Friday, December 16, 2016

Gray Catbird

This Gray Catbird is an exception to the rule that this species inhabits dense, shrubby vegetation. I found this bird foraging for insects from a Frisbee course basket. I was searching for dragonflies along Carleton College’s Lyman Lakes last June. Catbirds sometimes earn farmers’ ire by consuming fruit. This individual ate small caterpillars, perhaps redeeming its berry-eating reputation.

Gray Catbirds are one of the few birds that regularly eject cowbird eggs from their nests. This ability is learned. Catbirds only destroy cowbird eggs after they learn what their own eggs look like. If cowbirds lay their eggs in the nest before the catbirds, then the catbirds destroy their own eggs! Ornithologists do not know if, in subsequent years, older catbirds have to relearn the appearance their eggs (Smith et al. 2011).

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