MOSCOW, April 27. /TASS/. The Russian Academy of Sciences' Clean Arctic - Vostok-77 expedition found that southern species of spiders and birds get to the Arctic Circle through narrow corridors-petals that develop due to the thawing permafrost, the expedition's press service told TASS.

"The behavior of a species like heron in Yakutia confirms the "petal warming" supposition. The heron has spread far to the North, but its habitat looks like two narrow bands. It may be probable to identify clear boundaries of these "petals" that are narrowing towards the north," the expedition's headquarters' leader Oksana Tolstykh said.

During the expedition, experts have collected a large amount of materials on climate change over recent twenty years in different northern regions, and have interviewed local residents. The uneven spread of spiders and birds at the same geographical latitude has shown that the northern border of their habitats had shifted along not the entire length, but had formed several petal-shaped protrusions in the northern direction.

The experts have confirmed the "petal thawing" supposition - that is, the permafrost melting is observed right in those petal zones, 50 to 200 kilometers wide, at their southern base. The expedition participants have found the animals move northwards along those rather narrow petal-shaped corridors. This movement is not caused by natural obstacles like reservoirs or mountain ranges, they say.

"Our scientific groups have seen that the changes are not equal if considered in terms of geographical latitude. The first obvious conclusion from these observations is that permafrost at the same latitude may change at different speeds. Thus, buildings on permafrost just a hundred kilometers from each other may experience completely different loads - one may collapse, while the other may stand for another two hundred years," she added.

About Clean Arctic - Vostok-77 expedition

Clean Arctic - Vostok-77 is the biggest continental high-latitude scientific expedition in the history of the North's studies in terms of the number of participants. It will have 77 expedition teams. The 12,000-kilometer route has been structured to meet the objectives, set by the Russian Academy of Sciences' research centers, and in accordance with due studies under university grants. Over a year-long term, 700 participants from the Academy's more than 20 research centers and from federal universities, as well as the Russian Geographical Society's volunteers, will conduct 200 studies. One of the tasks the expedition is facing is to research and preserve the North's rare languages. TASS is the expedition's general information partner.