For the Birds Radio Program: Declining Species: Evening Grosbeak
When I moved to my house on Peabody Street in July, 1981, the very first thing I did was set out and fill bird feeders, and the first birds to show up that first day were Evening Grosbeaks. My yard had a big box elder tree and three maple trees, their seeds in the high branches waving like a big invitation to anyone passing overhead, and once any grosbeaks dropped into the trees, it was easy for them to discover the feeders. These birds prefer their seed on open platform feeders and I kept mine well stocked. That happened to be during a time when the species was abundant, so Evening Grosbeaks became a constant presence in my yard from then on, through the 80s and into the 90s. Evening Grosbeaks belong to what is called an irruptive species—their flocks wander here and there. But Duluth seemed to be right smack in the middle of their comings and going, so when there were huge numbers of them, my backyard was a great place to see them year-round, coming or going or sticking around for a while. In late winter through spring, I’d see adults in their green beaks, feeding their mates. By mid-summer they’d be bringing their babies to the feeders—the young birds begged for and received food from many adults, not just their own parents.
Evening Grosbeaks became part of the fabric of my life. They were a constant presence—when the windows were open, their soft, sibilant calls filled the house. When I was in the yard with my kids, no matter what the season, the grosbeaks were all around, picking up grit from the sandbox, feeding in the trees and at the feeders, flying about or just sitting on the fence. It never occurred to me that these abundant birds would ever disappear.
But disappear they did, and people are pretty mystified about why. This is a species that requires mature hardwoods, so how we manage our forests may well be part of the puzzle—managing for so much paper and wood products on rotation cycles too short for maples doesn’t provide for grosbeaks.
Windows are a serious causes of mortality for Evening Grosbeaks—Dr. Daniel Klem, an authority on bird collisions with windows, found that the grosbeak is the tenth-most frequently reported species killed by collision with buildings. In my own yard, four or five Evening Grosbeaks were killed at my windows over the years. Also, large numbers are killed by cars in winter when flocks are attracted to grit and salt on roads. There was one record of at least 2,000 dead adults on 16-km stretch of highway in British Columbia, with many more dead off-road. Evening Grosbeak populations apparently reach a peak during spruce budworm outbreaks. They provide a natural control for spruce budworm, but when we use pesticides to control this scourge, that both eliminates an important food source and may be indirectly toxic to the birds, though we virtually never do research on the secondary effects of pesticides on specific birds.
Whatever the reasons, the National Audubon Society has placed Evening Grosbeaks in the Number 2 spot on their list of most rapidly declining common birds. Based on Breeding Bird Survey and Christmas Bird Count data, they figure the species has dropped 78 percent in the past 40 years. That’s pretty scary for what really was such an abundant bird, especially because we really don’t know what has caused the decline so we don’t know what to do to correct it. But bird species really are like bridges—we need to heed the danger warnings ahead of time to prevent catastrophes.