Pine siskins: A welcome sight in the Adirondacks this winter

By Joan Collins

Winter birding in the Adirondacks is different each year, unlike the more predictable spring breeding season. Tree seed crops vary year to year in all regions. If birds to our north lack their normal food sources, they will shift to an area that does offer them, bringing a changing mix of winter irruptive species. It can be quite a puzzle to figure out, but one thing is certain: bird movements in winter are all about food.

This winter, one such irruptive species is the pine siskin. They departed the Canadian boreal forest in huge numbers during the fall due to poor cone crops. Pine siskins have been observed as far south as Georgia and flocks are all over the Adirondacks. Flock sizes can be small, or number in the hundreds or thousands, appearing as small, dark, erratically moving clouds.

The pine siskin is a small finch that is brown streaked with yellow edging on the wings and tail. It has a sharp pointed bill and a short, notched tail.

They have a wide breeding distribution in North America: from Alaska across the Canadian boreal forest; in parts of Maine, New Hampshire, Vermont, New York, Michigan, Wisconsin and Minnesota; western U.S. states; western Mexico and Guatemala.

In winter, they can range throughout the United States, and during these irruptive years, some will stay in areas south of their normal range to breed. The pine siskin’s winter movements north and south, and east and west across North America are considered unpredictable and nomadic.

Pine siskins primarily breed in coniferous forest, but also in mixed coniferous-deciduous forest. Their diet primarily consists of small seeds of conifers and deciduous trees such as alder and birch. They also eat insects. Thistle seed is their favorite feeder food, but they will also consume sunflower seed pieces. To get through the long winter nights, they will temporarily store seeds—up to 10% of their body weight—in part of their esophagus called the crop.

Continuous chatty sounds come from flocks —a distinctive buzzy call, zree-e-e-e-e-eet, with a rising inflection often compared to the ripping of a piece of paper.

They nest in loose colonies and continue to socialize with flock mates. Nest building often begins as soon as late February. They actively nest in late winter and early spring often leaving breeding areas by May. Nests have three to four eggs. The female remains on the nest and is fed by the male. Mate feeding is a common courtship behavior observed in winter feeding flocks.

To show aggression, a pine siskin will lower its head and spread its wings and tail when facing an opponent and will lunge forward. They usually win these confrontations, chasing off even larger birds such as purple finches.

Considered a “common bird in steep decline” by Partners in Flight, the pine siskin breeding population numbers 46 million, a decline of 69% from 1966 to 2019. Threats include predation by cats, red squirrels, hawks and corvids; salmonella outbreaks at feeding stations; poisoning by pesticides and cyanide (used in gold mining); attraction to salt in winter roadways and loss of forest habitat.

One winter, I saw a flock of pine siskins that had formed a circle around a road-killed flock mate. How other species respond to loss is a fascinating subject and this observation reminded me of how elephants behave when they lose a herd member.

In spring one year, I observed a red squirrel capture a pine siskin in our yard. The squirrel chewed and turned the bird like a corn-on-the-cob. The bird’s partner spent the entire afternoon searching the lawn for its missing mate.

Look for flocks of pine siskins throughout the Adirondacks this winter. A good place to view them is at feeding stations where they often join American goldfinches and common redpolls. Their continuous chatter adds life to the season.

Photo by Jeff Nadler