Members of the finch family, Red Crossbills (Loxia curvirostra) are best known for their unusual bill shape: The tips of the mandibles cross. This unique and highly specialized adaptation enables crossbills to pry open evergreen cones to extract the seeds. A crossbill can insert its bill between a cone's scales, spread them apart and lift out the seeds with its tongue.
Not surprisingly, male Red Crossbills are primarily red in color. Females are usually a dull olive-green. Both sexes can exhibit a lot of variation in the amount of color in their plumage. Young crossbills look like females, but are also heavily streaked.
Red Crossbills are known as Common Crossbills throughout much of the rest of the world. In addition to North America, their range includes all of Europe and much of Asia. Restricted to the Northern Hemisphere, they are found at approximately the same latitude around the globe.
Observing a feeding flock of crossbills, you will witness one of the most humorous and interesting feeding behaviors in the avian world. They enjoy clambering around the tops of pine trees, often hanging upside-down as they feed among the cones. Using both their bills and feet, they remind me of small parrots as they move slowly among the tree branches.
Crossbills are nomads. They can be found wherever feeding conditions are best at a particular time of year. They can be common in a particular area one year, and completely absent the next. They are known to wander widely around the country and are primarily found in the western, central and northeastern states. As food conditions change from year to year, however, these stubby little birds may turn up anywhere — birders should be alert for their kip-kip calls.
Some ornithologists now suspect that there may be as many as eight different species of Red Crossbills on this continent. Studies based on food preferences, bill size differences and call note variations may eventually lead this species to be split into a number of new species. If you're out birding, you may soon need some recording equipment and measuring devices if you want to try and add eight different crossbills to your life lists!
Mating: Males and females form monogamous pair bonds and engage in courtship feeding.
Nest Sites: Coniferous and mixed coniferous-deciduous forests. Nests are between 6 and 40 feet from the ground.
Nest: Often found on horizontal branches in conifer, well away from the trunk. Females builds a bulky open cup nest made of twigs, bark strips, grass rootlets and wood chips. The nest is then lined with grass, moss, lichen, feathers and hair.
Clutch: Usually three or four small eggs, sometimes five. Eggs are pale greenish white or bluish white with brown and purple spots. Most pairs typically raise only one brood per season.
Incubation Period: The female incubates the eggs for 12 to 15 days. The male feeds her during incubation.
Nestling Period: The altricial nestlings are brooded by the female, while the male brings food for both her and them.
Fledgling Period: Young generally leave the nest 18 to 20 days after hatching, and are fed by both parents.
Food: Prefers seeds of coniferous trees, such as pines. Also eats other tree buds, berries and insects.