Federal Register / Vol. 82, No. 181 / Wednesday, September 20, 2017 / Rules and Regulations 43897 

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. 

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 http://

www.regulations.gov and at http://

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 http://

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 

http://www.regulations.gov and at 

http://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 longterm 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 (°C) (113 

degrees Fahrenheit (°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 groundwaterfed 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

High (Good) Moderate Low None 

A population with high resilience is 

where: 

• All or the majority of turtles are 

able to complete their life functions; 

• Breeding is successful to maintain a stable or increasing population; 

• Population is able to withstand 

stochastic events or recover 

from stochastic events from connected populations. 

A population with moderate resilience is where: 

• Some turtles can complete life 

functions; 

• Some turtles have some successful breeding, but population 

is not increasing; 

• Population could be stable or 

decreasing; 

• Population could withstand 

some stochastic events or a 

portion of the population could 

withstand stochastic events, but 

population is not able to recover through the immigration 

of connected populations. 

A population with low resilience is 

one where: 

• Some or few turtles can complete life functions; 

• Some or few turtles have successful breeding, but population 

is decreasing; 

• Population is not able to withstand stochastic events, and is 

not able to recover through the 

immigration of connected populations. 

A population with no resiliency is 

one that might be extirpated 

completely. 

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 subadult 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, 


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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-theyear (< 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 markrecapture 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

Country Population name 

Current Moderate case scenario 

Condition 

7-year 35-year 70-year 

time step time step time step 

United States ........ Quitobaquito Springs .......................... Moderate .............. Moderate .............. Moderate .............. Low 

Mexico .................. Papalote Reach (Agua Dulce) ........... Moderate .............. Moderate .............. None .................... None 

Sonoyta Sewage Lagoon ................... Moderate .............. Low ...................... None .................... None 

New Sonoyta wastewater treatment 

plant.

None .................... Moderate .............. Moderate .............. Moderate 

Xochimilco Reach ...............................

(Sonoyta Reach) ................................

Low ...................... Low ...................... None .................... None 

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 


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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 


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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 longterm 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 


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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 


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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 

habitat. In accordance with the Act and 

our implementing regulations at 50 CFR 

424.12(b), we review available 

information pertaining to the habitat 

requirements of the species and identify 

specific areas within the geographical 

area occupied by the species at the time 

of listing and any specific areas outside 

the geographical area occupied by the 

species to be considered for designation 

as critical habitat. A careful assessment 

of the economic impacts that may occur 

due to a critical habitat designation is 

still ongoing, and we are in the process 

of working with Customs and Border 

Protection and the National Park Service 

in acquiring the necessary information 

needed to perform that assessment. The 

information sufficient to perform a 

required analysis of the impacts of the 

designation is lacking. Accordingly, we 

find that critical habitat for this 

subspecies, in accordance with section 

4(a)(3)(A) of the Act, to be not 

determinable at this time. When critical 

habitat is not determinable, the Act 

allows the Service an additional year to 

publish a critical habitat designation (16 

U.S.C. 1533(b)(6)(C)(ii)). 

Available Conservation Measures 

Conservation measures provided to 

species listed as endangered or 

threatened species under the Act 

include recognition, recovery actions, 

requirements for Federal protection, and 

prohibitions against certain practices. 

Recognition through listing results in 

public awareness, and conservation by 

Federal, State, Tribal, and local 

agencies, private organizations, and 

individuals. The Act encourages 

cooperation with the States and requires 

that recovery actions be carried out for 

all listed species. The protection 

required by Federal agencies and the 

prohibitions against certain activities 

are discussed, in part, below. 

The primary purpose of the Act is the 

conservation of endangered and 

threatened species and the ecosystems 

upon which they depend. The ultimate 

goal of such conservation efforts is the 

recovery of these listed species, so that 

they no longer need the protective 

measures of the Act. Subsection 4(f) of 

the Act requires the Service to develop 

and implement recovery plans for the 

conservation of endangered and 

threatened species. The recovery 

planning process involves the 

identification of actions that are 

necessary to halt or reverse the species’ 

decline by addressing the threats to its 

survival and recovery. The goal of this 

process is to restore listed species to a 

point where they are secure, selfsustaining, and functioning components 

of their ecosystems. 

Recovery planning includes the 

development of a recovery outline 

shortly after a species is listed and 

preparation of a draft and final recovery 

plan. The recovery outline guides the 

immediate implementation of urgent 

recovery actions and describes the 

process to be used to develop a recovery 

plan. Revisions of the plan may be done 

to address continuing or new threats to 

the species, as new substantive 

information becomes available. The 

recovery plan identifies site-specific 

management actions that set a trigger for 

review of the five factors that control 

whether a species remains endangered 

or may be downlisted or delisted, and 

methods for monitoring recovery 

progress. Recovery plans also establish 

a framework for agencies to coordinate 

their recovery efforts and provide 

estimates of the cost of implementing 

recovery tasks. Recovery teams 

(composed of species experts, Federal 

and State agencies, nongovernmental 

organizations, and stakeholders) are 


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43906 Federal Register / Vol. 82, No. 181 / Wednesday, September 20, 2017 / Rules and Regulations 

often established to develop recovery 

plans. When completed, the recovery 

outline, draft recovery plan, and the 

final recovery plan will be available on 

our Web site (http://www.fws.gov/ 

endangered) or from our Arizona 

Ecological Services Field Office (see FOR

FURTHER INFORMATION CONTACT). 

Implementation of recovery actions 

generally requires the participation of a 

broad range of partners, including other 

Federal agencies, States, Tribes, 

nongovernmental organizations, 

businesses, and private landowners. 

Examples of recovery actions include 

habitat restoration (e.g., restoration of 

native vegetation), research, captive 

propagation and reintroduction, and 

outreach and education. The recovery of 

many listed species cannot be 

accomplished solely on Federal lands 

because their range may occur primarily 

or solely on non-Federal lands. To 

achieve recovery of these species 

requires cooperative conservation efforts 

on private, State, and Tribal lands. 

Following publication of this final 

listing rule, funding for recovery actions 

will be available from a variety of 

sources, including Federal budgets, 

State programs, and cost share grants for 

non-Federal landowners, the academic 

community, and nongovernmental 

organizations. In addition, pursuant to 

section 6 of the Act, the State of Arizona 

will be eligible for Federal funds to 

implement management actions that 

promote the protection or recovery of 

the Sonoyta mud turtle. Information on 

our grant programs that are available to 

aid species recovery can be found at: 

http://www.fws.gov/grants. 

Please let us know if you are 

interested in participating in recovery 

efforts for the Sonoyta mud turtle. 

Additionally, we invite you to submit 

any new information on this subspecies 

whenever it becomes available and any 

information you may have for recovery 

planning purposes (see FOR FURTHER

INFORMATION CONTACT). 

Section 7(a) of the Act requires 

Federal agencies to evaluate their 

actions with respect to any species that 

is listed as an endangered or threatened 

species and with respect to its critical 

habitat, if any is designated. Regulations 

implementing this interagency 

cooperation provision of the Act are 

codified at 50 CFR part 402. Section 

7(a)(2) of the Act requires Federal 

agencies to ensure that activities they 

authorize, fund, or carry out are not 

likely to jeopardize the continued 

existence of any endangered or 

threatened species or destroy or 

adversely modify its critical habitat. If a 

Federal action may affect a listed 

species or its critical habitat, the 

responsible Federal agency must enter 

into consultation with the Service. 

Federal agency actions within the 

subspecies’ habitat that may require 

conference or consultation or both as 

described in the preceding paragraph 

include management and any other 

landscape-altering activities on Federal 

lands administered by NPS (Organ Pipe 

Cactus National Monument) and U.S. 

Customs and Border Protection. 

The Act and its implementing 

regulations set forth a series of general 

prohibitions and exceptions that apply 

to endangered wildlife. The prohibitions 

of section 9(a)(1) of the Act, codified at 

50 CFR 17.21, make it illegal for any 

person subject to the jurisdiction of the 

United States to take (which includes 

harass, harm, pursue, hunt, shoot, 

wound, kill, trap, capture, or collect; or 

to attempt any of these) endangered 

wildlife within the United States or on 

the high seas. In addition, it is unlawful 

to import; export; deliver, receive, carry, 

transport, or ship in interstate or foreign 

commerce in the course of commercial 

activity; or sell or offer for sale in 

interstate or foreign commerce any 

listed species. It is also illegal to 

possess, sell, deliver, carry, transport, or 

ship any such wildlife that has been 

taken illegally. Certain exceptions apply 

to employees of the Service, the 

National Marine Fisheries Service, other 

Federal land management agencies, and 

State conservation agencies. 

We may issue permits to carry out 

otherwise prohibited activities 

involving endangered wildlife under 

certain circumstances. Regulations 

governing permits are codified at 50 

CFR 17.22. With regard to endangered 

wildlife, a permit may be issued for the 

following purposes: for scientific 

purposes, to enhance the propagation or 

survival of the species, and for 

incidental take in connection with 

otherwise lawful activities. There are 

also certain statutory exemptions from 

the prohibitions, which are set forth at 

sections 9 and 10 of the Act. 

It is our policy, as published in the 

Federal Register on July 1, 1994 (59 FR 

34272), to identify to the maximum 

extent practicable at the time a species 

is listed, those activities that would or 

would not constitute a violation of 

section 9 of the Act. The intent of this 

policy is to increase public awareness of 

the effect of a final listing on proposed 

and ongoing activities within the range 

of a listed species. At this time, we are 

unable to identify specific activities that 

would not be considered to result in a 

violation of section 9 of the Act because 

the Sonoyta mud turtle sites where the 

species currently occurs are subject to a 

variety of potential activities, and it is 

likely that site-specific conservation 

measures may be needed for activities 

that may directly or indirectly affect the 

species. Based on the best available 

information, the following actions are 

likely to result in a violation of section 

9; this list is not comprehensive: 

(1) Unauthorized handling or 

collecting of the Sonoyta mud turtle. 

(2) Destruction/alteration of Sonoyta 

mud turtle habitat by discharge of fill 

material, draining, ditching, tiling, pond 

construction, stream channelization or 

diversion, removal or destruction of 

emergent aquatic vegetation; or 

diversion or alteration of surface or 

ground water flow into or out of the 

wetland (i.e., due to roads, 

impoundments, discharge pipes, storm 

water detention basins, etc.) or in any 

body of water in which the Sonoyta 

mud turtle is known to occur. 

(3) Direct or indirect destruction of 

riparian habitat. 

(4) Introduction of nonnative species 

that compete with or prey upon the 

Sonoyta mud turtle, such as the 

introduction of nonnative fish and 

crayfish species. 

(5) Release of biological control agents 

that attack any life stage of this 

subspecies. 

(6) Discharge of chemicals or fill 

material into any waters in which the 

Sonoyta mud turtle is known to occur. 

Questions regarding whether specific 

activities would constitute a violation of 

section 9 of the Act should be directed 

to the Arizona Ecological Services Field 

Office (see FOR FURTHER INFORMATION

CONTACT). 

Required Determinations 

National Environmental Policy Act (42 

U.S.C. 4321 et seq.) 

We have determined that 

environmental assessments and 

environmental impact statements, as 

defined under the authority of the 

National Environmental Policy Act 

(NEPA; 42 U.S.C. 4321 et seq.), need not 

be prepared in connection with listing 

a species as an endangered or 

threatened species under the 

Endangered Species 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), Executive 

Order 13175 (Consultation and 

Coordination With Indian Tribal 


sradovich on DSKBBY8HB2PROD with RULES
Federal Register / Vol. 82, No. 181 / Wednesday, September 20, 2017 / Rules and Regulations 43907 

Governments), 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. 

Based on cultural claims maps and 

reservation boundaries we have on file, 

the distribution of the Sonoyta mud 

turtle overlaps areas that may be of 

interest to the following tribes: Tohono 

O’odham Nation, Quechan Tribe, Hopi 

Tribe, Colorado River Indian Tribes, and 

Cocopah Indian Tribe. On November 20, 

2015, we notified these tribes via letter 

of our intent to conduct a status 

assessment for the purpose of 

determining whether the subspecies 

warrants protection under the Act. In 

our letter, we offered to meet with the 

tribe to discuss the process, potential 

impacts to the tribes, and how tribal 

information may be used in our 

assessment. In addition, we requested 

any information they have regarding the 

subspecies. On August 17, 2016, we 

invited comments from the five tribes, 

and on September 19, 2016, we 

submitted notification to tribal leaders 

of the proposed listing publication. To 

date, we have not received a response 

from these any of these tribes. Upon 

publication of this final rule, we will 

send notification letters to these tribes 

and again extend an invitation to meet 

and discuss. 

References Cited 

A complete list of references cited in 

this rulemaking is available in the SSA 

Report (U.S. Fish and Wildlife Service 

2017. Species status assessment report 

for the Sonoyta mud turtle (Kinosternon 

sonoriense longifemorale), Version 2.0. 

Albuquerque, NM) that is available on 

the Internet at http://

www.regulations.gov at Docket Number 

FWS–R2–ES–2016–0103, at https://

www.fws.gov/southwest/es/arizona/, 

and upon request from the Arizona 

Ecological Services Field Office (see FOR

FURTHER INFORMATION CONTACT). 

Authors 

The primary authors of this final rule 

are the staff members of the Arizona 

Ecological Services Field Office. 

List of Subjects in 50 CFR Part 17 

Endangered and threatened species, 

Exports, Imports, Reporting and 

recordkeeping requirements, 

Transportation. 

Regulation Promulgation 

Accordingly, we amend part 17, 

subchapter B of chapter I, title 50 of the 

Code of Federal Regulations, as follows: 

PART 17—ENDANGERED AND 

THREATENED WILDLIFE AND PLANTS 

■ 1. The authority citation for part 17 

continues to read as follows: 

Authority: 16 U.S.C. 1361–1407; 1531– 

1544; 4201–4245, unless otherwise noted. 

■ 2. In § 17.11(h), add an entry for 

‘‘Turtle, Sonoyta mud’’ to the List of 

Endangered and Threatened Wildlife in 

alphabetical order under REPTILES to 

read as set forth below: 

§ 17.11 Endangered and threatened 

wildlife. 

* * * * * 

(h) * * * 

Common name Scientific name Where listed Status Listing citations and 

applicable rules 

*******

REPTILES 

*******

Turtle, Sonoyta mud .......... Kinosternon .......................

sonoriense longifemorale ..

Wherever found ................ E ........................................ 82 FR [insert Federal 

Register page where 

the document begins], 9/ 

20/2017. 

*******

* * * * * Dated: September 7, 2017. 

James W. Kurth, 

Acting Director, U.S. Fish and Wildlife 

Service. 

[FR Doc. 2017–20072 Filed 9–19–17; 8:45 am] 

BILLING CODE 4333–15–P 


sradovich on DSKBBY8HB2PROD with RULES