Blanchard’s Cricket Frog

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Acris blanchardi Harper, 1947

One species that may have been extirpated from Arizona is Blanchard’s Cricket Frog, Acris blanchardi.  The species is known from a single specimen collected in 1905 about 16 km east of Douglas, Cochise County.  It seems likely that this little hylid disappeared from Arizona long ago, although its continued presence in the state cannot be completely ruled out.

Its skin is textured with small tubercles that make it appear rough.  It often has a dorsal blotch that may be orange or green or brown, and its toes have extensive webbing.  In eastern United States populations, it reproduces in late spring or early summer and becomes mature in less than a year.  Very few of these frogs live more than 12 or 14 months, and a drought in any given year may cause local populations to disappear.  Given the amount of attention paid to the Arizona herpetofauna, it is unlikely this frog is still present a supratympanic fold is present.  The fingers lack webbing, but the toes are webbed. The skin can be almost smooth to rugose.  The morphological variation is substantial in this species because it is a complex of multiple taxa (see below).  The call is a sheep-like ba-a-a that lasts about 0.3 seconds and is repeated about every second.

Distribution and Habitat. The species ranges from Colorado to Oaxaca, Mexico.  In Arizona, it would avoid desert extremes by staying close to streams or using wetlands.  Across its range it occurs from elevations near sea level to 2,986 m ASL.  Habitats includes most riparian environments, particularly boulder-strewn streams, canyons, and arroyos. It will wander away from water and is associated with both permanent and intermittent streams.  Three were found using a bird’s nest (Black Phoebe) for daytime refugia, possibly to reduce water loss or avoid predators.

Reproduction occurs in the spring and early in the monsoon.  From March to August, males call from stream edges or rock crevices during or after a rain, day or night.  Clutches of a hundred or more eggs are laid in a mass that may float or be attached to vegetation.  Egg development requires less than two weeks, and tadpoles typically metamorphose in 30 to 75 days, depending on the temperature.  Late breeders may produce tadpoles that overwinter.

Diet.  Prey includes a variety of invertebrates, particularly those found close to streams.  Predators on tadpoles and adults include gartersnakes and predaceous aquatic invertebrates, such as water scavenger beetles and crayfish.  Skin secretions that act as a predator deterrent are produced and may cause mucous membrane irritation in humans.

Taxonomy and Systematics. Seven distinct clades of this frog were found by Bryson et al. (2010) using mitochondrial DNA.  Five clades correspond to well-defined biogeographic regions: the Sonoran Desert, Chihuahuan Desert, Colorado Plateau, Central Mexican Plateau, and Balsas Basin.  Surprisingly, two other clades, one from the southwestern region of the Central Mexican Plateau and one from the Grand Canyon of Arizona, are nested within the Dryophytes eximius group.  Thus, the Canyon Treefrog is genetically split between the Sonoran Desert clade and the combined Chihuahuan Desert, Colorado Plateau, and Central Mexican Plateau clades.  Basal divergences in these frogs began as early as the mid-Miocene (about 13 MYA).

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