One clue, which applies to virtually all species and can be very useful in late summer and fall, is that juveniles, having just fledged, are then in very uniform fresh plumage, while adults are actively molting or showing a mixture of old and new plumage.
David Allen Sibley
One clue, which applies to virtually all species and can be very useful in late summer and fall, is that juveniles, having just fledged, are then in very uniform fresh plumage, while adults are actively molting or showing a mixture of old and new plumage.
David Allen Sibley (born October 22, 1961, in Plattsburgh, New York) is an American ornithologist. He is the author and illustrator of The Sibley Guide to Birds, which rivals Roger Tory Peterson's as the most comprehensive guides for North American ornithological field identification.
Sibley has also authored a follow-up book, The Sibley Guide to Bird Life & Behavior.
