Named for their bleating, sheep-like call, sheep frogs use their small mouths to consume ants and termites. Infrequently seen above ground, these frogs protect themselves by hiding in their burrows and emerging only at night. It is also likely that sheep frogs derive protection from their sticky skin secretions.
Sheep Frog Basics
Sheep frogs (Hypopachus variolosus) range from Costa Rica to Texas. They show a strong preference for areas with an average relative humidity of at least 80 percent. Sheep frogs begin breeding within 24 hours of significant rains, often assembling at temporary water sources. Males call out to females while floating in the shallow water. Sheep frog eggs hatch in about 12 hours, and the young must develop quickly, before their puddle or ditch dries up. Tadpoles typically complete metamorphosis in about one month. Adult frogs usually live in open forests or fields with short grass. Unless heavy rains force them to leave their burrows, they spend most of their time inside them, leaving only to feed or mate.
Sheep Frog Predators
Because sheep frogs are small—about 1½ inches long as adults—they are likely eaten by a variety of predators. The only recorded predator of sheep frogs is the Western ribbon snake (Thamnophis proximus), but garter snakes (Thamnophis sp.) inhabit the same range, and likely consume sheep frogs as well. Scientists have documented these snakes consuming up to 10 newly metamorphosed frogs at a time. Scientists speculate that aquatic turtles—specifically cooters (Pseudemys sp.)—consume many of the new frogs, and birds are likely important predators.
Newly metamorphosed sheep frogs disperse from the wetlands in which they emerged, and seek underground, upland sites. Along the way they must watch out for a variety of predators, so they travel near cover and hide as necessary. The frogs will hide under any object that provides protection, including logs, rocks, leaves, cow dung and human debris.
Nocturnal activity patterns are a common defensive tactic among amphibians. By restricting their movements by day, and primarily exiting their burrows at night, sheep frogs manage to avoid birds, as most of these are not active at night. Nocturnal behavior patterns also help sheep frogs avoid some of the strictly diurnal snakes.
Sheep frogs produce skin secretions, and scientists suspect that they serve a defensive purpose. Though scientists have not specifically studied sheep frog secretions in detail, these secretions are very sticky; sticky secretions produced by other amphibians often deter snakes. The skin secretions of many amphibians are toxic, and researchers suspect that sheep frog secretions are as well.