<P> Juvenile birds do not have the white patches on either side of the neck . When they are about six months old (about three months out of the nest) they gain small white patches on both sides of the neck, which gradually enlarge until they are fully formed when the bird is about 6--8 months old (approx . ages only). Juvenile birds also have a greyer beak and an overall lighter grey appearance than adult birds . </P> <P> Its flight is quick, performed by regular beats, with an occasional sharp flick of the wings, characteristic of pigeons in general . It takes off with a loud clattering . It perches well, and in its nuptial display walks along a horizontal branch with swelled neck, lowered wings, and fanned tail . During the display flight the bird climbs, the wings are smartly cracked like a whiplash, and the bird glides down on stiff wings . The common wood pigeon is gregarious, often forming very large flocks outside the breeding season . Like many species of pigeon, wood pigeons take advantage of trees and buildings to gain a vantage point over the surrounding area, and their distinctive call means that they are usually heard before they are seen . </P> <P> It breeds in trees in woods, parks and gardens, laying two white eggs in a simple stick nest which hatch after 17 to 19 days . Wood pigeons seem to have a preference for trees near roadways and rivers . Males exhibit aggressive behaviour towards each other during the breeding season by jumping and flapping wings at each other . Their plumage becomes much darker, especially the head, during hot summer periods . </P> <P> The nests are vulnerable to attack, particularly by crows, because they live in the countryside, the more so early in the year when the leaf cover is not fully formed . The young usually fly at 33 to 34 days; however, if the nest is disturbed, some young may be able to survive having left the nest as early as 20 days from hatching . </P>

How many babies does a wood pigeon have