Common crossbill  (Loxia curvirostra)

Crossbills have one of the most protracted breeding seasons of any British bird. It can begin as early as January and, in parts of their range, they have been recorded breeding in every month of the year. Up to four greenish-white, lightly-blotched eggs are laid, and incubated solely by the female. After 13 days, the eggs hatch and both parents take part in feeding duties. Like many other seed-eating birds, the chicks are fed on insects initially, as these are highly nutritious.