rising@utzoo.uucp (Jim Rising) (11/08/89)
Some birds do have intromittant organs, e.g. anatids (ducks & geese) and ostriches. That's perhaps why forced copulations occur so frequently in these (anatids, at least). Most birds, however, simply have cloacal contact, during which sperm are passed. In most, during the breeding season the seminiferous tubules around the cloacal oriface become greatly enlarged, so that there is a notable protruberance in males. This doubtless facilitates transfer. Generally males get on top, and females twist their tails around, as do males the other direction. However, males are not always on top--making this an uncertain way to sex monomorphic birds in the field. In birds copulation generally lasts only a few seconds, but may occur several times a day. Some species (e.g. swifts; hummingbirds) copulate on the wing--quite a trick! Generally, it is not difficult to witness this. I'd bet that most birdwatchers have seen it often. --Jim Rising -- Name: Jim Rising Mail: Dept. Zoology, Univ. Toronto, Toronto, Ontario, Canada M5S 1A1 UUCP: uunet!attcan!utzoo!rising BITNET: rising@utzoo.utoronto.bitnet