Friday, August 27, 2010

Golden-winged Warbler

On Thursday I banded a Golden-winged Warbler, our first for the Dundas banding site. I previously observed the species there but never banded it.  In my 14 June 2010 blog, I discussed some of the genetics and population dynamics of this bird.  But this warbler has more fascinating biology.

I caught this Golden-winged Warbler with four Black-capped Chickadees, perhaps not a coincidence.  These two species are often found with each other, especially in the late summer and during the fall migration.  This association may be to the benefit of both species.  The warbler learns from the resident chickadees where the best feeding areas are located (and the chickadees are familiar with local predators).  The warbler may be better able to open insect-laden buds that the chickadee would otherwise miss (the chickadee then steals from the warbler).  The somewhat similar plumage of the two species (black throats, gray bodies, and similar song pitch) may reduce aggression and thereby enable the species to occupy the same flocks (Eastman, Birds of Field and Shore).

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