Press Releases

The Mystery of the Disappearing Grosbeaks

October 25, 2006

The Evening Grosbeak is an enigma. Many people who used to see these raucous birds descend on their feeders in large numbers now report that they haven't spotted one in years. Reports from volunteers who count the birds at their feeders as part of Project FeederWatch, a bird-monitoring program coordinated by the Cornell Lab of Ornithology and Bird Studies Canada, show that grosbeaks are indeed declining. In fact, grosbeaks are completely missing from many areas where they were common as recently as the early 1990s.

Questions about Evening Grosbeaks began more than a century ago when these birds rapidly expanded their range from western North America to include many areas in the East. The range expansion brought these gluttons to feeders all across the northern half of the continent by the 1950s. Noisy flocks would routinely visit backyard bird feeders and devour sunflower seeds. Grosbeaks were one of the most common species reported to Project FeederWatch when the program began in 1987. Now, nearly 20 years later, Evening Grosbeaks have fallen off of the list of most common feeder birds in most regions.

The Evening Grosbeak is a yellow, black, and white finch with a bill that appears too big for its body. Its winter range typically covers the entire northern half the United States and it is found year-round in many western states and southern Canada. Evening Grosbeaks are an irruptive species, meaning their migration is irregular, linked to the availability of food. They may be abundant in an area one year and nearly nonexistent the next. However, the long-term trend shows that these irruptions have almost ceased in many areas of the East, and declines have been documented in their core western range as well.

The reasons for the decline are unclear—are the birds dying, are they failing to reproduce, or are they simply moving elsewhere? Scientists are not sure, but bird watchers may help unravel the mystery by counting birds at their own feeders and submitting information to Project FeederWatch. Participants report all of the birds seen, so researchers can learn where grosbeaks are found, as well as where they are missing. Participants may submit reports as often as once per week from November to April. Everyone is invited to participate.

The more eyes looking out for grosbeaks and other birds, the better! Anyone interested in signing up for Project FeederWatch in the United States can do so online at www.birds.cornell.edu/pfw or call the Lab toll-free at (800) 843-2473. In Canada, contact Bird Studies Canada at (888) 448-2473. For the $15 participation fee ($35 Canadian), participants receive the FeederWatcher's Handbook, a poster of the most common feeder birds, a subscription to the Lab's newsletter, BirdScope, instructions, a calendar, and the FeederWatch report, Winter Bird Highlights.