Countdown to extinction?
THANKS to global warming, the Arctic is slowly melting. And this climate change is affecting wildlife, according to a US biologist. Rising temperatures, which allowed the black guillemots to gain a foothold here some two-and-a-half decades back, are now pushing these birds out.
Black guillemots live right across the higher latitudes of the northern hemisphere. Since the early 17th century, however, they have not colonised northern parts of Alaska because there is too much snow there. The birds need at least 80 consecutive days without snow to make nests and fledge their young.
George Divoky of the Institute of Arctic Biology in Alaska in Fairbanks, USA, after studying the sea birds for decades, says from the late 1960s warmer temperatures in the Arctic caused snow to melt earlier in the spring. This gives the birds a better choice of nesting sites and a longer period in which to breed and nest.
In 1966, only one breeding pair was recorded on Alaska's north coast. In 1972, Divoky discovered a small colony of 10 pairs on Cooper Island, near Barrow. Between 1975 and 1990, the number of birds in the colony soared, reaching a peak of 225 pairs.
However, since 1990, numbers have dropped drastically. There are now only 110 pairs in the Cooper Island colony. The reason, says Divoky, is the reduction in sea in the area - caused by higher temperatures. Back guillemots feed on the Arctic cod that live beneath the floes. Ice-free areas harbour fewer fish, forcing the birds to fly farther in search of food.
Divoky says the correlation between reduced snow cover and guillemot numbers is one of the first documented biological effects of climate change in the Arctic. Brendan Kelly, marine biologist at the University of Alaska Southeast, says the findings are extremely interesting, but argues that theories about retreating sea ice remain inconclusive "because there is a lot of background noise" in the satellite data.
Previous research has shown that the average annual temperature has risen by 1 c over the last 40 years, but that temperatures have changed thrice as fast in Alaska and northwestern Canada as they have elsewhere in the Arctic.