David Allen Sibley Quotes

It can be difficult to accept the fact that a lot of birds have to be identified as possible or probable.

Many species undergo an additional partial molt each year, involving just some head and body feathers. This most often occurs in the late winter or early spring and is called the pre-alternate molt, r...

About Author

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.

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 active...

The H-P system indicates the age of the bird in essentially the same way as the Life-Year system. The bird is considered to be in its first year (with plumages labeled first basic and first alternate)...