American Robin (Turdus migratorius)
The American robin is an indicative sign of spring and the official state bird of Michigan.
American robins are a migratory species that breeds from April through July. Typical nesting habitats include residential areas and transition areas between forest and grassland. American robins can be found throughout the floodplain.
The goal of the American robin study was to assess the health and abundance of the robin population of the Tittabawassee River that may be exposed to site-specific contaminants, in particular, dioxins and furans.
Prey items, including earthworms, beetles, and other terrestrial invertebrates, were collected from various sites throughout the floodplain and analyzed for contaminant concentrations. These analyses provided an estimate of the amount of contaminants the American robins were exposed to through their diet.
Egg, nestling, and adult tissues were also analyzed to verify that their dietary exposure had been characterized correctly.
Reproductive variables were also measured to characterize the health of the American robin population. These variables included the number of eggs in each nest, hatching success, and fledging success.
American robin data were collected from reference areas in Sanford, Michigan, and the Pine and Chippewa rivers at and around the Chippewa Nature Center, and study areas downstream of Midland, Michigan, to the Shiawassee National Wildlife Refuge.
Interpreting dietary exposure, tissue concentration analysis, and reproductive variable analysis revealed the information necessary to estimate the possible risk to American robins in the Tittabawassee River area.