Houston toad
Encyclopedia
The Houston toad is an endangered species
of amphibian
that is endemic to Texas
in the United States
. This toad
was discovered in the late 1940s and named in 1953. Official estimates are that just 3,000 – 4,000 adult Houston Toads are left in the world.
During February and March, the male emits a high clear trill by distending a vocal sac on its throat, in hopes of attracting a mate. A female will choose a male based on certain characteristics of his call. Small isolated pools and ponds are the toad's main breeding ground. A female toad will lay several thousand eggs in long single-egg strands that are fertilized externally by the male as they are laid. The eggs hatch within seven days and tadpoles take between 15–100 days to turn into little toads. The toadlets then leave the breeding pond and begin to forage
for prey such as ant
s, beetle
s and moth
s.
They move by making short hops. Since they cannot usually out run their predators such as snake
s, turtle
s, large birds, raccoon
s, and other frog
s, the toads have developed coloration and rough skin to camouflage
themselves. Also, their skin secretes chemicals that are distasteful, and sometimes poisonous, to predators. In addition to protecting the Houston toad from being eaten, some of these chemicals have proven useful medicines to treat heart and nervous disorders in humans.
and oak
woodlands and savanna
with forb
s and bunchgrasses
present in open areas. Vegetation of its preferred habitat includes loblolly pine (Pinus taeda), post oak (Quercus stellata), bluejack oak (Quercus incana), yaupon holly (Ilex vomitoria), curly threeawn (Aristida desmantha), and little bluestem (Schizachyrium scoparium). They are generally found in areas with loose, sandy soils greater than 40 in (101.6 cm) in depth. Slow-moving or still bodies of water that last at least 30 days are needed for breeding and tadpole development. The toad's original range covered 12 counties in Texas; currently, it is often reported to occur in nine counties. However, choruses have only been actually reported in three counties since 2000, representing a seventy-five percent overall reduction in twenty years.
In 1970, the Houston toad was federally listed
as an endangered species. It was extirpated from the Houston, Texas
area by the 1960s, likely coincident with the severe drought of the 1950s and concurrent development of its forested habitat in that region. Though the largest and most immediate threat is habitat
loss, the reduced toad populations are also vulnerable to automobile
s, predators, pesticide
s and drought
.
The largest known chorusing groups persist in Bastrop County
, but the choruses monitored in Bastrop State Park
showed a dramatic decline during the mid-1990s, with little recovery of those numbers since then. Importantly, that state park is the only public land that supports consistent chorusing from year to year of the Houston toad. However, even there, the total numbers are very low.
Conservation groups are working with private landowners in Bastrop County to protect and restore Houston toad habitat, but even if recovery were to be achieved in Bastrop County, this effort would not have achieved recovery for the species. Efforts toward active conservation efforts in the remaining Houston toad occupied counties and even efforts within counties from which the toad has been extirpated are needed.
In spring 2008, the Lost Pines Habitat Conservation Plan was approved by the United States Fish and Wildlife Service
. The plan describes a management and recovery plan for the Houston toad in designated habitat in Bastrop County.
In September, 2011, the Bastrop County Complex fire
devastated a large part of the Houston toad's habitat. Parts of Buescher State Park
were among the affected areas, with large forested areas charred by the fire. The Lost Pines Forest
was heavily affected by the fire.
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
of amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...
that is endemic to Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. This toad
Toad
A toad is any of a number of species of amphibians in the order Anura characterized by dry, leathery skin , short legs, and snoat-like parotoid glands...
was discovered in the late 1940s and named in 1953. Official estimates are that just 3,000 – 4,000 adult Houston Toads are left in the world.
Characteristics
The male Houston toad grows to 2–3.5 inches when mature with the female being larger and bulkier. Although generally brown and speckled, their color can range from black to purplish gray, sometimes with green patches. The toads typically live 2–3 years and create burrows for protection from the cold in the winter and the hot, dry conditions of the summer. They are nocturnal and feed on insects and small invertebrates.During February and March, the male emits a high clear trill by distending a vocal sac on its throat, in hopes of attracting a mate. A female will choose a male based on certain characteristics of his call. Small isolated pools and ponds are the toad's main breeding ground. A female toad will lay several thousand eggs in long single-egg strands that are fertilized externally by the male as they are laid. The eggs hatch within seven days and tadpoles take between 15–100 days to turn into little toads. The toadlets then leave the breeding pond and begin to forage
Foraging
- Definitions and significance of foraging behavior :Foraging is the act of searching for and exploiting food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce...
for prey such as ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s, beetle
Beetle
Coleoptera is an order of insects commonly called beetles. The word "coleoptera" is from the Greek , koleos, "sheath"; and , pteron, "wing", thus "sheathed wing". Coleoptera contains more species than any other order, constituting almost 25% of all known life-forms...
s and moth
Moth
A moth is an insect closely related to the butterfly, both being of the order Lepidoptera. Moths form the majority of this order; there are thought to be 150,000 to 250,000 different species of moth , with thousands of species yet to be described...
s.
They move by making short hops. Since they cannot usually out run their predators such as snake
Snake
Snakes are elongate, legless, carnivorous reptiles of the suborder Serpentes that can be distinguished from legless lizards by their lack of eyelids and external ears. Like all squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales...
s, turtle
Turtle
Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield...
s, large birds, raccoon
Raccoon
Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...
s, and other frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...
s, the toads have developed coloration and rough skin to camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...
themselves. Also, their skin secretes chemicals that are distasteful, and sometimes poisonous, to predators. In addition to protecting the Houston toad from being eaten, some of these chemicals have proven useful medicines to treat heart and nervous disorders in humans.
Habitat and range
The Houston toad today lives exclusively in pinePiney Woods
The Piney Woods is a temperate coniferous forest terrestrial ecoregion in the Southern United States covering of East Texas, southern Arkansas, western Louisiana, and southeastern Oklahoma. These coniferous forests are dominated by several species of pine as well as hardwoods including hickory and...
and oak
East Central Texas forests
The East Central Texas forests is a small temperate broadleaf and mixed forests ecoregion almost entirely within the state of Texas, United States...
woodlands and savanna
Savanna
A savanna, or savannah, is a grassland ecosystem characterized by the trees being sufficiently small or widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of C4 grasses.Some...
with forb
Forb
A forb is a herbaceous flowering plant that is not a graminoid . The term is used in biology and in vegetation ecology, especially in relation to grasslands and understory.-Etymology:...
s and bunchgrasses
Tussock (grass)
Tussock grasses or bunch grasses are found as native plants in natural ecosystems, as forage in pastures, and as ornamental grasses in gardens....
present in open areas. Vegetation of its preferred habitat includes loblolly pine (Pinus taeda), post oak (Quercus stellata), bluejack oak (Quercus incana), yaupon holly (Ilex vomitoria), curly threeawn (Aristida desmantha), and little bluestem (Schizachyrium scoparium). They are generally found in areas with loose, sandy soils greater than 40 in (101.6 cm) in depth. Slow-moving or still bodies of water that last at least 30 days are needed for breeding and tadpole development. The toad's original range covered 12 counties in Texas; currently, it is often reported to occur in nine counties. However, choruses have only been actually reported in three counties since 2000, representing a seventy-five percent overall reduction in twenty years.
Conservation status
Endangered Species Act of 1969
The Endangered Species Act of 1969 was an expansion of the Endangered Species Preservation Act of 1966 which authorized the United States Secretary of the Interior to develop a comprehensive list of species or subspecies of animals threatened with worldwide extinction...
as an endangered species. It was extirpated from the Houston, Texas
Houston, Texas
Houston is the fourth-largest city in the United States, and the largest city in the state of Texas. According to the 2010 U.S. Census, the city had a population of 2.1 million people within an area of . Houston is the seat of Harris County and the economic center of , which is the ...
area by the 1960s, likely coincident with the severe drought of the 1950s and concurrent development of its forested habitat in that region. Though the largest and most immediate threat is habitat
Habitat (ecology)
A habitat is an ecological or environmental area that is inhabited by a particular species of animal, plant or other type of organism...
loss, the reduced toad populations are also vulnerable to automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s, predators, pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s and drought
Drought
A drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
.
The largest known chorusing groups persist in Bastrop County
Bastrop County, Texas
Bastrop County is a county located in the U.S. state of Texas. As of 2006, the population was 71,700. Its county seat is Bastrop. Bastrop County is named for Felipe Enrique Neri, Baron de Bastrop , an early Dutch settler who assisted Stephen F...
, but the choruses monitored in Bastrop State Park
Bastrop State Park
Bastrop State Park is a state park in Bastrop County in central Texas. The park was established in 1938 and consists of stands of Loblolly Pines mixed with Post Oak and junipers.-History:...
showed a dramatic decline during the mid-1990s, with little recovery of those numbers since then. Importantly, that state park is the only public land that supports consistent chorusing from year to year of the Houston toad. However, even there, the total numbers are very low.
Conservation groups are working with private landowners in Bastrop County to protect and restore Houston toad habitat, but even if recovery were to be achieved in Bastrop County, this effort would not have achieved recovery for the species. Efforts toward active conservation efforts in the remaining Houston toad occupied counties and even efforts within counties from which the toad has been extirpated are needed.
In spring 2008, the Lost Pines Habitat Conservation Plan was approved by the United States Fish and Wildlife Service
United States Fish and Wildlife Service
The United States Fish and Wildlife Service is a federal government agency within the United States Department of the Interior dedicated to the management of fish, wildlife, and natural habitats...
. The plan describes a management and recovery plan for the Houston toad in designated habitat in Bastrop County.
In September, 2011, the Bastrop County Complex fire
Bastrop County Complex fire
The Bastrop County Complex fire was a major wildfire that struck Bastrop County in the U.S. state of Texas in September 2011. The fire started on September 4, 2011, during Labor Day weekend, and burned east of the city of Bastrop. 1,645 homes were destroyed by the fire, making it the most...
devastated a large part of the Houston toad's habitat. Parts of Buescher State Park
Buescher State Park
Buescher State Park is a state park located just north of Smithville, Texas. The park consists of of public land donated to the state by Mr. Emil and Mrs. Elizabeth Buescher, as well as the City of Smithville.-History:...
were among the affected areas, with large forested areas charred by the fire. The Lost Pines Forest
Lost Pines Forest
The Lost Pines Forest is a belt of loblolly pines near Bastrop in Central Texas. The stand of pines is unique in Texas because it is a disjunct population of trees that is more than separated from, and yet closely genetically related to, the vast expanse of pine trees of the East Texas Piney...
was heavily affected by the fire.
Further reading
(1984) Reproductive ecology and hybridization of the endangered Houston toad (Bufo houstonensis). Journal of Herpetology 18: 56–72.- "The Endangered Houston Toad". U.S. Fish & Wildlife Service. Retrieved Nov. 17, 2005. (2004) The history of a Nearctic colonization: Molecular phylogenetics and biogeography of the Nearctic toads (Bufo). Evolution 58: 2517–2535.
- "Houston Toad". Environmental Defense. Retrieved Nov. 17, 2005.