Irruptive Bird Identification Guide
    What is an "irruptive" species?
      The term "irruptive" refers to species that typically spend the winter in a particular geographic region but may shift into other locations, usually following a cyclical pattern. This pattern is believed to be related to food availability. Common Redpolls, for example, irrupt from their typical wintering grounds in Canada into areas farther south every two years, presumably because the catkins on which they feed are generally produced every other year. A number of species have been shown to exhibit irruptive behavior. Most irruptives are in the finch family, although such species as the Red-breasted Nuthatch, Black-capped Chickadee, Varied Thrush, and Blue Jay have also been know to irrupt. To view images of irruptive birds, to listen to their calls, and to learn more about their distribution, use the pull-down menu (below) to select a species, then click on the "Go" button.

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Choose a species and press "Go".
What is an "Irruption?" ID Guide Count Instructions Fill Out a Checklist IBS Results Previous page BirdSource
What is an \'Irruption?\' Identification Guide Fill out a checklist Results