Upper Midwest Environmental Sciences Center

UMESC - Wildlife Toxicology - Great Lakes Restoration Initiative (GLRI) Project 80 - Swallows as indicators

Wildlife Toxicology

Great Lakes Restoration Initiative (GLRI) Project 80

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.

Swallow range

Because you can see them, you know where they are feeding and hence are accumulating the contaminants present in their tissues.


Swallows will nest in more diverse aquatic habitats within their breeding range than most other avian species.  
lakes and ponds
rivers and streams

- including highly industrial and urban locations where other species are often rare.

industrial photo

industrial photo  

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.

Dredging Sorting and processing dredged material  

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.

Field work Field work


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).


August 5, 2011
Page Last Modified: April 3, 2018