In many parts of North America, the onset of cold weather is heralded by the honking of Canadian geese as they flap their way south in V-shaped formations. The birds are monomorphic, with identical plumage in the male and female, making gender identification without a medical examination difficult at best.
In observing a mated pair, the largest of the two is usually the male. A physical examination of the cloacal vent can positively identify a male Canadian goose by his corkscrew penis. The exam should only be performed by someone trained in the procedure to prevent injury to the bird or the examiner.
Male Canadian gees are typically more aggressive and will attack humans or animals approaching their territories. An attack by a male goose involves biting with the beak and hitting with powerful wings. The attack is usually preceded with a lowered head, upraised wings and hissing. Females can be observed building or sitting on the nest, often plucking her own chest feathers to provide a downy bed for her offspring.
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