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What do American bullfrogs eat when they're away from home? Practically everything

Date:
March 14, 2013
Source:
Pensoft Publishers
Summary:
A control program on southern Vancouver Island provided the carcasses of over 5,000 adult and juvenile invasive alien American bullfrogs. Examination of their stomach contents confirms that bullfrogs eat virtually any organism that can fit into their large mouths, whether it be under water, at the surface, on land, even when it can defend itself with stingers, spines, or claws. So native ecosystems beware!

This picture shows a bullfrog and songbird removed from its stomach.
Credit: Stan A. Orchard/CC-BY 3.0

American bullfrogs are native to eastern North America but have been transported by people to many other parts of the globe, and other parts of North America, where they have readily established populations and become an invasive alien menace to native ecosystems. In the largest study of its kind to date, the stomach contents of over 5,000 invasive alien American bullfrogs from 60 lakes and ponds on southern Vancouver Island were examined to identify the native and exotic animals that they had preyed upon.

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The study was published in the open access journal NeoBiota.

Over 15 classes of animals were reported from a total of 18,814 identifiable prey remains, including terrestrial and aquatic insects, spiders, crayfish, fish, frogs, salamanders, newts, snakes, lizards, turtles, birds, and small mammals. The study examined the stomach contents of adults and juveniles of all size-classes, but excluded tadpoles. These results show that bullfrogs will attack and consume virtually any organism that is within reach and can be swallowed, including their own species.

Previous studies on bullfrog diet have examined relatively small numbers of stomachs from a comparatively small number of lakes and ponds. Our results reinforce the general consensus that there is good reason for concern about the ecological harm that uncontrolled populations of American bullfrogs might have, or are having, on populations of native species.

For decades, bullfrogs have been transported and released around the world by prospective frog-farmers, pet owners, game managers, recreational fishermen, biological supply houses; and even by entrants in frog jumping contests. They adapt readily to a variety of habitats from the tropics to temperate zones and once established, their numbers grow fast with each adult female producing about 20,000 or more eggs per year. For these reasons, American bullfrogs are internationally recognized as one of the 100 worst invasive alien species in the world.


Story Source:

The above story is based on materials provided by Pensoft Publishers. The original story is licensed under a Creative Commons License. Note: Materials may be edited for content and length.


Journal Reference:

  1. Kevin Jancowski, Stan Orchard. Stomach contents from invasive American bullfrogs Rana catesbeiana (= Lithobates catesbeianus) on southern Vancouver Island, British Columbia, Canada. NeoBiota, 2013; 16 (0): 17 DOI: 10.3897/neobiota.16.3806

Cite This Page:

Pensoft Publishers. "What do American bullfrogs eat when they're away from home? Practically everything." ScienceDaily. ScienceDaily, 14 March 2013. <www.sciencedaily.com/releases/2013/03/130314111644.htm>.
Pensoft Publishers. (2013, March 14). What do American bullfrogs eat when they're away from home? Practically everything. ScienceDaily. Retrieved November 1, 2014 from www.sciencedaily.com/releases/2013/03/130314111644.htm
Pensoft Publishers. "What do American bullfrogs eat when they're away from home? Practically everything." ScienceDaily. www.sciencedaily.com/releases/2013/03/130314111644.htm (accessed November 1, 2014).

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