The web Browser you are currently using is unsupported, and some features of this site may not work as intended. Please update to a modern browser such as Chrome, Firefox or Edge to experience all features Michigan.gov has to offer.
Fast Five with EGLE toxicologist on monitoring bald eagles for contaminants
July 20, 2023
MI Environment today in this Fast Five edition talks with Sara Nedrich, a toxicologist with the Water Resources Division of the Michigan Department of Environment, Great Lakes, and Energy (EGLE), about the department’s Wildlife Contaminant Monitoring Program.
Sara Nedrich, EGLE toxicologist, holds a bald eaglet's talons, while William Bowerman, distinguished professor at the University of Maryland, places an identification band on its leg.
What is the purpose of EGLE’s Wildlife Contaminant Monitoring Program?
EGLE, in partnership with the U.S. Fish and Wildlife Service and academic partners, conducts sampling of bald eagles, herring gull, and fish to assess the prevalence of bioaccumulative contaminants in the environment and health of wildlife populations in the state. Bioaccumulative contaminants become more concentrated up the food chain and examples include PCBs, dioxins, mercury, and chlorinated pesticides.
How often does bald eagle testing take place?
Bald eagle sampling has been conducted almost every year in Michigan since 1989. William Bowerman, professor at University of Maryland, started the sampling as his graduate thesis and he continues to lead the field sampling crew every spring/summer.
How do you capture the eagles for testing?
In April and May aerial surveys are conducted in Michigan to verify eagle nest occupancy and identify whether eggs/eaglets are present. The survey data informs our sampling teams, who then have a tight window of time (less than 10 weeks) to make it to the nest before the eaglets fledge. A solo certified climber scales the tree to reach the nest and will carefully handle the eaglets and place them in a secure bag to slowly lower them to the ground by a wire. A covering is placed over the eagle’s face to minimize stress, and with careful handling, a trained field member will then take blood from the wings and place a band on their leg. Once the blood draw is completed, the eagle is placed back into the bag and scaled back up the tree to be placed in the nest.
What does EGLE do with the eagle test results?
The blood samples are sent to a lab at Indiana University for contaminant testing. These test results are used to compare contaminant levels in eagles from year to year. It gives us a picture on whether food sources in the Great Lakes are contributing to deformities or low productivity and can help us track new contaminants of concern, like per- and polyfluoroalkyl substances (PFAS). Monitoring contaminants in wildlife can help determine whether they are at levels of concern in the ecosystem.
Do you have any examples of what has happened after other tests took place? Does it provide a better understanding of how contaminants affect wildlife? Has anything positive happened after testing -- improved health, for example?
When this project started, bald eagles were an endangered species. Eagle reproduction and productivity has generally increased over the last 30 years as contaminant concentrations decreased in the eaglets. The productivity data collected as part of this study helped inform the delisting of eagles in 2007. Thanks to funding from the Great Lakes Restoration Initiative, the data continues to be used to assess wildlife deformity impairments at five Michigan Areas of Concern sites, which are contaminated but improving with state and federal funded efforts. Since eagles are at the top of the food chain, they are the first line of detection for whether a bioaccumulative chemical may be at levels of concern. Currently, we have funding to investigate two new emerging chemicals, PFAS and short chain chlorinated paraffins.
Several scientific publications have been produced as part of this program. To learn more, check out EGLE’s Wildlife Contaminant Program.