A review of bufflehead sex and age criteria with notes on weights

Summary: Buftleheads Bucephala albeola were collected along the Oregon coast during the hunting season. Birds were first sexed and aged upon cloacal and internal characteristics. Results were then compared with data derived from wing plumage. A small change was made in Carney's (1964) wing plumage key to improve its accuracy. Although only a few studies have been made of Bufflehead weights, it seems that in at least several of these, some immature males have been included in the female category. This mistake has probably resulted from the extremely small penis in the immatures. The foot web length shows potential as a simple sexing criterion during the fall and winter for immatures which are the most difficult to sex under field conditions.