The Western Spadefoots
The Spadefoots at Splash were captured when they were just tadpoles. They were very slow to metamorphose, or change, into adults. By the time they were young adults, their vernal pool was too dry for them to be released because they would not be able to dig down and bury themselves to survive the dry phase.
The Western Spadefoot gets its name from the tiny black shovels (spades) on its hind feet. It uses these shovels to dig burrows in the ground where it stays most of the year. Adult Western Spadefoots are almost never seen in the wild. They spend nearly all of their lives buried underground and only come out on a few rainy nights in early spring.
In early spring, after a heavy rain fills up temporary pools, the Spadefoots congregate to breed. The males make a sound like a tiny snore to call females to the breeding pool. On a quiet night, a group of male Spadefoots can be heard almost a mile away.
Females lay several hundred eggs in small, clear, jelly-covered clusters of thirty eggs or less. The egg clusters are usually laid on plants, just below the surface of the water. They hatch into tadpoles in only 3 or 4 days, if the water is warm. Tadpoles metamorphose into adults quickly, in 3 – 11 weeks, depending on temperature and food availability. This rapid development is necessary because the breeding pools are short-lived. As the weather warms, the water in the pools warms, which accelerates the toads’ rate of development.
Like other toads, the Western Spadefoots have a toxin stored in the little bumps on their skin. The toxin won’t give you warts, but the skin secretion smells like peanuts and sometimes cause a runny nose and watery eyes in humans. This skin toxin makes the Spadefoots distasteful to predators. However, a few animals will eat Western Spadefoots, such as bullfrogs and some wading birds. California Tiger Salamander larvae and Aquatic Beetle larvae will sometimes eat the Spadefoot tadpoles.
Western Spadefoots are very picky about their habitat. They only breed in certain vernal pools and in some drinking ponds used by cattle. Scientists do not understand why they breed in some pools and not in others. When their breeding pools are destroyed, they often have nowhere else to go. The Western Spadefoot has lost a huge amount of habitat in the Central Valley due to urban and agricultural development of land that formerly supported its temporary breeding pools. The Spadefoot is estimated to be gone from almost 80 percent of its former habitat. To protect Spadefoots for the future, we will have to protect the vernal pool grasslands where they live today.
The Western Spadefoots in Critterville are several years old. Their favorite food is crickets but they also enjoy sow bugs (rolly pollies) and wax worms.