Saturday, September 1, 2012

American White Pelican

Yesterday, 31 August 2012, Erika and I looked up as we finished biking on the Cannon Valley Bike Trail at its terminus just north of Red Wing, Minnesota. A huge flock of what we estimate to be 400 American White Pelicans circled overhead. Try counting the individuals in the top photo--I come up with a different number every time I try. Imagine trying to count as the birds passed overhead. Only about a quarter of the total flock is captured in the first photo. Because White pelican flocks usually number only up to 180 individuals (Knopf et al. 2004), we may have seen four flocks intermingling.

The world population of American White Pelicans, which breed across the Canadian and American prairies, was reported by del Hoyo et al. (1992) to be at least 104,000 in 1979-1981. Since then, numbers have increased by at least 3% a year. Early lower numbers were the result of draining of prairie lands, human disturbance and agricultural contamination (Knopf et al. 2004). In any event, these pelicans seldom migrate at night, preferring to catch thermals of warm air high into the sky, and then saving energy by gliding south to the next thermal. The birds we saw will probably winter somewhere along the Gulf Coast. Birds breednig west of the Rocky Mountains winter in California or along western Mexico and Central America.

These pelicans reminded me of a huge flock of White Storks that I photographed in late August 1963 near Tarifa, Spain. Here again the birds were taking advantage of rising thermals of air. Because thermals do not form over water, these storks take advantage of the thermals over land. Thus these storks save up to 23 times of their energy resources by gliding, rather than flapping to Africa across the Strait of Gibraltar to Africa (Wikipedia)

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