Birds massively unwilling to fly south

Biologists are concerned about: the thousands and thousands of Pacific black kazarok (Branta bernicla nigricans) do not want to leave Alaska to be advanced to places of their usual wintering grounds on the shores of the Mexican California poluostrova.Dlya birds ready for such a long flight, the choice was clearly not easy. However, the reason it is quite understandable. Changing the planet's climate has led to that much-loved breasted goose sea grass (Zostera) has grown not only in the south. Previously, the lagoon western Alaska were infertile and unprotected from the winds, but with each passing year, these places are becoming more privlekatelnymi.Poslednee study showed that over the past 30 years the number of "refuseniks" increased from 4 to 40 thousand (in the meantime the second number - 30% of all populations of these birds). Branta not want to leave the National Park Izembek (Izembek National Wildlife Refuge), a protected area stretching almost 40 kilometers. "Usually, birds are waiting for the storm will pass through the Aleutian Islands, with winds they go to the south. But now things have changed", - says researcher David Ward (David Ward) from the U.S. Geological Committee, who is studying these birds for many let.Izmeneniyu distribution of winds accompanied by warm weather, which reduced the amount of ice that prevents the growth of sea grass. Of course, in such circumstances to remain in Alaska was to kazarok far preferable to fly several thousand kilometers away, and then another and back. Also available food from ex-migratory birds there is another advantage: wintered in the north, they could before the others return to the breeding grounds, and thus grow faster potomstvo.Uchenye suggest: the rejection of long-distance migrations lead to the fact that the population will rise sharply kazarok ( especially if it becomes a lot of food) that the birds will increase brood. (Spiders won already grown and multiplied.) However, global warming may destroy kazarok. For example, if sea-level rise would flood their native lands. No one thing is clear: the impact will be, but any accurate predictions be too early.