American oystercatchers are typically monogamous. Pair bonding occurs in the spring when both sexes arrive at the breeding grounds. While most birds choose a new mate each year, some individuals remain with their partner throughout their lives. American oystercatchers copulations are typically initiated by the female, who stiffens her body, raises her tail, straightens her legs, bends forwards, and draws in her neck. The male responds to this change in posture by mounting the female for 2 to 5 seconds and copulation occurs.
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animaldiversity.org
