Photo by Toby Hibbitts. Source
The Houston toad’s back coloration ranges from light tan to dark brown, sometimes in a mottled pattern. Their undersides are light and sandy-colored with dark spots. Adults range in size from 2 inches to 3.5 inches, with females being larger than males. Their average lifespan in the wild is believed to be 2 to 3 years.
The Houston toad is native to east and central Texas. However, after extreme population decline due to habitat loss, wild populations are present in only a handful of counties. They have not been documented in Houston since the 1970s.
Houston toads are habitat specialists, preferring pine or oak forests that have a deep, sandy soil. They prefer a loose soil that’s deeper than 40 inches because it allows them to burrow deeply enough to safely enter a state of brumation (to escape cold) or aestivation (to escape heat and drought) for much of the year.
Houston toads are nocturnal. Their diet consists of insects and other small invertebrates.
Main predators include snakes, birds, and raccoons. To defend against predators, the toad’s coloration acts as camouflage. They also have parotoid glands located just behind their heads that secrete chemicals that are foul-tasting and sometimes poisonous.
Breeding takes place any time from February to June, usually starting after the first heavy rains of spring and when nighttime temperatures stay above 50°F.
Groups of toads congregate in temporary pools (called vernal pools) or permanent bodies of water to breed. The male toad’s call is a high-pitched trill that lasts about 15 seconds. After a female chooses a male, the male clasps onto the female’s back in a position called amplexus, fertilizing the female’s eggs as she lays them in the water. Female Houston toads lay anywhere from 500 to 10,000 eggs at a time in long, narrow strands.
Eggs typically hatch within 1 week, and tadpoles live in the water between 2 and 7 weeks, depending on the abundance of food and on the water temperature. The tadpoles metamorphose into toadlets, which are miniature versions of adult toads that are small enough to fit on a human’s fingernail. The toadlets leave the water and begin their life on land.
First described in 1953, within 20 years the Houston toad population had plummeted. Human development – transforming wetlands and sandy forests into space for agriculture, housing, roads, and so on – reduced and fragmented the Houston toad’s habitat. In 1970, the Houston toad became the first amphibian to be federally declared endangered in the United States.
Additional current-day challenges for the Houston toad include being killed by cars on the road, as well as pollution and the introduction of fire ants. It’s estimated that fewer than 1,000 adults remain in the wild.
Several government departments and private entities are working to save the Houston toad. For example, some naturalists (in coordination with Texas Parks and Wildlife and Texas State University) are working with private landowners to help the landowners maintain suitable habitat for the Houston toad. In addition, the Houston Zoo operates a captive breeding program with about 600 permanent individuals. In 2019, the zoo released an estimated 985,000 Houston toad eggs, bringing the total number of eggs released to 4.5 million.
The chemicals found in the Houston toad’s skin and parotoid glands not only help protect them from being eaten, but some of these chemicals have been used in medicines for treating heart and nervous disorders in humans.
