University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln The aH ndbook: Prevention and Control of Wildlife Wildlife Damage Management, Internet Center for Damage 1-1-1994 BLACKBIRDS Richard A. Dolbeer Project Leader, Denver Wildlife Research Center, USDA-APHIS-ADC, Sandusky, Ohio 44870 Dolbeer, Richard A., "BLACKBIRDS" (1994). The Handbook: Prevention and Control of Wildlife Damage. Paper 59. http://digitalcommons.unl.edu/icwdmhandbook/59 This Article is brought to you for free and open access by the Wildlife Damage Management, Internet Center for at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in The aH ndbook: Prevention and Control of Wildlife Damage by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Richard A. Dolbeer Project Leader Denver Wildlife Research Center BLACKBIRDS USDA-APHIS-ADC Sandusky, Ohio 44870 Fig. 1. The red-winged blackbird (Agelaius phoeniceus) is the most abundant bird in North America. The black male, with red and yellow shoulder patches, is about 40% larger than the female. The female resembles a large sparrow more than a blackbird. Damage Prevention and Control Methods for Blackbirds Type of Crop Damage Method of Sprouting corn Ripening corn, sorghum, Ripening rice Fruit control and rice and sunflower and oats crops Feedlots Exclusion Generally not practical; Generally not practical; Generally not practical; Netting is cost-effective See chapter on netting can be used on netting can be used on netting can be used on for high-value crops. starlings. small plots. small plots; paper bags small plots. over ears or heads. Cultural Deep planting, avoid Grow nonpreferred crops Same as for ripening corn Provide alternative See chapter on methods early planting of rice. near roost; provide except resistant hybrids feeding site; early starlings. alternative feeding sites. are not available. harvest. Avoid early or late planting; use resistant hybrids. Harvest as early as possible. Frightening Several devices available; Several devices available; Several devices available; Several devices See chapter on most popular is propane most popular is propane most popular is propane available; most popular starlings; exploder. exploder; Avitrol®. exploder. is propane exploder. Avitrol®. Repellents Seed treatments. None available. None available. None available. See chapter on starlings. Toxicants None available. None available. None available. None available. Starlicide. Trapping Generally not practical. Generally not practical. Generally not practical. Decoy traps. Decoy traps. Shooting Helpful to reinforce Helpful to reinforce Helpful to reinforce Helpful to reinforce Helpful to reinforce frightening devices, frightening devices, frightening devices, frightening devices, frightening devices, futile for population futile for population futile for population futile for population futile for population reduction. reduction. reduction. reduction. reduction. PREVENTION AND CONTROL OF WILDLIFE DAMAGE — 1994 Cooperative Extension Division Institute of Agriculture and Natural Resources University of Nebraska - Lincoln United States Department of Agriculture Animal and Plant Health Inspection Service Animal Damage Control E-25 Great Plains Agricultural Council Wildlife Committee Introduction Food Habits and General Biology beetles and corn earworms, and on weed seeds, such as Johnson grass. The term blackbird loosely refers to a Insects are the dominant food during the nesting season (May through July), diverse group of about 10 species of Common Grackle North American birds that belong to with the diet shifting predominantly to the subfamily Icterinae. In addition to grain and weed seeds in late summer (Quiscalus quiscula) through winter. Males and females of- blackbirds, this subfamily includes ori- Identification oles, meadowlarks, and bobolinks. The ten forage in separated flocks, with fe- various species of blackbirds have sev- males being more insectivorous than An iridescent blackbird larger than a eral traits in common. The males are males. Except during nesting season, robin, the common grackle has a long predominantly black or iridescent in redwings congregate in large night- keel-shaped tail. The male, slightly color. All blackbirds have an omnivo- time roosts in marshes or woods con- larger than the female, has more irides- rous diet consisting primarily of taining up to several million birds. cence on the head and throat (Fig. 2). Annual survival rate is only about 50% grains, weed seeds, fruits, and insects. Range and Habitat The relative proportions of these food to 60%. This high mortality rate is off- groups, however, vary considerably set by a reproductive rate of 2 to 4 A common nester throughout North among species. Outside of the nesting young fledged per female per year. America east of the Rockies, the com- season, blackbirds generally feed in Females have 3 to 5 eggs in their open- mon grackle nests in shelterbelts, farm- flocks and roost at night in congrega- cup nests made of grasses and other yards, marshes, and towns. Flocks feed tions varying from a few birds to over vegetation. Eggs hatch after 12 days of in fields, lawns, woodlots, and bottom- one million birds. These flocks and incubation; the young grow rapidly lands. These birds winter in the southern roosting congregations are sometimes and are ready to fledge about 10 days United States, often in association with comprised of a single species, but often later. Females will often renest if their redwings, cowbirds, and starlings. initial nest is destroyed. several species mix together. Some- Food Habits and General Biology times they are joined by non-blackbird Damage to Crops species, notably European starlings The common grackle’s diet is some- (Sturnus vulgaris) and American robins Red-winged blackbirds can cause con- what similar to that of the redwing, (Turdus migratorius). siderable damage to ripening corn, but the grackle is more predatory. Its sunflower, sorghum, and oats in the diet occasionally includes small fish, The species also have many important milk and dough stages, and to sprout- field mice, songbird nestlings, and differences in their nesting biology, ing and ripening rice. These birds pro- eggs. Grackles have a larger, stronger preferred foods, migration patterns, vide some benefits by feeding on bill than redwings, allowing them to and their damage and benefits to agri- harmful insects, such as rootworm feed on acorns and other tree fruits in culture. Summarized below for each of seven species of blackbirds is informa- tion on identification, geographic range, preferred habitats, feeding hab- its, general biology, and damage. Red-winged Blackbird (Agelaius phoeniceus) Identification The male, a little smaller than a robin, is black with red and yellow shoulder patches. The smaller female is brownish, resembling a large sparrow (Fig. 1). Range and Habitat An abundant nester throughout much of North America, the red-winged blackbird nests in hayfields, marshes, and ditches. Large flocks feed in fields and bottomlands. Redwings winter in the southern United States. Fig. 2. The common grackle (Quiscalus quiscula) is an iridescent blackbird, larger than a robin, with a long, keel-shaped tail. E-26 winter. Grackles often roost with red- wings, but are more partial to roosting sites in upland deciduous or pine trees. Reproductive and survival rates are similar to redwings. Damage to Crops Damage is similar to that of redwings; however, grackles will feed on mature field corn in the dent stage, removing entire kernels from the cob. Also, grackles will pull up sprouting corn. Great-tailed Grackle (Quiscalus mexicanus) Identification This species is similar to the common grackle but with a much larger tail. The male is slightly smaller than a crow; the female is smaller and browner than the male. Fig. 3. The brown-headed cowbird (Molothrus Range and Habitat ater), smallest of the blackbirds, often feeds in close association with livestock. The female An abundant year-round resident in cowbird (lower) lays her eggs in the nests of coastal and southern Texas, the great- other birds. tailed grackle nests in colonies in shrubs or trees, sometimes in associa- tion with herons and egrets. The flocks Range and Habitat Yellow-headed Blackbird feed around farms, pastures, and Cowbirds occur in spring and summer (Xanthocephalus parks. throughout much of North America. xanthocephalus) Food Habits and General Biology Flocks feed in pastures and feedlots, and are often associated with live- Identification The diet is omnivorous: insects, stock. Cowbirds winter in the central aquatic organisms, eggs from nesting A robin-sized bird, the male has a to southern United States, often roost- birds, fruits, and grains. Reproductive striking appearance with his black ing with redwings, grackles, and star- and survival rates are similar to those body, conspicuous yellow head and lings. of redwings. breast, and a white wing patch in Food Habits and General Biology flight. The female is smaller and Damage to Crops browner, with a yellowish throat and The diet of cowbirds consists predomi- These birds damage all types of fruits breast. nantly of weed seeds and grains, and and melons, although the loss is gener- less than 25% insects. Cowbirds do not Range and Habitat ally minor. In recent years, however, build nests or incubate eggs; the their damage to citrus crops in local- Yellowheads are locally abundant female lays her eggs in nests of other ized areas