in animals, a condition existing between the sexes by which the male mates with one particular female for a relatively long period of time and usually participates in caring for the offspring. Most birds, including swans, storks, eagles, and vultures, have a single mate for several years or, in some cases, for life. Other birds mate for only one season; they separate after rearing the fledglings (for example, geese), immediately after nest building, or before egg laying (many ducks). Among mammals, the ape has a single mate for several years; wolves, arctic foxes, common foxes, badgers, ermines, and beavers rarely couple for more than one season. Monogamous animals include those insects and other invertebrates in which both sexes (or only the males) die soon after a single mating (the females die after egg laying).