Incilius periglenes

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Geographic Range

The golden toad once occupied a small area of 4 km2 of elfin cloud forest on the Cordillera de Tilaran in northern Costa Rica. This area is now known as the Monteverde Cloud Forest Preserve (Pounds, 1996).

Habitat

The golden toad occupies a wet, montane area of the forest in northern Costa Rica. The elevation of this habitat ranges from 2000 -- 2100 meters (Jacobson, 1991).

Physical Description

The golden toad is an extreme example of a sexually dimorphic amphibian. The males possess a very striking orange coloration. The females are black with scarlet blotches edged in yellow. The females range in length from 42 -- 56 mm while the males are 39 -- 48 mm. The striking physical differences between male and female cannot be determined until adulthood. Juveniles tend to be unsexable since they carry similar characteristics and body size (Jacobson, 1991).

Development

Reproduction

The golden toad is an explosive breeder during the months of April through June in which there is a heavy rainy season. The toads gather in enormous numbers around small, temporary pools and other water-filled depressions that are located within the forest. During this time, the competition between males for females is quite fierce. The males generally outnumber the females by an 8:1 ratio. It is at this time that males will mate with almost any moving object and molest other pairs that were in amplexus. Males also exhibited a behavior known as "toad balls" in which 4-10 males would clasp each other. However, a successful mating would produce around 200 to 400 eggs. The large diameter of the eggs is around 3.0 mm (Jacobson, 1991) The larval forms are all unsexable because of the same size and color. They remain in the pool and take up to 5 weeks to metamorphose (Harding, 1993).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)

Behavior

As with food habits, the behavior of the golden toad is poorly known. One clue to their existence is the shared behavioral and ecological characteristics with Bufo holdridgei. This small toad is distributed in the same area as Incilius periglenes. The two species also exhibit the same reproductive behavior such as intense male behaviors, small clutch size, and large eggs. It has been suggested that these two species exhibit similar phylogenetic history in order to live in the same harsh habitat. Bufo holdridgei were reported to live underground during different seasons. This could be a possible clue to the behavior of the Incilius periglenes (Jacobson, 1991).

Food Habits

There are little information regarding this species' food habits since they have been primarily observed during the breeding season and live very secretive lives within the forests. Judging by size, many would agree that they feed on smaller invertebrates (Jacobson, 1991).

Economic Importance for Humans: Positive

The golden toad is most important to the scientific world. They give us the opportunity to study rare and beautiful species up close and personal. They also strengthen the scientific community's resolution to find out why amphibians are decreasing globally.

Conservation Status

Unfortunately, the golden toad is a reproductively vulnerable species. They are classified as having a "narrow window of time" in order to breed. During the rainy season, just the right amount of rain must fall in order to have a successful year. If the rains are too heavy, the larva might flow onto the forest floor and be stranded. However, if the rains are too light, the larvae will desiccate. During 1987, there was a major population crash in the golden toads. Due to erratic weather, the pools dried up before the larva had matured. Out of potential 30,000 toads, only 29 had survived. Since then, only a few scattered individuals had been found up until 1991 when no toads were reported. Finding out why this happened is a mystery. Some say that global warming caused the erratic weather that destroyed the reproductive efforts of the golden toad. Others say it was deforestation around the preserve that killed many of the adults when they left the reproductive area. Finally, some say that the toads are simply hiding out until the conditions are right to reproduce. Overall, no one can say for sure and only time will tell. Until then, their reproductive area is still protected if and when they return (Harding, 1993).

Other Comments

The golden toad appears to use visual rather than vocal recognition used by most other toads. It only gives two types of calls, the release call and another call given by a male in amplexus. The frequency and duration of these calls could only be heard over a few meters. The calls could not even be heard on rainy days. It is suggested that the bright coloration and diurnal activities of this toad facilitated visual rather than acoustical identification (Jacobson, 1991).

Contributors

Jason DeGroot (author), Michigan State University, James Harding (editor), Michigan State University.

Glossary

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

References

Harding, K. 1993. Conservation and the Case of the Golden Toad. British Herpetological Bulletin, 44: 31-34.

Jacobson, S. 1991. Reproductive Ecology of the Endangered Golden Toad (Bufo periglenes). Journal of Herpetology, 25: 321-326.

Pounds, A. 1996. Conservation of the Golden Toad: A Brief History. British Herpetological Bulletin, 55: 5-7.