Agelaius phoeniceus

A small (7-9 ½ inches) blackbird, the male Red-winged Blackbird is most easily identified by its small size, black body, and red-and-yellow “shoulder” patches visible during the male’s breeding display. Female Red-winged Blackbirds are streaked brown overall with faint tan eye-stripes. Males of this species are unmistakable when their bright patches are visible, and no other female blackbird in North America is so heavily streaked. The Red-winged Blackbird primarily breeds from Alaska and northwestern Canada south to northern Central America. In winter, northerly-breeding populations migrate south to the southern U.S.Populations breeding further south are generally non-migratory. Red-winged Blackbirds breed in wetland habitats, including freshwater and saltwater marshes, damp grasslands, and flooded rice fields. Individuals that migrate utilize similar habitats in the winter as in summer. Red-winged Blackbirds primarily eat insects during the summer, switching over to a diet composed of seeds and grains in the winter. In appropriate habitat, Red-winged Blackbirds are most easily seen while foraging for food on the stalks and leaves of marsh grasses. During the breeding season, males may be observed displaying their “shoulder” patches from prominent perches in the grass while singing this species’ buzzing “konk-la-ree” song. Red-winged Blackbirds are primarily active during the day.

Threat Status: Least concern

The Red-winged blackbird is a common songbird distributed widely throughout wetlands and associated habitats in North America. Iconic features of fresh and saltwater marshes, males announce themselves with territorial displays of loud "konkeree" songs and bright, yellow-edged red shoulder patches (epaulets) on otherwise glossy black plumage. Females are much less conspicuous, dusky-brown with streaked bellies and off-white eyebrows. The sexes are similar in size, averaging 22 cm in length and 64 grams. Red-winged blackbirds are generalist feeders, eating more insects and mollusks when they are abundant but with the majority of the diet consisting of seeds and other plant material. Male red-winged blackbirds have on average five and up to 15 females breeding on their territories; the species is a well-studied example of polygyny. These gregarious birds are also known for large communal roosts and for mobbing predators such as crows and hawks.

Biogeographic Regions: nearctic (Native )

The range of red-winged blackbirds extends from southern Alaska at its northern most point, to the Yucatan peninsula in the south and covers the greater part of the continent reaching from the Pacific coast of California and Canada to the eastern seaboard. Winter ranges for red-winged blackbirds vary by geographic location. Northern populations migrate south to the southern United States and Central America beginning in September or October (or occasionally as early as August). Most western and middle American populations are non-migratory.

Biogeographic Regions: nearctic (Native ); neotropical (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Breeding range extends from southern Yukon across Canada to Nova Scotia, and south to Baja California, Costa Rica, western Cuba, and the northern Bahamas. This species winters over much of United Sates, especially in the southern part.

Easily distinguished by their glossy black feathers and red and yellow epaulets at the shoulder, males are the more brightly colored of the two sexes. Females tend to be dusty or brownish in color with dark stripes on their undersides. Females resemble large sparrows and are often recognized by their off-white eyebrow markings. Both males and females have dark legs and claws. The beak of male red-winged blackbirds tends to be totally black, whereas the beak of female red-winged blackbirds is dark brown on top with lighter brown on the underside. Both males and females have sharply pointed beaks.

Both male and female adult red-winged blackbirds are approximately 22 cm long, weigh 41.6 to 70.5 g and have a wingspan of 30 to 37 cm. Young males and females resemble adult females in coloration. Males undergo a transitional stage in which red epaulets appear orange in color before reaching their adult coloration. Olson (1994) showed that the average basal metabolic rate for adults in his experiments was 656 cm cubed/oxygen per minute and that the rate for three-day-old birds was 296 cm cubed/oxygen per minute.

Range mass: 41.6 to 70.5 g.

Range length: 18 to 24 cm.

Average length: 22 cm.

Range wingspan: 30 to 37 cm.

Average basal metabolic rate: 39360 cm^3 oxygen/hour.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful

Red-winged blackbirds weigh as much as 85.0 grams. They are approximately 24.0 centimeters long, and can have a wingspan of 37.0 centimeters. Red-winged blackbird males and females are different in size and coloration. The male is black overall with red "shoulders" edged with white, pink, or yellow feathers. Males are also slightly larger than females. The female is brownish overall and lacks any red color.

Range mass: 85.0 (high) g.

Range length: 24.0 (high) cm.

Range wingspan: 37.0 (high) cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger; male more colorful

Length: 22 cm

Weight: 64 grams

During the breeding season, the prefered habitat is marsh. Red-winged blackbirds are found in cattail, tule, sedge, and salt marshes as well as in wetlands. They are also found in wet shrubby fields, at the edge of secondary growth, hayfields, old fields, pastures, and even urban parks. During the winter, red-winged blackbirds are found in open fields and croplands.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: savanna or grassland

Aquatic Biomes: lakes and ponds

Wetlands: marsh ; swamp ; bog

Other Habitat Features: suburban ; agricultural ; riparian

Systems

• Terrestrial
• Freshwater

Red-winged blackbirds roost and breed in a variety of habitats, but tend to prefer wetlands. They have been known to live in fresh and saltwater marshes. On drier ground, red-winged blackbirds gravitate towards open fields (often in agricultural areas) and lightly wooded deciduous forests. In winter red-winged blackbirds are most often found in open fields and croplands.

Habitat Regions: temperate ; tropical ; terrestrial

Terrestrial Biomes: savanna or grassland

Aquatic Biomes: brackish water

Wetlands: marsh ; swamp

Other Habitat Features: suburban ; agricultural ; riparian ; estuarine

Comments: Habitat includes freshwater and brackish marshes, bushes and small trees along watercourses, and upland cultivated fields. In migration and winter, this blackbird also occurs in open cultivated lands, plowed fields, pastures, and prairies (AOU 1998). Nests usually are near water, in cattails, rushes, or sedges, occasionally in shrubs or trees.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Red-winged blackbirds withdraw from the northern part of the breeding range for winter, returning usually in February-March.

During the breeding season, red-winged blackbirds eat mostly Insecta, Araneae, and other invertebrates. At other times of the year, they diet on weed seeds, crop grains, as well as invertebrates. They have been known to forage (search for food) in rice fields and other croplands. They have been known to also eat a wide variety of other foods as they are available, including carrion, Annelida, Mollusca, fledgling Aves, eggs, and Lissamphibia.

Animal Foods: birds; amphibians; reptiles; eggs; carrion ; insects; terrestrial non-insect arthropods; mollusks; terrestrial worms

Plant Foods: seeds, grains, and nuts; fruit

Red-winged blackbirds tend to be generalized feeders, consuming a greater amount of plant tissue in the non-breeding season and a greater amount of animal material in the breeding season. Red-winged blackbirds will feed on almost any plant material they can consume, preferring seeds and agricultural products, such as corn and rice. Adult red-winged blackbirds will consume a wide variety of foods including snails, frogs, fledgling birds, eggs, carrion, worms and a wide array of arthropods. Insects, especially Odonata (dragonflies and damselflies), Lepidoptera (butterflies and moths), and Diptera (true flies) are preferred, although arachnids and other insect and non-insect arthropods are consumed. For the most part, red-winged blackbirds feed on whatever they can find, picking insects out of plants and feeding on seeds and plant material. At times, red-winged blackbirds will hunt using their beaks for gaping (opening up of crevices in plant material with the beak). Red-winged blackbirds will also catch insects in flight.

Animal Foods: birds; amphibians; reptiles; eggs; carrion ; insects; terrestrial non-insect arthropods; terrestrial worms

Plant Foods: roots and tubers; wood, bark, or stems; seeds, grains, and nuts

Primary Diet: omnivore

Comments: Approximately 73% of diet is vegetable matter, 27% animal matter (Terres 1980); animal component undoubtedly increases during breeding. Feeds in open fields on grain and seeds. Eats mayflies, moths, beetles, caterpillars, grubs, and mollusks, etc. Also eats some fruit.

Red-winged blackbirds are important predators on invertebrates in their breeding grounds and can have a large impact on grain and seed availability in their winter flocks.

Another species of bird, the Molothrus ater, uses red-winged blackbirds as a host to raise their young. Brown-headed cowbirds are nest parasites on red-winged blackbirds. These cowbirds will puncture one of the blackbird's eggs and lay their own egg in the nest. The cowbird egg is then hatched and taken care of along side the red-winged blackbird nestlings.

Red-winged blackbirds are aggressive birds, even attacking humans that accidentally wander into their nesting territories. Groups of red-winged blackbirds can drive away much larger predators by ganging up on them. Red-winged blackbirds are probably preyed upon by a diverse set of predators, including Procyon lotor, Mustela, Squamata, Vulpes vulpes, Mephitis mephitis, and Falconiformes. Most predation occurs on babies in the nest (called nestlings) and eggs. Red-winged blackbirds also avoid predation on their eggs and fledglings by making their nests over water, in dense foliage, and 1 to 2 meters above the ground. Females are brownish and drab in coloration, making them difficult to see when they are on their nest.

Known Predators:

• Procyon lotor
• Mephitis mephitis
• Mustela
• Squamata
• Vulpes vulpes
• Falconiformes

Anti-predator Adaptations: aposematic ; cryptic

As highly generalized foragers and predators, red-winged blackbirds can have a great and lasting impact on their environment. By controlling insect populations through predation and weed populations through the consumption of seeds, red-winged blackbirds allow larger plants and crops to flourish. Paradoxically, red-winged blackbirds can also devastate plant growth and crop yields by feeding on the very plants their predation protects. As one of the most numerous species of birds on the continent, red-winged blackbirds also play key roles in the dispersal of other species. Because red-winged blackbirds tend to flock and roost in such large numbers the survival of other species of birds that encroach upon their territory must surely be affected by their presence. Large roosting habitats can also greatly affect the physical terrain. In short, red-winged blackbirds are so numerous and active that their presence and natural behavior alone is enough to impact an ecosystem in a very visible way.

Ecosystem Impact: disperses seeds

As a result of high predation rates, especially of eggs and young, red-winged blackbirds have developed a number of anti-predator adaptations. Group nesting is one such trait which reduces the risk of individual predation by increasing the number of alert parents. Nesting over water reduces the likelihood of predation as do alarm calls. Nests, in particular, offer a strategic advantage over predators in that they are often well concealed in thick, waterside reeds and positioned at a height of one to two meters. 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).

Known predators include: racoons, American mink, black-billed magpies, marsh wrens, owls (family Strigidae) and hawks (order Falconiformes).

Known Predators:

• raccoons (Procyon lotor)
• American mink (Neovison vison)
• black-billed magpies Pica pica 
• marsh wrens Cistothorus palustris 
• owls (Strigiformes)
• diurnal raptors (Falconiformes)

Anti-predator Adaptations: aposematic ; cryptic

Agelaius phoeniceus is prey of:
Accipiter striatus
Accipiter cooperii
Strigiformes
Cistothorus palustris
Pica pica
Mustela vison
Procyon lotor
Falconiformes

Based on studies in:
Canada: Manitoba (Forest)

This list may not be complete but is based on published studies.

Agelaius phoeniceus preys on:
Gryllidae
Araneae
Insecta
Annelida
Arthropoda
Amphibia
Reptilia
Aves

Based on studies in:
USA: New York, Long Island (Marine)
Canada: Manitoba (Forest)

This list may not be complete but is based on published studies.

Gregarious; travels in large flocks, except during the breeding season. May travel in mixed flocks with cowbirds and grackles. Density of territorial males averaged 0.2-0.7 per ha in favorable habitat (Clark and Weatherhead 1987). Commutes up to 80 kilometers to foraging areas from winter roosts (Meanley 1965, Orians 1961).

Red-winged blackbirds communicate vocally and visually. In the eastern United States, male red-winged blackbirds utter their familiar song of "oak-a-lee" or "konkeree" in the spring. The last syllable is given more emphasis as a scratchy or buzzy trill. The common call used by both males and females is a "check" call. Males may utter a whistled "cheer" or "peet" call if alarmed. Other calls made by the male include a "seet," a "chuck," or a "cut." Females may utter a short chatter or sharp scream. A pre-mating call, "ti-ti-ti," may be uttered by both sexes.

Communication Channels: visual ; acoustic

Males learn songs from other males. Both males and females have a variety of calls, some of which are the same. Only the males produce flight calls, which signal their exit from the territory. Both males and females employ distress and alarm calls which differ with the nature of the threat. Specific calls seem to communicate the presence of specific predators, such as raccoons or American crows. Short contact calls are also quite common, especially between a territorial male and the females in his territory. Threat calls are used to ward off predators, other birds and other red-winged blackbirds. Courtship calls vary little between males and females and are used only in the breeding season. Male songs are used to announce territorial boundaries and to attract mates. Female songs occur in the early breeding season and are most common before the incubation period.

Male red-winged blackbirds utter their familiar territorial and mate attraction song of "oak-a-lee" or "konkeree" in the spring. The last syllable is given more emphasis as a scratchy or buzzy trill. The common call used by both males and females is a "check" call. Males may utter a whistled "cheer" or "peet" call if alarmed. Other calls made by the male include a "seet," a "chuck," or a "cut." Females may utter a short chatter or sharp scream. A pre-mating call, "ti-ti-ti," may be uttered by both sexes.

Visual displays are also a key form of communication, especial before and during mating. Males often use visual displays in order to attract females to their territories and to defend their territories and mates. An example is the "song spread" display. Males fluff their plumage, raise their shoulders, and spread their tail as they sing. As the display becomes more intense, the wings are more arched with the shoulders showing more prominently. Females will also engage in a "song spread" display directed at each other early in the breeding season. One possibility is that a female will defend a sub-territory within the male's territory. Females will engage in a "wing flip" display when a disturbance prevents them from returning to the nest.

Communication Channels: visual ; acoustic

In the wild, red-winged blackbirds live 2.14 years, on average. The olded recorded red-winged blackbird in the wild lived 15 years and 9 months.

Range lifespan
Status: wild: 16.0 (high) years.

Average lifespan
Status: wild: 2.14 years.

Average lifespan
Status: wild: 189 months.

In the wild, red-winged blackbirds live 2.14 years, on average. The olded recorded red-winged blackbird in the wild lived 15 years and 9 months.

Range lifespan
Status: wild: 20 (high) years.

Average lifespan
Status: wild: 2.14 years.

Average lifespan
Status: wild: 189 months.

Maximum longevity: 20 years

Male red-winged blackbirds defend territories in which as many as 15 females establish nesting areas. Most male territories contain about 5 females. Females mate mostly with the male in whose territory they live, but will also mate with other males.

Males attract females for mating by having large and attractive territories with plentiful resources. They also use vocalizations and postures to attract a female for mating.

Mating System: polygynous ; polygynandrous (promiscuous)

Nest building begins between March and May. Usually, the further south you go, the earlier the nest is built. Males select the nesting site and actively defend it. After a female accepts the male and his site, the nest is built in or near marshland or moist, grassy areas. Plant materials, such as cattail stalks, are woven together to form a basket above water level, and soft materials are used to line the nest. Three to five pale greenish-blue, black or purple streaked eggs are laid per clutch. Each egg is approximately 2.5 by 1.8 cm. Females will incubate the eggs (sit on the nest and keep the eggs warm until they hatch) while the male guards the nest. The female incubates the eggs for 11 to 13 days. Chicks fledge (are able to fly) in 10 to 14 days and are independent in 2 to 3 weeks. Juveniles usually reach adulthood in 2 to 3 years.

Breeding interval: Females may raise as many as three broods in a single season, although the average is 1.7 broods per season.

Breeding season: Breeding begins in the early spring and continues until mid-summer.

Range eggs per season: 3.0 to 7.0.

Average eggs per season: 4.

Range time to hatching: 11 to 13.0 days.

Average time to hatching: 12.6 days.

Range fledging age: 10 to 14 days.

Range time to independence: 2 to 3 weeks.

Average age at sexual or reproductive maturity (female): 2 minutes.

Range age at sexual or reproductive maturity (male): 2 to 4 minutes.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization

Average eggs per season: 4.

When the eggs hatch, the young are blind, uncoordinated, and dependent on care from adults. Females are generally responsible for feeding and caring for the young. However, at times, the male will help with the first clutch and later in the breeding season.

Parental Investment: altricial ; male parental care ; female parental care

Red-winged blackbirds are extremely polygynous with as many as 15 females nesting in the territory of a single male. On average, a single male has roughly 5 females. Although copulation occurs mostly between the sovereign male and those females that inhabit his territory, roaming males are known to mate with the females on other territories. These behaviors seem to increase the chances of successful reproduction within a given mating season, compensating for broods and individuals lost to nest-predation and nest parasitism.

Mating rituals begin with the song of the male. Females often do not return songs until they have established themselves in the territory of a male. Male pre-coital displays include vocalization in a crouched position with rapid and highly conspicuous fluttering of the wings. The female responds with a similar crouch and vocalization. Mating occurs in the egg-laying period or just prior and is characterized by a brief contact between the cloacal vents of the male and the female.

Mating System: polygynous ; polygynandrous (promiscuous)

Breeding begins in the early spring and continues until mid-summer. Females may raise as many as three broods in a single season, although the average is 1.7 broods per season. Females choose nesting sites most often in wetland or agricultural areas (although a wide variety of nesting habitats are know to be exploited) and males perform a nesting display, which constitutes his main involvement in the nest building process. Nest building begins between March and May. Usually, the further south you go, the earlier the nest is built. After a female accepts the male and his site, the nest is built in or near marshland or moist, grassy areas. Plant materials, such as cattail stalks, are woven together to form a basket above water level, and soft materials are used to line the nest. Three to five pale greenish-blue, black or purple streaked eggs are laid per clutch. Each egg is approximately 2.5 by 1.8 cm. Nests can be completed in as little as a single day, especially if no mud-lining is constructed.

Clutch size is from 3 to 7 eggs and the eggs are incubated for 3 to 11 days. Chicks fledge in 10 to 14 days and are independent in 2 to 3 weeks. Juveniles usually reach sexual maturity in 2 to 3 years.

Breeding interval: Females may raise as many as three broods in a single season, although the average is 1.7 broods per season.

Breeding season: Breeding begins in the early spring and continues until mid-summer.

Range eggs per season: 3 to 7.

Average eggs per season: 4.

Range time to hatching: 11 to 13 days.

Average time to hatching: 11 days.

Range fledging age: 14 to 10 days.

Average fledging age: 14 days.

Range time to independence: 2 to 3 weeks.

Average time to independence: 2 weeks.

Range age at sexual or reproductive maturity (female): 2 to 2 years.

Range age at sexual or reproductive maturity (male): 2 to 4 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization

Average eggs per season: 4.

Incubation is the sole responsibility of females. Red-winged blackbird eggs tend to hatch at different times and the mother will continue to incubate until the last egg has hatched. Nestlings are fed almost immediately after hatching. Parents often begin with smaller portions and increase food amounts progressively. Young red-winged blackbirds are fed small arthropods, especially Odonata (dragonflies and damselflies), Lepidoptera (moths and butterflies), and Diptera (true flies). The nestlings are fed primarily by the female although the male will, at times, take part in the feeding process. In cases in which the mother is absent, males are known to take over feeding responsibilities for the brood. Fledglings leave the nest after 14 days and are fed by the female and, to a lesser degree, the male for two to three weeks before joining a flock of females. Within a year most red-winged blackbirds have joined mixed flocks.

Parental Investment: no parental involvement; altricial ; pre-fertilization (Protecting: Female); pre-hatching/birth (Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

Nesting begins usually in April-May in most areas, sometimes in late March, and may continue into July. Clutch size is usually 3-5 (often 4) in the United States. Incubation, by the female, lasts 11-12 days. Nestlings are tended by both parents or, in some areas, by the female only. Young are able to leave the nest in about 10 days.

Most males have multiple females nesting in their territories. Up to 15 females have been found nesting within the territory of a single male, although the average number is 5 or fewer.

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 11 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 12
Specimens with Barcodes: 18
Species With Barcodes: 1

Red-winged blackbirds are widespread and abundant, as migratory birds they are protected under the U.S. Migratory Bird Act.

IUCN Red List of Threatened Species: least concern

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
• 2004
  Least Concern
• 1994
  Not Recognized
• 1988
  Not Recognized

As one of the most common, widespread, and numerous birds in North America, little is done to protect red-winged blackbirds from the effects of habitat loss and urbanization. Because they can survive in a wide array of habitats, many populations can overcome losses of natural terrain. Nonetheless, red-winged blackbirds thrive in wetland areas and with the loss of natural wetlands it is likely that this species will suffer. This species is a migratory bird, and is protected under the U.S. Migratory Bird Treaty Act.

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Management Requirements: See Glahn et al. (1991) for information on the impact of ground-based surfactant roost control treatments on local urban and agricultural blackbird/starling problems.

Red-winged blackbirds may act as crop pests during winter when they aggregate in large numbers.

Negative Impacts: crop pest

Red-winged blackbirds consume insects, which provides pest control.

Positive Impacts: controls pest population

Despite their consumption of the seeds of unwanted weed pests, red-wing blackbirds have been known to cause great agricultural damage due to their colonial roosting habits and taste for agricultural products. Red-winged blackbirds often open the husks of developing corn stalks to feed on corn kernels. They are also known to feed on rice paddies and sunflower seeds. This consumption of ripening crops has lead many agriculturalists to employ extremely effective and often inhumane tactics in battling red-winged blackbird populations. These tactics include the frequent use of traps, poisons, and Avitol, a chemical agent that causes birds to behave in abnormal ways. Surfactants, or wetting agents, have also caused considerable damage to red-winged blackbirds. These detergents break down the waterproofing properties of the blackbird's feathers making them extremely vulnerable to low temperatures. Because of the long history of human-blackbird conflict and their continued threat to agricultural initiatives many of these techniques are used to this day. Less harmful methods of red-winged blackbird control include the use of noisemakers and the reduction of post-harvest crop waste, which attracts hungry red-winged blackbirds to farmland.

Negative Impacts: crop pest

Red-winged blackbirds have been known to feed on the seeds of numerous weeds that are detrimental to agricultural production. They also control insect populations, which can devastate agricultural yields.

Positive Impacts: controls pest population

Comments: Regarded as a pest at certain times and places (e.g., in croplands, at large communal roosts during nonbreeding season). Damages sunflower crops in Dakotas and Minnesota (Cummings et al. 1989).

Species Impact: In Ohio, most damage to corn crops occurs in fields within 8 km of marshes with large late summer roosting populations; management recommendations include: planting of hybrids less attractive to birds, reduction of weed and insect populations to make fields less attractive to birds, judicious use of mechanical or chemical frightening devices/agents at the time birds initially damage maturing corn, provision of natural or planted food and cover sites outside the corn, and harvesting the crop as early as possible (Dolbeer 1980; see also Dolbeer et al. 1988). Attracted to infestations of corn borers; where insects are controlled, blackbird damage to corn is minimal (Straub 1989). See also Dolbeer (1990) for information on reducing damage to corn. Reflecting tapes may or may not reduce damage to ripening corn, depending in part on spacing of tapes (Conover and Dolbeer 1989). Blackbird damage to sunflowers may be reduced by used bird resistant varieties; sunflowers with concave head shape, inward-pointing bracts, and fibrous hulls appear to be the most effective morphological features for deterring feeding blackbirds (Mah and Nuechterlein 1991).