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Wildlife Contaminants

Bald Eagle Chicks
Environment, Great Lakes, and Energy

Wildlife Contaminants

EGLE’s surface water monitoring strategy includes wildlife contaminant monitoring. Monitoring the productivity (or population health) and contaminant levels in piscivorous (fish-eating) wildlife provides valuable information on the health of the Great Lakes ecosystem and Michigan’s inland lakes and streams. Some contaminants are persistent (break down slowly), bioaccumulative (build-up in tissues of fish and wildlife) and toxic (cause adverse effects to wildlife populations). Even though some of these contaminants are difficult to measure in water, they can still occur at levels in wildlife that can be harmful. Monitoring these contaminants in wildlife can help determine whether they are at levels of concern. In addition, wildlife can serve as a “first alert” for the detection of changes in environmental quality and the potential for adverse effects to occur on human health. Monitoring contaminants in wildlife can also provide useful information for understanding changes in contaminant levels over time (downward, upward, or no change) which assists EGLE in determining whether certain programs have resulted in environmental improvements. Wildlife monitoring also helps EGLE find contaminant “hotspots” and assess whether wildlife may be impacted.

The following are the objectives of the wildlife contaminant monitoring program:

  1. Determine contaminant levels in piscivorous wildlife.
  2. Assist in the identification of waters that may exceed standards and target additional monitoring activities.
  3. Evaluate the overall effectiveness of EGLE programs in protecting wildlife from toxic contaminants.
  4. Support Area of Concern (AOC) efforts to evaluate Beneficial Use Impairments (BUIs). For more information on AOCs and BUIs visit EGLE’s AOC web page.
  5. Determine whether new chemicals are accumulating in wildlife.

EGLE’s wildlife monitoring program is focused on the following fish-eating species and tissues:

  • Bald eagle (Haliaeetus leucocephalus) nestling plasma (component of blood) and feathers 
  • Herring gull (Larus argentatus) eggs

The bald eagle and herring gull monitoring projects were started in 1999 and 2002, respectively.  Bald eagle and herring gull samples are analyzed for bioaccumulative contaminants of concern(see list of contaminants below). Even though the overall environmental levels of these contaminants have decreased over time, they are still being found in wildlife tissues due to their persistence in the environment and slow rate of removal in fish and wildlife.

Contaminants monitored in bald eagle and herring gull:

  • Mercury – Mercury is a naturally occurring element found in the earth’s crust that exists in many forms (elemental, inorganic, and methylmercury). Mercury is released into the air when coal, oil, and wood fuels are burned. 
  • Polychlorinated biphenyls (PCBs) – PCBs are a group of man-made chemicals that were banned in 1979. PCBs were used in many industrial and commercial applications including electrical and heat transfer equipment, as plasticizers, and in pigments and dyes.
  • Chlorinated pesticides (for example, DDT or dichloro-diphenyl-trichloroethane) – DDT is a pesticide that was used widely prior to its ban in the United States in 1972. DDT is no longer manufactured or used in the United States but is still used to control mosquitoes that spread malaria in certain parts of the world. 
  • Dioxins and furans (herring gull eggs only) – Dioxins and furans are a group of toxic chemical compounds that share certain chemical structures. Dioxins and furans are not produced or used commercially in the United States, but are produced from industrial activities, burning of fuels and wastes, and bleaching processes. 

The wildlife monitoring projects are assessed periodically to determine whether samples should be analyzed for additional contaminants of concern or emerging contaminants. The monitoring of other fish-eating species may occur on a site-specific basis when additional information is needed. 

Efforts to assess perfluorinated and polyfluorinated alkyl substances (PFAS) in wildlife are on-going. Please visit the PFAS Wildlife Workgroup web page  for the latest information on PFAS wildlife monitoring efforts.

Related Links

Contaminant Impacts to Wildlife

The following reports were prepared by EGLE staff in support of wildlife objective (4): Support Area of Concern (AOC) efforts to evaluate Beneficial Use Impairments (BUIs) in Michigan.

Bald Eagles

All bald eagle contaminant data are maintained in partnership with EGLE, US Fish and Wildlife Service, University of Maryland, and Indiana University. Additional reports and data are available by request.

Productivity trend figure

Contaminant temporal trend figures

Contaminant temporal trend reports

Herring Gulls

All herring gull contaminant data are maintained in partnership with EGLE, United States Fish and Wildlife Service, University of Maryland, and Indiana University.

Contaminant temporal trend figures

Contaminant temporal trend reports

Publications and Emerging Contaminant Studies

The Publications and Emerging Contaminant Studies page provides a list of peer-reviewed publications that have in part resulted from EGLE’s wildlife contaminant program monitoring data and for studies that further examine emerging contaminants in Great Lakes piscivorous wildlife (including Michigan wildlife).


Brandon Armstrong, Ph.D.