Society

Endangered Houston Toad in Milam County

If it’s a warm, humid night, after a rainfall, you might hear a high clear trill that seems to last forever. If you happen to hear this trill, which can last upwards to 14 seconds, you could be in the presence of a male Houston Toad calling out to nearby females.

You would be lucky to hear it because the Houston Toad is endangered. It’s a Texas native, found no where else in the world, except nine counties in east Central Texas, including Milam. Bastrop County has the largest population, around 2,000 toads, mainly in Bastrop State Park.

Back in the 1960s, the Houston Toad disappeared from Harris County due to an extended drought and Houston’s continued expansion. Habitat fragmentation, conversion of shallow ponds to large bodies of water, and the red imported fire ant have spurred their decline.

The toads are two to three and a half inches long, and vary from a light brown to purplish gray color. Their underside is pale with dark splotches. They can be easily confused with the Gulf Coast Toad, which is bigger, and also has a scowling look to its eyes.

The Houston Toad requires sandy soils more than 40 inches deep in which to burrow. They also require shallow bodies of water or temporary ponds in which to breed.

The toads emerge from their sandy burrows to mate only if the temperature and humidity levels are just right. The shallow ponds should be free of predatory fish, and preferably shaded. The toads move from the wooded areas where they live to the water to breed.

If all these conditions come together, an “explosion” of toads occur where large numbers congregate along the water’s edge to lay and fertilize eggs, which are deposited in long strings in the water. Tadpoles are hatched in about seven days, and within 60 days the tadpoles metamorphose into half inch long toadlets.

Thousands of toadlets, streaming in a black hoard out of the water and onto the land, make a perilous journey across open land to the cover of the trees, which should optimally be 100 yards from the water. They have about a one percent chance of survival, but if they do make it, the toads can live up to three years.

Once under the trees, they burrow into the sand during the hot summer months, possibly emerging in fall for another spate of breeding, then back under the sand to hibernate for the winter. As long as the days are not too hot or too cold, the toads will remain active. Their diet consists of insects and other invertebrates.

The loblolly pine tree is closely associated with Houston Toad habitat, one reason why Bastrop County, with its sandy soil and pine trees, has become a Houston Toad refuge. However, the toads can also be found in the sandy soils of the Post Oak Savannah. Within the past year, Houston Toads have been heard calling in the eastern portions of Milam County.

The Houston Zoo and Texas State University in San Marcos are partnering to study and preserve the toad. The University collects egg strands from breeding sites in Bastrop State Park and sends them to the Houston Zoo for hatching.

Once the toads hatch in the zoo, they are taken back to their breeding sites and released. This is known as a “head start”, allowing the toads to mature past the most perilous stages of life, so they can be released and breed again. Some of the toads are kept at the zoo to protect the species in case a catastrophic event causes total extinction in the wild.

walton.shawn@gmail.com

El Camino Real Master Naturalists:

grovesite.com/tmn/ecrmn


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2010-02-25 digital edition



The burn ban for Milam County has been lifted. Burning is always prohibited in the county's municipalities.


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