Tree swallow 

(Tacycineta bicolor)


Cute bird: Male Tree swallow at Serpentine Fens, Surrey, B.C.
The Tree swallow is a small passerine common throughout much of North America. Both males and females have iridescent deep blue-green-brown heads and backs with white undersides, although young females (< 2 years) are dull brown above. Tree swallows reside near open water, feeding exclusively on insects that they catch on the wing. These birds are cavity nesters and utilize both natural tree cavities and human-constructed nest boxes. They are short-distance migrants, breeding across the northern U.S. and southern half of Canada, and wintering along the southern U.S. coastline down to the Caribbean.

 Over the past few years, Tree swallows have been increasingly studied in contaminated habitats as possible ãbioindicatorsä of local exposure and contaminant effects. Research* shows that Tree swallows are exposed through their insect diet to a wide variety of compounds, which can accumulate in their tissues, eggs and offspring. These compounds include persistent organochlorines (e.g. PCBs, DDT, dioxins), pesticides and heavy metals. Exposure to such substances may be associated with altered immune function, reproductive physiology and behavior.

Erinn Birmingham is currently studying Tree swallows for her Masters project, investigating immune and reproductive endpoints in Tree swallows exposed to a variety of endocrine-disrupting compounds (chemicals that interfere with normal hormonal communication). These compounds include 4-Nonylphenol, a common pollutant in industrial and municipal wastewater that is mildly estrogenic (and possibly androgenic). My field work supplements my laboratory research, which involves dosing Zebra finches (Taeniopygia guttata) with 4-Nonylphenol and measuring similar reproductive and immune endpoints. My ultimate objective is to determine the utility of these biomarkers for studying songbird health in contaminated environments.


Auk 2000, 117(4): 987-995

Auk 1999, 116(1): 55-63

Environ. Pollution 2000, 110(2): 307-320

Environ. Toxicol. Chem. 1999, 18(11): 2519-2525

Environ. Toxicol. Chem. 1999, 18(2): 263-271

Last updated on 4 Feb, 2003. Contact CWE webmaster.