Amphibians
Mexican Spadefoot
Spea multiplicata · also called Mexican spadefoots
A Mexican spadefoot waits underground through months of dry desert conditions, emerging only when heavy summer rain finally soaks through to trigger it. What follows is a race against the clock: breed, develop, and metamorphose before the temporary pool it depends on disappears again, sometimes within just a few short weeks.
Overview
The Mexican spadefoot, Spea multiplicata, is a burrowing toad native to desert and grassland habitat across the southwestern United States and Mexico. It spends most of the year buried, emerging specifically after heavy rain to breed in short-lived pools.
Two tadpoles, one pool
When conditions get crowded or food runs short, some Mexican spadefoot tadpoles develop into a larger-mouthed, carnivorous form capable of eating other tadpoles, a flexible backup strategy for surviving a pool that might not last long enough for everyone.
Status
Least Concern — widespread and stable across suitable desert and grassland habitat throughout the southwestern United States and Mexico.
Mexican Spadefoot: common questions
How does a Mexican spadefoot know when to come out of the ground?
A Mexican spadefoot remains buried underground for the great majority of the year and emerges specifically in response to heavy summer rainfall events that fill temporary desert pools, using cues such as ground vibration and moisture to detect that sufficient rain has fallen to make emergence and breeding worthwhile.
Why do some Mexican spadefoot tadpoles eat other tadpoles?
Mexican spadefoot tadpoles can develop into one of two distinct forms depending on local conditions, either a typical algae-grazing form or a more specialised, larger-mouthed carnivorous form capable of preying on other tadpoles, a flexible developmental strategy that can help at least some individuals survive when food becomes scarce in a rapidly shrinking temporary pool.
How does a Mexican spadefoot dig so quickly?
A Mexican spadefoot has a hardened, sickle-shaped structure called a spade on each hind foot, used to dig backward into loose desert soil with remarkable speed, allowing the toad to disappear beneath the surface within just seconds when conditions turn dry or a threat appears.
How is the Mexican spadefoot different from the western spadefoot?
The Mexican spadefoot and western spadefoot are separate species within the same genus, both adapted to breeding in temporary desert pools after heavy rain, but they occupy somewhat different, though sometimes overlapping, ranges across the southwestern United States and Mexico, with some subtle differences in call and specific habitat preference.