Birders excited by invaders from the north
As you read this, we are being invaded. Devious birds are sneaking across our defenseless borders. They are Canadian birds heading south for the winter, and we’re the south. Many of these birds gather in predictable numbers in predictable places each winter. But some are just plain unpredictable.
In birding terms, they are called winter irruptives. The words “erupt” and “irrupt” come from the same Latin root and mean roughly “exploding forth.” One particular definition of irrupt relates to the sudden upsurge in natural populations, especially when ecological balances and checks are disturbed. That’s exactly what happens when food shortages or frigid weather drives birds south. Irruptive owls were discussed last week, but there are plenty of other northern breeders on the list, including birds that eat seeds.
White-winged and red crossbills are highly irruptive, wandering south into Maine even in summer, where they may nest in a good cone year. Both species are widespread breeders across Canada, but the red crossbill tends to wander a little farther south in the western states.
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