Big original: why crossbill hatches chicks in winter
The end of winter is the most difficult time for the feathered inhabitants of the forest. Autumn stocks are drawing to a close, and finding food under a thick layer of snow is becoming increasingly difficult. Severe frosts and prolonged February snowstorms also do not increase the chances of survival. But, it turns out, not all birds suffer from hunger in the winter. An amazing bird lives in our country, which hatches chicks in the winter.
This is a well-known crossbill - a small bird the size of a sparrow or slightly larger. Crossbills inhabit coniferous and mixed forests of the northern hemisphere. In our country, they can be found from the Kola Peninsula to the Sea of Okhotsk. Several species are distinguished, which are combined into one genus of crossbills: crossbone-spruce, crossbill-pine, white-winged crossbred and others.
He got his name because the seeds of conifers are his main food. Crossbills eat seeds of spruce, pine, fir and larch, but pine nuts are not included in their diet. Such a narrow specialization in nutrition led to the development of a characteristic beak. In order to make it more convenient to extract seeds from the cones, the upper and lower parts of the beak (the upper beak and the mandible) of the crossbill have a curved appearance.
In addition to the fact that the beak of this bird was created exclusively for coniferous seeds, their whole life is completely dependent on the abundance of cones. Conifers, as you know, have irregular productivity in different years, and once every several years there is a complete absence of cones of one kind or another. Therefore, crossbills are nomadic birds: they move to those regions where there is a sufficient amount of food, even if for this it is necessary to leave their native lands and fly hundreds of kilometers.
Another characteristic of these amazing birds is associated with the seed crop. They hatch chicks at the end of winter, most often in February-March, when the rest of the birds are not even busy searching for a pair and building a nest. This event is also timed to coincide with the abundance of coniferous seeds, which occurs just at the end of autumn and in winter.
The fact is that the seeds of spruce and pine ripen in late autumn, but until February they remain in tightly closed cones. At the end of winter, cones begin to open gradually, and their seeds spill out into the snow, giving young crossbirds access to plentiful food. It turns out that young birds do not have such a powerful beak and themselves are not able to get food from cones. But they can pick up seeds that have poured out on the snow, and parents feed them until a real beak grows. That is why these amazing birds try to breed offspring at the end of winter, when coniferous seeds are revealed.
So it turns out that with the advent of summer, the young generation of crossbills already knows how to fly and independently obtain food, while other birds still hatch eggs.