Bird Courtship Display - Page 3

In many species females arrive on breeding grounds after males each spring, and to some extent have the privilege of choice among prospective mates. The female may base its choice on the song or appearance of the male, on the size or quality of the territory the male defends, or on aspects of compatibility not apparent to us. Whatever the method the female uses, the goal is the same: to find a mate likely to provide the offspring with the best chance of survival and continued reproduction. The potential pair may then engage in a series of displays by one or both birds over the next several hours, days, or weeks, to initiate and strengthen a bond between them. The early displays may be subtle, or they may be quite apparent. Rufous-sided Towhees of both sexes briefly spread their wings or tails, revealing white spots; a Scarlet Tanager male may drop its wings to expose its red back while a female perches in front of its mate, while Herring Gulls toss and turn their heads and provide choking or pecking displays.

Mating displays can also be quite spectacular, as in the sky dance of the Northern Harrier. Over fields or marshes across North America in April you may see this usually low-flying hawk climbing skyward on powerful wing strokes, and then plunging toward the ground while uttering a faint chipping call. The dive is usually repeated in a continuous series by the male, who traces a deep U-shaped pattern or cartwheels in the sky.