Breeding birds: 40,000 pairs
Crossbills are large plump finches with a distinctive bill. Adult male crossbills have brick-red plumage with grey-brown wings and black tails. The head is a duller red and it has a large, curved bill with crossed tips. Crossbills’ eyes are dark brown and their legs and feet are black.
Female crossbills are a dull greenish-yellow colour with a yellow rump. Juveniles are greyish-brown with dark streaks and pale underparts.
Crossbills build their nests high up in conifer trees on a horizontal branch amongst vegetation and twigs to protect them. The female builds the nest which is a bulky cup made from twigs, grass and pieces of bark and lined with finer material such as grasses, lichen, feathers and hair.
Crossbills lay 3-4 pale blue-green eggs, speckled with brown. The eggs are incubated by the female for 12-16 days. The chicks’ bills are not crossed when they are born and they are fed by the male for 5 days and then a further30 days by both parents until their bills become crossed so they can extract seeds themselves. Chicks leave the nest about 18-22 days after hatching.
Crossbills feed mainly on conifer seeds. They extract the seeds using their crossed bills using strong jaw muscles and a twisting movement. They break the cone from the tree using their feet and then use their beak working in a spiral movement upwards.
Crossbills can be seen all year round across the UK except central and south west England. In some years they will arrive en masse from the continent in late summer in a type of migration called an irruption.
Crossbills are the only birds in the world known to have crossed bills.