This behavior presumes a permanent territory. Assumes that it is fairly certain that a mated pair of birds has been observed. Permanent Territory presumed through defense of breeding territory by fighting or chasing individuals of same species. Because territoriality involves the defense of a fixed area, it is useful to map locations of individuals to determine if they are singing or defending the same general area when surveying the block a week or more later. Courtship behavior or copulation between a male and female.
Courtship behavior includes transfer of food, displays, and grooming between a pair of birds.
Examples include cavity nesters or for a shrub-nesting species that flies into the same thicket and disappears on several occasions. Agitated behavior or anxiety calls from adults usually indicate a nest site or young in the vicinity. Woodpeckers will drill holes for roosting. Physiological Evidence of breeding based on birds in the hand. Nest building seen at the actual nest site, excluding wrens and woodpeckers.