The red-winged blackbird (Agelaius phoeniceus) is a passerine bird of the family Icteridae found in most of North America and much of Central America. It breeds from Alaska and Newfoundland south to Florida, the Gulf of Mexico, Mexico, and Guatemala, with isolated populations in western El Salvador, northwestern Honduras, and northwestern Costa Rica. It may winter as far north as Pennsylvania and British Columbia, but northern populations are generally migratory, moving south to Mexico and the Southern United States.
Claims have been made that it is the most abundant living land bird in North America, as bird-counting censuses of wintering red-winged blackbirds sometimes show that loose flocks can number in excess of a million birds per flock and the full number of breeding pairs across North and Central America may exceed 250 million in peak years. It also ranks among the best-studied wild bird species in the world. The red-winged blackbird is sexually dimorphic; the male is all black with a red shoulder and yellow wing bar, while the female is a nondescript dark brown. Seeds and insects make up the bulk of the red-winged blackbird's diet.
Taxonomy
thumb|Male seen from behind, showing the absence of the typical yellow bands below the red spots
The red-winged blackbird is one of five species in the genus Agelaius and is included in the family Icteridae, which is made up of passerine birds found in North and South America.
The red-winged blackbird was formally described as Oriolus phoeniceus by Carl Linnaeus in 1766 in the twelfth edition of his Systema Naturae, but was later moved with the other American blackbirds to the genus Agelaius by Louis Pierre Vieillot in 1816. Linnaeus specified the type location as "America" but this was restricted to Charleston, South Carolina in 1928.
The red-winged blackbird is a sister species to the red-shouldered blackbird (Agelaius assimilis) that is endemic to Cuba. These two species are together sister to the tricolored blackbird (Agelaius tricolor) that is found on the Pacific coast region of the California and upper Baja California in Mexico.
Etymology
The genus name is derived from Ancient Greek , meaning "gregarious". The specific epithet, , is Latin meaning "crimson" or "red".
Subspecies
Depending on the authority, between 20 and 24 subspecies are recognised which are mostly quite similar in appearance. Despite the similarities in most forms of the red-winged blackbird, in the subspecies of Mexican Plateau, A. p. gubernator, the female's veining is greatly reduced and restricted to the throat; the rest of the plumage is very dark brown, and also in a different family from the European redwing and the Old World common blackbird, which are thrushes (Turdidae).
In the California subspecies, A. p. californicus and A. p. mailliardorum, the veining of the female specimens also covers a smaller surface and the plumage is dark brown, although not in the gubernator grade; The red-shouldered blackbird was formerly considered as a subspecies of red-winged blackbird. They were split by the American Ornithologists' Union in 1997.
Listed below are the red-winged blackbird subspecies and groups of subspecies recognized as of January 2014 with their respective distribution areas and the location of their wintering quarters: At rest, the male also shows a pale yellow wingbar. The spots of males less than one year old, generally subordinate, are smaller and more orange than those of adults. The female is blackish-brown and paler below. The female is smaller than the male, at long and weighing , against his length of and weight of . The smallest females may weigh as little as whereas the largest males can weigh up to . Each wing can range from , the tail measures , the culmen measures and the tarsus measures . also presents a whitish superciliary list. Observations in females in captivity indicate that small amounts of yellow pigment are present on the shoulders of these after leaving the nest, that the concentration of the pigment increases with the first winter plumage after the change of the feathers and that the passage from yellow to orange generally takes place in the second summer with the acquisition of the second winter plumage, after which no further changes in feather color occur. The colored area on the wing increases in surface with the age of the female, and varies in intensity from brown to a bright red-orange similar to that of the males in their first year.
Young birds resemble the female, but are paler below and have buff feather fringes. Both sexes have a sharply pointed bill. The tail is of medium length and is rounded. The eyes, bill, and feet are all black. Young males go through a transition stage in which the wing spots have an orange coloration before acquiring the most intense tone typical of adults.
The male measures between in length, while the female measures . in the female beak is dark brown and clear in the upper half at the bottom, Males are 50% heavier than females, 20% larger in its linear dimensions, and 20% larger compared to the length of their wings. The trend towards greater dimorphism in the size of non-monogamous ichterid species indicates that the larger size of males has evolved due to sexual selection. Males with larger spots are more effective at chasing away their non-territorial rivals and are more successful in contests within aviaries. When the red shoulder patches were dyed black as part of an experiment, 64% of males lost their territories, while only 8% of control subjects did. However, males whose wings had been dyed before they had mated could still attract females and successfully reproduce. In the red-winged blackbird, the spots on the wings are a sign of threat among males and have an unimportant role, if any, in intersex encounters. Therefore, the spots are likely to have evolved in response to pressures linked to intrasexual selection. Additionally, neither the size nor the coloration of the same are linked to the reproductive success of the males with those females that are not their mates, that is, those with which they eventually mate.
Vocalizations
thumb|Male red-winged blackbird singing
thumb|Vocalizing
The calls of the red-winged blackbird are a throaty check and a high slurred whistle, '. The male's song, accompanied by a display of his red shoulder patches, is a scratchy ', except that in many western birds, including bicolored blackbirds, it is '. The female also sings, typically a scolding chatter '.
Birds do not begin their migration to wintering quarters until the two outer primary sprouts and the two inner or central rectrices have completed at least two-thirds of their development. Therefore, there is a correlation between molting, particularly replacement of the remiges and rectrices, and fall migration in red-winged blackbirds.
- First pre-basic molt (or post-juvenile molt): Generally begins 45–60 days after individuals have left the nest.
Wing feathers
thumb|Wing feathers|270x270px
Complete replacement of wing feathers takes about eight weeks. However, birds in their first year frequently retain some of the under-wing coverts and juvenile tertiary remiges after post-juvenile moulting. Out of 70 immature males examined during the last week of October, 70% retained older lower primary blankets. In most cases where partial replacement of the covert feathers occurs, it is the proximal coverts that the bird retains. and Newfoundland in the northeast,
Preferences by habitat types during the breeding season
During the breeding season, the density of breeding adults is much higher in swamps than in highland fields. In a study conducted in the Wood County, Ohio between 1964 and 1968, the density of territorial males in wetland habitat was found to be 2.89 times those in upland habitat. But, because of the small amount of wetland habitat, the total estimated upland population of territorial males was 2.14 times the wetland population. Alfalfa (Medicago sativa) and other legume crops (hay) were the principal habitat for breeding redwings in the county. Despite the marked preference for wetland habitats, the greater population in uplands reflects wetlands' scarcity.
Vegetation type preferences during the breeding season
In that same study, reproductive individuals in upland habitats demonstrated a slight preference for old and new grasses such as Phleum pratense, Dactylis glomerata, Poa spp., Festuca spp., and Bromus spp. in the early part of the breeding season and new non-graminoid herbaceous plants in the mid and late season. In wetlands, they consistently preferred old and new broadleaf monocotyledons, primarily Carex spp., broadleaf, and Typha spp., and consistently rejected old and new narrow-leaved monocots, primarily narrow-leaved Phalaris arundinacea and Calamagrostis canadensis, and non-graminoid herbaceous plants. Red-winged blackbirds breeding in the highlands favored older tall vegetation only in the early part of the breeding season on April to May, and higher new vegetation and dense vegetation throughout the breeding season. For their part, those who settled in wetlands seemed to have a slight predilection for taller old vegetation. During the breeding season, this species is attracted to tall vegetation that restricts visibility.
Early season preferences for old grassland in the highlands and old broadleaf monocotyledons in wetlands point to the importance of upright residual vegetation. Highland grasses and broadleaf monocots in wetlands stand partially vertically and are easily visible in early spring, unlike clovers, narrow-leaved monocotyledons in wetlands and most non-graminoid herbaceous plants. Old alfalfa plants are also partially upright in early spring, but they are not as consistently chosen a species as old grasses. The start of the territorial activity is earlier when the amount of residual vegetation is large. Vegetation structural strength also appears to be important for nesting as females tend to broadleaf monocotyledons in wetlands throughout the breeding season and new non-graminoid herbaceous plants in the mid to late season. One found that red-winged blackbirds avoided the marsh wren (Pantaneros chivirenes), a predator common in nests of this species, reproducing among more dispersed vegetation, which was more easily defended from the chivirines; conversely, the chivirines seemed to prefer the denser vegetation, where they were more likely to avoid the aggressiveness of the red-winged blackbird. These differences in habitat selection between one species and another resulted in spatial segregation of their breeding areas. Females tend to stay low, prowling through the vegetation and building their nests. They can be found in home gardens, particularly during their migration, if seeds have been scattered on the ground. It prefers insects, such as dragonflies, damselflies, butterflies, moths, and flies, but also consumes snails, frogs, eggs, carrion, worms, spiders and mollusks. The red-winged blackbird forages for insects by picking them from plants, or by catching them in flight. The years of emergence of periodical cicadas provide an overabundant amount of food.
A clutch consists of three or four, rarely five, eggs. Eggs are oval, smooth and slightly glossy, and measure . On the other hand, in different states has been estimated that the period in which the active nests contained eggs lay between beginning in late April and early late August; and in northern Louisiana nests were found to harbor chicks from late April to late July. The peak of the nesting season (the time with the highest number of active nests) has been recorded between the first half of May and the beginning of June in different places. A study in eastern Ontario found that although red-winged blackbirds began nesting earlier in years with warm springs, associated with low winter values in the North Atlantic Oscillation Index, egg laying dates remained unchanged. Male testosterone levels peak in the early part of the breeding season, but remain high throughout the season.
Many aspects of territorialism (for example, the number of male songs and displays, and the number of intrusions into foreign territories) peak before mating. After this, the frequency of many of the territorial behaviors decreases and the males are mainly concerned with defending the females, eggs, and chicks against predation. Experiments in the systematic removal of birds from their territories suggest that the extra population of males that is present in swamps before copulations disappears after copulation.
Predation of eggs and nestlings is quite common. Nest predators include snakes, mink, raccoons, and other birds, even as small as marsh wrens. The red-winged blackbird is occasionally a victim of brood parasites, particularly brown-headed cowbirds. Males often act as sentinels, employing a variety of calls to denote the kind and severity of danger. Mobbing, especially by males, is also used to scare off unwanted predators, although mobbing often targets large animals and man-made devices by mistake. The brownish coloration of the female may also serve as an anti-predator trait in that it may provide camouflage for her and her nest while she is incubating. long-tailed weasels, black-billed magpies, common grackles, short-tailed hawks, and snakes (such as the northern water snake
The relative importance of different nest predators varies by geographic region: the top predators in different regions include the marsh wren in British Columbia, the magpies in Washington, and the raccoons in Ontario.
Due to high predation rates, especially of eggs and chicks, the red-winged blackbird has developed various adaptations to protect its nests. One of them consists of nesting in groups, which reduces the danger since there is a greater number of alert parents. Nesting over water also lowers the chances of an attack. Nests in particular offer a strategic advantage as they are often hidden among dense riparian reeds, at a height of one or two meters. Males in particular hunt down potential predators to scare them away, even when dealing with much larger animals. On the other hand, nocturnal predators such as raccoons and American mink are not attacked by adults. Coloration of the female could serve to camouflage it, protecting it and its nest when it is incubated. and hematophagous mites, like Ornithonyssus sylviarum,
Territorial
thumb|250x250px|Agitated male
thumb|Male red-winged blackbird [[Mobbing (animal behavior)|mobbing an osprey]]
The red-winged blackbird aggressively defends its territory from other animals, and will attack much larger birds. During breeding season, males will swoop at humans who encroach upon their nesting territory. Male red-winged blackbirds also exhibit important territorial behaviors, most of which provides them with the necessary fidelity for many years to come. A few important factors for male red-winged blackbirds' adherence to territories include food, hiding spaces from predators, types of neighbors, and reactions towards predators. Additionally, a study was done on site fidelity and movement patterns by Les D. Beletsky and Gordon H. Orians in 1987 which explained much of the males' territorial behaviors once migrated and settled onto a territory of their own.
Sufficient evidence had shown that males are committed to staying in their territory over a long period of time and are not more likely to change territories at a younger age due to limited experience of knowledge for success. Studies also showed that most of the males that were first-time movers to a new territory were between two and three years old. The majority of males that moved were young and inexperienced. Later on they had moved towards more available territories. If males had chosen to leave their territory for reproductive success, as an example, they would do so within a short distance. Males who moved shorter distances were more successful in reproducing than those who moved longer distances. Further studies showed that when males moved further away from their territories there was a decrease in probability of successfully fledging.
The maximum longevity of the red-winged blackbird in the wild is 15.8 years.
Migration
Red-winged blackbirds that breed in the northern part of their range, i.e., Canada and border states in the United States, migrate south for the winter. However, populations near the Pacific and Gulf coasts of North America and those of Middle America are year-round resident. They also eat on Anthonomus grandis and Hypera postica, two species of weevils affecting cotton and alfalfa respectively, as well as harmful caterpillars of the European gypsy moth (Lymantria dispar) and of the genus Malacosoma.
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During the breeding season, the approximately 8 million red-winged blackbirds nesting in Ohio and their chicks probably consume more than of insects, an average of almost . Many of these insects, such as the weevils (Hypera spp.), Come from alfalfa fields, pastures, oat fields and other crops. In cornfields, blackbirds often feed on corn worms (Helicoverpa zea) and beetles of the genus Diabrotica. In early spring, red-winged blackbirds consume corn borers (Ostrinia nubilalis) in fields with corn stubble.
Negative aspects: consumption of cultivated grains
thumb|Flock flying in the twilight|251x251px
The red-winged blackbirds can devastate farm fields. Despite the fact that they consume weed seeds, they are known to cause great damage to agriculture due to their habits of resting in massive groups and their taste for agricultural products. particularly important near roosts. From 215 birds Neotropical migrants have been identified as causing, by a wide margin, the greatest economic loss. and due to the reduction of small areas with stubble, hayfields and uncultivated land, which, in turn, accentuated the bird's dependence on corn to ensure its livelihood.
Apparently, the male does more damage to this grain than the female. In some areas of Ohio, corn can account for up to 75% of the diet of males and only 6% of that of females in August and September. In South Dakota, in the late summer, the gizzards of the males studied contained 29% corn, while in the case of the female that number was limited to 9%. In the northern part of the Great Plains, an area known as the Prairie Pothole Region, red-winged blackbirds are very abundant in summer. They congregate in post-reproductive flocks that significantly harm crops, particularly sunflower plantations near their home sites. Most sunflower damage occurs between mid-August and early September, when the calorie content of immature seeds is low and birds must consume more of them to satiate themselves.
During this initial stage of predation on sunflower crops in which more than 75% of the total damage is caused, the red-winged blackbird represent 80% of the blackbirds observed in the fields of this seed. This period predates the massive migration of birds and most of them are of local origin. Most remain within of their native sites until the molting of their feathers is complete or nearly complete in late August or early September. Damage can be quite serious in the center and southeast of North Dakota and Northeast South Dakota, areas of high concentration of sunflower production and abundant wetlands that attract red-winged blackbird during the breeding season.
Investigations conducted between 1968 and 1979 revealed that blackbirds, notably the black-winged blackbird and the common grackle, annually destroyed less than 1% of corn crops in Ohio, amounting to a loss between 4 and 6 million dollars according to 1979 prices.
Pest control
thumb|231x231px|Brown-headed cowbirds and red-winged blackbirds in [[Cayuga Lake Basin, New York, US]]
The two main options that farmers can choose from to avoid the presence of birds once corn has entered the milky stage of its maturation process are the use of the chemical 4-aminopyridine and the implementation of mechanical devices to frighten birds away.
Pest control history
As early as 1667, Massachusetts Bay settlers had enacted laws to try to reduce blackbird populations and mitigate damage to corn. According to Henry David Thoreau, a law provided that each single man in a town must kill six of those birds and, as a punishment for not doing so, he could not marry until he had complied with the aforementioned design. Obviously, since blackbirds reproduce at a much higher speed than humans marry, this control strategy was a failure. Pioneers traveling west to the Great Lakes region faced similar problems. By 1749, blackbirds were so abundant around western Lake Erie that people took turns watching over the maturing grain crops.
At the beginning of the 20th century, in some places, when the reeds dried up, these circumstances were used to kill these birds in the following way. A crew approached a roost in silence, hidden in the darkness of the night, and simultaneously lit the reeds at various points, which were quickly enveloped by a single great flame. This caused a huge tumult among the red-winged blackbird, which, lit by fire, were shot down in large numbers as they hovered in midair and screamed all over the place. Sometimes straw was used for the same purpose, which was previously scattered near reeds and alder bushes (Alnus spp.) in which they gathered to rest, the burning of which caused great consternation among the birds. The gang returned the next day to collect the hunted prey. but their effectiveness depends on certain atmospheric conditions, namely low temperatures and rainfall. The chemical DRC-1327, which has proven useful in mitigating damage to maturing corn, operates in the same way: when a bird ingests kernels from a partially hand-peeled cob to which the chemical has been applied with a sprayer manual, his erratic flight and his pre-death calls for suffering, which span a space of between five and fifteen minutes, chase away flocks from the fields. It has even been suggested that the continued use of 4-aminopyridine over the years could cause a change in the pattern of migration to the south, as if birds were learning to avoid areas persistently treated with the chemical.
The effects of this method would probably vary according to the type of habitat in which the treated males have established their territories. In general, there should be a higher proportion of fertile clutches in those densely populated habitats and with a greater number of renidifications (nest reconstructions). Renidifications are more common in swamps than in the highlands. In turn, individuals that reproduce in the highlands probably feed more often within their own territories than those that reproduce in swamps, which probably makes promiscuity difficult in the first type of habitat. Thus, chemical sterilization could be more effective among upland populations than among swamp populations. An extended incubation of unviable eggs would result in fewer renidification attempts and, therefore, it decreased the opportunities to find a fertile mate for a female who originally mated with a sterile male. In the United States, such efforts are illegal because no pesticide can be used on non-target organisms, or for any use not explicitly listed on the pesticide's label. However, the USDA has deliberately poisoned this species in the past: in 2009, the Animal and Plant Health Inspection Service reported poisoning over 950,000 red-winged blackbirds in Texas and Louisiana. This poisoning has been implicated as a potential cause of the decline of the rusty blackbird, a once abundant species that has declined 99% since the 1960s and has been recently listed as Threatened on the IUCN Red List.
In the Anishinaabe languages, an indigenous language group spoken throughout much of the bird's northeastern range, this bird's names are diverse. In the Oji-Cree language, the northernmost of the Anishinaabe languages, it is called , while the Ojibwe language spoken in Northwestern Ontario and into Manitoba ranging immediately south of the Oji-Cree's range, the bird is called (with the cognates cahcahkaniw (Swampy Cree), cahcahkaluw (coastal Southern East Cree), cahcahkayuw (inland Southern East Cree), cahcahkayow (Plains Cree); the northern Algonquian languages classify the red-winged blackbird as a type of a junco or grackle, deriving the bird's name from their word for "spotted" or "marked".
In the vast majority of the other Ojibwa language dialects, the bird is called memiskondinimaanganeshiinh, literally meaning "a bird with a very red damn-little shoulder-blade". However, in the Odawa language, an Anishinaabe language in southwestern Ontario and in Michigan, the bird is instead called either ("bird with a red [patch on its wing]") or memiskonigwiigaans ("[bird with a] wing of small and very red [patch]"). In Nsyilxcən the bird is known as . In the Hoocąk language they are known as , which describes the round red spot on its wing as well as identifying it as a blackbird.
In the Lakota language, another Indigenous language spoken throughout much of the bird's range, the bird is called ("wings of red"). Its songs are described in Lakota as ("oh! that I might die"), ("...and me"), ("me too!"), and ("a beaver's running sore").
Conservation status
It is a species of least-concern.