As its names suggests, the common crossbill (Loxia curvirostra) has a large bill that is crossed at the tip - perfect for picking the seeds out of pine cones. It is difficult to spot as it spends most of its time at the top of pine trees. Adult males tend to be red or orange, and females green or yellow, but there is much variation. Also known as the red crossbill, it breeds in the spruce forests of North America, as well as Europe and Asia.