View Pictures of Bird Damage
Click the image for a larger picture	Class Aves Order Passeriformes Family Icteridae Euphagus cyanocephalus

History and Biology:

Brewer's Blackbirds, Grackles, and their allies (including cowbirds) are grouped together as one of the five groups of Icterids. They are native to North America and come from a group of songbirds called the nine-primaried oscines. They are thought to be of relatively recent origin and found mainly in the Americas.

Brewer's Blackbirds are medium sized, approximately 7.5 to 9.5 inches in overall length. The males are black with yellowish eyes and a purple gloss on the head. Females are grayish brown, darker dorsally, and have a darker eye. The overall length of Brewer's Blackbirds is shorter than that of the Grackle and they have a proportionately shorter tail.

Brewer's Blackbirds are predominantly a western bird, but they extend eastward into Illinois, northward into Canada, and southward into Mexico. They favor wide-open areas (such as farmlands and marshes) and lakeshores. They have adapted to a commensal relationship with humans and are expanding throughout North America and into Canada associating with human activity. Its range overlaps with that of the Common Grackle, the blackbird takes over open grassy areas, while the Grackle dominates in the urban and suburban areas.

Brewer's Blackbirds forage mainly on the ground, often in large flocks with other blackbirds, for insects (beetles, grubs, grasshoppers, caterpillars, and others), millipedes, spiders, earthworms, crayfish, minnows, and frogs. They may wade to feed in aquatic habitat. They also eat fruits, nuts, and seeds when not breeding. They are primarily insectivorous when breeding; they feed singly, in pairs and in large flocks in both breeding and non-breeding seasons.

Brewer's Blackbirds build sturdy cup nests of twigs, grass, matrix of mud or cow dung, lined with soft vegetative material. Nest placement is variable. They remain social throughout the year. Blackbirds are highly variable in mating from monogamous pairs to polygamous. Most nest in colonies of 3 to 100 pairs in trees. Brewer's Blackbirds raise 1 to 2 broods per year of 3 to 7 eggs per clutch. Raising young is variable, one or both adults feed the young insects.

Brewer's Blackbirds may be controlled without a federal or state depredation permit when found committing or about to commit depredation on ornamental or shade trees, agricultural crops, livestock, or wildlife, or when concentrated in numbers and in a manner that constitutes a health hazard or other nuisance.

Public Health Damage:

Brewer's Blackbirds and their droppings create a serious and constant health problem. They may be a reservoir for the transmission of diseases to humans (zoonotic diseases) such as ornithosis, salmonellosis, and several forms of encephalitis, histoplasmosis, cryptococcosis, toxoplasmosis, and coccidiosis. Blackbirds are also a concern to farmers because they may carry and transmit many diseases, such as hog cholera, for livestock. In additional to the numerous infectious zoonotic diseases, Blackbirds also harbor and transmit a number of ectoparasites associated with the bird and its nests such as lice, mites, fleas, ticks, and bugs.

Structural Damage:

Brewer's Blackbirds roost in large flocks thereby defacing equipment, statues and buildings with excretory droppings and messy nest building. They also cause structural damage to agricultural barns and silos. They foul areas where people may walk and/or work

Agricultural Damage:

Blackbirds threaten the health of livestock in United States agriculture because they may be a reservoir for the potential transmission of many livestock diseases such as salmonella and hog cholera, especially around concentrated poultry and swine production facilities. They also do damage through the consumption and contamination of agricultural seed and grain products in the field, storage facilities, and wholesale and retail outlets.

Environmental Damage:

Because of their commensal relationship with humans and their potential for producing large flocks, blackbirds are a serious and constant public health and property damage problem.

Economic Damage:

Economic damage from Brewer's Blackbirds is difficult to assess when you consider the intangible costs of the impact of zoonotic diseases on the public health of humans, livestock, and wildlife. Additionally, it is also difficult to determine the real cost of equipment and structural damages from defacement. Also there is a significant cost to American consumers and business from the consumption and contamination of seed and grain damaged by blackbirds.

References:

Coded Federal Registry, 50CFR17.Subpart D, Endangered and Threatened Wildlife and Plants

Coded Federal Registry, 50CFR 20.43, Wildlife and Fisheries, Hunting and Migratory Bird Regulations

Coded Federal Registry, 50 CFR 21.43 Subpart D, Control of Depredating Birds

Fergus, C., 2000, Wildlife of Pennsylvania and the Northeast, Stackpole Books, Mechanicsburg, PA 17055

Oklahoma Wildlife Conservation Commission, 2004-2005, Oklahoma Hunting Guide, Protected Species. Page 9. Oklahoma Department of Wildlife Conservation, P.O. Box 53465, Oklahoma City, OK 73152.

Perrins, C. and Harrison, C.J.O. 1979. Birds: Their life, Their Ways, Their World. Reader's Digest Edition, The Reader's Digest Association, Inc. Pleasantville, N.Y.

Sibley, D.A., 2001, The Sibley Guide to Bird Life and Behavior, National Audubon Society, Alfred A Knopf, N.Y.

Texas Parks and Wildlife Department, 2004, Hunting and Fishing Regulations, Endangered, Threatened, and Other Protected Nongame Species, Protected and Unprotected Birds, Texas Parks and wildlife, 4200 Smith School Road, Austin, Texas 78744.

Wernert, S. J., 1982. North American Wildlife, The Reader's Digest Association, Inc. Pleasantville, N.Y.