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Photo by Lynn Chamberlain
Photo Copyright Lynn Chamberlain
American Bullfrog
Lithobates catesbeianus
Other common names: Bullfrog
NatureServe conservation status
Global (G-rank): G5
State (S-rank): SNA
- Reason: This species is introduced in Utah.
External links
General information
The American bullfrog, Rana catesbeiana, is NOT native to Utah; it has been introduced from east of the Rocky Mountains. Unfortunately, these introductions have apparently led to declines in many amphibian species native to Utah.
The American bullfrog is the largest frog found in Utah (and North America), and it remains near water its entire life, dispersing from permanent water bodies only during wet weather. American bullfrogs breed in the spring or early summer in Utah. Adult frogs are carnivorous, eating many types of vertebrate and invertebrate animals. Larval frogs (tadpoles) eat plants, detritus, and aquatic invertebrates.
Phenology
Bullfrogs are easily observed in daytime or (with a light) at night; movements and breeding activity during summer occur mostly at dusk and at night, though calling commonly occurs in daytime as well. Bullfrogs are relatively inactive during cold winter months, where they situate themselves at the bottom of pools or under various sorts of cover in or near water.
Species range
The native range extends from Nova Scotia, New Brunswick, and southern Quebec, Canada, west to the Great Lakes region, and south through most of the central and eastern United States and south into northeastern Mexico. The western limits of the native range are ambiguous due to widespread introductions in western North America. The species also has been introduced and is established in the Greater Antilles, Hawaii, and many other locations worldwide.
Migration
May make seasonal migrations to and from ephemeral bodies of water, or between adjacent permanent aquatic habitats. Usually remains in one pond or in a cluster of adjacent ponds throughout season but may move up to a mile or more from one year to the next. In Missouri, Willis et al. (1956) found that R. catesbeiana made interpond movements of 0.16-2.8 km.
Habitat
American bullfrogs inhabit ponds, swamps, lakes, reservoirs, marshes, brackish ponds (e.g., Hawaii), stream margins, and irrigation ditches, especially sites with abundant floating, emergent, or submerged vegetation. They may disperse from water in wet weather and sometimes are found in temporary waters hundreds of meters from permanent water. Bullfrogs sometimes make seasonal migrations to and from ephemeral bodies of water, or between adjacent permanent aquatic habitats. Individuals often remain in one pond or in a cluster of adjacent ponds throughout a season but may move up to a mile or more from one year to the next. Breeding sites are primarily permanent slow- or nonflowing bodies of water.
Food habits
Metamorphosed frogs eat any animal that can be captured and swallowed, including all kinds of vertebrates and invertebrates. Larvae eat suspended matter, organic debris, algae, plant tissue, and small aquatic invertebrates.
Ecology
Introduced bullfrogs apparently have detrimental effects on populations of native ranid frogs. Bullfrog larvae generally are not palatable to fish predators but are sensitive to invertebrate predators (e.g., see Smith et al. 1999).Bullfrogs in hand may go limp, then suddenly "revive" and leap away. Sometimes they produce a loud open-mouthed call lasting up to several seconds.
Reproductive characteristics
Breeding occurs when water temperatures are relatively warm, mainly in May-July in the northern part of the range, primarily late spring to late summer in Georgia, and mainly March through summer in Louisiana. Individual females produce 1-2 clutches/year. Larvae hatch in 4-20 days. In most areas, larvae overwinter at least once before metamorphosing, but larvae metamorphose in less than a year in warm climates (e.g., 5-6 months in Louisiana; less than 6 months in Hawaii, Tinker 1941). Individuals become sexually mature an average of 1-5 years after metamorphosis, with the oldest ages of maturity occurring in environments with the shortest growing seasons (e.g., average of 5 years after metamorphosis in central Ontario females); in a particular location, males tend to mature a year or so earlier than do females (Shirose et al. 1993).
Threats or limiting factors
There are no threats to this species. Outside of the United States this species is considered a pest.
References
- Biotics Database. 2005. Utah Division of Wildlife Resources, NatureServe, and the network of Natural Heritage Programs and Conservation Data Centers.
- Stebbins, R. C. 1985. A field guide to western reptiles and amphibians. Houghton Mifflin Company, Boston. 336 pp.
