25-gram Songbird Makes Miracle Migration to Africa Each Year
Published On Tuesday, Feb. 14, 2012 in the Toronto Star
by Leslie Scrivener, Feature Writer
The sharp-eyed northern wheatear is a songbird that weighs a mere 25 grams, about the same as two tablespoons of flour. With its spindly legs, its muted white, brown and black color, who would think such a lightweight capable of heroic endurance?
For the first time, Ontario scientists have proven what they long suspected — the wheatear is the only songbird that breeds in the Canadian Arctic and Alaska and spends the winter in Africa. The migration can take from one to three months.
They also showed that the wheatear completes the longest known flight over water of any songbird — 3,500 kilometers across the Atlantic. That remarkable passage takes about four days of non-stop flying.
There are two separate populations of wheatears in the far north. One breeds in Alaska, flies west over Russia, Kazakhstan and the Arabian Desert some 14,500 km, ending up in Sudan and Uganda in East Africa. Another, which breeds in the Canadian Arctic near Iqaluit heads the opposite direction, east over the Atlantic, stopping for the winter in Mauritania in West Africa, a journey of 7,500 km.
The study, published Wednesday in the journal Biology Letters, is the research of University of Guelph biology professor Ryan Norris; David Hussell, emeritus scientist from the Ontario Ministry of Natural Resources, and German scientists from the Institute of Avian Research.
“It’s impressive that a bird that size could do this,” says Hussell, speaking from Germany. “I don’t think a lot of North Americans are aware they have this bird migrating to Africa.”
The wheatear has one of the largest breeding ranges in the world, stretching across northern Europe, Asia and North America. With its white rump, the name is said to be a corruption of the Old English descriptor “white arse.”
Hussell, Norris and the German research team tagged 46 wheatears in Eagle Summit, Alaska, and near Iqaluit in 2009 and 2010. They trudged along the rocky tundra looking for birds carrying food back to their nests, which are usually hidden under boulders.
Once they found the birds, new technology allowed them to track their migratory path. Researchers attached tiny backpacks under the wheatears’ wings. The packs were fitted with geo-locators weighing 1.2 grams to record light levels — based on sunrise and sunset. The light levels allow scientists to measure latitude and longitude.
Wheatears have to bulk up for the long days of flight and stuff themselves with insects and spiders. By the time they leave the north, they may have doubled their weight. “If they weighed 25 grams when they took off, they wouldn’t make it,” says Hussell.
They traveled an average of 290 km a day. Those flying overland from Alaska could rest or feed along the way, but the Iqaluit birds flying over the ocean could not.
How migrating birds can fly for days without getting dehydrated has long puzzled scientists. But last year, researchers at Western University (formerly the University of Western Ontario) reported their discovery that birds burn their own muscle and organs as a source of water. Burning protein provides about five times as much water as burning fat.
The following year, the challenge for the scientists tracking the wheatear was to find the same birds once they returned to the summer breeding grounds in the north. They only found one in Iqaluit and three in Alaska.
But it was enough to provide evidence linking the African ecosystems with the Arctic ones.
“It makes it hard when we don’t get many back,” says Norris. “But it’s good evidence that these birds are likely not wintering in North America and make this incredible journey to Africa.”