Birds as Indicators of Contaminant Exposure in the Great Lakes

Science Center Objects

Story Map: Utilizing Tree Swallows as Indicators for Contaminants in the Great Lakes Area

Use tree swallows and colonial waterbirds in the Great Lakes to evaluate contaminant

  1. Exposure (geographic and spatial);
  2. Trends through time(temporal)
  3. Effects (reproductive, physiological, genetic)
  4. Monitor cleanup actions

Objectives 1 and 2 - Exposure data will concentrate on several classes of new and emerging contaminants, such as the now ubiquitous flame retardants (polybrominated diphenyl ethers [PBDCs]) and stain repellents (perfluorinated compounds [PFCs]).These data will be important in understanding the distribution of these relatively-little studied chemicals in birds. We will be gathering data on several well-studied chemical classes (PCBs, mercury, dioxins) as well because these can still be present in the environment at possible levels of concern.

Objective 3 - Effects of environmental contaminants on birds were first brought to the nation’s attention by Rachel Carson in her seminal book Silent Spring. Since then birds have been used effectively in contaminant effect assessments. Project 80 will be measuring numerous different types of endpoints ranging from genetic up to population-level endpoints.

Objective 4 - Cleaning up contaminated areas is an important component of the GLRI program. Equally important is assessing how effective those remedies have been.Project 80 will provide important documentation of remedy effectiveness.

A particular emphasis of GLRI as a whole is to make physical improvements to locations that result in a cleaner, safer, and better environment. One measure of this progress is the de-listing of Areas of Concern by removing Beneficial Use Impairments (BUIs). Project 80 provides data specific for two important BUIs: 'Degradation of Fish and Wildlife Populations' and 'Bird or Animal Deformities or Reproduction Problems'. 

Tree swallow study sites by Great Lakes

Tree swallow study sites by Great Lakes(Public domain.)

 

Swallows as indicators

Tree swallows nest across the northern half of the U.S. and because they nest in artificial nest boxes can be attracted to specific areas of interest. Tree swallows are very numerous so they are not as difficult to find and study as other avian species. 

 

Tree swallow breeding range

Tree swallow breeding range(Public domain.)

Swallows will nest in more diverse aquatic habitats within their breeding range than most other avian species - including highly industrial and urban locations where other species are often rare. 

Greater than 85% of swallow’s diet are benthic aquatic insects and they feed within ~ 1 km of their nest box so contamination in their tissues are closely tied to sediment contamination and the cleanup of those sediments. The short, consistent food chain makes data interpretation easier and more direct. 

The level of clean-up achieved can be readily quantified by the swallows. They integrate over appropriate time and spatial scales. Tree swallows are relatively easy and efficient to study. Because they nest in boxes, swallows can be attracted to almost any area where data are needed. By putting up many (20 – 50) nest boxes adequate sample sizes can be generated which results in strong statistical power to detect trends through time and to quantify adverse effects.

While much better looking  “ . . . tree swallows deserve equal standing beside fruit flies, nematodes, and mice as one of the classical model organisms in biology.”
(J.Jones 2003 Auk 120:591-599).