Originally posted by aslyfox 
Eared Grebes Podiceps nigricollis at the Cheyenne Bottoms near Great Bend Kansas
" . . . For perhaps 9–10 months each year the species is flightless; this is the longest flightless period of any bird in the world capable of flight at all."
At first I thought: that doesn't add up. I thought that all bird species that have a flightless period are flightless only during the once annual, simultaneous moult of their flight feathers (on the breeding grounds in the cases of ducks, geese, swans, and auks). If that were the case for grebes, it would preclude migration. That's not possible because this is a migratory species over 90% of its breeding range, and since it likely moults its flight feathers only once per year. Then I realized this species must have two flightless periods annually; one on the breeding grounds and the other on the wintering grounds. I knew that grebes gleefully abandon flight as soon as they arrive on the breeding grounds, but I didn't realize they do the same on the wintering grounds. Following the link back to the Cornell website confirms this. Grebes must be the only group that does this. Cornell should change "flightless period" to the plural "flightless period
s". [pardon spelling of "moult", spelled this way across all of the English-speaking world except the U.S.]
Post #6960 by WPRESTO
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