Fish-eating Birds

An afternoon on the river would not be complete without hearing the rattle call of a belted kingfisher letting you know you’ve entered its territory or watching a great blue heron steadily stalking its prey through the shallows. Our research aims to verify that the populations of these species that reside within the Tittabawassee River floodplain do not experience adverse effects from site-specific contaminants (furans and dioxins).

To do this, site-specific diets of each species are determined through the collection of prey remains and observations of foraging behavior. These prey items are then collected from the study area and analyzed for contaminant concentrations. For the great blue heron and belted kingfisher, this includes fish, crayfish, and amphibians. These collections allow us to estimate the concentration of contaminants the receptor species is exposed to through its diet.

Contaminant concentrations in tissues of the receptor species are also analyzed to verify that their exposure has been characterized correctly. The type of tissue collected depends on the receptor but may include eggs, nestlings, or blood plasma.

The health of receptor species’ populations are assessed through the evaluation of productivity, including nest success, number of nestlings per nest, fledgling success, and species abundance.

Fish-eating bird data have been collected from reference areas in Sanford, Michigan, and the Pine and Chippewa rivers in and around the Chippewa Nature Center downstream of Midland, Michigan, ranging to the Shiawassee National Wildlife Refuge.

Integrating the findings from all lines of evidence will provide us with the information necessary to estimate the risk of adverse effects to great blue herons and belted kingfishers residing within the Tittabawassee River basin.