Bacillus sphaericus

Birds on the Brink

Hardly anyone visits the desolate outpost of Coldfoot, one of Alaska’s few communities outside the Arctic Circle accessible by road. Its 34 residents live in rustic accommodations along the Dalton Highway. The town’s highlights include an inn, a café, a gas station and a basic airport with a gravel landing strip. All day long, 18-wheeler fuel trucks thunder by on supply runs between Fairbanks and the oil fields of Prudhoe Bay further north. Some will stop to eat and tank up at Coldfoot because the next human habitation is 234 miles away, a town grimly named Deadhorse.

They say Coldfoot got its name from the days of the 1900 Gold Rush when miners would come as far as this remote settlement before getting “cold feet” and turning back. It’s still a lonely place, but one unexpected visitor showed up recently inside an infected Swainson’s thrush (Catharus ustulatus): the avian malaria parasite, Plasmodium circumflexum.

In 2011, scientists tested 676 birds representing 32 resident and migratory bird species captured from three northern locations in Alaska: Anchorage (61°N), Fairbanks (64°N) and Coldfoot (67°N). In Anchorage and Fairbanks, they found 49 birds infected by Plasmodium parasites. In Anchorage, even resident birds and hatchlings of species such as the boreal chickadee (Poecile hudsonicus), the varied thrush (Zoothera naevia) and the fox sparrow  (Passerella iliaca) were found infected. The parasite was also detected in black-capped chickadees (Poecile atricapillus) and a myrtle warbler (Dendroica coronata coronata) in Fairbanks, indicating that transmission had occurred locally.

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