Evening Grosbeak - mystery species.
Article by Gerry Smith
The identity of this, large strikingly-colored finch is never a mystery, but until recently much of its life style was. Rare in the Northeastern United States before 1920, they became increasingly common by mid-century. A half century ago, flocks of these handsome northern visitors scoured the countryside for bird feeders and natural foods. Affectionately called "grospigs," these flocks could vacuum feeders of all sunflower seeds in short order. In a big year for Evening Grosbeak many comments regarding needing a second mortgage to feed these hordes were only said partly in jest.
During the 1980s migrations of several thousand a day were reported during May along the south shore of Lake Ontario. Then something happened, and by the mid-1990s a rapid decline began. During the last two decades this species has been very scarce in much of the eastern parts of its range. At first many theories were advanced, but possible answers were forthcoming only in the last few years. A plausible reason for the rapid decline has now been determined. It seems our winter sunflower seed gobblers are among many boreal forest species that are spruce budworm specialists on their breeding grounds (look here for more on spruce budworm). The spruce budworm is native species to the boreal forest of North America and is subject to periodic cyclic and explosive outbreaks. During the last thirty years these infestations have been at least partially controlled by forestry interests using pesticides to disrupt these natural events. Thus the law of unintended consequences applies and native bird populations are also adversely impacted. Hopefully, for the dependent bird species, some outbreaks overwhelm control efforts and perhaps humanity may learn that working with, rather than against natural events, makes sense.
For whatever the reasons. Evening Grosbeak populations in our region seem to be making at least a minor comeback in recent years. Recent reports from the areas where our birds originate suggest improved populations. There are already local arrivals to the North Country during late October, which is a good sign. It appears that possibly the best southbound movement in two decades is currently underway. If so, naturalists will have an opportunity to enjoy these wonderful northern finches that they have lacked in this century. So take out that second mortgage for lots of black oil sunflower seed and prepare a welcome for the hordes. Hopefully they will come and add their wonderful animation to the Northern New York winter scene.