Where have all the grosbeaks gone?
Sometimes our choices can make a positive difference, like selecting recycled paper for as many uses as possible.
People should be taking down their bird feeders now as bears are emerging from hibernation, hungry after losing up to 30% of their body weight over the winter.
But the issue in point is this question to those who love to feed birds: When was the last time you saw an evening grosbeak at the feeder? Anecdotal evidence from Thetford residents suggest this bird, a species of finch, has declined dramatically from "big flocks passing through" in the 1990's to recent decades of seeing just the odd one or two in an exceptional year, but mostly none at all.
Evening grosbeaks are easy to identify. They are large for a finch, about the size of a starling but more stocky, with a big head and a very large yellowish or pale greenish conical bill. The males are striking, dull yellow in color shading to a dark head with yellow "eyebrows." They sport conspicuous white wing patches contrasting with the otherwise black wings and tail. The females are a drab greyish brown, and their white wing patches are less showy.
Their scientific name, Coccothraustes, translates as "kernel-cracker." The name "evening grosbeak" is a misnomer, coined by early settlers who erroneously believed the bird came out to sing only after sundown.
National statistics bear out the worrisome decline of the evening grosbeak. Data from the Breeding Bird Survey indicates that since 1966 their once-stable population has dwindled to around 25% of its former numbers. In fact the evening grosbeak is cited as the landbird suffering the steepest reduction in numbers in the continental US. The State of the Birds 2022 Report places the evening grosbeak in the group of "tipping point" birds — species that have lost more than 50% of their population from 1970 to 2019.
Before the realization that evening grosbeaks were in trouble, surprisingly little was known about their habits. It wasn't till 2017 when David Yeaney, an avian ecologist at the Western Pennsylvanian Conservancy, launched a study in which tiny radio trackers were attached to grosbeaks, that details emerged about their wanderings. This startup project attracted the interest and help of the Road to Recovery (R2R) organization, an international project that coordinates research and conservation of most threatened birds. Their combined efforts showed that grosbeaks that overwintered in Minnesota migrated to boreal breeding grounds in Quebec. In addition, grosbeaks that appeared at the same feeder every winter may not be the previous year’s population returning. After overwintering they were observed to depart in all different directions, like Ontario, Manitoba, and the Great Lakes region. And a significant portion stayed near their Minnesota wintering sites to breed.
One constant pattern among grosbeaks, whether they were tagged in Maine, Minnesota, or Pennsylvania, was their migratory connection to outbreaks of spruce budworm in boreal forests. The larvae of the spruce budworm are a critical source of protein that enable grosbeaks to lay eggs and feed their young.
Researchers, including American Birding Association writer Laura Erickson, surmise that the decline of the evening grosbeak is linked to clear-cutting of their boreal coniferous breeding habitat plus the following: "Controlling spruce budworm has been an important forestry goal for many decades, with heavy use of pesticides over enormous swaths of northern forest. One of the pesticides currently used is Bacillus thuringiensis (a type of bacteria), which isn't known to harm birds, but regardless of the pesticide used, the loss of larval insects during the nesting season may well be implicated (in grosbeak decline)." In addition the forestry industry is replacing the maples and box elders, whose seeds nourish developing young grosbeaks, with fast-growing softwood trees, probably decimating another food source.
It is Yeaney's hope that there can be some collaboration with forestry agencies regarding the spraying of pesticides in zones of spruce budworm outbreaks.
Another cause of evening grosbeak mortality is death from window strikes near bird feeders. A scientist at the US Geological Survey Bird Banding Laboratory cited the evening grosbeak as the most-reported species among banded birds to die from window collisions. It is thought that grosbeaks are particularly susceptible to this sorry fate because they are social and come to feeders in flocks. People who are lucky enough to see evening grosbeaks at their feeder should do everything possible to make their windows bird-safe. (And for the sake of other species too!) The American Bird Conservancy sells tape specifically designed to make windows more visible to birds.
In general, luring birds of any species to human habitation with bird feeders can also put them in danger of cat predation. Outdoor cats kill huge numbers of birds; the American Bird Conservancy estimates 2.4 billion each year, a staggering figure.
There’s one more action we can all easily take to make a difference in the plight of the evening grosbeak. It is in the following area: Major toilet paper producers are clearcutting over one million acres of boreal forest every year for toilet paper alone — the same forest that provides breeding habitat for evening grosbeaks (not to mention numerous other bird species). In spite of readily available recycled paper, major corporations continue to use 100% virgin fiber for toilet paper.
While the majority of our consumer choices come at a price to the environment, sometimes our choices can make a positive difference, like selecting recycled paper for as many uses as possible, in particular the above. Putting bird tape on windows and keeping cats indoors are other actions that help to protect evening grosbeaks as well as the other birds we love to watch.