Where have all the finches gone?

Anchorage bird feeders came down this April heavy with uneaten seed and unresolved questions. Throughout the winter, local birdwatchers remarked on the absence of small passerines-an order of perching birds that includes more than half the world's avian species. Where were the redpolls, the pine grosbeaks, and white-winged crossbills? Last year these birds mobbed feeders and fir trees across the city. How could the flocks vanish like so many melting snowflakes?

Science offers important clues. All three species belong to the finch family, which is known for irruptions. Not like Mount Spurr-volcanoes erupt with an 'e'-but a sudden, non-cyclical migration in response to environmental conditions. For finches, these conditions usually involve food availability. "Their ecology is they go to where the food resources are abundant," said River Gates, the Pacific Shorebird Conservation Initiative Coordinator for Audubon Alaska. "If you look outside right now, you'll notice that we don't have a lot of spruce cones on our trees...what we're seeing is that this year, we don't have the food resources for these irruptive species."

Most of the finch species that winter in North America's boreal forests rely on seed. Some even specialize in a particular type to reduce competition. White-winged crossbills, as their name suggests, have a beak ideally shaped for prying open conifer cones. Others take a generalist approach. Trees have their own tricks to survive. "Mast years" yield a bumper crop to ensure some seeds will grow despite predation. In other years the trees produce very little, forcing hungry birds to switch food sources or move elsewhere.

Gates hypothesizes that abundant conifer seeds and extreme cold in the winter of 2023 drew the birds to Anchorage. This year, with fewer cones and milder temperatures, they likely stayed in the boreal forest. For evidence, Gates consults data from the National Audubon Society Christmas Bird Count. This annual event has tallied backyard birds for 125 years, making it the longest-running citizen science project in the United States. "Audubon has used that information to inform science and conservation planning across the hemisphere," Gates said. Those same data can offer insight into local population trends.

In December 2023, Anchorage's citizen scientists tallied an astonishing 4,180 redpolls, 546 pine grosbeaks, and 3,456 white-winged crossbills. The following year brought only 66 redpolls, 19 pine grosbeaks, and 0 white-winged crossbills. Comparing 20 years of surveys from 2004 to 2024 revealed a pattern of such peaks and valleys. While a winter without these species might seem strange to birdwatchers, the data indicate such variation is normal. "We're not seeing big declines in individuals, just a pattern of them shifting their behavior based on seasonally abundant food resources and probably the weather conditions, because it has been a remarkably warm, weird, dry, snowless winter here in Anchorage," Gates said.

Citizen science reassures us that a year without finches is part of a natural phenomenon, but it has also revealed more worrisome trends among bird species nationwide. A study published in May analyzed 36 million observations from the bird survey platform eBird to track population changes in nearly 500 bird species across North and Central America and the Caribbean. Results showed that 75% of species had declined in the last 14 years, often in areas where they were most abundant. This counterintuitive finding suggests that formerly ideal habitats were no longer suitable for the birds. Species that breed in the Arctic and northern latitudes showed the steepest declines, which researchers attributed to the warming climate. Anchorage's redpolls, grosbeaks, and crossbills might be at risk along with their biome.

Broad ecological studies like these would not be possible without contributions from birdwatchers across the continent. Knowing where population changes occurred can also support conservation. Gates agrees that citizen science can play an important role in preserving the wildlife that bring color and joy to our neighborhoods. "In addition to the technical and scientific information that comes out of the Christmas Bird Count, I really think that the community of citizen scientists that it's created has created a really strong network of people willing to advocate for bird conservation in the United States as well." Avian allies can also connect with BirdTLC in Anchorage to support local efforts, ensuring Alaskan bird feeders stay busy for many seasons to come. https://www.birdtlc.org/