Tree Swallows March North

BirdNote^®

Tree Swallows March North

Written by Bob Sundstrom

This is BirdNote!
[Rapid series of male Tree Swallow’s song-like notes]
    Every March, a vast, glittering blue wave sweeps northward across the North American continent. [Rapid series of male Tree Swallow’s song-like notes]
    This natural wonder is not a massive storm rushing forth from the tropics. It is the annual spring migration of Tree Swallows. Millions of Tree Swallows. [Rapid series of male Tree Swallow’s song-like notes] The swallows spend the winter along the Caribbean, in Central America, and in the warmest parts of South Texas and California. By March, they’re on the move. Some will nest as far north as there are trees, in northern Alaska and Canada. [Rapid series of male Tree Swallow’s song-like notes]
    Tree Swallows rank among the earliest northbound migrants. Most swallows eat only flying insects.  But these early arrivers in the north may be aided by their ability to subsist on berries during cold spells.
    But something else motivates the Tree Swallows’ northward push against the cold edge of winter: their choice of nest sites. They nest only in cavities, such as old woodpecker holes or man-made nestboxes. The supply of such specialized nest sites is limited, and competition is intense.
    So in this case, the “early bird” gets the nest.
[Rapid series of male Tree Swallow’s song-like notes]
For BirdNote, I'm Michael Stein.

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Song of the Tree Swallow provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Recorded by G.F. Budney
Producer: John Kessler
Executive Producer: Chris Peterson
© 2014 Tune In to Nature.org      March 2017 / 2021    Narrator: Michael Stein

ID#  2008-03-31-TRES-03-KPLU      TRES-03b