Uruguay eradicates invasive bullfrog from Santa Lucía Wetlands

Uruguay has achieved a rare victory against an invasive species, eradicating the bullfrog from the Santa Lucía Wetlands. This multi-year operation, led by the National Committee on Invasive Exotic Species, marks an unprecedented success for the country.

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In concrete terms, my experience is that where the frogs were, there was nothing else.

Researchers found thousands of tadpoles, each "the size of a hand," in invaded ponds, with little native fauna remaining. This grim landscape was the starting point for an operation that demanded years of monitoring. "In concrete terms, my experience is that where the frogs were, there was nothing else," summarized Marcelo Iturburu, a member of the committee.

The success was not due to a single solution but a combination of methods. These included fencing off ponds, conducting nocturnal captures, removing egg masses, desiccating water bodies when possible, and continuous monitoring. "The first answer is that there is no single method. It is a combination of methods, and that combination depends on the location," explained Iturburu.

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We filled five containers with tadpoles and ended the day because we had no more containers.

Introduced in the 1980s for frog farming, the North American bullfrog is considered one of the world's most problematic invasive species. It is an opportunistic predator that can consume amphibians, fish, reptiles, small birds, and even its own kind. Females can lay thousands of eggs per season, and tadpoles remain in the water for extended periods, allowing populations to grow rapidly.

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The first answer is that there is no single method. It is a combination of methods, and that combination depends on the location.

While Uruguay has a consensus list of 42 priority invasive species, the bullfrog is the only one for which local eradication is still a real possibility. "The frog itself does not affect resources of economic value to humans; it affects biodiversity. So, unfortunately, people do not perceive it directly as a threat," explained Ernesto Brugnoli, a researcher at the Faculty of Sciences of the University of the Republic. "Biodiversity is not necessarily measured in pesos; it is richness, heritage, ecological balance, but society always tends to monetize everything."

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The frog itself does not affect resources of economic value to humans; it affects biodiversity. So, unfortunately, people do not perceive it directly as a threat.