07 December 2009


Molt has a complex terminology. Sequences of feather replacement are quite variable although usually quite stereotyped for any one species. Some cranes keep feathers for two years, but most birds molt all feathers annually. A total replacement is termed a complete molt, which takes weeks to several months and is very energy costly. Most north temperate birds do a complete molt in late summer or early fall (Tyrannidae and Hirundinidae delay molt until on winter grounds)

Many species molt only once a year, others molt twice. The number of feathers molted the second time varies greatly (= partial molt). The Bobolink is one of the few birds to have two complete molts, basic and alternate. A very few birds have three molts a year, one complete and two partial.


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