Stepping Up Recovery for the Houston Toad

By Paige A. Najvar

Hidden beneath the sandy soils of the ecologically unique "Lost Pines" region of central Texas resides one of the state’s most imperiled species. The Houston toad (Bufo houstonensis) is a small, greenish-brown, speckled amphibian that can be distinguished from other toads by the high-pitched, trill-sounding call that males emit during breeding choruses each spring. It depends on the forests of loblolly pine (Pinus taeda) and various hardwood trees it inhabits for migrating, hibernating, and feeding. Ephemeral water sources serve as breeding sites.

In 1970, the Fish and Wildlife Service listed the Houston toad as an endangered species, in large part because of landscape fragmentation and destruction caused by urban development and agricultural conversion. Given its status as a rare and naturally restricted species, the Houston toad has long been known to be particularly vulnerable to anthropogenic changes in its habitat. After decades of habitat loss, intensive, range-wide survey efforts led by Texas State University in the past few years detected the species in only six counties.

One of the largest remaining Houston toad populations occurs within Bastrop State Park in Bastrop County, Texas. In the other five counties, breeding choruses have been few, and the number of males heard calling during any given chorusing event have ranged from only 5 to 20. In fact, only about 100 males were heard chorusing outside of Bastrop State Park during the 2008 breeding season. This indicates a substantial decline in the Houston toad’s status since the last range-wide surveys conducted by Texas Parks and Wildlife Department in the late 1980s and early 1990s. Given ongoing habitat loss throughout its range, recent Texas drought conditions, and dwindling populations, we now fear this species could face extinction in the wild within the next several years unless intensive recovery efforts are undertaken.

Headstarting

We are working with Texas State University and the Houston Zoo to ward against extinction of the Houston toad through headstarting. This practice involves easing individuals of an imperiled species through the most vulnerable stages of their life-cycle (i.e., eggs, tadpoles, and juveniles), when many would die naturally or be eaten by predators.

Although it is a new concept for Houston toad recovery, headstarting has proven to be a successful management tool for other species, such as the Chiricahua leopard frog (Lithobates chiricahuensis) and some sea turtle species. The Houston toad has an enormous reproductive potential, with the greatest mortality in the early stages of its life cycle. We believe headstarting may be an effective way to increase the number of Houston toads that successfully develop into adult toads and reproduce. Initial headstarting efforts for the Houston toad began in 2007 when a portion of three Houston toad egg strands were removed from the wild and transferred to the Houston Zoo for captive rearing.

Safe Harbor Agreements

Since 2003, the Service and the Environmental Defense Fund (EDF) have partnered with several private landowners to develop and implement Safe Harbor Agreements for the Houston toad in Bastrop County. Under the agreements currently in place, landowners are managing over 1,900 acres (770 hectares) to enhance or restore habitat for the Houston toad.

In addition to providing additional habitat for the Houston toad, a by-product of these Safe Harbor Agreements is the increased interest of private landowners in partnering with the federal government for endangered species conservation. Such agreements serve to alleviate landowners’ concerns about sound management that may attract endangered species to their properties or increase their populations if they are already present. In a state where 94 percent of the land is privately owned, Safe Harbor Agreements build trust with ranchers and other private landowners, and actively engage them in endangered species recovery. (For more information on Safe Harbor Agreements, visit http:// www.fws.gov/endangered/esa-library/pdf/harborqa.pdf.)

In response to the continued decline of the Houston toad, we are building on our initial Safe Harbor program by working with EDF to develop a regionally based programmatic Safe Harbor Agreement that will encourage non-federal landowners throughout the Houston toad’s ninecounty range to take part in Houston toad conservation.

Landowners enrolling in the programmatic agreement may choose to conduct a variety of conservation activities, including brush management, forest enhancement and restoration, prescribed burning, breeding pond creation or enhancement, and red imported fire ant (Solenopsis invicta) control to benefit the Houston toad on their properties. We hope that by providing Safe Harbor assurances, private landowners will also be more likely to participate in head-starting efforts by allowing access to their properties for egg collection, juvenile releases, and survivorship monitoring.

Despite the remaining obstacles, we remain optimistic that these endeavors and other conservation activities will lead to recovery of the Houston toad as its habitat improves.

Paige Najvar, a fish and wildlife biologist in the Service’s Austin, Texas, Office, can be reached at paige_najvar@fws.gov or 512-490-0057, ext. 229.