We had two inches of fresh snow last night and the landscape is wintry as I write this, so it is hard to believe that in just three weeks it is likely we will hear the first Red-winged Blackbirds in local marshes. T.S. Roberts records the earliest arrival in Minneapolis as Feb. 22 in 1926. A short distance migrator, red-winged blackbirds spend the winter just south of Minnesota, as far north as Missouri, and some southern Minnesota blackbirds don’t migrate at all.
What do the birds eat upon their extremely early arrival in a seemingly barren marsh? Blackbirds are omnivores, eating both insects (chiefly in summer) and seeds. In agricultural areas, their large flocks are notorious for gleaning cultivated seed, and Roberts notes that flocking blackbirds can do a number on wild rice beds. But most of their diet consists of noxious weed seeds like ragweed, smartweed and cocklebur.
Red-winged Blackbird males and females look very different, and many a novice birder has been confused by the streaky-brown bird at a feeder that she’s never seen before. The dimorphism (“di”-two; “morphos”-body) is directly tied to the roles each sex plays in reproduction. . The brightly colored males flash their scarlet epaulets warning intruders off the marsh territory and also puff them out to attract the ladies. The mousy-colored female plumage enables them to skulk through the marsh undetected as they go about building nests, laying eggs, and feeding young.
Male Red-winged Blackbirds are notable for their inclination to take on larger intruders into the territory—birds like crows and raptors, and even people. For several summers running, my offspring living in Minneapolis have complained about attacks from a particular male blackbird living near the bike path on the southern shore of Lake of the Isles.
Males defend one area of a marsh, and several females may build nests within the territory and mate with that male, a mating system known as “polygyny”) (“poly’- many “gyny”- females). However, the system is not so clear-cut—females are also known to mate with males of adjacent territories. Researchers have spent decades sorting it out. The system works because females take on most of the nest care, so the other territorial females do not detract from reproductive effort.
Red-winged Blackbirds are one of the most abundant birds in North America. Still, their population declined 30% from 1966-2014. They are still targets of farmers who poison, shoot or trap the birds in their roost sites that house huge numbers of birds. In the 1930s, the numbers were so vast that an observer noted that in the Red River Valley, a flock might rise from a field with a “sound like thunder.”
T.S. Roberts, who had an uncanny ability to see unusual bird behavior reported seeing female blackbirds hovering over the surface of the Minnesota River in Bloomington, legs dangling down. He watched as the birds plucked minnows from the surface, clasping the fish in their claws.
Recent Comments