Migrants, Vagrants, and New World Explorers
Searching for a snowy owl, Ed Clark followed the ravens. The black birds had been dive-bombing the owl, a seldom-seen visitor to interior Alaska that landed on the university campus in Fairbanks after it wandered south, probably from Alaska’s north slope.
Clark approached the owl to take its photograph. He was surprised at the owl’s tolerance as he stepped closer, until he noticed it was dead. He picked up the owl, which was frozen in a sitting position, and carried it to the University of Alaska Museum.
The owl was one of many birds that catch people’s attention for showing up in the wrong place at the right time, said Dan Gibson, bird collection manager at the University of Alaska Museum. Snowy owls normally don’t stray from treeless tundra, where they stand two-feet tall on hummocks and survey their surroundings for lemmings and voles.
Birds sometimes abandon their normal ranges because of food shortages, Gibson said. The snowy owl that recently died in Fairbanks was underweight, and a bad lemming year up north may have been the reason the bird showed up in Alaska’s second-largest city.
Another wayward bird probably traveled to Fairbanks as a misguided youth. A brown thrasher—a songbird not normally seen west of the Rockies—was found in mid-November hanging around a dog yard at a home near Fairbanks. Most brown thrashers are now flitting through backyards in the southeastern U.S. One is now breathing 20-below air in interior Alaska and living off sunflower seeds at a bird feeder.
The brown thrasher and other birds that find themselves way out of their known ranges are often juvenile birds hatched that same year, Gibson said.
“Some go the wrong way when they migrate, and to the wrong place,” he said. “Most of them probably don’t survive.”
Though many young birds that overshoot their normal boundaries often perish because of weather or vulnerability to predators, these rogues are sometimes the explorers that thrive in a new place.
“That’s how birds expand their range,” Gibson said. “If juveniles do exactly what their parents did, there’d be no chance for expansion.”
Alaska’s cities and towns offer birds an artificial refuge amid miles of tundra and taiga. One adventurous Eurasian bullfinch last winter showed up at a bird feeder outside Fairbanks. Gibson guessed the bird hit western Alaska in fall, then followed the course of the Yukon River, took a right at the Tanana River, and followed its furrow in the landscape to Fairbanks.
Bohemian waxwings that live in Anchorage and Fairbanks eat seeds and frozen berries on trees not native to Alaska, such as mountain ash and chokecherry. The birds show up in large flocks in Anchorage and Fairbanks, but are not found very far outside the cities.
“In winter, if you drive out of Fairbanks, you won’t see (a Bohemian waxwing) until you get to Anchorage or Whitehorse,” Gibson said.
Bird feeders and other amenities make cities and towns more attractive for birds that find themselves way out of their elements. A varied thrush that did not migrate south from Fairbanks one year survived for a while by roosting next to a warm air outlet at the university library, Gibson said.
Wheatears, bluethroats, yellow wagtails and white wagtails are several species that have recently expanded their territories into Alaska, Gibson said. All four come from eastern Asia and Russia. In springtime, they travel to Alaska across the Bering Strait to breed. If these birds develop a winter range in the Lower 48 or farther south, where they could find insects during winter just as they could in eastern Asia and Russia, they will be able to become full-time residents of the Americas.
“They’ve just barely got a foothold in the New World,” Gibson said.
