The Houston toad was the first amphibian to be listed under the USFWS Endangered Species Act in 1970. The toad has very specific habitat needs and is sensitive to environmental changes. This Texas native was first discovered in the 1940s by an amateur herpetologist in the Houston area. Rapid urbanization and habitat loss due to development had eliminated the Houston Toad from Harris County by 1975 and reduced populations in surrounding counties to critically low levels. Small populations are now found only in a few locations with the largest population residing in Bastrop County.
Project Description & History
The Houston Zoo, a Texan by Nature Conservation Partner, first became involved in toad recovery in 1981. The breeding program ran until 1988, when lack of funding halted Zoo participation. By 2006, startling population studies estimated that no more than 250 toads remained in the wild, prompting the Zoo’s re-engagement in toad conservation action. The Zoo and partners developed a Species Survival Plan (SSP), studbook, and assurance colony, and began releasing headstarted toadlets in Bastrop County in 2007. Following the fires that burned 36,000 acres of Bastrop County, extensive surveys between 2010 and 2012 found no Houston toads in the wild. In 2013, the Houston Zoo launched a new strategy that the team hoped would spike the toad population by following its natural breeding patterns. Instead of headstarting toadlets at the Zoo, keepers began transporting egg strands to Bastrop County to mature in situ protected by mesh enclosures. Since that time, more than 3.5 million captive-produced eggs have been released, along with thousands of toadlets and tadpoles from a second assurance colony established at the Fort Worth Zoo. Promising signs suggest the strategy is working.
Since 2007, The Houston Zoo has been home to the assurance colony that holds 90% of the world’s remaining Houston toads. This assurance colony fulfilled its purpose when drought and wildfires struck Bastrop County in 2011, devastating the remaining habitat and population. It is thanks to the Zoo’s innovative egg release strategy – as well as to the sustained efforts of US Fish and Wildlife, Texas Parks and Wildlife, Texas State University, and partners throughout the Bastrop County community – that a major milestone was passed in 2018: The toad population in the heart of the release area has returned to pre-decline levels.