REPRODUCTION With the approach of the breeding season there is instituted at once a conflict, active or passive, as the case may be, between males of the same kind for a breeding area in which. later. the nest will be located. (See also BIRD, Reproductive Habits.) Each male .
selects some section suited to nesting needs and remains within or near until a mate appears, if he is not already mated, and protects this tract against encroachment by others that may be considered rivals. In the case of gregarious species, like the sooty tern (Sterna fuscata) that nests in great colonies on islands in the sea, the nesting territory for each pair may be only a yard square, or even less, being a space in which the egg may be located, so that the incubating bird and her mate, on guard beside her, cannot quite reach the adjacent pair with whom, and with any others that intrude, they spar and fight on the slightest provoca tion. The male red-winged blackbird (Agelaius phoeniceus) of North America, also gregarious, selects an area of marsh or swamp, with his neighbours situated at a distance of a few feet or a few yards, and remains on guard, forbidding entrance of another male in that limited space. Solitary species hold larger areas, so that a red-eyed vireo (Vireo virescens) may hold a clump of three or four trees, or a blackbird (Turdus merula) may pre empt a small section, including thickets, trees and open ground. Possession of such a breeding ground at the beginning of the nest ing season is a paramount passion with each male, and to retain possession he will battle fiercely, even until death, with any others of his kind that may attempt definitely to locate within what have been selected as his limits. Under this urge, sanguinary combats are not unusual among species whose individuals live for the rest of the year wholly at peace with their kind.
Mating.—At the mating season the male bird resorts to a variety of artifices to attract attention on the part of the female, and to arouse her interest to the end that a nest be established.
(See also COURTSHIP OF ANIMALS ; SELECTION, SEXUAL ; BIRD, Re productive Habits.) Among perching birds this is first indicated by song (q.v.), by which the male not only gives expression to the pleasant sensations of merely living, but also, when established on his breeding ground, gives notice to rivals of his presence as a guard over his territory and notice to females that he is in search of a mate. The song may range from the polished effort of an expert, like many thrushes, the nightingale, or the mocking bird, to sounds that, to some human ears, may be merely disagree able noise, as the chatter of the house sparrow, or the strange music of the plant-cutter of South America (Phytotoma rutila), whose song is a curious squeaking that resembles exactly the rubbing produced by tree-limbs touching in the wind. The rhea booms, the hawk screams and the owl hoots, each producing music in the estimation of others of its kind.
Actual mating may be accompanied by a great variety of strange and unusual actions which the male alone, both sexes, or more rarely the female alone, may undertake (see COURTSHIP OF ANI MALS). The male ruffed grouse (Bonasa umbellus), of North America, selects a stand on some sheltered log or stump, to which he resorts each day to "drum," a resonant love-call for which he draws himself fully erect and begins a steady beat of his short, stiffly-feathered wings. The action of these against the air between wing and body is so strong and abrupt that a dull thump ing sound is produced, at first slowly, and then with increasing rapidity, until the sound comes as a steady, pulsating roar. The display of the peacock, in which the long, ornamented upper tail coverts (mistaken by many for the tail, which is short, stiff and dull in colour, entirely concealed beneath the longer feathers) are erected and fully spread, to be shaken finally with a dry rattle as the male faces the apparently indifferent female, is another well known example of activity on the part of the male alone.