation of factors affecting the species at the time of 
listing can be found in the listing determination (65 FR 62302; October 
18, 2000) and designation of critical habitat (70 FR 1940; January 11, 
2005). An evaluation of factors affecting the species after 2005 can be 
found in the 2012 5-year review (USFWS 2012, entire). The primary 
threats to the species identified at the time of listing include 
overgrazing by cattle or horses, haying or mowing at inappropriate 
times of the year, habitat degradation resulting from vegetation 
succession or urbanization of the habitat, habitat conversion to 
cropland or subdivision, water development, herbicide spraying, and 
competition with exotic plants (Marriott 1987, pp. 26-27; Fertig 1994, 
pp. 39-41, Fertig 2000a, pp. 16-17). Since the time of listing, oil and 
gas development and the effects of climate change have become potential 
threats to this species and are analyzed under Factor A and Factor E, 
respectively, below.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

Residential, Urban, and Energy Development
    At the time of listing (65 FR 62302; October 18, 2000), residential 
and urban development around the cities of Cheyenne and Fort Collins 
were identified as past causes of habitat conversion and habitat loss 
to the Colorado butterfly plant; these types of development were not a 
concern in Nebraska at the time of listing nor are they now. Although 
difficult to quantify because land conversion was not tracked during 
the settlement of the West, likely a few hundred acres of formerly 
suitable habitat were converted to residential and urban sites, 
contributing to loss of habitat (Fertig 1994, p. 38; Fertig 2000a, pp. 
16-17). Much of the species' range occurs along the northern Front 
Range of the Rocky Mountains in Colorado and Wyoming, which has 
experienced dramatic growth in the recent past and is predicted to grow 
considerably in the future (Regional Plan Association 2016, entire), 
particularly in Larimer and Weld Counties in Colorado (University of 
Colorado Boulder 2015, pp. 119-120). The demand that urban development 
places on water resources also has the ability to dewater the streams 
and lower groundwater levels required by the species to maintain self-
sustaining populations, and is explored below.
    The two large populations of the Colorado butterfly plant in 
Larimer and Weld Counties, Colorado, occur on lands managed as open 
space by Fort Collins, and are not directly subject to residential or 
urban development. Consequently, despite projected increases in human 
density and urban development along the northern Front Range, these 
lands are managed to allow for the persistence of these populations, 
with managed grazing or burning (CFCNAD 2016b, entire). Fort Collins 
does not own all mineral rights on these lands; therefore, sensitive 
areas within these boundaries may be impacted by mineral development. 
However, in light of this potential threat, the city completed a 
planning process in which they highlighted areas to be avoided by 
mineral development (The Nature Conservancy 2013, entire). While oil 
and gas development has increased in northern Colorado and southeastern 
Wyoming since the time of listing, no oil or gas wells have been 
proposed or likely will be proposed in areas that will directly or 
indirectly impact populations of the Colorado butterfly plant in 
Colorado or in Wyoming, particularly due to the species' occurrence in 
riparian and wetland habitats. Because the plant occurs in riparian and 
wetland habitats that routinely flood, it is likely that oil and gas 
wells will be sited outside of population boundaries. While there is 
potential for indirect effects through spills or sedimentation, we have 
no specific information about those effects on the species to date.
    According to publicly available information, there are no current 
proposals for urban or residential development on lands containing 
populations of Colorado butterfly plant in Wyoming. Monitoring of lands 
under agreement (CFCNAD, WEAs, and Warren AFB) has also shown that 
neither urbanization nor conversion to intensive agricultural 
activities has occurred as predicted in the final listing rule (65 FR 
62302, October 18, 2000; USFWS 2012, pp. 11-22; USFWS 2016c, entire). 
Populations at WAFB remained stable over the past 29 years without 
being managed for agricultural purposes, although numbers of 
reproductive individuals fluctuate during any given year (Heidel et 
al., 2016, pp. 14-18). Since the time of listing, the Service has 
received few requests for consultation under section 7 of the Act for 
projects that may adversely affect this species. Informal consultations 
have been limited to grazing, power lines, pipelines, road development, 
and drainage crossing projects, and avoidance and minimization of 
potential impacts has been readily achieved (USFWS 2017c, entire).
    Furthermore, chapters 3 and 4 of the Laramie County Land Use 
Regulations address floodplain management and require specific 
provisions and permits for construction within floodplains (Laramie 
County 2011, pp. 165-185), which encompass all Colorado butterfly plant 
habitat within the county; these regulations, therefore, extend some 
level of protection to the species and its habitat. These regulations 
are in place to ``promote public health, safety, and general welfare 
and to minimize public and private losses due to flood conditions'' 
(Laramie County 2011, p. 165), and protect many resources, including 
the Colorado butterfly plant and its habitat, by limiting development 
in the floodplains. These regulations are discussed in detail under 
Factor D, below.
    The threats of residential and urban development, once considered 
significant threats to the Colorado butterfly plant, have been largely 
avoided because most development has occurred outside of the habitat in 
which this species occurs. Annual monitoring conducted by the Service 
since 2004 indicates that populations are stable and unaffected by any 
development that has occurred within the species' range. While human 
population growth and development are predicted for the Front Range of 
the Rocky Mountains in Colorado into the future, these areas are 
outside of the species' occupied habitat, and we do not anticipate 
development in the protected areas under management of Fort Collins, 
and do not anticipate development due to continued restrictions against

[[Page 26631]]

development within the floodplain. Additionally, increases in oil and 
gas development in northern Colorado and southeastern Wyoming have not 
directly or indirectly impacted populations of the Colorado butterfly 
plant. Current ownership and management by Fort Collins and Warren AFB 
of lands containing a majority of large populations of the Colorado 
butterfly plant protect the species from current and future impacts due 
to residential, urban, and energy development.
Agricultural Practices
    At the time of listing (65 FR 62302; October 18, 2000), conversion 
of grassland to farmlands, mowing grasslands, and grazing were 
considered threats to the Colorado butterfly plant. Prior to listing, 
the conversion of moist, native grasslands to commercial croplands was 
widespread throughout much of southeastern Wyoming and northeastern 
Colorado (Compton and Hugie 1993, p. 22), as well as in Nebraska. 
However, conversion from native grassland to cropland has slowed 
throughout the species' range since the time of listing, with no lands 
converted in Laramie County and just 12 ha (30 ac) converted in Platte 
County between 2011 and 2012 (FSA 2013, entire).
    Mowing areas for hay production that are occupied by the Colorado 
butterfly plant was identified as a threat at the time of listing, if 
conducted at an inappropriate time of year (prior to seed maturation) 
(Fertig 1994, p. 40; USFWS 1997, p. 8). However, monitoring over the 
past 13 years indicates that mowing prior to seed maturation occurs 
infrequently. Even in areas where early season mowing has occurred, 
annual monitoring has shown high numbers of reproductive plants present 
in subsequent years, suggesting that mowing for hay production is not a 
threat to the species (USFWS 2016c, entire).
    The agricultural practices of grazing and herbicide application 
threatened the Colorado butterfly plant at the time of listing. 
However, since then, the Service has made and continues to make 
recommendations to cooperating landowners on agricultural management 
that fosters resiliency in populations of the species. We believe that 
these measures have decreased the severity of these stressors. We also 
anticipate that landowners will continue their current agricultural 
practices into the future, based on the data we have collected from 
WEAs (USFWS 2016c, entire) and analysis of aerial imagery of designated 
critical habitat (USFWS 2017b, entire). Through these agreements, we 
also learned that the species is highly adapted to withstand stochastic 
events. The assessment that the species is highly resilient is based on 
the information obtained through the WEAs; we do not rely on the 
implementation of the WEAs to ensure that the species remains highly 
resilient. Instead, we believe the plant will continue to thrive even 
if protections are removed. Grazing is further explored under Factor C, 
below, and herbicide spraying is further explored under Factor E, 
below.
Water Management
    At the time of listing (65 FR 62302; October 18, 2000), water 
management (actions that moved water to croplands, such as irrigation 
canals, diversions, and center pivot irrigation development) was 
considered a threat that would remove moisture from Colorado butterfly 
plant habitat. The management of water resources for livestock 
production and domestic and commercial human consumption, coupled with 
increasing conversion of lands for agricultural production, often led 
to channelization and isolation of water resources; changes in 
seasonality of flow; and fragmentation, realignment, and reduction of 
riparian and moist lowland habitat (Compton and Hugie 1993, p. 22). All 
of these actions could negatively impact suitable habitat for the 
species.
    Dewatering portions of Lodgepole Creek in Kimball County, Nebraska, 
has led to the extirpation of some of the species' known historical 
populations there, and low likelihood of long-term resiliency for the 
two extant populations last monitored in 2008 (Rabbe 2016, pers. 
comm.). Extant populations in Nebraska continue to experience 
dewatering and overgrazing on private land. However, when water was 
reintroduced to formerly occupied habitat after being absent for more 
than 10 years, a population was rediscovered (Wooten 2008, p. 4). While 
rediscovery of this population indicates persistence of a viable 
seedbank for at least 10 years, numbers of plants within the population 
declined from over 600 plants (Fertig 2000a, p. 12) to 12 plants 
(Wooten 2008, p. 4), and the application of water that allowed plants 
to grow was temporary, which suggests the population has a low 
likelihood of long-term resiliency.
    In 2016, the Colorado Water Conservation Board on behalf of Fort 
Collins filed an instream flow right on Graves Creek, the stream that 
feeds the population of Colorado butterfly plants in Soapstone Prairie 
(CFCNAD 2016b, entire). While the water right has not yet been granted, 
we believe that this instream flow right will protect and maintain 
subirrigation of this large and important population through ensuring 
adequate water availability to the species throughout the year.
    The entire range of the Colorado butterfly plant occurs within the 
Platte River Basin. Water usage in the Platte River system is managed 
collaboratively by the States of Colorado, Wyoming, and Nebraska, and 
the Department of the Interior, through the Platte River Recovery 
Implementation Program (PRRIP). The PRRIP, which began in 1997, 
provides a mechanism for existing and new water users and water-
development activities in the Platte River Basin to operate in 
regulatory compliance with the Act regarding potential impacts to the 
five Platte River ``target species'' in Nebraska: Grus americana 
(whooping crane), Sterna (Sternula) antillarum (interior least tern), 
Charadrius melodus (northern Great Plains population of piping plover), 
Scaphirhynchus albus (pallid sturgeon), and Platanthera praeclara 
(western prairie fringed orchid). Because the PRRIP ensures that 
shortages to the target flows in the central Platte River will be 
substantially reduced by keeping water within the basin more 
consistently throughout the year (PRRIP 2016), the hydrological 
component of habitat for the Colorado butterfly plant will be better 
maintained as well.
    In summary, water management can directly and indirectly impact the 
Colorado butterfly plant. While management of water resources has 
negatively impacted the species on a localized scale in the past, there 
is no indication that water management throughout the majority of the 
species' range poses a current threat to the species because programs 
and policies currently in place, such as the PRRIP and Graves Creek 
instream flow right, provide substantial assurances that the 
hydrological component of currently occupied habitat will remain 
protected over the long term.
Natural Succession and Competition With Nonnative, Invasive Species
    In the absence of periodic disturbance, natural succession of the 
plant community in areas occupied by the Colorado butterfly plant moves 
from open habitats to dense coverage of grasses and forbs, and then to 
willows and other woody species. The semi-open habitats preferred by 
this species can become choked by tall and dense growth of willows; 
grasses; and nonnative, invasive species (Fertig 1994, p. 19; Fertig 
2000a, p. 17). Natural disturbances such as flooding, fire, and native 
ungulate grazing were sufficient

[[Page 26632]]

in the past to create favorable habitat conditions for the species. 
However, the natural flooding regime within the species' floodplain 
habitat has been altered by construction of flood control structures 
and by irrigation and channelization practices (Compton and Hugie 1993, 
p. 23; Fertig 1994, pp. 39-40). Consequently, the species relies on an 
altered flood regime and other sources of disturbance to maintain its 
habitat.
    In the absence of natural disturbances today, managed disturbance 
may be necessary to maintain and create areas of suitable habitat 
(Fertig 1994, p. 22; Fertig 1996, pp. 12-14; Fertig 2000a, p. 15). 
However, populations can persist without natural disturbances such as 
fire and flooding through natural dieback of woody vegetation and 
native ungulate grazing (Heidel et al., 2016, pp. 2-5). Additionally, 
some Federal programs, such as those administered by the U.S. 
Department of Agriculture's Natural Resources Conservation Service, 
focus on enhancing or protecting riparian areas by increasing 
vegetation cover and pushing the habitat into later successional 
stages, which removes the types of disturbance the Colorado butterfly 
plant needs (65 FR 62302; October 18, 2000, p. 62307). However, these 
programs are implemented in only a small portion of the species' range. 
The Service learned from monitoring the 11 WEA properties that the 
typical approach of managing for livestock grazing, coupled with an 
altered flood regime, appears to provide the correct timing and 
intensity of disturbance to maintain suitable habitat for the species 
(USFWS 2012, pp. 9-21; USFWS 2016c, entire). There has been no 
noticeable change in general management practices or change in the 
natural succession rate in either the WEA properties or the designated 
critical habitat since the agreements were signed or the critical 
habitat was designated, and we have no reason to believe that these 
practices or rates will change in the foreseeable future. Therefore, 
through the information we have gathered since the time of listing, it 
appears that natural succession is not occurring at the level 
previously considered to threaten this species.
    The final listing rule (65 FR 62302; October 18, 2000) included 
competition with exotic plants and noxious weeds as a threat to the 
Colorado butterfly plant. Competition with exotic plants and noxious 
weeds, here referred to as nonnative, invasive species, may pose a 
threat to the Colorado butterfly plant, particularly given the species' 
adaptation to more open habitats. In areas of suitable habitat for 
Colorado butterfly plant, the following plants may become dominant: The 
native Salix exigua (coyote willow); nonnative, invasive Cirsium 
arvense (Canada thistle); and nonnative, invasive Euphorbia esula 
(leafy spurge). Salix in particular increases in the absence of grazing 
or mowing. These species can outcompete and displace the Colorado 
butterfly plant, presumably until another disturbance removes competing 
vegetation and creates openings for Colorado butterfly plant seedlings 
to germinate (Fertig 1998a, p. 17). Since 2004, we have monitored 
populations of the Colorado butterfly plant that have slowly decreased 
in numbers or disappeared following the invasion and establishment of 
these other plant species, only to see Colorado butterfly plants return 
to the area following disturbance (USFWS 2016c, entire). Additionally, 
at least one population has moved to an uninvaded area downstream of 
its former invaded habitat (Handwerk 2016, pers. comm.), suggesting 
that populations can move to find more suitable habitat nearby.
    Prior to listing, biological control agents were used to control 
nonnative, invasive species at Warren AFB and may have depressed 
numbers and extent of Canada thistle and leafy spurge. Introduced gall-
forming flies have slowly become established on Warren AFB and have 
reduced the vigor, height, and reproductive ability of small patches of 
Canada thistle (Fertig 1997, p. 15), at least in some years (Heidel et 
al., 2016, p. 16). Also on the Warren AFB, a biocontrol agent for leafy 
spurge, a different flea beetle than infests the Colorado butterfly 
plant, was observed in 1997 (Fertig 1998b, p. 18). While the effects of 
biocontrol agents on nonnative, invasive species appear promising, we 
do not have current information on the status of biocontrol of these 
agents.
    Natural succession was considered a threat to the Colorado 
butterfly plant at the time of listing. However, we now understand that 
the altered flood regime of today, coupled with disturbance from fire 
and grazing, is sufficient to maintain suitable habitat throughout much 
of the species' range. Competition with nonnative, invasive species is 
an ongoing stressor for portions of populations, although these 
invasive species tend not to survive the regular disturbances that 
create habitat for the Colorado butterfly plant. Therefore, while 
individuals or populations may be out-competed by native or nonnative, 
invasive species at higher succession levels, periodic disturbance 
maintains or creates new habitats for the Colorado butterfly plant.
Summary of Factor A
    The following stressors warranted consideration as possible current 
or future threats to the Colorado butterfly plant habitat under Factor 
A: (1) Residential, urban, and energy development; (2) agricultural 
practices; (3) water management; and (4) natural succession and 
competition with nonnative, invasive species. However, these stressors 
are either being adequately managed, have not occurred to the extent 
anticipated at the time of listing, or new information indicates that 
the species is tolerant of the stressor as described above. While these 
stressors may be responsible for loss of historical populations (they 
have negatively affected population redundancy), and are currently 
negatively affecting the populations in Nebraska, we do not anticipate 
a rangewide increase in these stressors in the future, although they 
will continue at some level.

B. Overutilization for Commercial, Recreational, Scientific, or 
Educational Purposes

    Factor B was not considered a threat to the species at the time of 
listing (65 FR 62302; October 18, 2000). We are aware of three 
unpermitted collections of seeds of the Colorado butterfly plant for 
scientific and/or commercial purposes since the publication of the 
final listing rule. These three collections were limited events that 
occurred at an introduction site in Colorado and from a large, robust 
population in Wyoming. Based on recent population data, these 
unpermitted collection events had no apparent impact on the number and 
distribution of plants within these populations or the species' habitat 
(based on Heidel et al., 2016, p. 13; USFWS 2016c, entire). Other than 
these collections, we are not aware of any attempts to use the Colorado 
butterfly plant for commercial, recreational, scientific, or 
educational purposes. In the future, we do not anticipate this species 
will be collected due to its lack of showiness for much of the year and 
because it occurs in generally inaccessible areas.
Summary of Factor B
    At the time of listing, Factor B was not considered a threat to the 
Colorado butterfly plant. We are aware of only three unpermitted 
collections of the seeds of the species since listing. These collection 
events had no apparent effect on the number and distribution of plants 
from which they were taken. Based on available information, we do not 
consider there to be threats now or

[[Page 26633]]

in the future related to overutilization for commercial, recreational, 
scientific, or educational purposes.

C. Disease or Predation

    The listing of the Colorado butterfly plant (65 FR 62302; October 
18, 2000) did not include threats from disease or predation, although 
livestock grazing was described as a potential threat if grazing 
pressures were high. No diseases are known to affect this species. In 
2007, a precipitous decline in plant numbers was observed in many 
populations monitored in Colorado and Wyoming. The exact cause of the 
decline was not positively identified, but weather and insect herbivory 
were two potential contributing factors. Weather-related impacts 
included an early start to the growing season, lower than normal spring 
precipitation levels (which were magnitudes lower than in all previous 
years), and higher mean temperatures in late summer. Insect herbivory 
also was suspected, as virtually all reproductive plants were riddled 
with holes, flowering and fruit production was curtailed or greatly 
reduced on all plants, and some bolted plants died before flowering. 
Interestingly, no vegetative (i.e., non-reproductive) plants showed 
similar evidence of herbivory (Heidel et al., 2011, pp. 284-285). 
Flowering plant numbers remained low or declined further in 2008. 
Surveyors identified one or more flea beetle species that may have been 
responsible for the herbivory. The likely flea beetle species (Altica 
foliaceae) is a native species, and its numbers are not known to be 
affected by human causes.
    Insect herbivory may not be a severe or immediate threat to 
Colorado or Wyoming populations as the above-referenced impacted 
populations rebounded to pre-infestation numbers in 2009 and 2010 
(Heidel et al., 2011, p. 286). However, insect herbivory may be 
episodic and potentially tied to climate; preliminary tests have been 
conducted on its potential impact on population resiliency (Heidel et 
al., 2011, p. 286). For example, in 2014, intense herbivory from flea 
beetles at Soapstone Prairie and Meadow Springs Ranch resulted in high 
mortality and a reduction in bolting of vegetative rosettes (Strouse 
2017, pers. comm.), and numbers of reproductive individuals in those 
populations were low in 2015 and 2016. We found that these populations 
rebounded in 2017 to record numbers, in the same way populations 
rebounded after the 2007 flea-beetle-caused decline. This herbivory has 
not been reported for the Nebraska populations, although it is possible 
that similar insect herbivory influenced 2008 survey results in 
Nebraska.
    Colorado butterfly plant is highly palatable to a variety of insect 
and mammalian herbivores including Gaura moth (Schinia gaura), cattle, 
horses, and pronghorn (Antilocapra americana), but the plant appears to 
have some capacity to compensate for herbivory by increasing branch and 
fruit production (Fertig 1994, p. 6; Fertig 2000a, p. 17). Livestock 
grazing can be a threat at some sites if grazing pressures are high or 
if use is concentrated during the summer flowering and fruiting period. 
Additionally, plants may be occasionally uprooted or trampled by 
livestock and wildlife. In at least two locations where a population 
was divided by a fence, the heavily grazed side of the fence had few or 
no Colorado butterfly plants, while the ungrazed side had many 
(Marriott 1987, p. 27; USFWS 2016c, entire).
    Heavy grazing at key times of the year during the life cycle of the 
Colorado butterfly plant may be detrimental to populations by 
temporarily removing reproductive individuals and eliminating seed 
production for that year. However, even after many years of intensive 
grazing, populations rebounded upon relief (USFWS 2012, pp. 11-21; 
USFWS 2016c, entire). This response is likely due to survival of non-
reproductive individuals and recruitment from the seedbank. Moderate 
grazing acts as a disturbance that keeps the habitat in an open or 
semi-open state suitable for this species, and light to medium grazing 
can provide benefits by reducing the competing vegetative cover and 
allowing seedlings to become established (USFWS 1997, p. 8).
Summary of Factor C
    In general, while disease or predation has had an occasional 
negative impact on individuals and localities, most of these impacts do 
not appear to affect entire populations, nor do these impacts persist 
for any extended period of time. Individuals are resilient to damage; 
vegetative plants (basal rosettes) appear to be resistant to damage 
from grazing activities and are capable of withstanding stochastic 
events, and reproductive plants send out additional flowering branches 
upon injury. Also, the lack of any known diseases affecting the species 
and the species' redundancy of many populations distributed across most 
of the historical range would likely provide a buffer to any type of 
catastrophic disease outbreak.

D. The Inadequacy of Existing Regulatory Mechanisms

    Under this factor, we examine whether the stressors identified 
within the other factors may be ameliorated or exacerbated by an 
existing regulatory mechanism. Section 4(b)(1)(A) of the Act requires 
the Service to take into account ``those efforts, if any, being made by 
any State or foreign nation, or any political subdivision of a State or 
foreign nation, to protect such species.'' In relation to Factor D 
under the Act, we interpret this language to require the Service to 
consider relevant Federal, State, and Tribal laws, regulations, and 
other such binding legal mechanisms that may ameliorate or exacerbate 
any of the threats we describe in threats analyses under the other four 
factors, or otherwise enhance conservation of the species. Our 
consideration of these mechanisms is described in detail within our 
analysis of each of the factors (see discussion under each of the other 
factors).
    For currently listed species, we consider the adequacy of existing 
regulatory mechanisms to address threats to the species absent the 
protections of the Act. Therefore, we examine whether other regulatory 
mechanisms would remain in place if the species were delisted, and the 
extent to which those mechanisms will continue to help ensure that 
future threats will be reduced or minimized.
    In our discussion under Factors A, B, C, and E, we evaluate the 
significance of threats as mitigated by any conservation efforts and 
existing regulatory mechanisms. Where threats exist, we analyze the 
extent to which conservation measures and existing regulatory 
mechanisms address the specific threats to the species. Regulatory 
mechanisms, if they exist, may reduce or eliminate the impacts from one 
or more identified threats. Presently, the Colorado butterfly plant is 
a Tier 1 species in the Plants of Greatest Conservation Need in 
Colorado (Colorado SWAP 2015, entire), and the species is listed on the 
State endangered species list for Nebraska, and will continue to be so 
designated due to the species' extreme rarity in Nebraska (Wooten 2008, 
p. 1).
    When we listed the Colorado butterfly plant in 2000 (65 FR 62302; 
October 18, 2000), the majority of known populations occurred on 
private lands managed primarily for agriculture, with one population at 
Warren AFB, and a few other populations throughout the species' range 
under various local jurisdictions. The listing decision described the 
species' status as

[[Page 26634]]

Sensitive by the U.S. Forest Service, although no populations occurred 
on Forest Service lands at the time. The listing decision also 
described the lack of protection extended to the Colorado butterfly 
plant through the Federal threatened status of Zapus hudsonius preblei 
(Preble's meadow jumping mouse) that occurs in the same range of 
habitats due to the two species' use of differing successional stages 
of riparian habitats (65 FR 62302; October 18, 2000).
    Today, the population on Warren AFB represents one of the largest 
and most highly resilient populations of the species, is managed under 
an integrated natural resources management plan (Warren AFB 2014, 
entire) and a conservation and management plan under Air Force 
Information 32-7064 (Warren AFB 2004, entire). These plans call for 
annual monitoring, protection and maintenance, and research on threats 
and genetic variability of the population located there. Additionally, 
a Service employee stationed at Warren AFB manages its natural 
resources, including management of the Colorado butterfly plant and its 
habitat, such as directing the application of herbicide in the vicinity 
of the species' habitat. These plans would remain post-delisting. The 
population of the Colorado butterfly plant at Warren AFB has been 
monitored since before listing to determine population trends, detect 
any changes in its habitat, pursue viability assessment, and assess 
population response to different hydrological conditions. The results 
indicate that plant numbers fluctuate depending on climate and 
hydrology, and seem to be capable of rebounding after extreme 
stochastic events such as the flea beetle infestation of 2007 (Heidel 
et al., 2016, pp. 15-17). Should the protections of the Act be removed 
from this species upon delisting, the aforementioned plans would remain 
in place, at least until the next plan revisions, which have yet to be 
scheduled.
    Discovery and subsequent protection of large populations of the 
Colorado butterfly plant on lands owned and managed by Fort Collins are 
an important addition to conservation of the species after it was 
listed in 2000. The regulatory protections that these two populations 
receive from occurring on municipal natural areas lands include 
indefinite protections of land and water and restoring and 
rehabilitating land and natural systems to build ecological diversity 
and permanence (City of Fort Collins 2014, pp. 1-2). Populations 
managed by Fort Collins are afforded protection from oil and gas 
development (The Nature Conservancy 2013, entire) and from water 
withdrawals (CFCNAD 2016b, entire), as discussed above under Factor A. 
Also, as mentioned in ``Residential, Urban, and Energy Development'' 
under Factor A, the Laramie County Land Use Regulations address 
floodplain management and require specific provisions and permits for 
construction within floodplains (Laramie County 2011, pp. 165-185), 
which encompass all Colorado butterfly plant habitat within the county; 
therefore, these regulations extend some level of protection to the 
species and its habitat. While protecting riparian and wetland species 
is not the intent of these regulations, plants growing within the 
floodplain receive the habitat protections outlined as part of the 
floodplain construction avoidance provisions.
    Lands without specific regulatory mechanisms contain most 
populations of the Colorado butterfly plant. Over a decade of 
monitoring 11 occurrences on private lands in Wyoming has documented 
fluctuations in population size about a stable mean, apparently driven 
by changes in precipitation and disturbance regime (USFWS 2012, pp. 11-
22; USFWS 2016c, entire). Management of lands under WEAs is discussed 
in Conservation Efforts, above.
    Populations of Colorado butterfly plant are not known to occur on 
lands managed by the Bureau of Land Management (BLM) at this time, 
although there is potential for populations to be discovered on BLM 
lands in the future. Because of this possibility, the Service and BLM 
in Wyoming have developed conservation measures under a Statewide 
programmatic consultation under section 7 of the Act for the Colorado 
butterfly plant. These conservation measures are incorporated into 
BLM's 2008 Record of Decision and Approved Rawlins Resource Management 
Plan (RMP; BLM 2008, entire) and include, but are not limited to: (1) 
Buffering individuals and populations by 800 m (0.5 mi); (2) 
implementing standards for healthy rangelands and guidelines for 
livestock grazing management for the public lands administered by BLM 
in the State of Wyoming; (3) limiting the number of grazing animals 
within the permit area; and (4) protecting surface water through 
prohibiting surface development in the following areas: Within 400 m 
(0.25 mi) of the North Platte River; within 152 m (500 ft) of live 
streams, lakes, reservoirs, and canals and associated riparian habitat; 
and within 152 m (500 ft) of water wells, springs, or artesian and 
flowing wells (BLM 2005, pp. 4-2 through 4-4). The newly discovered 
population on Wild Horse Creek (WY-23) occurs within the agreement area 
that BLM developed with the landowners, and so the conservation 
measures included in the Rawlins RMP are applied to this population.
    Water use is managed under the PRRIP, as described above under 
Factor A, which ensures that water use in the Platte River is conducted 
in a way to maintain volume at certain times of the year in the central 
and lower reaches of the Platte River in Nebraska. Because all of the 
watersheds in which the Colorado butterfly plant is found occur within 
the PRRIP, the water on which the species depends is managed under this 
program (PRRIP 2006). The water that this species requires would 
continue to be included under the PRRIP even if the Colorado butterfly 
plant is removed from the List of Threatened and Endangered Plants.
Summary of Factor D
    At the time of listing (65 FR 62302; October 18, 2000), no Federal 
or State laws or regulations specifically protected populations of the 
Colorado butterfly plant and its habitat. However, two of the three 
largest populations occur on Warren AFB and lands owned and managed for 
the species by Fort Collins where regulatory mechanisms now exist. 
Additionally, 13 years of annual monitoring of 11 survey areas on 
private lands under WEAs that has occurred since the species was listed 
has shown that land used for agricultural purposes can be compatible 
with the resilience of the species, even without any regulatory 
mechanism in place (see discussions under Factors A, C, and E). 
Consequently, we find that existing regulatory mechanisms, as discussed 
above, will continue to address stressors to the Colorado butterfly 
plant absent protections under the Act.

E. Other Natural or Manmade Factors Affecting Its Continued Existence

    Factor E requires the Service to consider any other factors that 
may be affecting the Colorado butterfly plant. Under this factor, we 
discuss small population size and restricted range, herbicide spraying, 
and effects of climate change.
Small Population Size and Restricted Range
    The final listing decision (65 FR 62302; October 18, 2000) included 
the limited range and the small population size of many populations to 
be a threat

[[Page 26635]]

to the Colorado butterfly plant. However, small population size and a 
restricted range is not a threat in and of itself. Historically, 
Colorado butterfly plant populations occurred from Castle Rock, 
Colorado, north to Chugwater, Wyoming, and east into a small portion of 
southwest Nebraska. The extent of its range was approximately 6,880 ha 
(17,000 ac). Most of this range is still occupied, although some small 
and/or peripheral populations in Nebraska and Colorado have been 
extirpated since intensive survey efforts began. Despite the loss of 
these populations, the species continues to maintain multiple 
resilient, representative, and redundant populations throughout nearly 
all of its range known at the time of listing (see figure, above).
    We have evidence that populations throughout the range have 
persisted despite stochastic events that may have caused short-term 
declines in number of individuals. For example, a 100-year flood in 
August 1985 on the Warren AFB inundated the Crow Creek portion of the 
population, knocking down some plants and surrounding vegetation, and 
depositing sediments (Rocky Mountain Heritage Task Force 1987, as cited 
in Heidel et al., 2016, p. 2). Instead of being extirpated, these 
populations rebounded in 1986 and continue to persist (summarized in 
Heidel et al., 2016, pp. 2-18). Additionally, based on annual 
monitoring of populations on private property in Wyoming, stochastic 
events such as floods and hail storms have reduced population numbers 
during the event year, then populations rebounded in following years 
(USFWS 2012, pp. 11-22; USFWS 2016c, entire). Individual plants may be 
vulnerable to random events such as fires, insect or disease outbreaks, 
or other unpredictable events. However, this species is adapted to 
disturbance, and rather than being extirpated, the seedbank can provide 
opportunity for populations to rebound after such events.
    The historical range included populations farther south into 
Larimer and Weld Counties in Colorado that were lost prior to the 
listing of the species in 2000. No populations in Larimer and Weld 
Counties in Colorado have been extirpated since the species was listed, 
and we do not think that further range restriction has occurred in this 
portion of the species' range. In the future, species range restriction 
may occur through loss of peripheral populations in Nebraska where 
dewatering has removed formerly suitable habitat (Wooten 2008, entire). 
However, these populations are downstream of highly viable populations 
in Wyoming, and do not constitute a removal of the species from this 
drainage entirely. The resiliency and redundancy of populations across 
much of the species' range indicate that further range restriction is 
not likely.
Herbicide Spraying
    At the time of listing (65 FR 62302; October 18, 2000), the non-
selective use of broadleaf herbicides to control Canada thistle, leafy 
spurge, and other nonnative, invasive plants was considered a threat to 
the Colorado butterfly plant. Non-selective spraying has had negative 
effects on some Colorado butterfly plant populations (Fertig 2000a, p. 
16). For example, in 1983, which was prior to listing, nearly one-half 
of the mapped population on Warren AFB was inadvertently destroyed when 
sprayed with Tordon[supreg], a persistent herbicide (Miller 1987, as 
cited in 65 FR 62302, October 18, 2000, p. 62307). The status of that 
portion of the population is unknown due to a subsequent lack of clear 
record-keeping at that time, prior to a Service biologist being 
employed on site; all plant locations have been tracked in the time 
after the Service biologist and Wyoming Natural Diversity Database 
began working at Warren AFB. Herbicide use along road crossings in and 
adjacent to plant populations was also noted (65 FR 62302, October 18, 
2000, p. 62307).
    After the 2000 listing of the Colorado butterfly plant, the Service 
worked with Warren AFB and private landowners under WEAs to develop 
best management practices for applying herbicides within the vicinity 
of known occurrences to remove nonnative, invasive species while 
minimizing adverse effects to individual Colorado butterfly plants. For 
example, the WEAs require an herbicide-application buffer of 30.5 m 
(100 ft) from known locations of the Colorado butterfly plant. However, 
at one property, the landowner inadvertently sprayed individual plants 
in spring 2016. During subsequent monitoring, Service staff observed 
reddened plants with shriveled leaves, which likely reduced the vigor 
of those individuals (USFWS 2016c, entire). We presume that there will 
be no long-term effects on the population, and in fact, we found 
vigorous Colorado butterfly plants growing in this area during surveys 
in 2017. Furthermore, if the species is delisted, we anticipate that 
landowners will continue to maintain this buffer in accordance with 
requirements under the WEAs and that Warren AFB will continue to avoid 
spraying herbicide in the vicinity of the species' habitat as 
stipulated in their integrated natural resources management plan and 
conservation and management plan.
    While herbicide application may continue to occasionally occur 
within Colorado butterfly habitat, we know that unsprayed individuals 
persist in the population and can repopulate Colorado butterfly plants 
in areas where plants were killed. The seedbank can play an additional 
role in restoring Colorado butterfly plants to areas that have been 
sprayed. Based on our records, herbicide application is a management 
tool used in conjunction with nonnative, invasive species removal in 
only four of the known occurrences of the species, and these are among 
our largest and most resilient populations of the species. Our records 
indicate that, in general, application of buffers has been successful 
at reducing the presence of invasive species and competition near the 
Colorado butterfly plant (USFWS 2012, pp. 24-25; USFWS 2016c, entire), 
and when conducted appropriately, herbicide application can help 
improve habitat for the Colorado butterfly plant by eliminating 
competition.
Effects of Climate Change
    Impacts from climate change were not considered in the final rule 
to list the species (65 FR 62302; October 18, 2000) or in the critical 
habitat designation (70 FR 1940; January 11, 2005). Our current 
analyses under the Act include consideration of ongoing and projected 
changes in climate. The terms ``climate'' and ``climate change'' are 
defined by the Intergovernmental Panel on Climate Change (IPCC). 
``Climate'' refers to the mean and variability of different types of 
weather conditions over time, with 30 years being a typical period for 
such measurements, although shorter or longer periods also may be used 
(IPCC 2007, p. 78). The term ``climate change'' thus refers to a change 
in the mean or variability of one or more measures of climate (e.g., 
temperature or precipitation) that persists for an extended period, 
typically decades or longer, whether the change is due to natural 
variability, human activity, or both (IPCC 2007, p. 78). Various types 
of changes in climate can have direct or indirect effects on species. 
These effects may be positive, neutral, or negative and they may change 
over time, depending on the species and other relevant considerations, 
such as the effects of interactions of climate with other variables 
(e.g., habitat fragmentation) (IPCC 2007, pp. 8-14, 18-19). In our 
analyses, we use our expert judgment to weigh relevant information, 
including uncertainty, in our consideration of various aspects of 
climate change.

[[Page 26636]]

    According to IPCC, ``most plant species cannot naturally shift 
their geographical ranges sufficiently fast to keep up with current and 
high projected rates of climate change on most landscapes'' (IPCC 2014, 
p. 13). Plant species with restricted ranges may experience population 
declines as a result of the effects of climate change. The concept of 
changing climate can be meaningfully assessed both by looking into the 
future and reviewing past changes. A review of Wyoming climate since 
1895 indicates that there has been a significant increase in the 
frequency of warmer-than-normal years, an increase in temperatures 
throughout all regions of the State, and a decline in the frequency of 
``wet'' winters (Shumann 2011). Data from the Cheyenne area over the 
past 30 years indicate a rise in spring temperatures (Heidel et al. 
2016). The current climate in Colorado butterfly plant habitat is quite 
variable, with annual precipitation ranging from 25-50 cm (10-20 in) of 
rain and 81-275 cm (32-108 in) of snow per year near the center of the 
species' range at Cheyenne Municipal Airport (NOAA 2016, entire). The 
years 2000 through 2006 appeared to have lower than average 
precipitation (NOAA 2016, entire), which may have affected the ability 
of plants to withstand flea beetle outbreak in 2007 (Heidel et al. 
2011, p. 286). The Colorado butterfly plant is semelparous (individual 
plants are first vegetative, then flower and fruit, and then die). 
Therefore, individuals are likely capable of remaining in a vegetative 
state under some conditions and duration until suitable flowering 
conditions exist, suggesting that the species is adapted to variability 
in the amount and timing of precipitation.
    Climate change may affect the timing and amount of precipitation as 
well as other factors linked to habitat conditions for the Colorado 
butterfly plant. For example, climate models predict that by 2050, 
watersheds containing the species will become warmer for all four 
seasons, precipitation will increase in the winter, and remain about 
the same in spring, summer, and fall (USGS 2016, pp. 1-3). Snow water 
equivalent will decrease in winter and spring, and soil water storage 
will decrease in all four seasons (USGS 2016, pp. 4-5). Modeling 
predicts an increase in winter precipitation, but decreases in soil 
water storage will mean less water for subirrigation of the species' 
habitat. This may mean a shorter window for seed germination, lower 
seed production, and potentially increased years at the rosette stage 
to obtain sufficient resources to bolt and flower. However, we also 
understand that C<INF>3</INF> plants (plants which combine water, 
sugar, and carbon dioxide in carbon fixation), including this species, 
have a 41 percent proportional increase in growth resulting from a 100 
percent increase in carbon dioxide (Poorter 1993, p. 77). This increase 
in growth rate due to higher carbon dioxide may counteract the need to 
spend more time in the vegetative portion of the life cycle in response 
to climate change. Additionally, monitoring indicates that populations 
are able to withstand several consecutive years of poor growing 
conditions, and still rebound with suitable conditions (USFWS 2012, pp. 
11-22; USFWS 2016c, entire). Climate change has the potential to affect 
the species and its habitat if flea beetle outbreaks are fostered or if 
flowering levels are suppressed. Although we lack scientific certainty 
regarding what those changes may ultimately mean for the species, we 
expect that the species' current adaptations to cope with climate 
variability will mitigate the impact on population persistence.
Summary of Factor E
    Under this factor, we discussed the Colorado butterfly plant's 
small population size and restricted range, herbicide spraying, and 
climate change.
    In 2000, when we listed the species, the stochastic extirpation of 
individual populations suggested that the range of the species might be 
declining. Despite the fact that some populations in Colorado, Wyoming, 
and Nebraska were extirpated prior to listing, and others in Nebraska 
were extirpated after listing, four additional populations have been 
discovered, two of which are protected, and there are still 
representative and redundant populations occurring throughout the range 
of the species. Further, individuals and populations are resilient to a 
single herbicide application, and have been shown to survive or bounce 
back from such events. Education of landowners has greatly reduced the 
indiscriminate application of herbicides near populations of the 
Colorado butterfly plant. Finally, while climate change presents a 
largely unknown potential stressor to the species, individual plants 
are capable of deferring the reproductive stage until suitable 
conditions are available, populations are made up of individuals found 
in a range of microhabitats, and populations are located within various 
ecological settings within the species' range. This indicates that the 
resiliency, redundancy, and representation of populations will maintain 
the species in the face of climate change.

Combination of Factors

    Many of the stressors discussed in this analysis could work in 
concert with each other and result in a cumulative adverse effect to 
the Colorado butterfly plant, e.g., one stressor may make the species 
more vulnerable to other threats. For example, stressors discussed 
under Factor A that individually do not rise to the level of a threat 
could together result in habitat loss. Similarly, small population size 
and a restricted range in combination with stressors discussed under 
Factor A could present a potential concern. However, most of the 
potential stressors we identified either have not occurred to the 
extent originally anticipated at the time of listing or are adequately 
managed as described in this proposal to delist the species. 
Furthermore, those stressors that are evident, such as climate change 
and grazing, appear well-tolerated by the species. In addition, for the 
reasons discussed in this proposed rule, we do not anticipate stressors 
to increase on lands that afford protections to the species (Warren AFB 
and CFCNAD lands) where many of the largest populations occur. 
Furthermore, the increases documented in the number and size of many 
populations since the species was listed do not indicate that 
cumulative effects of various activities and stressors are affecting 
the viability of the species at this time or into the future.

Proposed Determination of Species Status

    Section 4 of the Act (16 U.S.C. 1533), and its implementing 
regulations at 50 CFR part 424, set forth the procedures for 
determining whether a species is an endangered species or threatened 
species and should be included on the Federal Lists of Endangered and 
Threatened Wildlife and Plants (listed). The Act defines an endangered 
species as any species that is ``in danger of extinction throughout all 
or a significant portion of its range'' and a threatened species as any 
species that is ``likely to become an endangered species within the 
foreseeable future throughout all or a significant portion of its 
range.'' We may delist a species according to 50 CFR 424.11(d) if the 
best available scientific and commercial data indicate that the species 
is neither endangered or threatened for the following reasons: (1) The 
species is extinct; (2) the species has recovered and is no longer 
endangered or threatened; and/or (3) the original scientific data used 
at the time the species was classified were in error.

[[Page 26637]]

Determination of Status Throughout All of the Colorado Butterfly 
Plant's Range

    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Colorado butterfly plant. We examined the status of the species 
based on the 2010 Colorado butterfly plant recovery outline (USFWS 
2010, entire). We also consulted with species experts and land 
management staff with Fort Collins and Warren AFB who are actively 
managing for the conservation of the Colorado butterfly plant.
    The 2010 Colorado butterfly plant recovery outline presented a 
recovery vision for the species in which the primary focus was 
protection of existing populations, threats abatement, and research 
(USFWS 2010, entire). The initial action plan focused on protection of 
existing populations through partnerships with Warren AFB, Fort 
Collins, and private landowners, followed by developing a recovery plan 
that would contain objective, measurable recovery criteria which, when 
met, would indicate that the species could be removed from the Federal 
List of Endangered and Threatened Plants. In 2016, the Service's 
Wyoming Ecological Services Field Office began development of a 
recovery plan for the Colorado butterfly plant. In reviewing 
information regarding population numbers and trends, as well as 
threats, it appeared that most monitored extant populations were doing 
well. Threats named at the time of listing were either affecting the 
species at low levels, likely due to management actions to recover the 
species, or not affecting the species at all, as was observed in 
preparing the 2012 5-year status review (USFWS 2012, entire). 
Therefore, the Service conducted an assessment of the status of the 
species and whether it should remain on the List of Endangered and 
Threatened Plants under the Act.
    We carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Colorado butterfly plant. We considered all of the stressors 
identified at the time of listing in 2000, as well as newly identified 
potential stressors such as oil and gas energy development and the 
effects of climate change. The stressors considered in our five-factor 
analysis (discussed in detail above under Summary of Factors Affecting 
the Species) fall into one or more of the following categories:
    <bullet> Minimized or mitigated: The following stressors are 
adequately managed, and existing information indicates that this will 
not change in the future: Residential, urban, and energy development; 
agricultural practices; water management; overutilization; and 
herbicide spraying.
    <bullet> Avoided: The following stressor has not occurred to the 
extent anticipated at the time of listing, and existing information 
indicates that this will not change in the future: Restricted range.
    <bullet> Tolerated: The species is tolerant of the following 
stressors, and existing information indicates that this will not change 
in the future: Natural succession and competition with nonnative, 
invasive species; disease and predation; and climate change.
    These conclusions are supported by the available information 
regarding the species' abundance, distribution, and trends, and are in 
agreement with conclusions presented in our 2010 recovery outline 
(USFWS 2010, entire) and in our 5-year review (USFWS 2012, entire). 
Thus, after assessing the best available information, we conclude that 
the Colorado butterfly plant is not in danger of extinction, nor is it 
likely to become so in the foreseeable future.

Determination of Status Throughout a Significant Portion of the 
Colorado Butterfly Plant's Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is an endangered or a threatened species 
throughout all or a significant portion of its range. The Act defines 
``endangered species'' as any species which is ``in danger of 
extinction throughout all or a significant portion of its range,'' and 
``threatened species'' as any species which is ``likely to become an 
endangered species within the foreseeable future throughout all or a 
significant portion of its range.'' The term ``species'' includes ``any 
subspecies of fish or wildlife or plants, and any distinct population 
segment [DPS] of any species of vertebrate fish or wildlife which 
interbreeds when mature.'' We published a final policy interpretating 
the phrase ``Significant Portion of its Range'' (SPR) (79 FR 37578). 
The final policy states that (1) if a species is found to be an 
endangered or a threatened species throughout a significant portion of 
its range, the entire species is listed as an endangered or a 
threatened species, respectively, and the Act's protections apply to 
all individuals of the species wherever found; (2) a portion of the 
range of a species is ``significant'' if the species is not currently 
an endangered or a threatened species throughout all of its range, but 
the portion's contribution to the viability of the species is so 
important that, without the members in that portion, the species would 
be in danger of extinction, or likely to become so in the foreseeable 
future, throughout all of its range; (3) the range of a species is 
considered to be the general geographical area within which that 
species can be found at the time FWS or NMFS makes any particular 
status determination; and (4) if a vertebrate species is an endangered 
or a threatened species throughout an SPR, and the population in that 
significant portion is a valid DPS, we will list the DPS rather than 
the entire taxonomic species or subspecies.
    The SPR policy is applied to all status determinations, including 
analyses for the purposes of making listing, delisting, and 
reclassification determinations. The procedure for analyzing whether 
any portion is an SPR is similar, regardless of the type of status 
determination we are making. The first step in our analysis of the 
status of a species is to determine its status throughout all of its 
range. If we determine that the species is in danger of extinction, or 
likely to become so in the foreseeable future, throughout all of its 
range, we list the species as an endangered (or threatened) species and 
no SPR analysis will be required. If the species is neither an 
endangered nor a threatened species throughout all of its range, we 
determine whether the species is an endangered or a threatened species 
throughout a significant portion of its range. If it is, we list the 
species as an endangered or a threatened species, respectively; if it 
is not, we conclude that listing the species is not warranted.
    When we conduct an SPR analysis, we first identify any portions of 
the species' range that warrant further consideration. The range of a 
species can theoretically be divided into portions in an infinite 
number of ways. However, there is no purpose to analyzing portions of 
the range that are not reasonably likely to be significant and either 
an endangered or a threatened species. To identify only those portions 
that warrant further consideration, we determine whether there is 
substantial information indicating that (1) the portions may be 
significant and (2) the species may be in danger of extinction in those 
portions or likely to become so within the foreseeable future. We 
emphasize that answering these questions in the affirmative is not a 
determination that the species is an endangered or a threatened species 
throughout a significant portion of its range--rather, it is a step in 
determining whether a more detailed analysis of the issue is

[[Page 26638]]

required. In practice, a key part of this analysis is whether the 
threats are geographically concentrated in some way. If the threats to 
the species are affecting it uniformly throughout its range, no portion 
is likely to warrant further consideration. Moreover, if any 
concentration of threats apply only to portions of the range that 
clearly do not meet the biologically based definition of 
``significant'' (i.e., the loss of that portion clearly would not be 
expected to increase the vulnerability to extinction of the entire 
species), those portions will not warrant further consideration.
    If we identify any portions that may be both (1) significant and 
(2) endangered or threatened, we engage in a more detailed analysis to 
determine whether these standards are indeed met. The identification of 
an SPR does not create a presumption, prejudgment, or other 
determination as to whether the species in that identified SPR is an 
endangered or a threatened species. We must go through a separate 
analysis to determine whether the species is an endangered or a 
threatened species in the SPR. To determine whether a species is an 
endangered or a threatened species throughout an SPR, we will use the 
same standards and methodology that we use to determine if a species is 
an endangered or a threatened species throughout its range.
    Depending on the biology of the species, its range, and the threats 
it faces, it may be more efficient to address the ``significant'' 
question first, or the status question first. Thus, if we determine 
that a portion of the range is not ``significant,'' we do not need to 
determine whether the species is an endangered or a threatened species 
there; if we determine that the species is not an endangered or a 
threatened species in a portion of its range, we do not need to 
determine if that portion is ``significant.''
    We evaluated the range of the Colorado butterfly plant to determine 
if any area could be considered a significant portion of its range. The 
only portion of the range where threats are geographically concentrated 
are the three populations in Nebraska. Grazing and water management, 
particularly the dewatering of Lodgepole Creek downstream of the 
Wyoming/Nebraska border in the three populations in Nebraska, has 
proven to impact populations in that portion of the species' range. 
This stressor has affected these populations to a level that the 
populations were presumed extirpated at the time we designated critical 
habitat for this species (70 FR 1940; January 11, 2005). However, after 
water was reintroduced to the creek by a landowner, Colorado butterfly 
plants were again observed in Lodgepole Creek (Wooten 2008, p. 4). It 
is possible that the species only occurs in this portion of its range 
during times of adequate subirrigation and surface flows, and that 
seeds either remain dormant at this location for several years or are 
transported from neighboring populations located upstream on Lodgepole 
Creek in Wyoming. Nevertheless, the removal of water from Lodgepole 
Creek impacts populations of the Colorado butterfly plant within this 
portion of the species' range.
    Because we identified an area on the periphery of the species' 
current range as warranting further consideration due to the geographic 
concentration of threats from water management, we then evaluated 
whether this area may be significant to the Colorado butterfly plant 
such that, without the members in that portion, the entire species 
would be in danger of extinction, or likely to become so in the 
foreseeable future, throughout all of its range. We can accomplish this 
by considering the viability of the remainder of the range without the 
portion and the biological or conservation importance of the portion. 
The viability of the remainder of the range, should the three 
populations in Nebraska be lost, will remain high: All of the highly 
and moderately resilient populations occur in the remainder of the 
range, which is comprised of more than 20 populations distributed 
through a geographically connected area, and which contains all of the 
ecological settings this species is known to inhabit.
    Additionally, to determine significance of this threatened portion 
of the range, we examined its contribution to the species' viability in 
terms of its resiliency, redundancy, and representation. Regarding 
redundancy, the populations within this portion of the range occur on 
the eastern extreme of the historical range of the species and 
represent a very small component of the total distribution of the 
species, occurring downstream of several highly viable populations. 
Therefore, these populations do not substantially increase redundancy 
at the species level. Regarding resiliency, individual plants in this 
portion of the range may be resilient to dewatering or other stressors, 
but populations contain few individuals and are, therefore, threatened 
by stochastic events. Regarding representation, we understand that 
there may be connectivity among the populations occurring in Nebraska 
and the populations upstream on Lodgepole Creek in Wyoming. However, 
this connectivity is likely only through limited pollinator movement 
among the few flowering plants at any location, and through seed 
dispersal downstream from Wyoming to Nebraska, considering the distance 
is too great (>1 km/0.6 mi) for most pollinators to travel (Heidel 
2016, pers. comm.). Consequently, the populations in Nebraska are 
likely not contributing any genetic information upstream. We do not 
have genetic information on these populations, but we understand that 
the populations in this portion of the species' range do not occupy 
unique ecological settings, have unique morphology, or have differing 
phenology than other populations of the species on Lodgepole Creek or 
in the rest of the species' range.
    After careful examination of the Colorado butterfly plant 
population in the context of our definition of ``significant portion of 
its range,'' we determine an area on the periphery of the range 
warranted further consideration because threats are geographically 
concentrated there. After identifying this area, we evaluate whether it 
is significant and determine that it is not significant because, even 
without Colorado butterfly plants in this area, the species would not 
be in danger of extinction, or likely to become so in the foreseeable 
future. This is because the remainder of the species is characterized 
by high levels of resiliency, redundancy, and representation; the 
remainder of the species contains all of the highly and moderately 
resilient populations (high resiliency), is comprised of more than 20 
populations distributed through a geographically connected area (high 
redundancy), and includes all of the ecological settings this species 
is known to inhabit (high representation). Therefore, we did not need 
to determine if the species is in danger of extinction or likely to 
become so in the foreseeable future in this peripheral area in 
Nebraska.

Determination of Status for the Colorado Butterfly Plant

    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Colorado butterfly plant. The threats that led to the species 
being listed under the Act (primarily loss of the species' habitat 
(Factor A) and small population size, restricted range, and herbicide 
spraying (Factor E)) have not occurred to the extent anticipated at the 
time of listing, or are being appropriately managed by the actions of 
multiple conservation partners over the past 18 years. These actions 
include habitat management,

[[Page 26639]]

monitoring, and research. Given commitments shown by private 
landowners, local governments, cooperating agencies, and other partners 
as discussed under Factor D, we expect conservation efforts will 
continue to support a healthy, viable population of the species post-
delisting and into the foreseeable future. Furthermore, there is no 
information to conclude that at any time over the next 20 years (as we 
define the foreseeable future for this species) the species will be in 
danger of extinction. Because the species is not in danger of 
extinction now or within the foreseeable future throughout all or any 
significant portion of its range, the species does not meet the 
definition of an endangered species or threatened species. We therefore 
propose to remove the Colorado butterfly plant from the Federal List of 
Endangered and Threatened Wildlife at 50 CFR 17.11(h) due to recovery. 
Because the species is neither in danger of extinction now nor likely 
to become so in the foreseeable future throughout all or any 
significant portion of its range, the species does not meet the 
definition of an endangered species or a threatened species under the 
Act.

Effects of the Rule

    This proposal, if made final, would revise 50 CFR 17.12(h) to 
remove the Colorado butterfly plant from the Federal List of Endangered 
and Threatened Plants. The prohibitions and conservation measures 
provided by the Act, particularly through sections 7 and 9, would no 
longer apply to this species. Federal agencies would no longer be 
required to consult with the Service under section 7 of the Act in the 
event that activities they authorize, fund, or carry out may affect the 
Colorado butterfly plant or its designated critical habitat. This 
proposal, if made final, would also remove the designation of critical 
habitat for the Colorado butterfly plant in Wyoming (codified at 50 CFR 
17.96(a)).

Post-Delisting Monitoring

    Section 4(g)(1) of the Act requires us, in cooperation with the 
States, to implement a monitoring program for not less than 5 years for 
all species that have been delisted due to recovery. The purpose of 
this requirement is to develop a program that detects the failure of 
any delisted species to sustain itself without the protective measures 
provided by the Act. If, at any time during the monitoring period, data 
indicate that protective status under the Act should be reinstated, we 
can initiate listing procedures, including, if appropriate, emergency 
listing.
    We are proposing delisting for the Colorado butterfly plant based 
on recovery actions taken and new information we have received. Since 
delisting would be due in part to recovery actions taken by Warren AFB, 
Fort Collins, and BLM, we have prepared a draft post-delisting 
monitoring plan for the Colorado butterfly plant. The plan has been 
developed with input from these and other partners.
    It is our intent to work with our partners towards maintaining the 
recovered status of the Colorado butterfly plant. While not required, 
we intend to seek peer review comments on the draft post-delisting 
monitoring plan (PDM plan), including its objectives and procedures. A 
copy of the draft PDM plan is available at http://www.regulations.gov 
under Docket No. FWS-R6-ES-2018-0008. You can submit your comments on 
the draft PDM plan by one of the methods listed above under ADDRESSES.

Required Determinations

Clarity of This Proposed Rule

    We are required by Executive Orders 12866 and 12988 and by the 
Presidential Memorandum of June 1, 1998, to write all rules in plain 
language. This means that each rule we publish must:
    (a) Be logically organized;
    (b) Use the active voice to address readers directly;
    (c) Use clear language rather than jargon;
    (d) Be divided into short sections and sentences; and
    (e) Use lists and tables wherever possible.
    If you feel that we have not met these requirements, send us 
comments by one of the methods listed in ADDRESSES. To better help us 
revise the rule, your comments should be as specific as possible. For 
example, you should tell us the numbers of the sections or paragraphs 
that are unclearly written, which sections or sentences are too long, 
the sections where you feel lists or tables would be useful, etc.

National Environmental Policy Act

    We have determined that environmental assessments and environmental 
impact statements, as defined under the authority of the National 
Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.), need not be 
prepared in connection with regulations pursuant to section 4(a) of the 
Act. We published a notice outlining our reasons for this determination 
in the Federal Register on October 25, 1983 (48 FR 49244).

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994, 
Government-to-Government Relations with Native American Tribal 
Governments (59 FR 22951), E.O. 13175, and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. In accordance with 
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered Species Act), 
we readily acknowledge our responsibilities to work directly with 
Tribes in developing programs for healthy ecosystems, to acknowledge 
that tribal lands are not subject to the same controls as Federal 
public lands, to remain sensitive to Indian culture, and to make 
information available to Tribes. We have determined that no Tribes will 
be affected by this rule.

References Cited

    A complete list of all references cited in this proposed rule is 
available at http://www.regulations.gov at Docket No. FWS-R6-ES-2018-
0008, or upon request from the Wyoming Ecological Services Field Office 
(see ADDRESSES).

Authors

    The primary authors of this proposed rule are staff members of the 
Wyoming Ecological Services Field Office.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Proposed Regulation Promulgation

    Accordingly, we hereby propose to amend part 17, subchapter B of 
chapter I, title 50 of the Code of Federal Regulations, as set forth 
below:

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

0
1. The authority citation for part 17 continues to read as follows:

    Authority:  16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, 
unless otherwise noted.


Sec.  17.12  [Amended]

0
2. Amend Sec.  17.12(h) by removing the entry ``Gaura neomexicana ssp. 
coloradensis'' under ``FLOWERING PLANTS'' from the List of Endangered 
and Threatened Plants.

[[Page 26640]]

Sec.  17.96  [Amended]

0
3. Amend Sec.  17.96(a) by removing the entry ``Family Onagraceae: 
Gaura neomexicana ssp. coloradensis (Colorado butterfly plant)''.

    Dated: May 15, 2018.
James W. Kurth,
Deputy Director, U.S. Fish and Wildlife Service, Exercising the 
Authority of the Director, for the U.S. Fish and Wildlife Service.
[FR Doc. 2018-12409 Filed 6-7-18; 8:45 am]
 BILLING CODE 4333-15-P