One of the more conspicuous signs of late summer into fall are the large flocks of red-winged blackbirds wheeling around area marshes and croplands. If you haven’t noticed them yet, you should soon.
Red-winged blackbirds are a common sight in the wetlands during the summer months where they nest amongst the cattails and bulrushes. The males are easily identified by their black body with red and yellow epaulets. Red-winged blackbirds are polygamous, and the males fiercely defend their territory. If all goes well, the females will produce one or two broods of young from an average clutch size of 3-4 eggs.
The red-winged blackbird is among the most abundant birds native to North America. North Dakotans might be surprised to learn that they are year-round residents over much of the United States and Central America. They are, however, just summer residents (breeding range) in some of the northern border states, such as North Dakota, South Dakota, Montana, Minnesota, as well as much of Canada.
The summer diet of red-winged blackbirds is mainly insects, some of which are pests of crops. They also consume weed seeds. But when fall comes around, they are widely known for their habit of feasting on crops, particularly sunflowers.
Arthur Cleveland Bent noted this propensity for crop depredation in his "Life Histories of Familiar North American Birds." An excerpt reads:
“In the Middle West, where the redwings are much more abundant and where the cereal crops are more extensively cultivated, these and other blackbirds, in late summer and fall, swoop down in vast hordes on the grain fields and do an immense amount of damage to the grain both while it is ripening and while it is being harvested.”
The damage to crops, fruits, and berries has been estimated to be in the hundreds of millions of dollars a year. The damage to sunflower fields in North Dakota and South Dakota has been estimated to be in the range of 4-7 million dollars annually.
Although still abundant, like many other bird species, the red-winged blackbird populations are on the decline. Between 1966 and 2019 they have declined by a little under 1% per year. That may not sound like much, but cumulatively that is nearly a 40% decline!
