(Laura Erickson; 14 April 2017)
In the past few weeks, I’ve received a couple of letters from listeners about their backyard birds eating unusual items.
Craig Magnuson of Forks, Washington, wrote that he’s seen Evening Grosbeaks, during several different summers, eating cold campfire charcoal shortly after dawn at the Lake Kachess campground in the Wenatchee National Forest. He noted that someone else posted photos of Evening Grosbeaks eating campfire charcoal at a different location about 20 miles east of where he’s seen it.
True finches, such as Evening and Pine Grosbeak, crossbills, siskins, goldfinches, and Purple Finch, eat mostly seeds. This diet has two problems: birds don’t have teeth, so can’t chew seeds to mash them up, and seeds are missing many minerals and other nutrients that birds need. By eating various forms of grit, birds solve both problems. The grit remains in the first chamber of their stomach—the gizzard—for a while, helping the muscular walls to pulverize the food. And little by little, the grit itself gets pulverized, and the minerals within are picked up by the body, too.
According to the Cornell Lab of Ornithology’s Birds of North America, Evening Grosbeaks are known to eat snow, salt, and mineral-rich soil, and are drawn to areas where salt or calcium carbonate are artificially added to soil. A few studies have shown that they eat coal and coke ashes, and a scientist named Orr, in a 1951 paper titled “Observations on the birds of northeastern Idaho” in The Proceedings of the California Academy of Science, wrote that they regularly take charcoal from campfires.
Back in the 1980s and early 90s, when Evening Grosbeaks were abundant in my own neighborhood…..