Red-winged blackbird

Name and taxonomy

Carl Linnaeus described the bird in 1766 as Oriolus phoeniceus. The description appeared in the twelfth edition of Systema Naturae. Louis Pierre Vieillot moved it to the genus Agelaius in 1816. Linnaeus gave the type locality only as America. A later author narrowed it to Charleston, South Carolina, in 1928.

The genus name comes from a Greek word that means gregarious. The species name is the Latin word for crimson. Both halves of the name appear to describe the bird well. Agelaius holds five species in all. The closest relative is the red-shouldered blackbird, which lives only in Cuba. Those two together sit beside the tricolored blackbird of California.

Evolution and relatives

The species belongs to the Icteridae, the New World blackbirds and orioles. That family lives only in North and South America. Like other members of that family, it sits near the grackles, cowbirds and meadowlarks. The red-winged blackbird has many named subspecies across its huge range. The bicolored blackbirds of California are among them.

Western birds sing a different song from eastern ones. The species is one of the best studied wild birds anywhere. Its numbers, its open marsh habitat and its bold males probably explain that. Work on this bird probably shaped much of what biologists know about territory and polygyny. The strong difference between the sexes may have drawn researchers as well.

Appearance

The adult male is black all over except for the shoulder. There he carries a red patch, called an epaulet, over a pale yellow bar. At rest he can cover the red and show only the yellow. A male under one year old has a smaller patch that leans towards orange. The female is blackish brown above and heavily streaked below, with a pale eyebrow. Young birds look like the female, with buff edges to the feathers.

Males measure 22 to 24 centimetres and females 17 to 18 cm. The wings span 31 to 40 cm. The smallest females weigh 29 grams and the largest males 82 g. The tail is of middling length, at 6.1 to 10.9 cm, and it ends in a rounded shape. The bill is sharply pointed, and the eyes, bill and feet are black. The shoulder of a female reddens as she ages, from brown towards orange-red.

Habitat and range

The breeding range runs from central Alaska and Yukon east to Newfoundland. It reaches south to Florida, the Gulf coast, Mexico, Guatemala and northern Costa Rica. The bird avoids desert, high mountains, the Arctic and closed forest. Fresh and salt marsh suit it best, above all where cattail grows. It also nests in meadows, prairie, old fields, hayfields and roadside ditches.

Northern birds move south in autumn, and southern birds stay put all year. Migration starts in September or October, and sometimes in August. Great Lakes birds travel nearly 1,200 kilometres between summer and winter. Females go farther than males, by about 230 km in that population. In the winter of 1975 to 1976 a Tennessee roost held 11 million birds. They packed into a pine plantation of only 4.5 hectares.

Diet and feeding

About three quarters of the food is plant matter. Weed seeds make up most of that, together with spilt corn and rice. Insects and other small animals make up the last quarter, and far more in summer. Dragonflies, damselflies, moths, butterflies and flies are the favourites. The bird also eats snails, spiders, worms, frogs, eggs and carrion.

It picks insects off plants and catches others in the air. It prises open plant stems with its bill to reach grubs inside. Marsh birds take newly emerged dragonflies as they climb a stem to harden. A year when periodical cicadas emerge brings more food than the birds can use. Flocks follow the plough to pick up grubs, earthworms and caterpillars. In season the birds turn to blueberries, blackberries and other fruit.

Behaviour and social life

The species is territorial, polygynous, gregarious and a short-distance migrant. It flies with quick wingbeats broken by short glides. Males sit high on reeds, fence posts and wires where every rival can see them. Females keep low and move through the stems. A female probably spends most of her day building, feeding and watching the nest. A male attacks birds far larger than himself inside his patch.

During the breeding season a male will swoop at a person who walks into the marsh. Males arrive first in spring and spend some weeks in flocks of their own sex. Most males keep the same territory for years. The ones that do move are usually two or three years old. A male that moves a short way breeds better than one that moves far. In autumn the birds join grackles, cowbirds and starlings in flocks of thousands.

Communication and senses

The male's song is a scratchy oak-a-lee, with a buzzy trill on the last note. Western birds sing a different phrase again. The everyday call of both sexes is a throaty check. An alarmed male whistles a thin cheer or peet. The female answers with a scolding chatter or a sharp scream. Some calls seem to name the danger, with one for a raccoon and another for a crow.

The shoulder patch appears to do as much work as the voice. In the song spread display the male fluffs up, lifts his shoulders and fans his tail. The wings arch further as the display grows stronger, which shows more red. Researchers dyed the patches black, and 64 percent of those males lost their ground. Only 8 percent of the untreated males lost theirs. Females use the display against each other early in the season.

Reproduction and life cycle

The birds nest in loose colonies in the marsh. The female builds alone, over three to six days. She weaves a basket of grass, sedge and moss, lines it with mud and lashes it to the stems. The nest sits anywhere from 7.6 centimetres to 4.3 metres above the water. The breeding season runs from late April to the end of July.

A clutch holds three or four eggs, and five only rarely. The eggs are pale blue-green with brown, purple and black marks at the blunt end. They are smooth, slightly glossy and oval in shape. Each egg measures about 24.8 by 17.55 millimetres. The female incubates alone, and the eggs hatch after 11 to 12 days. Chicks hatch blind and naked and leave the nest 11 to 14 days later. They feed themselves two to three weeks after that.

A male may hold a territory containing as many as 10 nesting females. Females often mate with other males, so one nest can hold chicks of several fathers. A pair raises two or three broods a season, in a fresh nest each time. Females can go on breeding for up to ten years. The average bird lives only about 2.14 years. The record for the wild is 20 years.

Predators and threats

Raccoons, mink, long-tailed weasels and snakes raid the nests. Magpies, grackles, ravens and marsh wrens take eggs and small chicks. Owls, red-tailed hawks and short-tailed hawks catch grown birds. Which predator matters most changes with the region. Marsh wrens lead in British Columbia, magpies in Washington and raccoons in Ontario.

Nesting in a group means more adults on watch at once. A nest over water is harder for a land animal to reach. Males act as sentinels and chase off animals much bigger than they are. They leave night raiders such as raccoons and mink alone. The dull colour of the female probably hides her on the nest. Lice, mites, blood parasites and worms all live on or in the birds.

Population and conservation

The global listing for the species is Least Concern. Little has been spent on protecting a bird this common. Numbers in Illinois doubled between 1908 and 1958. The birds moved out of marshes and into hayfields, ditches and roadsides. That flexibility probably carried them through a century of drainage.

The range has narrowed since the middle of the twentieth century. In Ohio the birds fell back between 1966 and 1996. Less hay, earlier cutting and more row crops all worked against them. Further loss of wetland would probably shrink the population again. NatureServe still ranks the bird as secure across most of Canada. iNaturalist holds 314,445 observations of the species. GBIF has records from 27 countries.

Relationship with humans

Farmers seem to have argued about this bird for two centuries. It eats weed seeds and crop pests, which helps the grower. It also tears open sweet corn while the grain is still soft. In the southern states it pulls up rice seedlings and strips the soft grain. Hard, ripe corn defeats it, because its bill and gut cannot handle whole kernels. A common grackle has a longer, stronger bill and takes the hard grain instead. Males eat more grain than females do, which the study of stomach contents showed.

Control has, in general, been harsh. Aircraft have spread treated corn bait at about 3.4 kilograms a hectare. Pesticides such as parathion have been used illegally against flocks. In 2009 a United States agency reported poisoning over 950,000 of these birds. That work has been blamed for part of the fall of the rusty blackbird. The Migratory Bird Treaty Act of 1918 protects the species, with an exception for crop damage.

In culture and myth

Many Indigenous languages of North America name this bird for its shoulder. In Ojibwe it is memiskondinimaanganeshiinh, a word built around a very red little shoulder blade. Odawa names point at the small red mark on the wing. In Lakota it is wablosa, which means wings of red. In the Hoocak language the name describes the round red spot and calls the bird a blackbird.

Northern Algonquian languages group it with the juncos and grackles. Their names for it come from a word meaning spotted or marked. Oji-Cree and Ojibwe use jachakanoob and jachakanoo for the same bird. Lakota speakers put words to the song, and one version means oh, that I might die. Other readings of the song run and me, me too, and a beaver's running sore.

For many people in the north the first oak-a-lee of the year probably marks the start of spring. The bird seems to be a fixture of North American nature writing and bird study. Edward Howe Forbush described the flocks following the plough for grubs.