Column: Where have all the evening grosbeaks gone?
Published 7:31 pm Thursday, February 9, 2006
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One of my fonder childhood memories is of the flocks of evening grosbeaks that used to come to moms bird feeder during the winter. That was back in the late 1950s and early1960s. Time has a way of changing memories to suit your fancies but as I recall they came every year with the snow and stayed all winter.
Their stately, contrasting colors of dusky bronze-gold, shiny obsidian black and titanium white made them one of my favorite birds. When I returned to Michigan in the 1980s I was really looking forward to renewing my friendship with evening grosbeaks. Alas, over the next twenty years of tending feeders just a half block away from where I grew up not one evening grosbeak appeared. As the 1960s folk song asks, “Where have all the flowers gone?” I find myself asking, “Where have all the grosbeaks gone?”
As a kid I assumed evening grosbeaks were always around but we only saw them in the winter when mom stoked up the feeder. Not so. Come to find out, they were far wandering visitors.
Originally, evening grosbeaks only inhabited the northern Rocky Mountains from the northwestern U.S. states up through British Columbia and Alberta to the southern Yukon. Like many far north birds they occasionally irrupted out of their home range to other areas when some phenomena made food sources scarce, but this only happens irregularly.
However, for some unknown reason during the early to mid 1900s evening grosbeaks began expanding their range. They moved down the Rockies clear to Mexico and spread eastward across southern Canada, eventually extending clear to the east coast.
Some speculate this expansion was due to extensive planting of box elder trees as ornamental shade trees. Evening grosbeaks eat primarily fruits, seeds and buds of which those of the box elder are among their favorites.
Whatever the reason, apparently my childhood grosbeaks appeared here in Southern Michigan when this new population irrupted from their newly established breeding range to the north. In theory, this should only have happened every few years rather than every winter as I remember, but who knows?
One thing we do know is evening grosbeaks are no longer irrupting into this area to the extent they did back in the 1960s. Extensive, long term surveys by amateur bird watchers such as the Christmas Bird Count and Great Backyard Bird Count show the overall evening grosbeak population to be stable but with major declines over the last 25 years in Michigan, Wisconsin and the New England states.
The problem is no one knows what this means. Since their summer breeding range in Canada is so inaccessible the only meaningful data we have comes from their winter haunts down here in civilization. It could mean a population decline in these areas.
On the other hand, maybe they are just changing habits. It could be a factor of different forestry and land use practices where food sources in these former winter areas are lacking so the grosbeaks irrupt elsewhere. Or perhaps they just aren't irrupting as much due to some changing condition in their summer breeding range. This could be from global warming and generally milder winters up in Canada. Or perhaps logging of the conifers up there is creating more deciduous trees, providing more food sources and allowing them to stay home year around. Maybe it's a combination of these things.
Whatever the cause of this local decline, my hopes remain high that someday I will look out and see my feeders alive with evening grosbeaks.
As previously mentioned, the overall population appears to be well and good. From their original tiny range in the northern Rockies they have homesteaded the entire width of Canada.
In irruptive years they now appear all across the country as far south as Texas, Tennessee and the Carolinas. Out of all that, sooner or later some are bound to find my place. Carpe diem.