Courtship
Courtship is a collection of instinctive behaviors that result in mating and eventual reproduction. Courtship is important because it helps to ensure that breeding will occur. Organisms within a species must reproduce successfully in order for the species to survive. Courtship has many other functions, including mate selection, regulation of sexual readiness so that the reproductive physiology of a pair may be synchronized, the reduction of hostility between potential sex partners in territorial animals, and species recognition. Courtship may be rather simple, involving a small number of visual, chemical, or auditory stimuli, or it may be a highly complex series of acts involving several types of communication. Some of the most complex courtship behaviors are found in birds.
Mating Systems
In addition to complex courtship patterns, birds also have interesting and varied breeding or mating systems. The most common type of mating system is monogamy, which resembles a traditional human marriage. Ninety percent of birds are monogamous. In this type of mating system, two birds come together or form a pair bond for the procreation of young. The length of the pair bond varies greatly between species and between individuals. A mated pair may remain together for life, as in the case of albatrosses, petrels, swans, geese, eagles, and some owls and parrots. They may remain together for several years, as in the case of American robins, tree swallows, and mourning doves. They may remain together for one year, which is the case with most birds; just for one brood, as is the case with house wrens; or for even shorter periods.
The two birds in a pair are usually faithful to each other during the time that they are together. Pair faithfulness appears to depend on the outward appearance of a bird's mate. This might be a simple matter of recognition. Ringed plovers, for example, establish enduring bonds. In one known instance involving two couples, however, one of the mates in each pair had lost a foot and was rejected by its former mate. Fortunately, the two rejected birds were opposite sexes. They met, paired, and successfully raised normal offspring.
It is difficult to determine, however, the exact nature of the physiological bond that holds a pair together. Other factors may be territory, familiarity with one another, or even something similar to human affection. In fact, it is thought that affectionate bonds actually exist between birds. On two separate occasions, it was observed that the partner of a black duck refused to leave its dying mate when the rest of the flock fled from hunters.
Courtship Displays
While birds have a wide variety of mating systems, they have an equally vast array of courtship behaviors or displays including dancing, singing, sparring with bills, kissing, caressing, entwining necks, nibbling at each other's feathers, and side-by-side body contact. Some male birds even take on a completely different physical appearance during breeding season, when unique features such as specialized combs, wattles, and pouches appear.
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