No. 8 Article 3/May 13, 2005

Why So Much Bird Damage to Early-Planted Corn? How Can It Be Prevented During Replanting?

We have been able to identify several causes for this year's excessive bird damage on early-planted corn. Most of them have been encountered in previous research attempts to minimize this annual problem. What needs to be done during replanting to prevent reoccurrence may be the toughest question.

The two most common blackbirds causing corn plant stand reduction include the common grackle (Quiscalus quiscula) and the red-winged blackbird (Agelaius phoeniceus). Spring planting season is nesting season for blackbirds. Their peak energy and food requirement needs to raise their young coincide with corn crop emergence. They are constantly looking for readily available food.

Insects appear to be the food preference for female blackbirds during nesting because of their high protein content and the ease of feeding to young birds. However, male grackles and red-wings, while eating insects, appear to feed on seeds just as readily.

Nesting habits are also important to know. The common grackle primarily nests in the trees of windbreaks and shelterbelts, including pine tree plantings. The red-winged blackbird nests close to the ground in or near small-grain fields, hayfields, areas with common reed, marshes, and ditches. While nesting, both prefer food sources close to their nesting sites. Planting an attractive food source near a common nesting site always offers a potential for crop injury.

In general this spring, most of these events occurred across Illinois:

What can be done to help prevent the same stand reduction in the replanting? Our research experience has shown us the following:

Blackbirds, including grackles, are classified as migratory birds and are under the protection of the Migratory Bird Treaty Act, enforced by the U.S. Fish and Wildlife Service (USFWS). Because of the extent of agricultural damage these birds have historically caused, the USFWS has issued a blackbird depredation order, which allows for the control of these birds without a federal depredation permit when they are causing, or are about to cause, damage to agricultural resources. Despite a federal control permit not being needed, these birds are also under state protection. Therefore, a Nuisance Animal Removal Permit is needed from the Illinois Department of Natural Resources (IDNR). You should contact your District Wildlife Biologist or Conservation Police Officer from the IDNR to obtain this permit and a list of accep-table control options. For add-itional information, you may contact USDA's Wildlife Services office in Springfield at (217)241-6700.--Ron Hines

Close this window