The Houston toad is limited to an extremely small range in southeastern Texas. Since its discovery in 1953 it has never been found north of Burleson County, south of Fort Bend County, east of Liberty County, or west of Bastrop County.

Biogeographic Regions: nearctic (Native )

endemic to a single state or province

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (1000-5000 square km (about 400-2000 square miles)) Historically, this toad ranged across the central coastal region of Texas. Houston toads disappeared from the Houston area (Harris, Fort Bend and Liberty counties) during the 1960s following an extended drought and the rapid urban expansion of the city of Houston. Although this species has been found in nine additional counties (Austin, Bastrop, Burleson, Colorado, Lavaca, Lee, Leon, Milam, Robertson) as recently as the 1990s, several of these populations have not been seen since they were first discovered (recorded in Lee County in 2001; Gaston et al. 2001). Of the few remaining populations, the largest is in Bastrop County.

The upper part of Houston toads is usually light brown in color, though it may sometimes be reddish. It possesses a variable number of dark brown or black spots. The underbelly is cream colored and usually very mottled. There is always at least one brown spot on the pectoral region. Females are 52-80 mm long (snout to vent). Males are smaller, being 45-70 mm long. Tadpoles are 13.7-22 mm long. Tadpole bodies and the upper 75% of their tails are heavily pigmented.

Length: 8 cm

• Terrestrial

Tadpoles are found in non-flowing pools that last for at least 60 days. Adults are restricted to sandy soils and prefer wooded areas interspersed with open grass. They are also found in coastal prairies. Within these habitats they are never far from water, and during the breeding season are located almost exclusively near ponds and rain pools.

Terrestrial Biomes: savanna or grassland ; forest

Comments: Restricted to areas with soft sandy soils; pine forest, mixed deciduous forest, coastal prairie. Extant populations occur in sandy forested areas with pine. When inactive, occupies burrows in soil or seeks refuge in leaf litter or under objects.

Eggs and larvae develop in shallow water of roadside ditches, temporary ponds in residential areas and pastures, and other seasonally flooded low spots; for successful breeding, water must persist for at least 60 days.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Migrates between breeding and nonbreeding habitats.

Tadpoles feed primarily on pollen (usually from nearby pines), the jelly envelopes of other recently hatched Houston toads, and algae on floating leaves. Adults feed primarily on ground beetles, although they have been known to eat smaller toads and ants. They utilize two methods to capture prey: sit-and-wait and active search. For the sit-and-wait method, A. houstonensis first digs a small depression in the soil with its powerful hind legs. The toad then rests in the depression and scans the surrounding area for movement. When prey is detected B. Houstonensis leaps forwards and takes the prey into its mouth. Depressions are abandoned many times per day and new ones dug nearby.

Comments: Metamorphosed toads probably eat various small terrestrial arthropods. Larvae eat suspended material, organic debris, algae, and plant tissue.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 1 - 20

Comments: Difficult to specify number, but relatively few occurrences.

1000 - 2500 individuals

Comments: At least 2000 adults occur in Bastrop County; unknown numbers in 7 other counties (http://www.tpwd.state.tx.us/nature/endang/htoad.htm). Fairly common in the vicinity of a few ponds (Bartlett and Bartlett 1999).

Comments: Inactive during hot, dry season and during coldest months.

Breeding occurs between the end of January and the end of June, but peaks in late February. Early breeding often begins when the prior 24-hour period's temperature has not fallen below 14 degrees C. Mating occurs at night near shallow pools of water or ponds. Males begin their mating calls twenty minutes before sunset while still in their burrows. After ten minutes they begin moving toward a breeding pond, arriving between sunset and midnight. Once there, they seek elevated places from which to call. This call consists of a long high pitched trill. The first females begin arriving several hours after sunset.  Once a female has selected a mate, the male remains clasped to the female for at least six hours. Between 500 and 6000 eggs are laid and fertilized in the water during the early morning hours. Afterwards males issue a release call consisting of a short barely audible release vibration, and an even shorter release chirp. Eggs hatch in seven days and metamorphosis begins in 60-65 days. Males reach sexual maturity in 1 year, and females at 1-2 years. Males typically breed for 2 seasons; females, for at least as long.

Most breeding occurs February-April, when minimum air temperature is above 14 C; breeding reported as late as June. Larvae hatch in 4-7 days, metamorphose in 3-9 weeks, depending on water temperature. Males sexually mature in 1 year, females possibly in 2 years. See Jacobson (1989).

• 1996
  Endangered
• 1994
  Endangered
  (Groombridge 1994)
• 1990
  Endangered
  (IUCN 1990)
• 1988
  Endangered
  (IUCN Conservation Monitoring Centre 1988)
• 1986
  Endangered
  (IUCN Conservation Monitoring Centre 1986)

Throughout the 1950s the Houston toad's populations declined sharply. Regional drought was the largest contributor to this, followed by loss of suitable habitat due to land development. Soil erosion, cattle grazing, and pesticide run-off have all limited the number of suitable breeding ponds.  Conservation efforts have attempted to counter habitat loss. Most notably have been two land purchases in the 1970s. In 1971 the University of Texas Environmental Science Department purchased 1400 acres of forested land adjacent to Bastrop State Park to use as a study area. In 1979 the Texas Parks and Wildlife Department purchased another 717 acres. In 1974 the Houston toad was listed as an Endangered Species, and a recovery plan was created. Its goal is the removal of A. houstonensis from the endangered species list through habitat expansion and enhancement.

US Federal List: endangered

CITES: no special status

IUCN Red List of Threatened Species: endangered

United States

Rounded National Status Rank: N1 - Critically Imperiled

Rounded Global Status Rank: G1 - Critically Imperiled

Reasons: Small range in Texas; populations are few, small, and declining, due mainly to habitat destruction.

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Moderate to broad.

Global Short Term Trend: Decline of 10-50%

Comments: Recent trend analyses suggest that Houston toads are declining in Bastrop State Park, which lies near the center of its critical habitat in Bastrop County.

Global Long Term Trend: Increase of 10-25% to decline of 70%

Comments: This species is believed to have undergone a substantial decline in range extent, area of occupnacy, population size, and habitat qunatity and quality.

Degree of Threat: A : Very threatened throughout its range communities directly exploited or their composition and structure irreversibly threatened by man-made forces, including exotic species

Comments: Habitat conversion poses the most serious threat to the Houston toad. Several populations were eliminated with the expansion of Houston, and the largest remaining population in Bastrop County is also under intense and immediate threat from urban development.

Many Houston toads are killed each year by automobiles. Roadway mortality will increase as human populations continue to increase within the species¿ habitat and as the habitat continues to be dissected by more roads. Road construction further isolates populations and disrupts or prevents the movement of individual toads between populations. This movement of toads is necessary to maintain gene flow, and thus genetic diversity, and to supplement small or declining local populations. It is possible to build roads with underpasses or other structures that allow toads and other wildlife to pass safely beneath the roads.

While converting woodlands to pastures or plowed fields destroys Houston toad habitat and favors the proliferation of other toad species, certain agricultural practices can be beneficial to Houston toads. These include maintaining low to moderate numbers of livestock to avoid overgrazing, protecting pond habitat from livestock and predatory fishes, planting native bunchgrasses instead of sod-forming grasses, such as Bermuda grass, which are difficult for the toads to move through, and conserving large blocks of woodlands.

Certain forestry practices may benefit the Houston toad, while others, such as clearcutting, are harmful. Thinning and burning have been shown to benefit some species of amphibians and reptiles by opening up the forest canopy and allowing more sunlight to reach the forest floor. This practice encourages the growth of vegetation and, in turn, increases insect numbers. This may be beneficial to the Houston toad.

Other threats that often appear in conjunction with the factors outlined above include drought and the presence of fire ants, an unwelcome species from Brazil. Fire ants have been observed preying on toadlets as they leave their breeding pond. Fire ants thrive in open, sunny areas where the soil has been disturbed and woody vegetation uprooted, as in agricultural fields and urban areas. Protecting large forested areas is one of the most effective deterrents to fire ants. Where fire ant control with pesticides is necessary, mounds should be treated individually, rather than broadcasting the chemicals, to avoid impacting other invertebrates that the Houston toad eats.

This information is from a USFWS website: http://ifw2es.fws.gov/HoustonToad.

Management Research Needs: Research is urgently needed to determine the status of Houston toad populations outside of Bastrop County and promote conservation efforts in these areas. Research is also critical to determine which management practices are most conducive to the Houston toad and the ecosystem on which it depends.

Global Protection: Few (1-3) occurrences appropriately protected and managed

Comments: Several breeding sites are on protected park lands (Bartlett and Bartlett 1999). Occurs in a state park in Bastrop County. Critical habitat was designated in 1978 in Bastrop and Burleson counties, in areas supporting the largest populations known at that time. The population within critical habitat in Burleson County has not been seen since 1983. The University of Texas Environmental Science Park, comprising several hundred hectares, is managed as toad habitat.

Needs: Protect several EOs in widespread areas to preserve genetic diversity of population.

Besides the aesthetics of the Houston toad's bell-like calls (perhaps appreciated only by enthusiasts), it has little economic value to humans. Although Houston toads do limit insect populations, other more abundant sympatric toad species also fulfill this role.

Comments: Treated as a subspecies of B. americanus in older literature. Natural hybridization with B. valliceps and with B. woodhousii has been recorded (Brown 1973). A study of the taxonomic relationship between B. houstonensis and B. americanus charlesmithi was underway in 1990 (USFWS 1990).