Mesoamerican Burrowing Toads: Rhinophrynidae

The frog uses its strong legs to dig backwards into the ground. As its legs work, the frog twists while blowing up its body with air and then letting the air out. When it is deep enough into the soil, the dirt falls in on top of the frog and eventually covers up the tunneling frog completely. It stays underground most of the time, coming up to the surface during the rainy season, which is when it mates. It may leave its burrows and move above ground at night to look for food, but its large body and short legs make it rather clumsy on land.

The breeding season begins when the heavy rains come. Sometimes, the males make a few calls from their burrows, but they do most of their calling once they find little pools of water. These can be puddles in a farm field, water-filled ditches along a road, or any other small watering hole that forms when the rains come. Males do not breed in ponds that have water in them all year long. From its pool of water, the male begins calling. In many species of frogs, one or two vocal sacs inflate when they call, and each sac looks like a balloon that blows up around its chin. The burrowing toad's sac stays on the inside of its body, so when it fills up with air, the frog's entire body blows up. Every time the male makes his loud mooing call, the air rushes out of his body and pushes the frog backward in the water. Since the male may make its short "ooo" calls 15 to 20 times a minute, the frog continues to scoot around the water backward.

A female comes to a breeding pool, which may contain many males, and picks out a mate by bumping her snout into his chest and throat. He responds by climbing onto her back and grabs onto her with his forelegs just in front of her back legs. She lays a few eggs at a time, sometimes only one, and may mate with different males on several different days, especially if the area gets more than one drenching rain. By the end of the breeding season, each female may have produced thousands of eggs. After she lays the eggs, they sink to the bottom of the water, where they hatch into tadpoles a few days later. The tadpoles group closely together, forming living balls of tadpoles. The larger tadpole balls can reach 3.3 feet (1 meter) in diameter. The tadpoles change into froglets in one to three months. If the water is warmer, they make the change, called metamorphosis (MEH-tuh-MORE-feh-sis), sooner. In cooler water, metamorphosis occurs later.