Where does your bird sleep?

WHERE do birds sleep? A small and simple question that somebody asked me the other day. Unfortunately roosting is rather a complicated subject so there isn’t a small and simple answer.

All birds sleep but some birds, like swifts and a few sea-birds, do it in flight, showing their sleep is somewhat different to ours. The majority of Irish birds sleep at night, though owls are an obvious exception, and snipe, woodcock and some ducks and geese are less obvious ones. Very few birds sleep in their nests outside the breeding season, though again there are some exceptions. Wrens and long-tailed tits build very well-insulated domed nests and sometimes roost in them in cold weather. Several birds will often crowd into one nest for extra warmth.

Communal roosting normally occurs among species that spend the day in flocks, at least outside the breeding season. Examples would be starlings or geese. But again there are exceptions. Cormorants and pied wagtails are not flocking birds but they normally roost together in large numbers. The reason for communal roosting is argued about among ornithologists. The three main theories are that it provides extra warmth in winter, it provides protection from predators or when the birds wake in the morning, it improves the foraging success of the individual.