Houston Toad Program Overview

It has been over sixty years since John Wottring, an amateur herpetologist, first suspected the lengthy trill of the toad in south Houston belonged to an undescribed species. Over the next several years Wottring worked with Ottys Sanders and in 1953 the species was described in the journal Herpetologica as Bufo houstonensis, the Wottring Toad. The scientific name refers to the location of its discovery and the common name was in honor of the discoverer. After discussions with an enthusiastic University of Texas at Austin zoology professor Clark Hubbs, the keeper of the “redbook”, James Peters from the National Museum of Natural History, added Bufo houstonensis, to the list of “Rare and Endangered Fish and Wildlife of the United States” in 1968. And so it was, with little fanfare the toad was subsequently included in the passing of the Endangered Species Act in 1973. It should be noted this species was likely one of the first amphibian species in the United States, maybe even the world, to be recognized as declining. It should also be noted at some point between then and now, the common name changed to the Houston Toad, likely a consequence of the regional uproar that took place in the namesake city, despite the fact the toad would not be seen again in Houston after 1976, only 3 short years after the passing of the ESA. Critical habitat was designated in Bastrop and Burleson counties in 1978, in areas supporting the largest populations known at that time. Primary threats to this species' survival are habitat loss and fragmentation through land uses changes and fire suppression. Prolonged drought, pollution, and introduced predators also take their toll.

Historically, the Houston toad ranged across the state's eastern-central region, but disappeared from Harris, Liberty, and Fort Bend counties in the 1960s following an extended drought and Houston's urban expansion. Although Texas Parks and Wildlife surveys in the late 1980’s and early 1990’s found this species in a total of nine counties (Austin, Bastrop, Burleson, Colorado, Lavaca, Lee, Leon, Milam, and Robertson), several of these populations have not been detected since their discovery. In 2006, the species was heard calling only in Bastrop and Leon counties; in Leon only a single male was located. Bastrop County is the species' final stronghold, but studies also suggest its population is in decline.

 

At this time, the toad may only persist in four habitat patches within its central-eastern Texas counties, the remaining severely fragmented habitat is reduced both in quantity and quality, and the region is entering what would become a drought of record. No one was sure what would happen, even the toads in the last stronghold within the Lost Pines region of Bastrop County were declining, and it was going to get worse, based on previous multi-year drought experience. It is under these dire circumstances that, in the spring of 2007, parts of the only known egg strands laid by Houston Toads that year were collected for head starting by biologists at Texas State University and delivered to the Houston Zoo.

 

 

The eggs came to the zoo for a few purposes. The first is as a safe guard or "assurance population" against a catastrophic event that might cause the Houston Toad to go extinct in the wild. If this happens, Toads in captivity will serve as a source for individuals for reintroductions. The second reason was for the potential reintroduction of toads into appropriate habitat. It is hoped the captive toads will serve as a source for individuals who might be reintroduced into historical localities. The third reason is for head starting. Head starting is a process where high-mortality life stages (such as larval and juvenile in amphibians) are protected and released after they had reached a certain size or life stage. This technique has proved helpful in the recovery of other endangered species. The fourth and final reason is research. Toads can be very difficult to find in the wild, even during the breeding season. With toads in captivity we can study various aspects of their natural history and biology, such as activity temperatures, burrowing abilities, and substrate preferences that are very difficult to study in the wild. The eggs hatched and about 1,500 toads completed metamorphosis. We performed three releases in 2007 (May, July, and September) and another in April 2008. About 1,200 toads were released in total. The remaining toads were kept at the zoo to start the formation of our assurance colony.

 

Since 2007 we have head started and released about another 20,000 toads at sites in two counties within the toads range. In order to determine the best life-stage to release (large enough to have higher survivorship but released quick enough to not become adapted to captivity) we are trialing different life stages and tracking the DNA of the entire clutch or cohort of toads from the same parents. Using these tools, we can tell how far the toads have travelled from the release site and how many have survived to adulthood.

 

 

The Houston Zoo’s main role in Houston toad recovery is head starting and the development of a captive assurance colony. However, the zoo wears a few different hats in regards to the recovery effort of this species. The Department of Conservation and Science and Department of Herpetology staff at the Houston Zoo have been assisting Texas State University with range-wide monitoring surveys for the past 5 years, putting in between 10 and 30 survey nights each toad season. The zoo also has increasing involvement with educational and outreach programs for the Houston toad, focused on both the general public and landowners. Interpretive programming and presentations to these groups are also enhanced with the addition of the Houston Zoo “Ambassador Toads” to local events, education programs and landowner meetings. In addition, we have developed a Houston toad media kit and a landowner support sign for those individuals who are actively managing their properties for recovery of the toad.

 

While this narrative focuses on the Houston Zoo’s involvement in Houston toad recovery, the zoo is just one supportive player in the whole effort. The US Fish and Wildlife Service and Texas Parks and Wildlife Department are the organizations charged with conserving the toad and work with partners such as Texas State University, the Environmental Defense Fund, and the myriad of private landowners who recognize the need for and appreciate having the little toad around. Knowing the situation is grim, everyone is responding with active stewardship increasing the chance for long lasting positive changes for the species.

Click here for 2011 updates on the Houston Toad program

 

 

If you are a member of the press and would like a copy of our Houston toad Media Kit please contact Rachel Rommel rrommel@houstonzoo.org.