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Kroodsma Donald E. Birdsong by the Seasons: a Year of Listening to Birds

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Kroodsma Donald E. Birdsong by the Seasons: a Year of Listening to Birds
Boston, MA: Houghton Mifflin Company, 2009. — 356 p. — ISBN 978-0-618-75336-9.
The seasons of birdsong follow the seasons of the sun. As the sun dips low in the winter sky, the northern woods fall quiet; those few birds who remain call softly as they search for food to survive the short days and long, cold nights. As the sun makes its comeback, beginning in late December on the winter solstice, so too does song; gonads grow and hormones surge through transforming bodies, the urge to sing now irrepressible as the thoughts of these same birds turn to seeking mates for the coming spring.
Following the sun, migrants from the Tropics soon flood the northern latitudes, culminating in a peak of sun and song by late May to early June. At the summer solstice in late June, the sun begins to slip away again, as does song.
Migrants soon depart for southern latitudes, and those who stay behind retreat to survival mode, calling more softly as thoughts turn again to finding fuel to survive the short days and long, cold nights.
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