Always in Season: Grosbeaks may bring winter birding thrills
The evening grosbeak is often a spoiler and always a thrill — a spoiler because it is always keenly anticipated but seldom shows up, and a thrill whenever it does appear.
The grosbeak is another of the northern species that sometimes move south in large numbers. Of these so-called "irruptives," the evening grosbeak is the least dependable.
This relative rarity adds to the thrill of any evening grosbeak sighting. So does the bird itself. This bird is a stunner by any measure.
The evening grosbeak stands out for its shape, its plumage and its bill.
In his "Guide to Eastern Birds," David Crossley calls the evening grosbeak "a hulking bird with dark through the eye that gives it a mean look." I've also heard the evening grosbeak described as "bandit like."
The grosbeak is about the size of a robin, but it is a much stockier bird.
In flight, the grosbeak shows a large patch of white in the wings. This is sufficient to clinch its identification. No other wintering bird shows so much white in flight, except pileated woodpeckers, and grosbeaks and woodpeckers do not behave at all alike.
The grosbeak shows a lot of yellow on the back, breast and belly. Males have a patch of yellow behind the bill and over the eye. The cheeks and upper back are duller, ranging from gray to dull brown. The wings and tail are black.
Overall, this creates a vivid impression.
The bill is enormous for the size of the bird and accounts for its name. The grosbeak's bill is a crushing machine capable of opening just about any seed casing.
Grosbeaks are seedeaters, and they come to feeders. Some lore suggests they favor open platforms rather than closed feeders with perches.
Chances of seeing these grosbeaks are very much better to the north and east of Grand Forks. They are birds of open woodlands — habitat that's not widespread west of the Red River. Nevertheless, evening grosbeaks have occurred here. I encountered evening grosbeaks on the Grand Forks Christmas Bird Count in 2012. Honesty compels me to report that the birds were found in East Grand Forks — making them countable in Minnesota.
Sightings of evening grosbeaks have become less frequent, making them all the more thrilling. Crossley says, "Numbers have decreased drastically recently and former large movements appear to have stopped."
Why this is so is another of the mysteries about bird movements.
The history of grosbeak populations is unusual; at settlement, the species was unknown in most of eastern North America. In the late 19th century, grosbeaks exploded eastward.
The monograph about the species (No. 599 in "The Birds of North America," published by the American Ornithologists Union) notes, "Eastern expansion commonly attributed to widespread planting of box elder trees in prairie windbreaks and as an ornamental in northeastern cities."
Box elders grow quickly and were widely planted across the Great Plains. The trees hold their seeds over winter and provide a dependable food source for birds.
The box elder has lost its popularity, however. It is a short-lived tree; its timber has little value and it tends to be invasive, forming unattractive tangles. What's more, prairie farmsteads have been turned to farmland, and shelterbelts have been removed to create larger fields that are more easily tilled.
The consequence is many fewer box elder trees.
In "the Birds of Manitoba," the Manitoba Naturalists' Association suggests the grosbeak's winter movements "seem to stall near the forest edge, where the sunflower-seed supply at innumerable feeders often outstrips demand."
The pine grosbeak is another winter irruptive that's much more common in the Red River Valley. Males are pinkish in color and often occur in trees with hanging fruit.
Three grosbeak species nest in North Dakota. The most common and most familiar is the rose-breasted grosbeak. The black-headed grosbeak occurs in the western part of the state mostly from the Missouri River Valley westward. In his "Breeding Birds of North Dakota," Robert Stewart lists the blue grosbeak as a "hypothetical" nesting species. I've had reports of this species from Steele County, N.D.