New wetlands ecological research aviary will measure mercury impact on wildlife

October 27, 2005

GAINESVILLE, Fla. — To learn how tiny amounts of mercury affect wildlife – especially wading birds in the Florida Everglades – University of Florida scientists are beginning a five-year study at the new Wetlands Ecological Research Aviary in Gainesville.

Formal opening of the aviary is set for 10 a.m. Nov. 2 when officials from UF’s Institute of Food and Agricultural Sciences, the U.S. Department of Agriculture’s Wildlife Services program and other cooperating agencies will gather at the facility. The UF aviary is located at USDA Wildlife Services, 2820 E. University Ave. in Gainesville.

“The research aviary will provide a unique environment for studying the effects of Everglades-appropriate levels of mercury on the development and reproduction of aquatic birdlife,” said Peter Frederick, an associate research professor in UF’s wildlife ecology and conservation department and leader of the project.

“Results of the research will help wildlife managers and other federal and state agencies determine safe mercury levels for wildlife that may be different from existing human health standards,” he said.

Built on USDA land and managed by UF, the research project is funded by the Florida Department of Environmental Protection, the U.S. Fish and Wildlife Service, the U.S. Geological Survey and the U.S. Army Corps of Engineers. Funds from the federal Comprehensive Everglades Restoration Plan – described as the world’s largest ecosystem restoration effort – also help support the UF research project.

Frederick said the 13,000-square-foot outdoor aviary, one of the nation’s largest, houses more than 160 white ibises (Eudocimus albus). About the size of a chicken, the ibis has a long, decurved bill and blue eyes.

“They are kept in outdoor conditions with plenty of room to fly and lots of water to drink and bathe in – we want the birds to be in as natural an environment as possible,” he said.

“The birds are exposed to mercury, but no more than they would get in the wild. When the research is completed, the birds will be placed in zoos.”

The reproductive success and health of wading birds such as herons, egrets, ibises and storks in the Everglades are important measures of the success of ecological restoration, Frederick said.

“As the Everglades restoration plan moves forward, we need to increase our ability to predict how wading birds will respond,” he said. “We are very confident that the hydrological restoration – getting the water flows right – will be good for wading bird populations. But we are now aware that mercury might also have an effect – maybe even one that partially cancels the positive effects of hydrological restoration.”

When fish ingest mercury, either by absorbing it through their gills or by eating other contaminated fish, the toxin is stored in their bodies. Wading birds, which consume large amounts of fish, are particularly at risk for mercury contamination because they are at or near the end of long aquatic food webs that can accumulate the toxin, Frederick said.

Selected because of their abundance in South Florida, white ibises serve as representative fish-eating birds for much of the southeastern United States, he said. They comprise 40 to 60 percent of the wading bird population in the Everglades.

“At high contamination levels, mercury has very obvious effects on wild animals and humans,” Frederick said. “With this project, we are asking whether effects also occur at very low, but chronic, contamination levels. The effects we are looking for are unlikely to kill the bird, but they might impair the immune system, reduce foraging abilities or alter hormones to the point that birds don’t breed. And these are the things that could affect population size and response to Everglades restoration.

“Our regulatory agencies protect people from eating too much mercury in fish or other food, but unlike people, the birds are out there eating 24/7 and are unprotected,” he said. “For years, scientists have been trying to isolate the effects of low-level mercury contamination on wild wading birds, but have been unsuccessful because it’s nearly impossible to separate the effects of mercury from other things such as age, predation and weather.”

In previous research funded by the Florida Department of Environmental Protection and the Florida Fish and Wildlife Conservation Commission, Frederick and other scientists found a dramatic decline in mercury contamination levels in Everglades wildlife during the past decade. Between the 1930s and 1980s, bird populations in the wetland declined by up to 90 percent depending on species, and Frederick believes mercury contamination may have impaired the restoration of these populations.

“One hint comes from the fact that the numbers of wading bird nests in the Everglades increased by two or three times immediately following the sharp, local decline in mercury,” he said. “While tantalizing, that doesn’t prove mercury was keeping birds from breeding. For that, you need a controlled experiment, and the new aviary will provide the setting for that work.”

Scientists attribute the recent mercury declines in the Everglades to tougher emission standards for power plants and incinerators, along with a big reduction in the use of mercury in household products such as flashlight batteries and paint. The toxin, which causes reproductive and behavioral problems in birds, also causes serious neurological damage and developmental problems for people who ingest it.

Once the mercury study is completed, the research aviary will be transferred to the USDA and be used for other avian studies.

Michael Avery, director of the Florida field station for the USDA’s National Wildlife Research Center, said other research at the Gainesville facility includes the development and testing of new tools and techniques for managing depredation and nuisance problems caused by vultures, identifying and testing repellents to reduce the impacts of exotic monk parakeets on electric utility facilities and evaluating reproductive inhibitors for managing nonnative bird species.

He said the Wildlife Services program, which is part of the USDA’s Animal and Plant Health Inspection Service, helps solve human-wildlife conflicts and create a balance that allows people and wildlife to coexist peacefully.

The UF research aviary was designed by Gainesville architects Claude Armstrong and Donna Cohen.