A tight swirl of 75 small birds nervously flew up from the alder thicket near the Loop Road bridge over the Mendenhall River, but then quickly settled into the next grove of alders only a few yards away with constant "chett-chett-chett" calls.
Some of the birds have a rosy hue on their chest (adult males) although most have a white breast with dark streaks on the sides. All of the birds have a reddish cap (poll) on the top of their head with a black chin under their stout yellow bill.
These winter visitors to Juneau are common redpolls, although a hoary redpoll or two, less streaked and frostier close cousins, are probably mixed in.
Pine siskins, who lack the red cap and black chin, and are slightly smaller and more heavily streaked, also often flock with redpolls. Although sometimes quiet and inconspicuous, a large flock of several hundred redpolls usually is noticed by all, especially since these birds are often remarkably tame.
For the first winter in about six years, Juneau has been invaded by large numbers of redpolls. These periodic invasions of northern populations of seed-eating birds are termed "irruptions" and the common redpoll is one of several bird species including crossbills and pine siskins that show this behavior.
Crossbills, in contrast with the high numbers of redpolls, are currently almost impossible to find in the Juneau area.
Redpolls currently do not breed on the Juneau road system or further south; however, a few birds were reported as probable breeders in the late 1960s near Mendenhall Lake. Redpolls nest in Chilkat Pass about 60 miles north of Haines as well as in Glacier Bay. These are some of the more southerly locations for nesting redpolls, which nest in suitable habitats throughout most of the rest of Alaska. Nesting habitats include open scrubby tundra and subarctic forest.
The worldwide range of the redpoll includes all of northern North America, Europe and Asia. Banding studies conducted by an amateur birder in Fairbanks have shown a few Alaska birds travel at least as far east as Montreal, Canada, a distance of 3,000 miles.
Small flocks of 10 to 20 redpolls are sometimes noted in the Juneau area in November and December and up to 100 are occasionally seen during the Juneau Christmas Bird Count. In invasion years, flocks of up to 300 to 400 birds occur primarily during the months of February and March.
It is thought that food shortages in more northerly areas drive the birds south in search of food, which primarily includes seeds in catkins on alders and birch trees. In most winters, some redpolls move into the northern tier of states such as Minnesota and North Dakota. In 1995 and 2001, few redpolls moved south of the Canadian provinces and almost no redpolls were seen in the Juneau area in February and March of those years.
Movement of birds into the Juneau area this winter showed some interesting patterns. In late January, the first few flocks of the developing redpoll irruption were noted. Peak numbers occurred in mid-February, although some birds will probably linger through mid-March.
At first the flocks seemed to concentrate on feeding on alder catkins, often hanging upside down as they tore into the catkins. A few days later, large flocks frequented weedy fields on the Mendenhall Wetlands where they tore into seed heads, often while standing in the snow. After snow covered more of these weedy areas, flocks also began to frequent bird feeders as they discovered the easy pickings available there.
Redpolls are able to survive some of the coldest temperatures encountered by any songbird in the world as they range through the subarctic winter. Besides their fluffy feather coat, they also have an unusual pouch about mid-way down their neck which allows them to store seeds for a snack later on to get them through cold winter nights or stormy weather when feeding is difficult. This pouch is similar to the crop on grouse and pheasants, and is shared by only a few other bIrd species.
For these avian invaders, Juneau must seem balmy in comparison to their normal winter haunts in central Alaska or the Yukon.
For more information concerning redpoll irruptions in North America, check out a Web site run by Cornell Laboratory of Ornithology and other cooperators (www.birdsource.org). The "Project Feederwatch" section of this site provides animated maps of redpoll (and other backyard bird species) distributions over a number of years.
Paul Suchanek is a local birder who works for the Division of Sport Fish in the Alaska Department of Fish and Game. Brent Keeney, local nature photographer and artist, will give a talk and slide show on outdoor nature photography at the monthly meeting of Juneau Audubon Society, 7:30 p.m. Thursday, March 14, at the Dzantik'i Heeni Middle School library.