|Taxonomic Notes: This species was placed in the genus Lithobates by Frost et al. (2006). However, Yuan et al. (2016, Systematic Biology, doi: 10.1093/sysbio/syw055) showed that this action created problems of paraphyly in other genera. Yuan et al. (2016) recognized subgenera within Rana for the major traditional species groups, with Lithobates used as the subgenus for the Rana palmipes group. AmphibiaWeb recommends the optional use of these subgenera to refer to these major species groups, with names written as Rana (Aquarana) catesbeiana, for example.|
© 2017 Ricardo Ramírez Chaparro (1 of 6)
Rana tarahumarae Boulenger, 1917
James C. Rorabaugh1
1. Historical versus Current Distribution. Tarahumara frogs (Rana tarahumarae) are known from 63 localities in montane canyons in extreme southern Arizona, south to northern Sinaloa and southwestern Chihuahua, Mexico (Campbell, 1931a; Zweifel, 1968c; Hale et al., 1977, 1995; Hale, 2001). Reports of the species from New Mexico (Linsdale, 1933b; Little and Keller, 1937; Wright and Wright, 1949) and at Rose Creek near Roosevelt Reservoir, Arizona, were based on misidentified specimens of American bullfrogs (Rana catesbeiana; Stebbins, 1951; Zweifel, 1968c). The range of Tarahumara frogs is centered in the northern Sierra Madre Occidental of Mexico (McCranie and Wilson, 1987); however, the eastern and southern distributional limits are not clear. Tarahumara frogs may not occur south of the Sierra Surutato in Sinaloa. Apparently suitable habitat occurs in Durango, well south of the current known range, but other ranid frogs occur there, and Tarahumara frogs have not been collected in Durango (Hale and Jarchow, 1988; Hale et al., 1995). Rangewide, most localities are in the mountains of eastern Sonora. In the United States, Tarahumara frogs were known historically from six locales, including three from the Santa Rita Mountains and three from the Atascosa‑Pajarito–Tumacacori Mountains complex, which are located north and west, respectively, of Nogales in Santa Cruz County, Arizona (Campbell, 1931a; Zweifel, 1968c; Hale et al., 1977, 1995). Tarahumara frogs have been extirpated from all localities in Arizona. The last observation of Tarahumara frogs in Arizona, and thus in the United States, was in May 1983 in Big Casa Blanca Canyon in the Santa Rita Mountains. Surveys from May 1998–May 2000 in Sonora yielded Tarahumara frogs at 6 of 11 historical localities and 3 new localities (Hale et al., 1998; Hale, 2001).
2. Historical versus Current Abundance. From 1975–‘77, the mean number of adult Tarahumara frogs was 509 in a 4.8-km reach of Big Casa Blanca Canyon, Santa Rita Mountains, Arizona. Thirty Tarahumara frogs were reported in a 300-m reach of Arroyo el Cobre, southern Sonora, and 22 were found in a 50-m reach of Sycamore Canyon, Pajarito Mountains, Arizona (Hale and May, 1983). Based on qualitative observations, generally, where the species is currently extant, no long-term declines are apparent. However, Hale and May (1983), Hale and Jarchow (1988), and Hale et al. (1995, 1998) describe population declines in progress in Sycamore Canyon in the Pajarito Mountains in 1974, in Big Casa Blanca and Gardner canyons in the Santa Rita Mountains in 1977–‘83, and in northeastern Sonora in the lower reach of Arroyo La Carabina (La Bota) in the Sierra El Tigre in 1981. These declines resulted in extirpation from these locales. Occasional frogs were observed in lower Arroyo La Carabina from 1982–'84 and larvae through 1986, apparently as a result of immigration from the upper canyon where healthy frogs were observed in 1982 and 1983. Healthy, affected, and dead frogs were found during every visit to a site between the lower and upper portions of the canyon from 1982–'86 (Hale and Jarchow, 1988). Frogs were not found during a re‑survey of lower Arroyo La Carabina in May 1998, suggesting that recolonization of the lower canyon by upstream immigrants had not occurred, despite the presence of apparently excellent habitat. In Arroyo El Tigre, Sierra El Tigre, flooding during the summer of 1998–'99 may have eliminated most Tarahumara frog tadpoles (Hale, 2001).
3. Life History Features.
A. Breeding. Reproduction is aquatic.
i. Breeding migrations. Unknown.
ii. Breeding habitat. Breeding habitat is located within oak and pine‑oak woodland and the Pacific coast tropical area (foothill thornscrub and tropical deciduous forest; Hale and May, 1983; McCranie and Wilson, 1987). Breeding occurs primarily toward the end of the dry season (April–May), when permanent water is often restricted to springs and “plunge pools” (deep [> 1 m] pools in bedrock or among boulders) with deep underwater and streamside retreats. Plunge pools in canyons with low mean flows (< 0.2 cubic ft/s) and relatively steep gradients (> 60 m/km of stream) provide the best breeding sites (Hale and May, 1983; Hale, 2001). Permanent water is necessary for metamorphosis. At Pena Blanca Spring, Arizona, and Arroyo El Salto, northeastern Sonora, Tarahumara frogs inhabited artificial impoundments (Hale and May, 1983; Hale, 2001).
i. Egg deposition sites. Richard Zweifel, in a personal communication to Robert Stebbins (Stebbins, 1951), reported an egg mass from Alamo Canyon, Arizona, that was located in a pool in an intermittent stream. The eggs were on the bottom in about 18 cm of water, covered by a layer of sediment. Egg masses in Big Casa Blanca Canyon, Arizona, were found in calm shallows of bedrock pools, attached to the bedrock surface (Hale and May, 1983). A free-floating egg mass was found in the sandy shallows of a bedrock and boulder pool in Arroyo El Chorro, northern Sonora (Hale, 2001).
ii. Clutch size. Based on seven egg masses, Hale and May (1983) report number of eggs/egg mass ranged from 527–1,635 (mean = 1,083, s.e. = 161.4). Approximately 1/2 of an egg mass collected in the Sierra La Madera, Sonora, contained about 900 eggs (Hale, 2001; J.C.R., personal observation).
In Arizona, amplectic frogs and egg masses were typically observed from April to mid May (Hale and May, 1983); however, an egg mass was reported by Zweifel (1955) in late August in Alamo Canyon, Arizona. Hale (2001) reported small tadpoles at Arroyo El Tigre, northeastern Sonora, on 26 October 1999, suggesting egg deposition in late summer or fall.
i. Length of larval stage. Hale and May (1983) reported that tadpoles metamorphose in 2 yr (Hale and May, 1983). Tadpoles reared in semi-wild conditions in Arizona metamorphosed in as little as 86 d, but most took longer than 10 mo (J.C.R. personal observations). Compared to other ranids, Tarahumara frog larvae are large at all stages of development (Webb and Korky, 1977). Larvae grow as large as 106 mm before metamorphosing (Campbell, 1931a). At metamorphosis, frogs are as small as 21 mm SVL, but most are 35–40 mm. Size of larvae vary within and across populations, with larvae of the same stage varying in size by ≤ 20 mm (Webb and Korky, 1977).
ii. Larval requirements. Permanent water.
a. Food. As with most ranid tadpoles, larvae likely are omnivorous with a strong tendency towards algivory. Tadpoles reared in captivity ate spinach, sliced vegetables, fish food, algae, and boiled egg whites (U.S.F.W.S., 2001a).
b. Cover. Probably necessary to avoid currents. Tadpoles are likely transported passively downstream in drainages (Hale and May, 1983).
iii. Larval polymorphisms. None.
iv. Features of metamorphosis. Moderately long; metamorphosed frogs were typically found from June–August in Big Casa Blanca Canyon, Arizona (Hale and May, 1983).
v. Post-metamorphic migrations. Hale and May (1983) report movements along stream courses of ≤ 1,885 m for juveniles (n = 23) in Big Casa Blanca Canyon.
D. Juvenile Habitat. No differences between adult and juvenile frog habitat use have been described.
E. Adult Habitat. Same as breeding habitats. The presence of hibernacula where frogs can remain moist and protected from predators and freezing temperatures is an important habitat feature (Hale and May, 1983), particularly in the northern portion of the species’ range or at higher elevation sites. Hibernacula may include moist refugia among rocks and boulders along streams and at plunge pools.
F. Home Range Size. Hale and May (1983) report movements of ≤ 1,885 m for juveniles (n = 23) and males (n = 21), and ≤ 651 m for females (n = 9) in Big Casa Blanca Canyon. Movements apparently were along stream courses, suggesting linear home ranges, although the authors suggest limited overland movement also occurred. The longest movements occurred between the end of the dry season (June) and the middle of the summer rainy season (August).
G. Territories. Establishment and defense of territories has not been observed, but it is apparent that some individuals prefer to remain at certain pools or stream reaches (Hale and May, 1983).
H. Aestivation/Avoiding Dessication. Hale and May (1983) speculated that some Tarahumara frogs may aestivate during the dry season before the onset of summer rains in July; however, most probably congregate at plunge pools.
I. Seasonal Migrations. Tadpoles are probably transported passively downstream in drainages. Hale and May (1983) observed upstream movements by a majority of frogs during the summer rainy season, followed by mostly downstream movements as fall approached. Juveniles may move upstream in late summer or fall, offsetting downstream dispersal by tadpoles. Frogs may also move upstream in the fall to access hibernacula.
J. Torpor (Hibernation). Tarahumara frogs have been observed from March–October (Zweifel, 1955; Hale and May, 1983), but were not reported during February in Big Casa Blanca Canyon. Whether Tarahumara frogs remain active through the winter in the southern portion of their range is unknown.
K. Interspecific Associations/Exclusions. Tarahumara frogs have been observed in association with canyon treefrogs (Hyla arenicolor) at all localities. In southern Arizona, Tarahumara frogs usually were found in association with Chiricahua leopard frogs (Rana chiricahuensis), while lowland leopard frogs (Rana yavapaiensis) were also present in Sycamore Canyon and at Alamo Spring. Lowland leopard frogs usually are found in association with Tarahumara frogs in northern and central Sonora and are replaced by big-eyed leopard frogs (Rana magnaocularis) in southern Sonora and adjacent areas in western Chihuahua. Arroyo El Cobre in southern Sonora is unique in that it supports both Tarahumara frogs and pustulose frogs (Rana pustulosa). Possible hybrids or intergrades of these species were observed in Arroyo El Cobre by S. Hale in 1999. Erosion from hillsides where tropical deciduous forest has been cut to plant bufflegrass (Pennisetum ciliare) has resulted in siltation of plunge pools at Arroyo El Cobre. This conversion of habitat has favored pustulose frogs (Hale, 2001). In the Sierra Surutato in northern Sinaloa, pustulose frogs apparently replace Tarahumara frogs at low elevation sites and Tarahumara frogs occur at higher elevations (Hale and Jarchow, 1988). Rosy salamanders (Ambystoma rosaceum) are present at most Tarahumara frog sites in Mexico ≥ 1,000 m (Hale and Jarchow, 1988), but also have been found in association with Tarahumara frogs at 700 m in the Sierra Aconchi, northern Sonora (Hale et al., 1998). Tarahumara frogs may be excluded in habitats that support large populations of nonnative predators, such as American bullfrogs and fishes (i.e., green sunfish [Lepomis cyanellus], largemouth bass [Micropterus salmoides]; Hale and May, 1983). Hale (2001) suggested predation by a large chub species (Gila sp.) may have eliminated Tarahumara frogs from two sites in Sonora.
L. Age/Size at Reproductive Maturity. Reproduction probably begins in the second spring following metamorphosis. In Big Casa Blanca Canyon, males matured at ± 64 mm SUL, females at ± 67 mm SUL (Hale and May, 1983).
M. Longevity. The oldest frogs in Big Casa Blanca Canyon were estimated to be at least 6 yr post metamorphosis (Hale and May, 1983).
N. Feeding Behavior. Prey items are diverse and include juvenile Sonoran mud turtles (Kinosternon sonoriense); Sonora chubs (Gila ditaenia); snakes, including black headed snakes (Tantilla atriceps); beetles (including Tenebrionidae, Scarabaeidae, and Buprestidae); moths (Lepidoptera); water bugs (Belostomatidae); scorpions (Scorpionida); centipedes (Chilopoda); grasshoppers (Agrididae); mantids (Mantidae); wasps (Hymenoptera); spiders (Lycosidae); crickets (Gryllidae); caddisflies (Tricoptera); and katydids (Tettigoniidae; Zweifel, 1955; Hale and May, 1983). Both diurnal and nocturnal feeding is indicated based on the activity patterns of prey species.
O. Predators. Hale and May (1983) report a possible predation attempt on a Tarahumara frog by a pair of ringtail cats (Bassariscus astutus) in Sonora. A variety of animals likely prey on frogs, tadpoles, and/or egg masses, including garter snakes (Thamnophis spp.) and other snakes, birds, other frogs, Rosy salamanders, fishes, and invertebrates, particularly species of water bugs, Belostoma and Lethocerus (Hale and May, 1983; Hale, 2001). Predation by non-native fish, particularly sunfishes (Centrarchidae) and American bullfrogs, may have contributed to the disappearance of the species from Pena Blanca Spring and portions of Pena Blanca Canyon, Arizona.
P. Anti‑Predator Mechanisms. When disturbed, frogs typically hop into water where they take refuge under leaf litter, rocks, or other debris. In addition, Tarahumara frogs have skin secretions that can cause mild skin irritation and may be noxious tasting.
Q. Diseases. Hale and Jarchow (1988) list the following possible causal mechanisms in the extirpation of Tarahumara frog populations: (1) winter cold; (2) flooding or severe drought; (3) competition; (4) predation; (5) disease; and (6) heavy metal poisoning. Metals occur naturally in streamside deposits and may be mobilized by acid precipitation events. Acidic rainfall in southeastern Arizona and northern Sonora may have occurred as a result of atmospheric emissions from copper smelters at Cananea and Nacozari, northeastern Sonora, and Douglas, Arizona (Blanchard and Stromberg, 1987; Hale et al., 1995). Cadmium toxicity is a possible cause of observed Tarahumara frog die‑offs in Arroyo La Carabina, Arroyo Pinos Altos, and Arroyo La Colonia in northeastern Sonora, and Big Casa Blanca and Sycamore canyons in Arizona (Hale and Jarchow, 1988; Hale et al., 1998). Cadmium is highly toxic due to its propensity to substitute for zinc and/or copper in enzymes (Coombs, 1979). Absorption through the skin or ingestion of zinc by frogs may act to reduce cadmium toxicity. Thus, in areas of relatively high zinc to cadmium ratios, frogs may be less affected (Hale and Jarchow, 1988; Hale et al., 1998). The solubility of zinc in weak acids may account for its depletion from decades of acidic precipitation on rhyolitic stream banks. Elevated levels of cadmium occur in and near tailings of copper, lead, and zinc mines (Peterson and Alloway, 1979). Cumulative sedimentation from physical erosion and deposition in drainages likely result in elevated concentrations of cadmium in downstream reaches. Thus, stream headwaters and springs may be important refuges for frogs when toxic conditions exist in downstream reaches (Hale et al., 1998). Die‑offs of ranid frogs (Tarahumara frogs, lowland leopard frogs, and Chiricahua leopard frogs) in Sycamore Canyon, Arizona, are similar to die‑offs of Chiricahua leopard frogs reported (Anonymous, 1993) in New Mexico, which were attributed to “post-metamorphic death syndrome.” These die‑offs are also consistent with chytridiomycosis, a fungal disease implicated in declines of anurans in Australia, Central America, (Berger et al., 1998) and elsewhere. Tarahumara frogs collected during a die-off in Sycamore Canyon in 1974 were infected with chytridiomycosis (T.R. Jones and P.J. Fernandez, personal communication). Chytridiomycosis was also confirmed from frogs collected in northeastern and east-central Sonora at Arroyo La Carabina (1981, 1982), Arroyo El Tigre (1999), Arroyo La Colonia (1982), Arroyo El Trigo (1982), and Arroya El Aguaje (1999; Hale, 2001). Tarahumara frogs are extirpated from Sycamore Canyon, Arroyo La Carabina, and Arroyo La Colonia; however, they have persisted at Arroyo El Trigo despite the presence of chytridiomycosis. As well, Hale (2001) presents evidence of population persistence despite chytridiomycosis at Arroyo El Aguaje, Arroyo La Colonia, and Arroyo El Cobre.
R. Parasites. Hale and Jarchow (1988) report mild infestations of nematodes and trematodes in Tarahumara frogs from Arroyo La Carabina and Arroyo El Tigre, northeastern Sonora. Fifteen species of helminths were identified from 42 Tarahumara frogs from Sonora, including a new species (Falcaustra lowei; Bursey and Goldberg, 2001).
4. Conservation. Tarahumara frogs are considered an Endangered species by the Arizona Game and Fish Department (1988) and are included on a draft state list of Species of Concern (Arizona Game and Fish Department, 1996b). Tarahumara frogs have no status under the Federal Endangered Species Act, C.I.T.E.S., or Mexican law. A team of state, federal, and other partners are working to re-introduce this species into suitable habitats in Arizona. A re-introduction plan, awaiting approval by the Arizona Game and Fish Commission, proposes to re-introduce Tarahumara frogs into Sycamore and Big Casa Blanca Canyons (Field et al., 2000; U.S.F.W.S., 2001a; Rorabaugh and Humphrey, 2002).
1James C. Rorabaugh
2Stephen F. Hale
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2017. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 20 Oct 2017.
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