Bullfrog Predation on a Juvenile Coho Salmon in Humboldt County, California

Garwood, Justin M.; Ricker, Seth J.; Anderson, Colin

doi:10.1898/nwn09-17.1

Cited by 2 publications

(2 citation statements)

References 12 publications

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“…However, many streams on southern Vancouver Island become intermittent in late summer and in shallow isolated pools salmon fry could be more vulnerable to bullfrog predation. Garwood et al (2010) recently documented an adult bullfrog from a stream in California with an 11.6 cm long coho salmon in its stomach. Lotic habitats were not sampled in our study because bullfrogs aggregate and reproduce locally only in the warmer standing water of lakes and ponds.…”

Section: Prey Species Of Special Concernmentioning

confidence: 99%

Stomach contents from invasive American bullfrogs Rana catesbeiana (= Lithobates catesbeianus) on southern Vancouver Island, British Columbia, Canada

Jancowski¹,

Orchard²

2013

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Invasive alien American bullfrog populations are commonly identified as a pernicious influence on the survival of native species due to their adaptability, proliferation and consequent ecological impacts through competition and predation. However, it has been difficult to determine conclusively their destructive influence due to the fragmentary and geographically dispersed nature of the historical database. An expanding meta-population of invasive American bullfrogs, Rana catesbeiana (= Lithobates catesbeianus), became established on southern Vancouver Island, British Columbia, Canada in the mid-to late 1980s. An on-going bullfrog control program begun in 2006 offered a unique opportunity to examine the stomach contents removed from 5,075 adult and juvenile bullfrogs collected from 60 sites throughout the active season (April to October). Of 15 classes of organisms identified in the diet, insects were numerically dominant, particularly social wasps and odonates (damselflies and dragonflies). Seasonality and site-specific habitat characteristics influenced prey occurrence and abundance. Native vertebrates in the diet included fish, frogs, salamanders, snakes, lizards, turtles, birds, and mammals, including some of conservation concern. Certain predators of bullfrog tadpoles and juveniles are commonly preyed upon by adult bullfrogs, thereby suppressing their effectiveness as biological checks to bullfrog population growth. Prey species with antipredator defences, such as wasps and sticklebacks, were sometimes eaten in abundance. Many prey species have some type of anti-predator defence, such as wasp stingers or stickleback spines, but there was no indication of conditioned avoidance to any of these. Results from this study reinforce the conclusion that, as an invasive alien, the American bullfrog is an opportunistic and seemingly unspecialized predator that has a uniquely large and complex ecological footprint both above and below the water surface.

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Section: Prey Species Of Special Concernmentioning

confidence: 99%

Stomach contents from invasive American bullfrogs Rana catesbeiana (= Lithobates catesbeianus) on southern Vancouver Island, British Columbia, Canada

Jancowski¹,

Orchard²

2013

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“…The worldwide expansion and negative effects of bullfrogs on native species have resulted in its inclusion in the list of the 100 worst invasive species (Lowe et al 2001). Bullfrogs readily adapt to anthropogenic habitat modifications and are opportunistic feeders (Batista 2002; Carpenter et al 2002; Cross & Gerstenberger 2002; King et al 2002) that will prey upon threatened species including R. draytonii (California red‐legged frog; Moyle 1973; D’Amore et al 2010) and Oncorhynchus kisutch (coho salmon; Garwood et al 2010).…”

Section: Introductionmentioning

confidence: 94%

Linking the Distribution of an Invasive Amphibian (Rana catesbeiana) to Habitat Conditions in a Managed River System in Northern California

Fuller

Pope

Ashton

et al. 2011

Restoration Ecology

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Extensive modifications of river systems have left floodplains some of the most endangered ecosystems in the world and made restoration of these systems a priority. Modified river ecosystems frequently support invasive species to the detriment of native species. Rana catesbeiana (American bullfrog) is an invasive amphibian that thrives in modified aquatic habitats. In 2004-2005 we studied the distribution of bullfrogs along a 98-km reach of the Trinity River below the Lewiston Dam to identify habitat characteristics associated with bullfrogs and to recommend actions to reduce their prevalence in the system. We also examined native amphibian distributions relative to bullfrogs and disturbance regimes. We used regression techniques to model the distribution of bullfrogs in relation to environmental conditions. Models assessing breeding habitat outperformed models assessing bullfrog presence. Top-ranked predictor variables of bullfrog distribution included water depth, percent rooted floating vegetation, and river km. Most breeding sites of bullfrogs were relict mine tailing ponds or inactive side channels created during restoration activities in the 1990s. Native species were more common in the lower reach where habitats were less modified, in contrast to the distribution of bullfrogs that dominated the upper, more modified reach. To control bullfrogs along a managed river, we suggest reducing the suitability of breeding sites by decreasing depth or reducing hydroperiod and increasing connection with the active river channel. Current management goals of restoring salmonid habitat and returning the river to a more natural hydrologic condition should aid in control of bullfrogs and improve conditions for native amphibians.

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Bullfrog Predation on a Juvenile Coho Salmon in Humboldt County, California

Cited by 2 publications

References 12 publications

Stomach contents from invasive American bullfrogs Rana catesbeiana (= Lithobates catesbeianus) on southern Vancouver Island, British Columbia, Canada

Stomach contents from invasive American bullfrogs Rana catesbeiana (= Lithobates catesbeianus) on southern Vancouver Island, British Columbia, Canada

Linking the Distribution of an Invasive Amphibian (Rana catesbeiana) to Habitat Conditions in a Managed River System in Northern California

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