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Et tu, Tegu? Florida scientists, FWC fight against alarming increase in invasive lizards

Argentine black and white tegu FWC photo (Florida Fish and Wildlife Conservation Commission, University of Florida)

A large lizard that is sometimes kept as a pet is wreaking havoc on Florida’s native wildlife and scientists at the University of Florida are working on a solution.

Argentine black and white tegus have spread and established populations in and around Florida at a rapid and growing rate and that could have critical implications for natural areas and even restoration efforts for Everglades National Park, according to UF scientists at the Institute of Food and Agricultural Sciences.

Scientists said the spread of tegus can impact Everglade’s restoration efforts by increasing predation on threatened and endangered species, including the American crocodile, the Key Largo woodrat, the Cape Sable seaside sparrow, as well as all other ground-nesting birds and reptiles.

Wildlife experts and scientists have developed cooperative programs over the last decade to locate, survey, monitor and trap tegus where they have spread and established populations in order to reduce their numbers and control the species in Florida and outlying areas before it continues to spread.

“Our work has shown that tegu populations can be controlled with sustained trapping efforts and resources,” said Melissa Miller, invasive species research coordinator for The Croc Docs at UF’s Fort Lauderdale Research and Education Center (REC). “Knowing we can achieve success in reducing tegu abundance and dispersal allows us to strategically prioritize efforts and protect at-risk native wildlife. However, dedicated multi-year funding is needed to continue enacting a successful interagency tegu control program across the landscape”.

Counties where tegus have been reported. (University of Florida)

After tegus were introduced to south Florida they spread into areas impacting wildlife, threatening nesting areas of protected and endangered species, and entered natural areas including Everglades National Park.

Tegus have since spread beyond south Florida and are likely to continue establishing without sustained control, research and monitoring efforts by partnering agencies, scientists say.

To date, Argentine black and white tegu populations have grown in numbers, with distinct populations established in four Florida counties. Tegus have been reported in 31 additional Florida counties, including Duval County, which may represent individuals that are escaped or released pets and that have not yet formed breeding populations. Tegu sightings have also been reported in four Georgia counties. Both the number of tegus removed, and the effort expended to catch them have increased.

These totals do not include tegus removed by private trappers, some who reported removing more than 400 tegus in a year.

UF scientists at the Institute of Food and Agricultural Sciences (UF/IFAS) and partnering agencies have co-authored the “Growth and Spread of the Argentine Black and White Tegu Population in Florida” illustrating the depth and breadth of the tegu problem.

To directly mitigate the impacts of tegus on its native ecosystems, the FWC uses staff and private contractors to detect, trap, and remove tegus in areas to decrease population size and spread. They also contract with research institutions to determine potential spread, evaluate detection and removal methods, and better understand impacts to native wildlife.

“Tegus are an invasive wildlife species that have significant impacts on our native wildlife and ecosystems and are a high priority for our agency to control. While tegus are an increasing concern, we can slow their spread and minimize their impacts by increasing efforts to prevent releases, rapidly responding to reports in new locations, and continuing management activities that reduce and contain breeding populations,” said Melissa Tucker, director of the Division of Habitat and Species Conservation, FWC.