Endangered and Threatened Wildlife and Plants; Endangered Species Status for Sonoyta Mud Turtle, 43897-43907 [2017-20072]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 82, Number 181 (Wednesday, September 20, 2017)]
[Rules and Regulations]
[Pages 43897-43907]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2017-20072]



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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2016-0103; 4500030113]
RIN 1018-AZ02


Endangered and Threatened Wildlife and Plants; Endangered Species 
Status for Sonoyta Mud Turtle

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), list the 
Sonoyta mud turtle (Kinosternon sonoriense longifemorale), a turtle 
from Arizona in the United States and Sonora in Mexico, as an 
endangered species under the Endangered Species Act of 1973 (Act), as 
amended. This rule adds the Sonoyta mud turtle to the Federal List of 
Endangered and Threatened Wildlife and extends the Act's protections to 
this subspecies.

DATES: This rule is effective October 20, 2017.

ADDRESSES: This final rule is available on the Internet at https://www.regulations.gov and at https://www.fws.gov/southwest/es/arizona/. 
Comments and materials we received, as well as supporting documentation 
we used in preparing this rule, are available for public inspection at 
https://www.regulations.gov. Comments, materials, and documentation that 
we considered in this rulemaking will be available by appointment, 
during normal business hours at: U.S. Fish and Wildlife Service, 
Arizona Ecological Services Field Office, 9828 North 31st Ave #C3, 
Phoenix, AZ 85051-2517; telephone 602-242-0210.

FOR FURTHER INFORMATION CONTACT: Steve Spangle, Field Supervisor, U.S. 
Fish and Wildlife Service, Arizona Ecological Services Field Office, 
9828 North 31st Ave #C3, Phoenix, AZ 85051-2517; telephone 602-242-
0210. Persons who use a telecommunications device for the deaf (TDD) 
may call the Federal Relay Service at 800-877-8339.

SUPPLEMENTARY INFORMATION: 

Previous Federal Action

    Please refer to the proposed listing rule for the Sonoyta mud 
turtle (81 FR 64829; September 21, 2016) for a detailed description of 
previous Federal actions concerning this subspecies.

Background

    We completed a comprehensive assessment of the biological status of 
the Sonoyta mud turtle, and prepared a report of the assessment, which 
provides a thorough account of the subspecies' overall viability. We 
define viability as the ability of the subspecies to persist over the 
long term and avoid extinction. In this section, we summarize the 
conclusions of that assessment, which can be accessed at Docket No. 
FWS-R2-ES-2016-0103 on https://www.regulations.gov and at https://www.fws.gov/southwest/es/arizona/. The Sonoyta mud turtle's Species 
Status Assessment (SSA Report; Service 2017, chapter 4) contains a 
detailed discussion of our evaluation of the biological status of the 
Sonoyta mud turtle and the influences that may affect its continued 
existence.
    To assess Sonoyta mud turtle viability, we used the three 
conservation biology principles of resiliency, representation, and 
redundancy (Shaffer and Stein 2000, pp. 306-310). Briefly, resiliency 
supports the ability of the species to withstand environmental and 
demographic stochasticity (for example, wet or dry, warm or cold 
years); representation supports the ability of the species to adapt 
over time to long-term changes in the environment (for example, climate 
changes); and redundancy supports the ability of the species to 
withstand catastrophic events (for example, droughts). In general, the 
more redundant, representative, and resilient a species is, the more 
likely it is to sustain populations over time, even under changing 
environmental conditions. Using these principles, we identified the 
Sonoyta mud turtle's ecological requirements for survival and 
reproduction at the individual, population, and subspecies levels, and 
described the beneficial and risk factors influencing the subspecies' 
viability.
    We evaluated the change in resiliency, representation, and 
redundancy from the past until the present, and projected the 
anticipated future states of these conditions. To forecast the 
biological condition into the future, we devised plausible future 
scenarios by using expert information on the primary stressors 
anticipated in the future to the Sonoyta mud turtle: habitat loss and 
degradation (i.e., surface water loss and riparian vegetation loss), 
effects of climate change, and small population dynamics. To assess 
population resiliency of the Sonoyta mud turtle, we evaluated habitat 
conditions and recruitment over time. To assess representation (as an 
indicator of adaptive capacity) of the Sonoyta mud turtle, we evaluated 
the ecological and genetic diversity and connectivity over time. To 
assess redundancy, we calculated the risk of population extirpations 
given the catastrophic events. That is, we tallied the number of 
populations historically, currently, and projected into the future to 
assess the viability of the subspecies.

Subspecies Description

    The Sonoyta mud turtle is a freshwater turtle encountered in or 
near water in an otherwise arid environment that commonly experiences 
drought and extreme heat (ambient temperatures can exceed 45 degrees 
Celsius ([deg]C) (113 degrees Fahrenheit ([deg]F)). The Sonoyta mud 
turtle is one of two recognized subspecies of Sonora mud turtle 
(Kinosternon sonoriense) and has been differentiated from the other 
subspecies based on shell measurements and DNA analysis (Iverson 1981, 
p. 62; Rosen 2003, entire; Rosen et al. 2006, entire). The other 
subspecies, K. s. sonoriense, is commonly referred to as Sonora mud 
turtle. The Sonoyta mud turtle is an isolated, native endemic found in 
southern Arizona and northern Sonora, Mexico. The Sonoyta mud turtle is 
a dark, medium-sized freshwater turtle with a mottled pattern on the 
head, neck, and limbs. Average lifespan is from 10 to 12 years; 
however, one has been reported to be 39 years old.
    Minimum age of sexual maturity of female Sonoyta mud turtles is 
just under 6 years, and males around 4 years (Rosen and Lowe 1996, pp. 
14-16). Mating occurs in water from April to late June. Ovulation and 
shelling of eggs begins in June, and eggs remain in the oviducts until 
the monsoon rains occur from mid to late July through September (van 
Loben Sels et al. 1997, p. 343). In mid to late July through September, 
females leave the water briefly to lay eggs in terrestrial nests. Eggs 
may undergo embryonic diapause (delayed embryo development) in the nest 
for up to 11 months after being laid. Development begins as eggs warm 
during the following spring and takes about 80 days, and hatchlings 
emerge and disperse from the nest the following year to coincide with 
the onset of summer rains (van Lobel Sels et al. 1997, p. 343; Ernst 
and Lovich 2009, p. 497; Stone et al. 2015, p. 735).

Habitat and Range

    The Sonoyta mud turtle is found in southern Arizona and 
northwestern Mexico and depends on aquatic habitat with adjacent 
terrestrial habitat. Its habitats commonly experience drought and 
extreme heat. Historically, the Sonoyta mud turtle was limited in its

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distribution to the Rio Sonoyta basin in Arizona and Sonora, Mexico. 
There are five historical records of the subspecies being found within 
three historical perennial sections of the Rio Sonoyta, including the 
Sonoyta, Santo Domingo, and Papalote (also referred to as Agua Dulce) 
reaches (Rosen et al. 2010, p. 152), which we assume supported three 
populations. Perennial waters likely flowed through these three 
sections of the Rio Sonoyta separated by seasonally ephemeral sections 
(figure 3.1.1.b of the SSA Report), and groundwater also supported 
springs and cienegas (wet, marshy areas) in the area (Miller and Fuiman 
1987, p. 602; Schoenherr 1988, p. 110; Hendrickson and Varela-Romero 
1989, p. 481). These three distinct perennial reaches of the Rio 
Sonoyta together likely provided 19 to 27 kilometers (km) (12 to 17 
miles (mi)) of stream habitat for the Sonoyta mud turtle. The Rio 
Sonoyta probably flowed for short periods during wet seasons, providing 
connectivity for mud turtles, with the stream rapidly retracting during 
the dry season, as it still does today. During periods of above-average 
precipitation, the river may have been continuous for longer periods, 
making turtle population connectivity more likely along Rio Sonoyta. We 
assume that the historical locations of the Sonoyta mud turtles were in 
areas of the Rio Sonoyta basin that maintained perennial surface water 
at all times except, possibly, during rare, protracted drought periods. 
These locations may no longer have reliable surface water to support 
mud turtles or sufficient surface water to support as large a 
population as they used to (Paredes-Aguilar and Rosen 2003, p. 2; Rosen 
et al. 2010, p. 155). Perennial water also existed outside of the Rio 
Sonoyta in cienegas such as one fed by Quitobaquito Springs on Organ 
Pipe Cactus National Monument. Quitobaquito Springs is predominately 
supplied by groundwater (Carruth 1996, pp. 14, 18).
    In the SSA Report, we define a population of Sonoyta mud turtles as 
a group of interbreeding individuals living in an ecological community 
and separated from other populations by barriers including desert 
upland (overland, not connected by riparian or xeroriparian habitat) or 
in-channel distances that lack water most of the time. Currently, five 
populations of Sonoyta mud turtles occur. Three of these populations 
are historical populations--Quitobaquito Springs, and the Sonoyta and 
Papalote reaches of the Rio Sonoyta. However, the Sonoyta reach has now 
been reduced to a much smaller reach referred to as Xochimilco. There 
are two new populations--the Sonoyta sewage lagoon and Quitovac in 
Mexico, which were historically unknown and only discovered in 2002 but 
likely were present since the 1990s (Knowles et al. 2002, p. 74). These 
two new populations are not connected hydrologically to each other or 
to the Rio Sonoyta populations and it is likely that humans 
transplanted turtles from the Rio Sonoyta to these sites. One other 
historical population is considered extirpated--Santo Domingo. Of the 
five extant populations, one is in the United States in the pond and 
channel associated with Quitobaquito Springs in Organ Pipe Cactus 
National Monument, Arizona. The other four populations are in Sonora, 
Mexico (Rosen et al. 2010, p. 152). Two populations in the Rio Sonoyta 
in the Papalote reach and Xochimilco reach are extant, but perennial 
water flow in these reaches is reduced from historical levels. Since 
these perennial reaches in the Rio Sonoyta are greatly reduced or gone, 
the connectivity among these remaining populations is highly unlikely. 
The other two extant populations are the Sonoyta sewage lagoon and 
Quitovac in Mexico. Quitovac consists of multiple springs impounded to 
form a pond. The Sonoyta sewage lagoon site consists of two lagoons of 
raw sewage. A new wastewater treatment plant has been constructed to 
replace the Sonoyta sewage lagoons. However, this new plant has yet to 
begin operating and it is unclear when it will open. The amount of 
water and riparian vegetation provided at the new plant is less than 
that provided at the sewage lagoons and only a portion of the Sonoyta 
mud turtles are likely to be transplanted.
    The population at Quitobaquito Springs has been extensively 
monitored since the early 1980s. Surveys in the Rio Sonoyta basin in 
Sonora, Mexico, from 2001 through 2006 provide most of our knowledge of 
the current populations in Mexico (table 3.2.2 of the SSA Report; 
Paredes-Aguilar and Rosen 2003, entire; Knowles et al. 2002, entire; 
Rosen et al. 2010, pp. 152-153). However, we have low confidence that 
the population sizes for the Sonora populations remain at 2006 levels 
today, as many changes since the early 2000s have reduced or degraded 
habitat at most of the sites that still support Sonoyta mud turtles. In 
October 2001, a single turtle was found in a soup-bowl-sized remnant of 
water at the semi-perennial spring in the Santo Domingo reach (Santo 
Domingo is in the Rio Sonoyta and is the location of one of the five 
historical records of Sonoyta mud turtle listed above; Rosen et al. 
2010, pp. 152-153), and we now think this historical population is 
likely extirpated due to loss of perennial surface water in this reach 
(Rosen 2016, pers. comm.).

Species Needs

    Sonoyta mud turtles depend on aquatic habitat for foraging, 
shelter, and mating and terrestrial habitat for nesting and estivating. 
The Sonoyta mud turtle historically occupied habitat in cienegas and 
streams supported by groundwater-fed springs. Natural aquatic habitats 
of Sonoyta mud turtles are sustained by groundwater discharged from 
springs and augmented by seasonal rainfall. Terrestrial habitat that 
maintains soil moisture needed for Sonoyta mud turtles occurs in 
riparian areas along the banks of ponds and streams, including 
intermittently dry sections of a stream channel. However, natural 
aquatic habitats are highly limited. Sonoyta mud turtles can also be 
sustained by modified natural habitats or completely human-created 
habitats that provide similar permanent or almost permanent surface 
water. Currently, populations still occur within stream habitat, but 
all the cienegas have been modified from their natural state.
    For the Sonoyta mud turtle to maintain viability, its populations, 
or some portion of its populations, must be resilient enough to 
withstand stochastic events such as fluctuations in water levels, 
habitat modification, and introduction of nonnative predators. In the 
SSA Report, we categorized the potential resiliency of populations of 
the subspecies. We developed four different resiliency levels: High, 
medium, low, and none. In a highly resilient Sonoyta mud turtle 
population, all or the majority of turtles are able to complete their 
life functions, breeding maintains a stable or increasing population, 
and the population is able to withstand stochastic events or recover 
from stochastic events from connected populations. Influencing those 
factors are elements of Sonoyta mud turtle habitat that determine 
whether survivorship among age classes is achieved, thereby increasing 
the resiliency of populations. These factors include perennial or near 
perennial water (i.e., 10 to 11 months annually for consecutive years) 
of sufficient volume and extent with connectivity to other populations, 
terrestrial riparian habitat with soil moisture, high invertebrate prey 
abundance, and lack of problem nonnative species. The factors used to 
develop these resiliency levels are discussed below.

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                        Table 1--Population Resiliency Categories for Sonoyta Mud Turtle
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             High (Good)                       Moderate                   Low                      None
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A population with high resilience is   A population with        A population with low    A population with no
 where:                                 moderate resilience is   resilience is one        resiliency is one that
 All or the majority of         where:                   where:                   might be extirpated
 turtles are able to complete their     Some turtles     Some or few      completely.
 life functions;                        can complete life        turtles can complete
 Breeding is successful to      functions;.              life functions;.
 maintain a stable or increasing        Some turtles     Some or few
 population;                            have some successful     turtles have
 Population is able to          breeding, but            successful breeding,
 withstand stochastic events or         population is not        but population is
 recover from stochastic events from    increasing;.             decreasing;.
 connected populations.                 Population       Population is
                                        could be stable or       not able to withstand
                                        decreasing;.             stochastic events, and
                                        Population       is not able to recover
                                        could withstand some     through the
                                        stochastic events or a   immigration of
                                        portion of the           connected populations..
                                        population could
                                        withstand stochastic
                                        events, but population
                                        is not able to recover
                                        through the
                                        immigration of
                                        connected populations..
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Surface Water

    Sonoyta mud turtles require perennial or mostly perennial water to 
complete their life-history functions and avoid desiccation. We define 
near-perennial as water present more than 10 to 11 months of the year 
for multiple years. Aquatic habitat in ponds and streams with water 2 
meters (m) (6.5 feet (ft)) deep, with a rocky, muddy, or sandy 
substrate, and emergent or submergent vegetation, or both is needed 
(NPS 2015, p. 2; Paredes-Aguilar and Rosen 2003, p. 5-7; Rosen 2003, p. 
5; Rosen et al. 2010, p. 14). Hatchling, juvenile, and sub-adult 
turtles prefer aquatic habitat with shallow water and dense emergent 
vegetation and overhanging vegetation along the stream channel or pond 
margin that provides foraging opportunities as well as protection from 
predators (Rosen 1986, pp. 14 and 36; Rosen and Lowe 1996, p. 11). 
Adults will also use shallow water habitat, but prefer aquatic habitat 
with accessible, deeper, open water (up to 2 m (6.5 ft)) when 
available, and submerged vegetation for feeding on benthic and plant-
crawling invertebrates along the substrate (Rosen 1986, pp. 14, 16; 
Rosen and Lowe 1996, p. 11). Adults, juveniles, and subadults also use 
aquatic habitat with structure that provides protection from predators 
such as root masses, complex rock features, and undercut banks. Turtle 
recruitment can be affected by the amount of surface water available, 
how long it is available, as well as its fluctuation. In addition, 
hydrologic connectivity is needed for a population to recover from a 
stochastic event.

Terrestrial Habitat

    Sonoyta mud turtles need terrestrial habitat that maintains soil 
moisture for Sonoyta mud turtles in riparian areas along the banks of 
ponds and streams, including intermittently dry sections of stream 
channels. Riparian habitat provides shadier, cooler, and moister 
conditions than the adjacent upland areas. Sonoyta mud turtles likely 
need moist soil for nesting to prevent desiccation of eggs and 
estivation sites to prevent desiccation of juveniles and adults. 
Riparian vegetation may also provide some level of protection from 
terrestrial predators while turtles are out of the water. Sonoyta mud 
turtles further need accessible shoreline without insurmountable rock 
or artificial vertical barriers to allow for movement between wetted 
sites, between aquatic habitat and terrestrial nest sites, and between 
water and estivation sites.

Invertebrate Prey

    Sonoyta mud turtle hatchlings and juveniles need shoreline 
invertebrate fauna, while subadults and adults need bottom dwelling 
(i.e. on or in the sediment) and plant-crawling invertebrates. Aquatic 
habitat with emergent and submerged vegetation or the substrate of 
ponds and streams is needed to support prey for Sonoyta mud turtles 
(Rosen 1986, pp. 14, 31; Rosen and Lowe 1996, pp. 32-35). Aquatic 
invertebrates primarily live on and require a variety of prey such as 
algae, diatoms, and other microorganisms. In habitats with poor aquatic 
invertebrate faunas, Sonoyta mud turtles will shift to omnivorous 
feeding, including plants and vertebrates. When invertebrates are 
abundant, and competition is low, turtles grow rapidly and have 
sufficient fat content to support reproduction.

Nonnative Predators and Competitors

    Sonoyta mud turtles need aquatic habitat free of problematic 
nonnative predators and competitors such as crayfish, American 
bullfrogs, sunfish, black bullheads, African cichlid fishes (tilapia), 
western mosquitofish, and exotic turtles. Competition between nonnative 
species and mud turtles for food likely results in disruption of the 
food chain and alteration of the invertebrate community (Taylor et al. 
1984, pp. 330-331; Fernandez and Rosen 1996, pp. 39-40; Duncan 2013, p. 
1). Such competition, in turn, likely decreases the type and amount of 
aquatic invertebrate prey available to Sonoyta mud turtles (Fernandez 
and Rosen 1996, pp. 39-40) and leads to lower fitness of turtles.
    Sonoyta mud turtles need genetic or ecological diversity to adapt 
to changing environmental conditions. The more representation, or 
diversity, a species has, the more it is capable of adapting to changes 
(natural or human-caused) in its environment. Representation can be 
measured by the breadth of genetic or environmental diversity within 
and among populations and gauges the probability that a species is 
capable of adapting to environmental changes. Currently, the Sonoyta 
mud turtle exhibits genetic and ecological diversity. Maintaining gene 
flow among populations and counteracting genetic drift and deleterious 
effects of inbreeding connectivity among populations are needed. A 
minimum of 1 and maximum of 10 migrants per generation is needed to 
successfully breed in populations of a species (Mills and Allendorf 
1996, p. 1517; Nathan et al. 2017, p. 270; Wang 2004, p. 341). This is 
a large range of migrants per generation, and we do not know where 
within this range the Sonoyta mud turtle falls to maintain genetic 
diversity among the fragmented populations of the subspecies. Genetic 
analysis conducted in the mid-2000s reveals that successful migration 
has likely occurred

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in the past (Rosen 2006, p. 10). Maintaining representation in the form 
of genetic or ecological diversity is important to maintain the Sonoyta 
mud turtle's capacity to adapt to future environmental changes.
    The Sonoyta mud turtle needs multiple resilient populations spread 
over its historical range distributed in such a way that a catastrophic 
event will not result in the loss of all populations. In addition, 
hydrologic connectivity is needed for a population to recover from a 
catastrophic event. We do not have an estimate of how many populations 
are needed to withstand localized loss of habitat and maintain 
redundancy. However, the loss of Quitobaquito Springs, Quitovac, and 
either Rio Sonoyta Papalote or Rio Sonoyta Xochimilco would reduce the 
representation for the subspecies.

Summary of Biological Status and Threats

    The primary negative factor affecting the future viability of the 
Sonoyta mud turtle is continued loss of water that supports aquatic and 
riparian habitat. The sources of water loss affecting Sonoyta mud 
turtles include groundwater pumping, drought, changes to wastewater 
infrastructure, consumption by livestock, surface water diversion, and 
habitat manipulation. Of these sources, water loss caused by drought 
and groundwater pumping, both of which are exacerbated by climate 
change and changes to wastewater infrastructure, are the primary causes 
of population-level impacts to the Sonoyta mud turtle. The other 
sources of water loss are not likely to have population-level impacts 
unless mining near Quitovac is intensified and unregulated. However, 
the Quitovac site is routinely dredged, resulting in direct impacts to 
Sonoyta mud turtles and prey. All of these factors are additive in 
terms of impacts to populations that are already stressed by the 
primary activities causing population-level impacts. In addition, 
impacts from climate change (discussed below) are expected to 
exacerbate water loss.
    Ground water pumping impacts the amount of surface water in areas 
used by Sonoyta mud turtles because the perennial sections of the Rio 
Sonoyta as well as the pond at Quitobaquito Springs and Quitovac are 
supplied by ground water. Diminished water reduces the amount of space, 
prey, and cover (from predators and for estivation) available to mud 
turtles. Reduction in aquatic habitat (i.e., space) leads to crowding 
and increased competition for limited resources (Stanila 2009, p. 45). 
Sonoyta mud turtles in dry or low surface water reaches will burrow in 
channels to escape desiccation for a short period of time. However, the 
ability of Sonoyta mud turtles to estivate may depend on behavioral 
cues provided by the level of permanence of water they reside in (Ligon 
and Stone 2003, p. 753; Stanila 2009, p. 45). After time, burrows 
themselves may become too dry; turtles will lose fat reserves due to 
lack of foraging opportunity; females may not have viable eggs due to 
lack of nutrition and fat reserves, thereby reducing reproduction; and 
eventually turtles will die from either starvation or desiccation. If 
water is not reliably present all year and absent beyond the dry 
season, turtles are not able to forage; may not reproduce; and, as 
drought periods lengthen, may eventually desiccate (Stanila 2009, p. 
45).
    Sonora mud turtles that live in permanent bodies of water have 
shown highly aquatic behavior with little terrestrial behavior or 
movement between water sources, while Sonora mud turtles in more 
ephemeral habits have been documented moving through or out of dry 
stream beds to reach wetted pools, for winter hibernation, or for 
estivation during drought as a drought-survival strategy (Hall and 
Steidl, 2007, pp. 406-408; Hensley et al. 2010, pp. 181-182; Ligon and 
Stone 2003, pp. 752-753; Stone 2001, pp. 46-51). Prolonged and 
recurrent estivation is expected to reduce fitness and increase 
mortality (Peterson and Stone 2000, pp. 692-698). Variation in body 
size among populations of Sonora mud turtles appears to be related to 
water permanence, and body size was significantly larger in permanent 
habitats compared to intermittent and ephemeral habitats (Stanila 2009, 
p. 31). In permanent water sites, growth and body size are positively 
correlated with aquatic invertebrate abundance at a site (Rosen and 
Lowe 1996, pp. 33, 35).
    Reduced surface water and ground water reduce the survival and 
growth of vegetation in the riparian areas. Reductions in riparian 
habitat decrease subsurface moisture needed for nesting sites; drought 
refuge for hatchlings, juvenile, and adult turtles; and shelter from 
large flooding events for hatchlings, juveniles, and adults. It is 
likely that only adults will be the most resistant to severe droughts. 
Decreased riparian vegetation will lead to deterioration of the 
microclimate that provides soil moisture for nest sites and burrows.
    Water permanence may also affect the diversity of aquatic 
invertebrate prey available for mud turtles, with ephemeral habitats 
having lower diversity than intermittent or perennial habitats (Stanila 
2009, p. 38), in addition to the presence of nonnative aquatic species 
that compete for prey. When invertebrates are abundant, and competition 
is low, turtles grow rapidly and have sufficient lipid content to 
support reproduction. Turtle recruitment is likely driven in 
significant part by invertebrate prey available because nutritional 
stress on females may result in a reduction in annual survivorship 
(Rosen and Lowe 1996, p. 41). Competition from nonnatives could 
decrease the type and amount of aquatic invertebrate prey available to 
Sonoyta mud turtles (Fernandez and Rosen 1996, pp. 39-40) and lead to 
lower fitness of turtles. Because high average annual juvenile 
survivorship is required for populations of long-lived organisms to 
maintain population stability (Congdon et al. 1993, pp. 831-832; 
Congdon et al. 1994, pp. 405-406), nonnative predators that reduce 
recruitment in Sonoyta mud turtle populations likely cause population 
declines.
    The current prognosis of climate change impacts on the Sonoran 
Desert includes fewer frost days; warmer temperatures; greater water 
demand by plants, animals, and people; and an increased frequency of 
extreme weather events (heat waves, droughts, and floods) (Weiss and 
Overpeck 2005, p. 2074; Archer and Predick 2008, p. 24). Any reductions 
in annual rainfall, coupled with the hotter temperatures that are 
projected with very high confidence (and that will alone bring 
reductions in aquifer inputs due to higher evaporation rates), would 
have negative effects on aquifers across the Southwest. Virtually any 
plausible future climate scenario projects longer dry spells between 
rains, which can have more severe impacts on the landscape, especially 
in spring and summer (Lenart 2008, entire).

Current Condition

    Currently, five known populations of Sonoyta mud turtle remain. The 
perennial water supporting four of the five turtle extant populations 
has been reduced, and all five populations are isolated from one 
another. For the sole population in the United States, discharge from 
Quitobaquito Springs has diminished by 42 percent over the past 35 
years, with 5,500 cubic feet (cf)/day average discharge measured in the 
period 1981-1992, down to 3,157 cf/day measured from 2005-present 
(Carruth 1996, pp. 13, 21; Holm 2016, pers. comm.). Thus far, declining 
spring flow has been associated with less than 30 centimeters (cm) (12 
inches (in)) of surface water level decline at the pond,

[[Page 43901]]

the depth of which ranges from 81 to 94 cm (32 to 37 in). This could 
indicate that current lower water levels of the pond are also caused by 
leakage or evapotranspiration, not just reduced spring flow. Excluding 
young-of-the-year (< 40 mm (1.6 in) carapace length), population 
estimates since 1984 ranged from a low of 39 turtles in 2005 to a high 
of 189 in 2013 with an average annual population estimate of 110 
turtles. The population estimate for 2015 was 141 turtles.
    In Mexico, the two populations in the Xochimilco and Papalote 
reaches of the Rio Sonoyta are isolated from one another even more than 
they used to be historically because the lengths of the perennial 
reaches have contracted. Added to this, a previously extant population 
in the Santa Domingo reach that was located between Xochimilco and 
Papalote reaches is no longer extant due to a complete lack of 
perennial water. The perennial waters in these three reaches have 
decreased by 80 to 92 percent from 19-27 km (11.8-16.8 mi) historically 
to approximately 1.5-5.5 km (0.9-3.4 mi) currently (table 1 and figure 
3.1.1 of the SSA Report). Periodic movement between populations in the 
Rio Sonoyta basin may occur during prolonged periods of high rainfall, 
but the extent of immigration and emigration of turtles is unknown. 
However, it is thought to be rare to limited due to distances between 
populations coupled with limited hydrological connection.
    Currently, the status of the Xochimilco population is unknown, but 
abundance is almost certainly far less, considering the reduced spatial 
and temporal extent of surface water. A total of 57 turtles have been 
marked in the Papalote reach in 2017, for a mark-recapture study that 
will provide better information on the status of the Sonoyta mud turtle 
in this reach in the next few years.
    The population at the Sonoyta sewage lagoon adjacent to the Rio 
Sonoyta has the most reliable source of water at this time and may be 
the largest of the five populations based on water availability, but we 
have no current data on numbers of turtles at this site. If a new 
wastewater treatment plant is completed for the town of Sonoyta, the 
existing Sonoyta sewage lagoons will be drained and the new wastewater 
treatment plant will have 75 percent less habitat available for Sonoyta 
mud turtles. The fourth population in Mexico at Quitovac is outside of 
the Rio Sonoyta watershed, in the Rio Guadalupe basin, and has no 
present-day hydrological connection to the Rio Sonoyta. In addition, 
the Quitovac site was just recently completely dredged and the current 
status of Sonoyta mud turtles at that location is unknown.

Future Condition

    The future resiliency of Sonoyta mud turtle populations depends on 
future water quantity, available riparian habitat, available 
invertebrate prey, and absence of certain nonnative aquatic species. In 
addition, if the new wastewater treatment plant becomes operational and 
replaces the Sonoyta sewage lagoons, this will be a reduction in water 
and riparian habitat for the Sonoyta mud turtle. Further, only a 
portion of the Sonoyta mud turtles are likely to be transplanted. 
Because there is uncertainty regarding how and when surface water loss 
and associated riparian habitat impairment may occur, as well as if and 
when various nonnative species may occur, we projected what the effects 
to the Sonoyta mud turtle may be in terms of population resiliency and 
species redundancy and representation under three plausible future 
scenarios over three meaningful time frames: 7 years, 35 years, and 70 
years. We chose 7 years based on the area's drought cycle, 35 years 
because it incorporates both the maximum life span of the species and 
the mid-century climate projections for the southwestern United States, 
and 70 years because it is within the range of the available drought 
and climate change model forecasts and is about twice the maximum life 
span of the species (Lenart 2008, entire; Strittholt et al. 2012, 
entire; Garfin et al. 2013, entire).
    Since surface water availability limits the other elements and the 
carrying capacity of the site, the ranking of the surface water was 
weighted higher than the other metrics. This means that if surface 
water was ranked moderate and all other elements were ranked high, the 
overall ranking would be moderate. We are presenting the moderate case 
scenarios, as we have determined that this is the most likely future 
scenario based on our understanding of the future conditions of climate 
change and groundwater pumping.

      Table 2--Summary of Sonoyta Mud Turtle Population Resiliency Under Scenario 2--Moderate Case at Each Time Step Compared To Current Condition
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Current                                Moderate case scenario
                                                            --------------------------------------------------------------------------------------------
              Country                    Population name                                     7-year                35-year                70-year
                                                                    Condition       --------------------------------------------------------------------
                                                                                           time step              time step              time step
--------------------------------------------------------------------------------------------------------------------------------------------------------
United States......................  Quitobaquito Springs..  Moderate..............  Moderate.............  Moderate.............  Low
Mexico.............................  Papalote Reach (Agua    Moderate..............  Moderate.............  None.................  None
                                      Dulce).
                                     Sonoyta Sewage Lagoon.  Moderate..............  Low..................  None.................  None
                                     New Sonoyta wastewater  None..................  Moderate.............  Moderate.............  Moderate
                                      treatment plant.
                                     Xochimilco Reach......  Low...................  Low..................  None.................  None
                                     (Sonoyta Reach).......
                                     Quitovac..............  Low...................  Low..................  Low..................  Low
                                     Santo Domingo.........  None..................  None.................  None.................  None
--------------------------------------------------------------------------------------------------------------------------------------------------------

Summary of Changes From the Proposed Rule

    In preparing this final rule, we reviewed and fully considered 
comments we received from the public and peer reviewers on the SSA 
Report and proposed rule. We received numerous comments and new 
information from peer reviewers on the science and analysis in the SSA 
Report, and we have updated the SSA Report to incorporate these 
accordingly. In addition, we met with the National Park Service (NPS) 
to discuss the SSA Report, and we updated the SSA Report with the 
information NPS provided. This final rule incorporates minor changes to 
our proposed listing based on the comments we received, as discussed 
below in Summary of Comments and Recommendations. We

[[Page 43902]]

received multiple comments from peer reviewers that we underestimated 
some of the future risks to Sonoyta mud turtle populations. We have 
reevaluated the viability of the Sonoyta mud turtle in the SSA Report 
given this new information. These data allowed us to refine our risk 
assessment; thus, the final results are slightly different from those 
in the proposed rule. We found the probability of persistence lower 
than in the proposed rule. The new information we received in response 
to the proposed rule did not change our determination that the Sonoyta 
mud turtle is an endangered species, nor was it significant enough to 
warrant reopening the public comment period on the proposed rule.

Summary of Comments and Recommendations

    In the proposed rule published on September 21, 2016 (81 FR 64829), 
we requested that all interested parties submit written comments on the 
proposal by November 21, 2016. We also contacted appropriate Federal 
and State agencies, scientific experts and organizations, and other 
interested parties and invited them to comment on the proposal. 
Newspaper notices inviting general public comment were published in the 
Arizona Daily Star. We did not receive any requests for a public 
hearing.
    We reviewed all comments we received in response to the proposed 
rule for substantive issues and new information. We did not receive any 
comments from Federal agencies, States, or Tribes, and the public 
comments we received only stated a preference for listing or not 
listing the subspecies without including any substantive comments 
regarding the sufficiency of our analysis. All substantive information 
provided by peer reviewers during the comment period has either been 
incorporated directly into this final determination or is addressed 
below.

Peer Reviewer Comments

    In accordance with our peer review policy published on July 1, 1994 
(59 FR 34270), we solicited expert opinion from eight knowledgeable 
individuals with scientific expertise that included familiarity with 
the Sonoyta mud turtle and its habitat, biological needs, and threats, 
or the nominate subspecies Sonora mud turtle. We received responses 
from six of the peer reviewers.
    We reviewed all comments received from the peer reviewers for 
substantive issues and new information regarding the listing of Sonoyta 
mud turtle. The peer reviewers generally concurred with our methods and 
conclusion, and provided additional and pertinent information, 
clarifications, and suggestions to improve the SSA Report and, 
therefore, the final rule. Peer reviewer comments are addressed in the 
following summary and incorporated into the SSA Report and this final 
rule as appropriate.
    (1) Comment: One peer reviewer stated that the new wastewater 
treatment facility is not constructed, nor are there in-place plans to 
populate it, and there is currently no guarantee that whatever habitat 
is constructed will actually be suitable.
    Our Response: We made revisions throughout the SSA Report to 
acknowledge the uncertainty related to future habitat for the Sonoyta 
mud turtle at the new wastewater treatment plant in the town of 
Sonoyta, Sonora, Mexico.
    (2) Comment: One peer reviewer identified the importance of 
stipulating that the historical range and populations of the Sonoyta 
mud turtle are only those that are known or have been documented.
    Our Response: We acknowledge that these are only the known 
populations of the Sonoyta mud turtle. While historically there could 
have been other populations, the best available commercial and 
scientific information does not indicate any other additional 
populations.
    (3) Comment: One peer reviewer stated that he is not convinced that 
development of Sonoyta mud turtle embryos takes 80 days and is delayed 
after the eggs are laid, as stated in Ernst and Lovich (2009, p. 497).
    Our Response: We acknowledge uncertainty regarding the timing of 
embryo development, or diapause, in the Sonoyta mud turtle. However, 
these specific steps in the reproductive process are also noted in van 
Lobel Sels et al. (1997, p. 497) and Stone et al. (2015, p. 735). The 
best available commercial and scientific information indicates that 
diapause likely occurs in this subspecies as it does in the nominate 
subspecies.
    (4) Comment: One peer reviewer stated that we are assuming that 
Sonoyta mud turtles need riparian areas with moist soil.
    Our Response: We acknowledge uncertainty around the terrestrial 
habitat needs of the Sonoyta mud turtle. However, we have high 
confidence that this subspecies uses areas with more shade and 
increased soil moisture to prevent desiccation of eggs in nest sites 
and turtles in estivation sites. Without suitable soil moisture, eggs 
will desiccate, and while the threshold is unknown, at some point the 
loss of soil moisture will impact egg survival. In the extremely arid 
environment where the Sonoyta mud turtle exists, riparian areas provide 
more shade and soil moisture than the surrounding uplands and, 
therefore, provide better habitat for nests.
    (5) Comment: One peer reviewer stated that some nonnative aquatic 
species can be both predator and competitor to the Sonoyta mud turtle, 
and that not all nonnatives are harmful to the Sonoyta mud turtle.
    Our Response: In the SSA Report, we clarified that only certain 
nonnative aquatic species are predators of the Sonoyta mud turtle, and 
we identify those that are a potential threat. We also clarified that 
only certain other nonnative aquatic species, as well as native fish 
species, may compete with Sonoyta mud turtles for invertebrate prey or 
disrupt the prey food chain. Further, we clarified the effects to the 
Sonoyta mud turtle from predation and competition from these specific 
nonnatives.
    (6) Comment: Multiple peer reviewers thought that our viability 
projections for the Sonoyta mud turtle in chapter 5 of the SSA Report 
were overly optimistic based on uncertainty of the current status of 
populations in Mexico and because we underestimated the threats of 
introduction of nonnative aquatic species and climate change to the 
subspecies. Conversely, one peer reviewer thought we overestimated the 
threat of nonnatives persisting at Quitobaquito Springs because NPS 
would probably remove the threat.
    Our Response: We agree that viability projections for the Sonoyta 
mud turtle were overly optimistic because of the high uncertainty of 
the number of turtles in the Mexico populations and that we 
underestimated some of the threats, such as long-term drought, 
nonnatives, and loss of connectivity, to the Sonoyta mud turtle. We 
modified the SSA Report accordingly. We also agree that the nonnatives 
at Quitobaquito Springs have been removed by NPS in the past; however, 
no mechanism ensures that changing resource priorities and funding 
constraints will not be an issue in the future. We have modified the 
SSA Report accordingly.
    (7) Comment: Several peer reviewers noted that statements in the 
SSA Report that require citations to support them. For example, one 
peer reviewer believed that the statement ``prolonged and recurrent 
estivation will reduce fitness and increase mortality'' was entirely 
speculative. Similarly, another peer reviewer indicated the 
uncertainties acknowledged in the SSA Report reduce

[[Page 43903]]

its predictive value (e.g., effects of transitioning to the new sewage 
treatment plant, likelihood of introduction of nonnative species, 
status of the turtle on Tohono O'odham Nation lands, long-term genetic 
viability, and continued ability of State and Federal agencies to 
manage for this species).
    Our Response: We revised the SSA Report to add citations to support 
statements where needed throughout the document. We also recognize that 
the SSA Report contains uncertainties, and throughout the document we 
identify these uncertainties as well as quantify or clarify our level 
of uncertainty. However, because we are required by the Act (16 U.S.C. 
1531 et seq.) to complete this determination based on the best 
available scientific and commercial information, we must move forward 
without resolving all potential uncertainties.
    (8) Comment: One peer reviewer noted that the distribution map on 
page 4, figure 2.1.1., of the SSA Report is a bit out of date. 
Specifically, the Quitovac locality is not shown, and there are now 
many more localities in northeastern Sonora (see the Madrean 
Archipelago Biodiversity Assessment and Madrean Discovery Expeditions 
databases).
    Our Response: Figure 2.1.1. in the SSA Report is used to 
demonstrate the general distribution of the two mud turtle subspecies, 
Sonora and Sonoyta, in relation to each other, not to delineate the 
current range or distribution of either subspecies.

Public Comments

    We received only comments stating a preference for listing or not 
listing the subspecies. We did not receive any substantive comments 
regarding the sufficiency of the analysis.

Determination

Standard for Review

    Section 4 of the Act (16 U.S.C. 1533), and its implementing 
regulations at 50 CFR part 424, set forth the procedures for adding 
species to the Federal Lists of Endangered and Threatened Wildlife and 
Plants. Under section 4(a)(1) of the Act, we may list a species based 
on (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. Listing actions may be warranted based on any of 
the above threat factors, singly or in combination.
    The fundamental question before the Service is whether the species 
meets the definition of ``endangered species'' or ``threatened 
species'' under the Act. To make this determination, we evaluated the 
projections of extinction risk, described in terms of the condition of 
current and future populations and their distribution (taking into 
account the risk factors and their effects on those populations). For 
any species, as population condition declines and distribution shrinks, 
the species' extinction risk increases and overall viability declines.

Sonoyta Mud Turtle Determination of Status Throughout All of Its Range

    We have carefully assessed the best scientific and commercial 
information available regarding the past, present, and future threats 
to the Sonoyta mud turtle. Currently, the five extant populations are 
all significantly isolated from one another such that recolonization of 
areas previously extirpated or areas that may be extirpated is 
extremely unlikely. Expert input provided during the development of the 
SSA Report indicated that connectivity or movement among the 
populations is a rare or nonexistent occurrence. The species' range has 
been reduced by 80 to 92 percent in the Rio Sonoyta (Factor A) in 
Mexico, and current distribution is limited to five populations in 
three ponds totaling less than 7 ha (less than 17.5 ac) and two 
perennial sections of the Rio Sonoyta totaling 1.5 to 5.5 km (0.9 to 
3.4 mi). Two historical populations are extirpated due to loss of 
perennial water. There are two newly discovered extant populations in 
addition to the three historical populations that remain. One is within 
a wastewater treatment plant where the impacts from facility management 
and water quality make monitoring difficult and may be adverse to 
Sonoyta mud turtle viability, and the other is outside the Rio Sonoyta 
basin, which is likely outside the historical range of the species. 
None of the five populations are classified as having ``high'' 
resiliency, described in the SSA Report as ``all or the majority of 
turtles are able to complete their life functions and breeding is 
successful to maintain a stable or increasing population, and able to 
withstand stochastic events or recover from stochastic events from 
connected populations.'' Even with a resiliency classified as 
``moderate'' in three populations, we expect stable or decreasing 
populations that are not able to recover from stochastic events. The 
remaining two populations have few turtles able to complete life 
functions, a decreasing population, and inability to withstand or 
recover from stochastic events. All five of these populations are 
currently facing stressors and are susceptible to current and ongoing 
impacts.
    Habitat loss from anthropogenic ground water withdrawals and long-
term drought is occurring rangewide and is likely to continue and 
increase in the near term (Factors A and E). This reduction in water 
restricts the limited available habitat and decreases the resiliency of 
Sonoyta mud turtle populations within those habitats. We find that 
ongoing cyclical drought is likely to continue and be exacerbated by 
climate change, further decreasing water availability and increasing 
evapotranspiration losses (Factors A and E). This threat is ongoing, 
rangewide, and expected to increase in the future. Predation by 
nonnative aquatic species has occurred at two sites in Mexico, although 
there is uncertainty with regard to the population effects (Factor C). 
Predation by nonnative aquatic species reduces recruitment and 
population size of populations of Sonora mud turtle, and it is likely 
to continue to affect Sonoyta mud turtle populations in the future. The 
Quitovac population's current habitat was just recently completely 
dredged (Factor A), and the current status of Sonoyta mud turtles at 
that location is unknown. Partial dredging in the near term is likely 
to occur based on past dredging activity. It is reasonably likely that 
a catastrophic event could occur imminently at one or more of the 
population sites, and current population resiliency and redundancy are 
inadequate to maintain population viability.
    The implementation of the conservation measures by NPS and the 
Quitobaquito Rio Sonoyta Working Group has resulted in maintaining the 
only Sonoyta mud turtle population in the United States and reduces the 
risk of loss of at least one population in Mexico. However, the 
conservation measures do not alleviate the threats that are influencing 
the resiliency, redundancy, and representation of the Sonoyta mud 
turtle across its range (as described above).
    The Act defines a ``species'' as including any ``subspecies of fish 
or wildlife or plants, and any distinct population segment of any 
species of vertebrate fish or wildlife which interbreeds when mature.'' 
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

[[Page 43904]]

any species ``that is likely to become endangered throughout all or a 
significant portion of its range within the foreseeable future.'' Based 
on the information presented in the SSA Report for the Sonoyta mud 
turtle, and the discussion above, we find that the best available 
scientific and commercial information indicates that the Sonoyta mud 
turtle is presently in danger of extinction throughout its entire range 
based on the severity and immediacy of threats currently impacting the 
subspecies. The overall range has been significantly reduced; the 
limited remaining habitat and populations are currently threatened by 
an increase in ground water pumping, which results in reduced spring 
flows and, therefore, reduced surface water. Discharge from 
Quitobaquito Springs has diminished by 42 percent over the past 35 
years, and the pond depth has been declining since the early 1990s due 
to evapotranspiration, leakage, and the reduction in spring water 
discharge. The perennial waters in the three historical reaches of the 
Rio Sonoyta have decreased by 80 to 92 percent. Current distribution is 
limited to five populations in three ponds totaling less than 7 ha 
(less than 17.5 ac) and two perennial sections of the Rio Sonoyta 
totaling 1.5 to 5.5 km (0.9 to 3.4 mi). The new wastewater treatment 
plant, if utilized, will provide 75 percent less habitat available for 
Sonoyta mud turtles than the current sewage lagoon. Reduced surface 
water results in reduced aquatic habitat where the subspecies spends 
the majority of its time and that is needed to avoid desiccation of all 
life stages. Further, the reduction in surface water impacts aquatic 
vegetation used by the Sonoyta mud turtle for cover and by its prey 
species. Lastly, the reduction in ground water reduces the soil 
moisture of the riparian area, resulting in habitat that is too dry for 
Sonoyta mud turtles to use for estivation and nesting.
    These factors, acting in combination, reduce the overall viability 
of the subspecies. Each of the five remaining populations are exposed 
to threats that may eliminate them individually at any time. The risk 
of extinction for this subspecies is currently high because the five 
remaining populations are small, isolated, and have limited (if any) 
potential for recolonization. Each population's isolation from other 
populations means that once a population is extirpated, it is likely to 
remain extirpated. The estimated current conditions of the known 
Sonoyta mud turtle populations as described in the SSA Report lead us 
to find that the condition and distribution of populations do not 
provide sufficient resiliency, redundancy, and representation for this 
subspecies at this time; therefore, we find that the subspecies meets 
the definition of an endangered species under the Act. Accordingly, on 
the basis of the best available scientific and commercial information, 
we are listing the Sonoyta mud turtle as endangered in accordance with 
sections 3(6) and 4(a)(1) of the Act.
    We find that a threatened status is not appropriate for the Sonoyta 
mud turtle because the danger of extinction for this subspecies exists 
now. The current restricted range and ubiquitous and imminent threats 
occur rangewide. Consequently, we find the Sonoyta mud turtle to be in 
danger of extinction now throughout its range.

Determination of Status Throughout a Significant Portion of Its Range

    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 endangered within the foreseeable future throughout all or a 
significant portion of its range.'' The phrase ``significant portion of 
its range'' is not defined by the Act, and a district court has held 
that aspects of the Service's Final Policy on Interpretation of the 
Phrase ``Significant Portion of Its Range'' in the Endangered Species 
Act's Definitions of ``Endangered Species and ``Threatened Species'' 
(79 FR 37577 (July 1, 2014)) (SPR Policy) were not valid. Center for 
Biological Diversity v. Jewell, No. 14-cv-02506-RM (D. Ariz. Mar. 29, 
2017) (Pygmy-Owl Decision).
    Although the court's order in that case has not yet gone into 
effect, if the court denies the pending motion for reconsideration, the 
SPR Policy would become vacated. Therefore, we have examined the plain 
language of the Act and court decisions addressing the Service's 
application of the SPR phrase in various listing decisions, and for 
purposes of this rulemaking we are applying the interpretation set out 
below for the phrase ``significant portion of its range'' and its 
context in determining whether or not a species is an endangered 
species or a threatened species. Because the interpretation we are 
applying is consistent with the SPR Policy, we summarize herein the 
bases for our interpretation, and also refer the public to the SPR 
Policy itself for a more-detailed explanation of our reasons for 
interpreting the phrase in this way.
    An important factor that influences the question of whether an SPR 
analysis is necessary here is what the consequence would be if the 
Service were to find that the Sonoyta mud turtle is in danger of 
extinction or likely to become so throughout a significant portion of 
its range. Two district court decisions have evaluated whether the 
outcomes of the Service's SPR determinations were reasonable. As 
described in the SPR Policy, both courts found that, once the Service 
determines that a ``species''--which can include a species, subspecies, 
or DPS under ESA Section 3(16)--meets the definition of ``endangered 
species'' or ``threatened species,'' the species must be listed in its 
entirety and the Act's protections applied consistently to all members 
of that species (subject to modification of protections through special 
rules under sections 4(d) and 10(j) of the Act). See Defenders of 
Wildlife v. Salazar, 729 F. Supp. 2d 1207, 1222 (D. Mont. 2010) 
(delisting of the Northern Rocky Mountains DPS of gray wolf; appeal 
dismissed as moot because of public law vacating the listing, 2012 U.S. 
App. LEXIS 26769 (9th Cir. Nov. 7, 2012)); WildEarth Guardians v. 
Salazar, No. 09-00574-PHX-FJM, 2010 U.S. Dist. LEXIS 105253, 15-16 (D. 
Ariz. Sept. 30, 2010) (Gunnison's prairie dog). The issue has not been 
addressed by a Federal Court of Appeals.
    Consistent with the district court case law, we interpret that the 
consequence of finding that the Sonoyta mud turtle is in danger of 
extinction or likely to become so throughout a significant portion of 
its range would be that the entire species would be listed as an 
endangered species or threatened species, respectively, and the Act's 
protections would be applied to all individuals of the species wherever 
found. Thus, the ``throughout all'' phrase and the SPR phrase provide 
two independent bases for listing. We note that in the Act Congress 
placed the ``all'' language before the SPR phrase in the definitions of 
``endangered species'' and ``threatened species.'' This suggests that 
Congress intended that an analysis based on consideration of the entire 
range should receive primary focus. Thus, the first step we undertook, 
above, in our assessment of the status of the species was to determine 
its status throughout all of its range. Having determined that the 
species is in danger of extinction throughout all of its range, we now 
examine whether it is necessary to determine its status throughout a 
significant portion of its range.
    We conclude that in this situation we do not need to conduct an SPR 
analysis. This conclusion is consistent with the Act because the 
species is currently in danger of extinction throughout all of its

[[Page 43905]]

range due either to high-magnitude threats across its range, or to 
threats that are so high in particular areas that they severely affect 
the species across its range. Therefore, the species is in danger of 
extinction throughout every portion of its range, and an analysis of 
whether the species is in danger of extinction or likely to become so 
throughout any significant portion of its range would be redundant and 
unnecessary. We accordingly conclude that we do not need to conduct 
further analysis of whether the Sonoyta mud turtle is in danger of 
extinction or likely to become so in the foreseeable future throughout 
a significant portion of its range.
    Therefore, on the basis of the best available scientific and 
commercial information, we are adding Sonoyta mud turtle to the List of 
Endangered and Threatened Wildlife as an endangered species in 
accordance with sections 3(6) and 4(a)(1) of the Act. We find that a 
threatened species status is not appropriate for Sonoyta mud turtle 
because of the immediacy of threats facing the species with only five 
known populations, at least one of which is declining in abundance.

Critical Habitat Determination

    Section 4(a)(3) of the Act, as amended, and implementing 
regulations (50 CFR 424.12), require that, to the maximum extent 
prudent and determinable, the Secretary shall designate critical 
habitat at the time the species is determined to be an endangered or 
threatened species. Our regulations (50 CFR 424.12(a)(1)) state that 
the designation of critical habitat is not prudent when one or both of 
the following situations exist:
    (1) The species is threatened by taking or other human activity, 
and identification of critical habitat can be expected to increase the 
degree of threat to the species, or
    (2) Such designation of critical habitat would not be beneficial to 
the species. In determining whether a designation would not be 
beneficial, the factors the Service may consider include but are not 
limited to: Whether the present or threatened destruction, 
modification, or curtailment of a species' habitat or range is not a 
threat to the species, or whether any areas meet the definition of 
``critical habitat.''

Prudency of Critical Habitat

    There is currently no imminent threat of take attributed to 
collection or vandalism identified under Factor B for this subspecies, 
and identification and mapping of critical habitat is not expected to 
initiate any such threat. In the absence of finding that the 
designation of critical habitat would increase threats to a species, we 
next determine whether such designation of critical habitat would not 
be beneficial to the species. In our proposed listing rule, we 
determined that there are habitat-based threats to the Sonoyta mud 
turtle identified under Factor A. Therefore, we find that the 
designation of critical habitat would be beneficial to Sonoyta mud 
turtle through the provisions of section 7 of the Act. Because we have 
determined that the designation of critical habitat will not likely 
increase the degree of threat to the subspecies and would be 
beneficial, we find that designation of critical habitat is prudent for 
the Sonoyta mud turtle.

Critical Habitat Determinability

    Having determined that designation is prudent, under section 
4(a)(3) of the Act, we must find whether critical habitat for the 
Sonoyta mud turtle is determinable. Our regulations at 50 CFR 
424.12(a)(2) state that critical habitat is not determinable when one 
or both of the following situations exist:
    (i) Information sufficient to perform required analysis of the 
impacts of the designation is lacking, or
    (ii) The biological needs of the species are not sufficiently well 
known to identify any area that meets the definition of ``critical 
habitat.''
    As required by section 4(b)(2) of the Act, we use the best 
scientific data available to designate critical habitat after taking 
into consideration the economic impact, national security impact, and 
any other relevant impact of specifying any particular area as critical 
ha