Blackbirds and Starlings in Large Roosts
Blackbirds and Starlings in Large Roosts
During the summer, fall and occasionally winter, large numbers of starlings, grackles, redwings and cowbirds may take up residence in large roosts near human dwellings. The noise, odor, filth and health hazard make the removal of these roosts desirable.
Repulsion-Frightening Devices
Large roosts of these birds can be dispersed by the intelligent use of frightening techniques. The uncoordinated, random use of frightening devices is not effective.
Follow these guidelines to use frightening devices effectively:
1. Apply the techniques as the birds arrive at the roost, but before they enter the roost. Frightening devices are not effective once the birds land in the roosting area.
2. Apply the frightening devices around the roost and not in the roost itself. Frightening devices are not effective in the roosting area proper.
3. Apply the frightening devices persistently. It normally requires 3 to 4 successive evenings before the roosting birds move.
The necessary frightening devices include automatic acetylene or propane exploders, double-shot shells, recorded alarm and distress calls broadcast over loudspeakers, and other pyrotechnique devices. Where possible, use regular shotgun ammunition as well.
When preparing for roost-moving, buy enough materials to last at least three to four nights. This usually means at least a tank of gas or 2 lb., of carbide for the automatic exploders, a case of double shotgun shells, a good supply of batteries to operate portable recording equipment and ample live ammunition.
A director should see that these devices are placed at appropriate points around the roost and that their operators are instructed in their proper and safe use. Equipment should be set up and operators prepared to perform at least a half hour before birds arrive. As the birds arrive, begin operating the equipment and continue until full dark. The decrease in birds in the roost the first night may not be perceptible, and observers and the press may report that the operation is a failure. Do not judge success or failure until the third or fourth night when the roost should be empty. Occasionally, roost-moving operations may require up to seven days.
Roost Alteration
An alternative to frightening devices is altering the roost to make it unacceptable to the birds. It is not necessary to destroy the vegetation completely. Experience shows that if 50% of the trees in the roost can be cut down, the roost then becomes unacceptable to the birds, and they leave.
One hazard always present in roost moving is the location of the new roosting site. It may be necessary to move the birds from several locations until the birds select a roosting site acceptable to the site owners. Occasionally a large roost may split into three or four smaller roosts, intensifying the problem.
Special assistance and instruction in roost moving is available from the U.S. Fish and Wildlife Service and the MSU Extension Service.
