Although wood pigeons often breed in pairs, they sometimes form small colonies, this affords their nests' extra protection from attacks by crows in spring. The nest is a flimsy platform of twigs high up in a tree. The female will lay 2 eggs and can raise 2 or 3 broods a year. Eggs hatch after 17-19 days. Breeding can happen year-round is there is an abundant food supply, although most commonly occurs in autumn.
For more information on wood pigeon nesting, check out this article.