During the breeding season, insects make up the bulk of a Red-winged Blackbird’s diet, but during the rest of the year, plant seeds are preferred. While the seeds of ragweed, corn, oats and smartweed are more staple food sources, cattail seeds are not overlooked. At maturity, and under dry conditions, the cattail spike bursts, releasing the seeds (some estimates are as high as 228,000 seeds/spike). When this happens, blackbirds take advantage of the easily accessible source of food, but the minute size of each seed (.0079 inches long) means obtaining a meal is a labor-intensive endeavor.
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The first reports of Red-winged Blackbird sightings are coming in, and with two feet of snow in some places, frigid temperatures, and very few insects in flight, one can’t help but wonder how they are surviving. A number of factors allow Red-wings to sustain themselves in these conditions, including the fact that their foraging is not restricted to one habitat – they look for food in marshes, pastures, overgrown fields, shores of lakes and ponds and windblown, exposed corn fields and crop lands. Secondly, they look for food in and on a variety of substrates, including but not limited to tree trunks and vegetation, which are accessible even with snow on the ground. Thirdly, they are very adept at gaping – forcing their bill open against the resistance of bark, etc. in order to reach into the crooks and crannies where insects are overwintering. And lastly, their diet fluctuates with the food that is available. During the breeding season, the majority of a Red-winged Blackbird’s diet is insects, and during fall, winter and early spring, Red-wings are primarily plant eaters – weed seeds, tree seeds and in agricultural areas, grains. In many ways, Red-winged blackbirds are more successfully adapted than humans are to this interminable winter!
Male red-winged blackbirds have returned to Vermont, and their most notable features are the brightly-colored reddish-orange feathers on their “shoulders”, referred to as epaulettes. In the military, an epaulette is a shoulder ornament that indicates, through its position, color, length and diameter, the bearer’s rank. Some birds, including male redwings, also possess this badge, or visual cue, which indicates the social status of the bird to other birds of the same species. Studies of male red-winged blackbirds and their epaulettes indicate (through dyeing their bright orange/red shoulder patches black) that epaulettes play a significant role in the male’s defense of his territory. Over 60% of the redwings that had their epaulettes dyed black lost their territories to other males. Further research revealed that aggression by a territorial male redwing is proportional to the epaulette size of the encroaching male redwing. It also indicated that male redwings intruding into redwing-occupied territories greatly limit the exposure of their epaulettes by covering them with black feathers. (Female red-winged blackbird plumage is brown and lacks epaulettes.)