Breeding and nesting habits
Choughs are usually solitary nesters, although high densities occur in a few places in the British Isles.
Materials and position
Nests are built in dark recesses in caves, crevices on rock faces and in buildings. In Scotland a third of nests are in buildings.
The pair builds the nest of dry twigs, roots, moss, and plant stems, occasionally bound with mud. The nest is thickly lined with wool and occasionally other animal hair, man-made material, and thistle down. It is often used in successive years, freshly re-lined each time.
The life of a chough
Pair bond is monogamous and of long duration. Pair-members remain together all year, and tend to join and leave flocks in pairs.
They roost communally outside breeding season, and non-breeders often do so all year. During the breeding season nesting pairs roost at or close to their nest site, and fledged young will return to the nest to roost for about two months after fledging. Nesting pairs will join daytime feeding flocks to forage outside their immediate territory.
The female lays 3-5 eggs at 1-3 day intervals in April. She incubates alone for 17-21 days, beginning with the third or fourth egg. The female broods the young almost continuously for the first two weeks with the male supplying all the food. Both adults bring food later. The young are fed on regurgitated food consisting of a variety of insect matter, especially ants.
The young fly at 6-7 weeks of age. They are able to feed themselves three weeks later, but remain with their parents for a further 1-2 weeks. Once the young are independent, they join a flock of other immature birds, sometimes many miles from their birth place. They only leave the flock when ready to breed themselves. There are occasional reports of a helper at the nest of an established pair.
The first six months after fledging are dangerous for the young birds, and many of them perish. The birds reach maturity and breed for the first time when they are between two and four years old. Birds that get this far can expect to live for a further three years.
Maximum life expectancy of a chough is 10 years, though occasional older ones have been recorded - the oldest known individual was 20 years old.