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Chiricahua Leopard Frog (Rana chiricahuensis)

[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”723″ img_size=”large” alignment=”center” style=”vc_box_rounded”][vc_column_text]Chiricahua Leopard Frog, Santa Cruz Co., AZ. Photo by Jim Rorabaugh[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”1425″ img_size=”medium” add_caption=”yes” alignment=”center” onclick=”img_link_large”][vc_column_text]Chiricahua Leopard Frog, Santa Cruz County, AZ. Photo by Jim Rorabaugh[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”1424″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Chiricahua Leopard Frog egg masses, Huachuca Mtns, AZ. Photo by Jim Rorabaugh[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”1428″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sonoran Whipsnake eating Chiricahua Leopard Frog, Dragoon Mtns, AZ. Photo by Jim Rorabaugh[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”1426″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Reproductive interference. Male Chiricahua Leopard Frog in amplexus with a female Bullfrog. Pieper Hatchery Spring, Tonto Nat Forest. Photo by Abi King[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”1430″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]IChiricahua Leopard Frog, Dragoon Mtns, AZ. Photo by Jim Rorabaugh[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column width=”1/6″][/vc_column][vc_column width=”2/3″][vc_column_text]

Description

Editor’s Note: We follow Amphibiaweb and Yuan et al. (2016: Systematic Biology, doi: 10.1093/sysbio/syw055) in our usage of Rana rather than Lithobates for Arizona’s ranid frogs.

The relationships of anurans commonly called “leopard frogs” or “meadow frogs” have baffled herpetologists for over 100 years (Moore 1975, Hillis 1988). From the mid-1920s through the early-1960s, most authorities listed only one to three species of leopard frog in the southwestern United States (Moore 1944, Wright and Wright 1949, Stebbins 1951), including the broad-ranging Rana pipiens, as well as R. fisheri and R. onca of southwestern Nevada and adjacent portions of Utah and Arizona (although some considered the latter two to be subspecies of pipiens, or to be synonyms – see Pace 1974). Wright and Wright (1949) recognized considerable variation within R. pipiens in North America, even singling out questionable frogs in a section of their book called “Arizona Puzzles.” In addition, they were among the first authorities to refer to the leopard frogs as the R. pipiens complex. Interestingly, they noted large leopard frogs from Carr

Canyon, Huachuca Mountains, AZ that they keyed out to R. montezumae of Mexico, which was among the first recognition of a frog that would later be named Lithobates chiricahuensis. Mecham (1968) quantified the morphological differences between the “southern form” (=L. chiricahuensis) and the Northern Leopard Frog (L. pipiens) in the White Mountains of Arizona. He stated that this southern form resembled frogs from southwestern New Mexico and southeastern Arizona. Employing electrophoresis of frog hemoglobin, Platz and Platz (1973) presented evidence for three species of leopard frogs in Arizona, including the northern form (= L. pipiens), Mecham’s southern form, and the lowland form. Platz and Mecham (1979) subsequently described the southern form as the Chiricahua Leopard Frog (Rana [=Lithobates] chiricahuensis) and Platz and Frost (1984) described the lowland form as the Lowland Leopard Frog (Rana [=Lithobates] yavapaiensis). The type locality for the Chiricahua Leopard Frog is Herb Martyr Reservoir in Cave Creek of the Chiricahua Mountains, AZ. Frost et al. (2006) proposed the genus name Lithobates for all leopard frogs and other related Ranid frogs, which was subsequently adopted by the Society for the Study of Reptiles and Amphibians (Crother 2008, 2012), but remains controversial (see Pauly et al. 2009). 

Based primarily on its propensity to call underwater, large, knob-like toe-tips, and unique body proportions, Platz (1993) described the Ramsey Canyon Leopard Frog (Rana [=Lithobates] subaquavocalis) as distinct from the Chiricahua Leopard Frog. However, subsequent genetic studies did not support this designation (Goldberg et al. 2004, Hillis and Wilcox 2005), and subaquavocalis is now considered synonymous with L. chiricahuensis (Crother 2012). Using a 50-loci starch gel survey, morphometrics, and analyses of nuclear DNA, Platz and Grudzien (1999) presented evidence that northern populations of the Chiricahua Leopard Frog (north of the Gila River) represent a species distinct from the southern populations. Goldberg et al. (2004) demonstrated that frogs from these two regions showed a 2.4% average divergence in mitochondrial DNA sequences. Hillis and Wilcox (2005) suggested the northern populations could be the Vegas Valley Leopard Frog (Rana [=Lithobates] fisheri), a species not seen since 1942 and thought to be extinct (Jennings 2005). In a recent study, Hekkala et al. (2011) confirmed that mitochondrial and nuclear DNA differed between most northern and southern populations, and that populations in the western part of the Mogollon Rim were concordant with Rana (=Lithobates) fisheri. The Gila River is a rough boundary between the two forms in Arizona, but the southern populations include frogs from Dix Creek and adjacent areas north of the Gila River, and in west-central New Mexico the boundary between these taxa may be an east-west, rather than north-south divide. However, further work in the lab of Dr. Melanie Culver at the University of Arizona using samples collected throughout the range of the species should clarify these relationships. Until this study is complete, we consider the northern and southern populations to be L. chiricahuensis. 

Description and Similar Species

The Chiricahua Leopard Frog is a large (< 125 mm SVL) and stocky frog with a relatively rugose or tuberculate dorsum and dorsolateral folds that are broken posteriorly and inset medially (Platz and Mecham 1979, Platz et al. 1997, Figs. 1 and 2). The eyes are protuberant, positioned relatively high on the head, and have been called “upturned” (Stebbins 2003). The snout is rounded. Males possess prominent vocal sacs, one on each side just below and behind the tympanum. Webbing is lacking between the digits of the hands, but usually extends to the knuckle between the second to the last and distal phalanges on all but the third (and longest) digit of the feet. Webbing extends from about half to most of the distance along that third digit. Males from the southern populations have rudimentary vestigial oviducts, whereas northern males generally lack any evidence of oviducts (Platz and Mecham 1979, Degenhardt et al. 1996, pers. obs.).

The dorsal background color varies from light brown to dark brownish-gray or green. In some populations, such as in the Huachuca Mountains, most frogs are a bright green over most of the dorsum. In other areas, green may be present only atop the head and on the upper back, or it may be absent entirely. Frogs from northern populations are much less likely to be green. The back, sides, and head have numerous small dark brown to black spots. One or more spots are usually present on the head anterior to the eyes. Most individuals lack a light spot on the tympanum. The hind limbs have dark crossbars, and the front limbs are

similarly barred or have dark spots. Dorsal spots and crossbars often fade with age and are absent in some very large frogs. The rear of the thigh in adults from southern populations typically is a salt and pepper pattern consisting of a very dark background overlain with numerous white-tipped pustules that are most prominent near the urostyle (Fig. 3). Juveniles may exhibit a dark reticulation on the rear of the thigh or have the salt and pepper pattern. The salt and pepper pattern is also present in many northern frogs, but some juveniles and adults exhibit a dark and light reticulate pattern. There is no discernible light upper lip stripe anterior to the eyes, although that area may be a green that is somewhat lighter in color than surrounding pigment. The venter is cream to yellowish cream, often with grayish mottling on the chin and throat (Platz and Mecham 1979, Degenhardt et al. 1996, Dodd 2013, pers. obs.). Individual Chiricahua Leopard Frogs can darken their skin color in response to low water temperature and reduced reflectance off the water’s surface (Fernandez and Bagnara 1991, 1993).

Lemos-Espinal et al. (2013) noted some differences in Chiricahua Leopard Frogs from southwestern Chihuahua as compared to those in Sonora and the United States. The maximum SVL is 58 mm, and they are dark gray-brown and have fewer spots on the dorsum. The authors suggest these differences may reflect taxonomic distinctiveness.

Chiricahua Leopard Frog tadpoles are relatively stocky for a leopard frog and grow to > 80 mm total length prior to metamorphosis. Small tadpoles are a dark velvety olive dorsally and on the sides, and white to pale gray with bronze patches ventrally. Large tadpoles are generally dark gray or olive dorsally with pale venters and heavy mottling on the tail fin (Scott and Jennings 1985, Fig. 4). Mouth parts are illustrated in Scott and Jennings (1985). Lateral lines of southwestern US leopard frog tadpoles may be diagnostic (Fritts et al. 1984), but these differences need to be more fully explored.

None of the other five leopard frogs in Arizona, or other three leopard frogs in the 100-Mile Circle, ever exhibit a salt and pepper pattern on the rear of the thigh. The Chiricahua Leopard Frog is also the only leopard frog species in our area likely to have a dorsum that is entirely green (although many Chiricahua Leopard Frogs lack green in the dorsal pattern). The upturned eyes are also diagnostic. In all other leopard frogs in our area the eyes are positioned lower down, so the angle of view is more or less lateral to the head, rather than upturned. These characters combined with a preponderance of small, dark spots on the dorsum and relatively rough skin are usually enough to distinguish this species from other southwestern leopard frogs. The advertisement call of the Chiricahua Leopard Frog is also diagnostic (see Activity and Reproduction). American Bullfrogs (Lithobates catesbeianus) sometimes have irregular dark spots on the dorsum, but they grow to a much larger size (< 203 mm SVL) and lack dorsolateral folds. The Chiricahua Leopard Frog is known to hybridize with the Northern Leopard Frog and Lowland Leopard Frog. In wild populations, rates of hybridization are low (0-7%, Platz and Mecham 1979), although Green and Delisle (1985) noted two of four frogs were hybrids at a site with Northern and Chiricahua leopard frogs in Coconino County, AZ. Frost and Bagnara (1977) found no evidence for hybridization between the Chiricahua and Plains (L. blairi) leopard frogs.

Distribution and Habitat Use

The distribution of the species as recognized herein is divided into northern and southern disjunct regions, separated by lower elevation deserts and grassland (Platz and Mecham 1984, USFWS 2007, Fig. 5). These areas do not match precisely Hekkala et al.’s northern and southern genetic units discussed above. The northern distributional unit lies north of the Gila River in Arizona, and north of Interstate 10 in New Mexico. Populations in this unit occur or occurred at scattered localities from the upper Fossil Creek drainage in extreme eastern Yavapai County, AZ east through the mountains (above and below the Mogollon Rim) to the eastern bajada of the Black Range in the Río Grande drainage of Sierra and Socorro counties, NM. In Arizona, the species occurred historically as far north as Chevelon Creek and other sites in the Little Colorado River drainage and as far south as Ash Creek on the San Carlos Apache Reservation and sites in the Eagle, Dix, and Coal creek drainages of the Apache-Sitgreaves National Forest in Greenlee County. In New Mexico, northern populations occurred from the Tularosa River in Catron County south to the Mimbres River and vicinity in Grant County. The extirpated Las Vegas Valley, Nevada frogs (Hekkala et al. 2011) occurred about 370 km northwest of the nearest traditionally recognized Chiricahua Leopard Frog population.

To the south, populations occur or occurred from the Baboquivari Mountains in Pima County, AZ eastward to the Animas Mountains and Playas Valley, Hidalgo County, NM and south well into Mexico. The northern-most records south of the Gila River in Arizona are two specimens from the base of the Pinaleño Mountains, Graham County. The species is also known from the nearby Galiuro Mountains. In Mexico, the Chiricahua Leopard Frog occurs or occurred in eastern Sonora, western Chihuahua, and adjacent Durango, Mexico (Rorabaugh 2008, Lemos-Espinal and Smith 2007, Streicher et al. 2012). The southern distributional limit is unclear. Diaz and Diaz (1997) reported the species from Aguascalientes; however, chiricahuensis-like frogs of Mexico, including Lithobates montezumae and L. lemosespinali could be confused with the Chiricahua Leopard Frog, and the relationships of these similar frogs to each other and L. chiricahuensis need further work, particularly in regard to L. lemosespinali.

The Chiricahua Leopard Frog is a species of high valleys and mountains, from about 1,034 m elevation in the Altar Valley, Pima County, to 2,709 m in the White Mountains, AZ. Vegetation communities in these areas include Chihuahuan desertscrub, semi-desert grassland, plains grassland, oak woodland, pinyon-juniper woodland, pine-oak woodland, and mixed conifer forest. Within these communities, the Chiricahua Leopard Frog is typically found at or near ciénegas, pools, livestock tanks, mine adits, wells, lakes, reservoirs, streams, and rivers with permanent or nearly permanent surface water. This species is rare or absent in high gradient, shallow flowing water, and more likely to be found in deep, still pools.

Some other Ranid frogs (e.g. Northern Leopard Frog) use different habitats seasonally, and move among those habitats as the seasons change. No marked seasonal use has been noted in the Chiricahua Leopard Frog, except that when the summer rains come, the frogs often spread out along drainages into ephemeral reaches and likely use the uplands to a greater degree than during the dry foresummer. Based on our anecdotal observations, juveniles may use shallow water and marshy areas more than adults, as well. During drought, when water is scarce, Chiricahua Leopard Frogs concentrate into the last remaining pools. At dry cattle tanks, they have been found in cracks in the mud where conditions remain moist.

Individuals are known to travel overland or along arroyos for several kilometers, hence occasional individuals may be found in the uplands or along ephemeral drainages far from permanent water. In 1974, Frost and Bagnara (1977) noted passive or active movement of Chiricahua and Plains leopard frogs for 8 km or more along West Turkey Creek in the Chiricahua Mountains. In August 1996, Rosen and Schwalbe (1998) found up to 25 young adult and subadult Chiricahua Leopard Frogs at a roadside puddle in the San Bernardino Valley, AZ.  They believed the only possible origin of these frogs was a stock tank 5.4 km away. In September 2009, 15-20 Chiricahua Leopard Frogs were found at Peña Blanca Lake west of Nogales, AZ. The nearest likely source population was Summit Tank, a straight line distance of 5 km overland and approximately 6.6 km along intermittent drainages. Five of eight frogs tracked with telemetry moved 220-2,450 m along a drainage in New Mexico during about six weeks in September and October. The other three moved minimally (Christman et al. 2003). These frogs often occur in metapopulations that may include one or more sites where water is dependable and breeding occurs in most years, and other satellite occurrences in less suitable habitat where breeding only occurs in wet years, breeding does not result in recruitment, or frogs occur only as dispersing individuals that do not breed. These wetland sites are usually no more than 8 km apart, and may be connected via permanent or ephemeral streams (USFWS 2007).

Activity and Reproduction

Activity depends primarily on water temperature. As water temperature drops to 12-13⁰ C or below, frogs are rarely seen. At water temperatures of 14⁰ C and above usually some frogs are found active. Active frogs have been found year-round in warm springs in New Mexico, but where water temperature varies with ambient air temperature, frogs are most active from April through September. Chiricahua Leopard Frogs are easiest to approach and identify at night with a flashlight or headlamp, but they are active day and night. Juveniles are perhaps more active by day, and adults more active at night (Jennings 1988). Winter retreats have not been identified; however, Northern Leopard Frogs are known to overwinter at the bottom of well-oxygenated ponds or lakes, they may dig shallow depressions or bury themselves in mud, and they have been found during the winter in caves (Rand 1950, Emery et al. 1972, Nussbaum et al. 1983, Cunjak 1986, Harding 1997).

Breeding has been observed every month of the year (Frost and Platz 1983, Scott and Jennings 1985, Sredl and Jennings 2005), although most breeding likely occurs from February into September. Breeding in the winter months may be limited to warm springs (Scott and Jennings 1985).  Frost and Platz (1983) noted that populations occurring above 1,800 m tend to have a shorter breeding season, primarily from June through August; although Scott and Jennings (1985) noted no elevational differences in breeding activity in New Mexico. Reduced oviposition has been noted in the hot, dry period of May and June (Scott and Jennings 1985). The male advertisement is a snore with a pulse rate of 16.8-38.7/second and lasting 1-2 seconds that may be followed by grunts, mew, or croak calls (Platz and Mecham 1979, Davidson 1996). Frost and Platz (1983) provide a sonogram. The call can be heard by following this link:

http://amphibiaweb.org/sounds/Rana_chiricahuensis65.mp3

Males usually call from the water’s edge, from shallows, or while floating in mats of aquatic vegetation. Most calling occurs by frogs that are partially submerged, but some call underwater.  Calls recorded underwater sound quite different from those recorded out of water (compare L. chiricahuensis and L. “subaquavocalis” recordings on the Davidson 1996 CD). But to the ear, heard out of the water, both sound similar (the underwater calls are muffled and not as loud). While calling, males have been observed to engage in fisticuffs with other males, presumably to defend prime calling locations (Sredl and Jennings 2005). No other territorial behavior is known.

Males from Socorro and Catron counties, NM exhibited adult characteristics at > 53.5 and > 56.2 mm SVL, respectively (Sredl and Jennings 2005). Size at maturity for females is unknown. In ideal conditions, maturity may be reached in the first year of life; however, Platz (1997) suggested frogs may not mature until age six in Ramsey Canyon. Amplexus is axillary, takes place in water, and may last as long as 20 hours (Platz 1997, Sredl and Jennings 2005). Eggs are laid in spherical masses that are usually attached to submerged vegetation or may be set atop mats of algae or other submerged aquatic plants. They are usually placed within 5 cm of the water’s surface and contain 300-2,040 eggs (Jennings and Scott 1991, Platz 1997, Fig. 6). Size of the egg mass is typically correlated with female body size. Time to hatching depends at least in part on water temperature and varies from about 8-14 days (Zweifel 1968, Platz 1997, Sredl and Jennings 2005). Tadpoles take from 3-9 months to metamorphose (Jennings 1988, 1990), and they often overwinter. Because of this, and the extended breeding season, multiple size classes of tadpoles are commonly found at breeding sites.

Skeletochronology of frogs from the east side of the Huachuca Mountains, Cochise County, AZ revealed that 47 percent of sampled adults were age six or older. The oldest frogs were estimated at 10 years post-metamorphosis (Platz et al. 1997). However, this area may be anomalous, as Durkin (1995) found no evidence of Chiricahua Leopard Frogs living longer than six years.  Platz et al.’s work in the Huachuca Mountains was before the onset of periodic disease-related die offs. Longevity at that site is probably much less now.

Diet

Christman and Cummer (2006) examined stomach contents of 56 Chiricahua Leopard Frogs from New Mexico. The most common prey items were insects (Coleoptera, Hemiptera, and Diptera – 75.2% by frequency). Vertebrates were uncommon in the diet, and included one Cyprinid fish and remnants of a frog or late stage tadpole. Both terrestrial and aquatic prey were taken in similar proportions (44.6 and 37.3%, respectively). Incidental material in the stomachs included plant material, wood, and stones. The authors concluded that the Chiricahua Leopard Frog is a prey generalist, taking what is available. However, they suggested Bombardier beetles (Brachinus sp.) are avoided. Those beetles were common at frog collection sites but were not found in stomachs.

Field et al. (2003) noted a Rufous or Allen’s Hummingbird taken by a Chiricahua Leopard Frog in Miller Canyon of the Huachuca Mountains, AZ. Captives readily take crickets, mealworm larvae and adults, silkworm larvae, other invertebrates, and small fish (Demlong 1997, USFWS 2007). Cannibalism of larger frogs on smaller frogs occurs in captive colonies and likely occurs in the wild (Jennings 1988). The tadpoles are probably mostly herbivorous. Marti and Fisher (1998) listed the following likely tadpole food items in Ramsey Canyon, Huachuca Mountains: bacteria, diatoms, phytoplankton, filamentous algae, water milfoil, duckweed, and detritus. We have observed wild Chiricahua Leopard Frog tadpoles feeding upon floating algal mats. Large tadpoles have been observed consuming the gelatinous envelopes of conspecific egg masses (Platz 1997). In captivity, tadpoles have been fed rabbit pellets suspended in agar-gelatin blocks, boiled spinach, romaine lettuce, cucumber slices, frozen trout, duckweed, and spirulina fish food (Frost 1982, Demlong 1997).

Predators, Parasites, and Disease

A wide variety of vertebrates and invertebrates likely prey upon Chiricahua Leopard Frogs and their tadpoles and eggs, including aquatic insects, fishes, snakes, birds, American Bullfrogs and possibly other anurans, and a variety of mammals (Sredl and Jennings 2005). However, predation in the wild has rarely been reported. Eric Enderson has a picture on the Tucson Herpetological Society website of a Black-necked Gartersnake (Thamnophis cyrtopsis) eating a metamorph Chiricahua Leopard Frog. Rorabaugh and Jones (in press) observed a Sonoran Whipsnake (Coluber bilineatus) with an adult Chiricahua Leopard Frog in its mouth in the Dragoon Mountains, AZ. Tom Deecken (pers. comm. 2014) watched a Mexican Gartersnake (T. eques) feeding on young Chiricahua Leopard Frogs in the Huachuca Mountains, AZ.

In the laboratory, crayfish (Orconectes virilis) can kill and consume tadpole, metamorph, and adult Chiricahua Leopards Frogs, and their presence has been linked to the disappearance of Chiricahua Leopard Frog populations (Fernandez and Rosen 1996, 1999). Sredl and Howland (1995) found that Chiricahua Leopard Frogs were almost always absent from sites with American Bullfrogs and non-native predatory fishes, such as Bluegill and other sunfishes, Largemouth Bass, and Carp (including Koi). Tiger Salamanders (Ambystoma mavortium) likely prey upon Chiricahua Leopard Frog tadpoles and juvenile frogs. Chiricahua Leopard Frogs coexist with a number of native fishes, and in some sites persist with Mosquitofish (Gambusia affinis, USFWS 2007). The likelihood of coexisting with predators, especially non-native species, is likely correlated with habitat complexity and the presence of escape cover.  Chiricahua Leopard Frogs typically jump into water when threatened, but do not emit an alarm call (Sredl and Jennings 2005).

Goldberg et al. (1998) documented six species of trematodes and one species of nematode in Chiricahua Leopard Frogs from Arizona. A generalized discussion of amphibian parasites and their effects is found in USFWS (2007).

Disease was recognized as an important factor in global amphibian decline in the 1990s, although enigmatic, unexplained population decline and disappearance in seemingly pristine areas had been noted well before that, particularly in the 1970s and 1980’s (Carey et al. 2003). Berger et al. (1998) were the first to describe the amphibian skin disease (Chytridiomycosis) caused by the fungal pathogen Batrachochytium dendrobatidis (Bd). The disease was found to be the cause of wavelike global mortality of metamorphosed amphibians, rapid population decline, with many mortalities in high elevation sites that were often protected from habitat degradation (Carey 2000). This apparently introduced disease (James et al. 2009) was first detected in Arizona in a Lowland Leopard Frog collected in 1972 from Sycamore Canyon, Pajarito Mountains, AZ (T. Jones, pers. comm., also see Sredl 2000 and Bradley et al. 2002 for additional background). The factors governing the likelihood of Bd causing population decline are likely extraordinarily complex; however, the disease appears to cause the greatest impact to populations of Chiricahua Leopard Frogs north of Interstate 10 in New Mexico, although it is present in many populations, and sometimes is associated with die-offs in southern Arizona. Chiricahua Leopard Frogs at warm springs or otherwise warmer sites appear to survive and persist better and longer than frogs at cooler locales. Ranavirus, another emerging infectious disease causing amphibian, reptile, and fish declines in the northern hemisphere, was found in a Chiricahua Leopard Frog in New Mexico (R. Jennings, pers. comm.), but neither its prevalence in Chiricahua Leopard Frog populations nor its effects on the species are understood.

Conservation

Clarkson et al. (1986) were the first to report declining populations of Chiricahua and other leopard frog species in Arizona. Elaborating on that earlier report, Clarkson and Rorabaugh (1989) found Chiricahua Leopard Frogs at only two of 36 sites in Arizona that supported the species in the 1960s and 1970s. They suggested that predation by introduced American Bullfrogs and fishes, as well as habitat alteration were likely contributing factors in observed leopard frog declines in Arizona, but that disappearances of Chiricahua Leopard Frogs were often in places that lacked introduced predators and significant habitat disturbance. In a status assessment of Mexican and Narrow-headed Gartersnakes (Thamnophis eques and T. rufipunctatus, respectively), Rosen and Schwalbe (1988) noted that American Bullfrogs prey upon and had replaced leopard frogs at some sites in southern Arizona. They suggested that non-native predatory fish may have the same effect.

In New Mexico, Randy Jennings did not consider the Chiricahua Leopard Frog in jeopardy based on surveys from 1983-87 (pers. comm. in Clarkson and Rorabaugh 1989), but in a subsequent report, he found the species at only 6 of 33 sites that had supported the species during the previous 11 years (Jennings 1995).

The Chiricahua Leopard Frog was placed on the list of candidate species for federal listing under the Endangered Species Act (ESA) in November 1991. Subsequent studies reinforced earlier findings that the species was declining in Arizona and New Mexico (Hale 1992, Fernandez and Bagnara 1995, Sredl and Howland 1995, Zweifel 1995, Rosen et al. 1996, Sredl et al. 1997, Painter 2000, Rosen and Schwalbe 2002, Boykin and McDaniel 2008, Witte et al. 2008, Rorabaugh 2010, USFWS 2010, and others). Causes of decline are not always clear, but contributing factors mentioned in these reports include predation by introduced species, habitat loss and degradation from a variety of causes, die-offs associated with Bd, loss of metapopulation function, drought, and climate change. Livestock grazing can degrade Chiricahua Leopard Frog habitat, but small impoundments built as water sources for cattle are often important frog habitats. As of 2009, the Chiricahua Leopard Frog occupied at least 131 sites in Arizona and New Mexico, but robust breeding populations were very few in number (only 11 in Arizona). USFWS (2010) concluded that from 2002 to 2009 the status of the Chiricahua Leopard Frog was at least stable and probably improving in Arizona, declining in New Mexico, and unknown in Mexico. More recent status summaries are not available; however, we believe these general conclusions are still valid in 2014.

The Chiricahua Leopard Frog was proposed for federal listing as a threatened species in a Federal Register notice published on 14 June 2000 (65 FR 37343). The final rule was published 13 June 2002 (67 FR 40794) and included a special rule promulgated under section 4d of the ESA that excluded livestock operations and maintenance at cattle tanks on non-federal lands from the ESA’s section 9 take prohibitions. Collection of the species is prohibited by Arizona Game and Fish Commission Order 41, except with special permits. Collection is similarly prohibited in Mexico where the Chiricahua Leopard Frog is listed as a threatened species by the Mexican government. Chiricahua Leopard Frogs are not protected by state regulations in New Mexico. In a 20 March 2012 Federal Register notice, 10,346 acres (4,187 hectares) in 39 units in Arizona and New Mexico were designated as critical habitat for the Chiricahua Leopard Frog (77 FR 16347).

The Chiricahua Leopard Frog Recovery Plan (USFWS 2007) is the primary document guiding conservation activities for this species. It includes recommended recovery actions to reduce or eliminate threats, an implementation schedule for those actions, measurable criteria to gauge recovery success, and much other information needed to conserve the species. Recovery criteria need to be met in each of eight recovery units. The primary recovery actions include 1) protecting remaining populations, 2) identifying, restoring or creating, and protecting unoccupied sites as necessary to support viable Chiricahua Leopard Frog populations and metapopulations, 3) establishing new or reestablishing former populations, 4) augmenting populations as needed to increase persistence, 5) monitoring populations and recovery, 6) conducting research that promotes recovery, 7) developing support for the recovery program, 8) developing cooperative projects with non-federal landowners, 9) amending land use plans as needed, 10) working with Tribal partners, 11) working with Mexican partners, and 12) practicing adaptive management.  The recovery program is guided by a recovery team, three regional steering committees, and numerous local recovery groups, most of which meet on a regular basis. The recovery plan and other documents pertaining to the species can be downloaded from the following site:

http://www.fws.gov/southwest/es/arizona/CLF.htm

In a 5-year review of the frog and the recovery program, USFWS (2010) found that although the requisite number of metapopulations and isolated robust populations needed for recovery had only been met in one recovery unit, through aggressive rearing and introduction, particularly in Arizona (the Phoenix Zoo alone has reared more than 20,000 Chiricahua Leopard Frogs), progress was being made in several other units towards meeting those population criteria. However, in most cases threats had not been adequately addressed, and many management issues still remained to be resolved. Although significant progress has been made, particularly in regard to establishing or reestablishing populations, if on-going recovery actions are interrupted, drought worsens, or other threats intensify, the status of the species could easily deteriorate (USFWS 2010). Chytridiomycosis has been an especially difficult problem in New Mexico where recovery efforts have often focused on conserving existing populations through establishment of secure refugial sites. Dramatically successful American Bullfrog eradication efforts have been conducted in some areas (Peña Blanca Lake area, Altar Valley, Scotia Canyon and vicinity, Las Cienegas and vicinity) with subsequent recovery of Chiricahua Leopard Frog populations; however, continued vigilance will be necessary to ensure bullfrogs are not reintroduced or reinvade from adjacent areas. Other threat abatement and locking in favorable management practices are also needed to complement establishment of frog populations. Successes (Aguilar et al. 2008, Rorabaugh et al. 2008) need to be expanded upon and the momentum accelerated if this frog is to be recovered to the point that it no longer needs the protection of the ESA.

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Authors: James C. Rorabaugh and Michael J. Sredl.   Originally published in the Sonoran Herpetologist: 2014 Sep:61-70.

For additional information on this species, please see the following volumes and pages in the Sonoran Herpetologist: 1995 Sep:95; 1999 Aug:87; 2002 Jul:77; 2003 Mar:32; 2006 Jul:74-77; 2008 Jul:74-77.[/vc_column_text][/vc_column][vc_column width=”1/6″][/vc_column][/vc_row][vc_row][vc_column][gap size=”30px” id=”” class=”” style=””][/vc_column][/vc_row]