The corticosterone stress response and mercury contamination in free-living tree swallows, Tachycineta bicolor.
We determined mercury concentrations in tree swallows, Tachycineta bicolor, from Massachusetts and Maine with different levels of contamination. Baseline and stress-induced plasma corticosterone concentrations from adults and nestlings (Massachusetts only) were compared with mercury concentrations. In Massachusetts, adult baseline corticosterone was negatively correlated with blood mercury, but showed a nearly-significant positive correlation with feather mercury. There was a negative relationship between baseline corticosterone and blood mercury in nestlings and between baseline corticosterone and egg mercury. There was no relationship between mercury and stress-induced corticosterone in any of the groups, or with baseline corticosterone in Maine sites where mercury levels were lower. The findings suggest blood and egg mercury may be a better indicator of current condition than feather mercury. Further, mercury contamination may not alter stress-induced corticosterone concentrations in tree swallows but appears to have a significant impact on baseline circulating corticosterone.
Department of Biology, Tufts University, Medford, MA 02155, USA. melfrances@earthlink.net
Melinda D
MD
Franceschini
Oksana P
OP
Lane
David C
DC
Evers
J Michael
JM
Reed
Bart
B
Hoskins
L Michael
LM
Romero
D000818:Animals; D003345:Corticosterone / Q000097:blood*; D005260:Female; D008281:Maine; D008297:Male; D008404:Massachusetts; D008628:Mercury / Q000097:blood / Q000633:toxicity*; D013312:Stress, Physiological / Q000187:drug effects*; D046388:Swallows / Q000097:blood*
D008628:Mercury; D003345:Corticosterone