Common Crossbills (Latin name: Loxia curvirostra) have been seen on the reserve this week. These distinctive, chunky birds are part of the finch family. They have a large head and bill and a forked tail, measure about 16.5 cm in length, weigh between 35 and 50g and have a wingspan of 27 to 30.5 cm. Their bills cross over at the tips (which gives them their name) and are used to extract seeds from conifer cones.
Common Crossbills are usually seen in large family groups or flocks, flying at treetop height and coming down to pools to drink. They feed by flying from cone to cone in the trees and build small cup-shaped nests in trees out of twigs and moss, lined with hair. They nest very early in the year, with chicks hatching in February and March so that they can feed on the new pine cone crop.
While male Common Crossbills are a brick red colour, females are greenish-brown with a yellow rump. Common Crossbills are found across the north and south of the UK, but are mainly absent from central and south western England. They are resident in the UK all year round, but in some years ‘irruptions’ occur, when the species becomes more widespread and appears in greater numbers. This is due to birds from Europe and Asia migrating to the UK to look for food and staying to breed – sometimes for a few years – before their offspring return to their origins. Two similar species are the Parrot Crossbill, which is slightly larger than the Common Crossbill and has a heavier bill, and the Scottish Crossbill, which is found in Scots Pine woods in Scotland and has a slightly smaller bill. All species of Crossbill are designated as Schedule 1 under the Wildlife and Countryside Act 1981, meaning it is an offence to intentionally or recklessly disturb an active nest.