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Behaviour and ecology

Swallows are excellent flyers and use these skills to feed and attract mates. Some species, such as the mangrove swallow, are territorial, whereas others are not and simply defend their nesting sites. In general, the male selects a nest site, and then attracts a female using song and flight and (dependent on the species) guards his territory. The size of the territory varies depending on the species of swallow; in colonial-nesting species, it tends to be small, but it may be much larger for solitary nesters. Outside the breeding season, some species may form large flocks, and species may also roost communally. This is thought to provide protection from predators, such as sparrowhawks and hobbies. These roosts can be enormous; one winter-roosting site of barn swallows in Nigeria attracted 1.5 million individuals. Nonsocial species do not form flocks, but recently fledged chicks may remain with their parents for a while after the breeding season. If a human being gets too close to their territory, swallows attack them within the perimeter of the nest. Colonial species may mob predators and humans that are too close to the colony.