What is the Puerto Rican crested toad?
The Puerto Rican crested toad is the only toad species native to Puerto Rico. Named for the bony crests above its large, golden eyes, this toad is also identifiable by an upturned snout and bumpy skin that feels like it’s covered in pebbles. Males are olive green with pads on their thumbs, and females have rougher, dull-brown skin and more prominent crests.
The Puerto Rican crested toad is semi-fossorial, meaning it sometimes digs or burrows underground. Among the crested toad’s ideal hiding spots are crab burrows, spider lairs, and nest cavities created by small Caribbean birds called todies. It is also an adept climber for its size, being able to scale up almost 18 inches to openings in limestone karsts. When it needs to hide from predators, the toad can squeeze itself into snug rock crevices that are smaller than two inches tall and two inches wide.
Diet and habitat
A carnivorous amphibian, the Puerto Rican crested toad feeds on a variety of arachnids and insects, including ants, beetles, crickets, and spiders. Tadpoles aren’t very picky either, and will eat algae, dead scorpions, and even dead tadpoles—that is, if they aren’t eaten first by invasive species that prey on Puerto Rican crested toad tadpoles.
Tadpoles that survive to adulthood find their ideal habitat in the subtropical dry forests of Puerto Rico. Wild Puerto Rican crested toads are only found in or adjacent to Guánica Commonwealth Forest on the southern part of the island. Although the toad lives at elevations ranging from sea level to 164 feet, it prefers to spend most of the time burrowed underground—alone.
The Puerto Rican crested toad is solitary by nature, but once a year, several toads will congregate to reproduce. When, however, is a little complicated. Breeding season varies annually and depends on the weather: Rainfall creates temporary, shallow pools of water, called leks, which are ideal environments for toad eggs.
Mating requires at least four inches of rain—and heavier precipitation brings more individuals to the breeding grounds. If the rain is especially heavy, male crested toads may even trek to the pools from as far as two miles away. On the other hand, not enough rain could mean no breeding that year.
Once males arrive at their breeding grounds, they croak to attract females. A female crested toad can lay up to 15,000 eggs, which hatch into tadpoles within a day. Those that don’t succumb to predation or habitat destruction reach the metamorphosis stage within 18 to 24 days to become toadlets. Approximately 99 percent of crested toad eggs never make it to adulthood, though.
Threats to survival
Puerto Rican crested toads were thought to be extinct from 1931 to 1967, when a population was discovered in northern Puerto Rico. Today, the International Union for the Conservation of Nature classifies the Puerto Rican crested toad as critically endangered. Scientists estimate that only a thousand to 3,000 adult toads remain in the wild.
Threats to the Puerto Rican crested toad’s survival include habitat competition from invasive cane toads, which also eat Puerto Rican crested toad tadpoles and toadlets. The crested toad’s long list of predators includes cats, crabs, dogs, heron, lizards, mongooses, and rats.
Humans play a role in the toad’s decline as well, with agriculture and urban development leading to the drainage and destruction of lek breeding pools. Other threats stem from natural disasters like hurricanes and drought, which damage vital habitats and prevent mating gatherings.
Conservation initiatives to save the Puerto Rican crested toad include captive breeding programs. In 1984, the crested toad became the first amphibian involved in the American Zoological Association’s Species Survival Plan (SSP). Zoos and government entities continue to collaborate on breeding and reintroduction efforts. SSP partners have successfully bred more than 300,000 tadpoles, many of which are monitored in artificial ponds in Puerto Rico. In 2019, the first crested toad was hatched via in vitro fertilization.