Bird Exclusion: Lines, Wires, and Hoop Devices
by Ron Johnson, Extension Wildlife Specialist, University of Nebraska Cooperative Extension.
Reprinted with permission by Soni Cochran, Extension Associate

Physical Exclusion:

*Access closed completely, a common practice for bird control around structures.

*With lines, site made too narrow, small, or otherwise less suitable for normal passage or use. [example: pigeons (rock doves) at stadium site] .

Examples and potential applications:  

*Pigeons on stadium ledges: White 75-kg lines deterred pigeons from using stadium ledges; 1 to 3 lines were placed 8 cm (3 inches) in front of ledges and at 1 or more of 3 heights above ledges: 5, 12, and 18 cm (2, 4.7, 7 inches). Using more lines (3 lines) generally was most effective. Results indicate moderate to good short-term success; long-term observations were not made.  

*Birds on perch sites: Place a thin line or wire over perch to physically prevent perching: low enough that bird cannot stand under it but high enough that bird cannot straddle it. Observations indicate that this deters perching but not research tested.

Behavioral Exclusion:

*Widely-spaced lines interfere behaviorally with rapid escape when there is predation risk.

*Response varies by species and site.

*Spacings from 6 to 12 inches (certain swallow applications around structures) to 50 to 80 feet (some gulls and some waterfowl on reservoirs).

*Lines generally repel adult birds more strongly than juveniles.

Example, lines:  

Line spacing: 1 or 2 feet apart at feeding sites

Birds repelled: House Sparrows, Blue Jays - Lines 2 feet apart repelled an average of 98% of all house sparrows and 87% of blue jays in winter. In summer, these lines repelled 89% of house sparrows and 68% of blue jays.

Birds moderately repelled (generally preferred feeders without lines but high numbers used feeders with lines): Common Grackles and Northern cardinals - cardinals shifted to feeders with lines when large grackle flocks were present.

Birds not repelled: Pigeons, European starlings, other backyard birds

Example, hoop device (Magic Halo):  

Hoop device over backyard feeders repelled House sparrows (88-94% in winter; 84% of males and 67% of females/juveniles in summer).

Other birds were not repelled

Potential applications, behavioral exclusion:  

House sparrows -  

Hoop device at backyard feeders

Lines at feeding sites (spacing: 1 or 2 feet apart)

Potential: Lines at outdoor roosting sites (trees) may repel house sparrows but this has not been tested. In mixed-species roosts, other species (e.g., starlings, blackbirds) would probably not be repelled.

Not effective: Lines at house sparrow nesting sites do not prevent nesting.

Barn Swallows and Cliff Swallows nesting on structures -  

Observations and preliminary trials in Nebraska and other states indicate that lines spaced about 6 to 12 inches apart prevent nesting on structures.

Successful use reported in and around buildings on porches, light fixtures, eaves, and similar sites.

Gulls and waterfowl -  

Lines have been used to effectively repel certain gulls from public places such as outdoor food areas and to repel certain gulls and waterfowl from ponds or water reservoirs.

For more information:  

Agüero, D. A., R. J. Johnson, and K. M. Eskridge. 1991. Monofilament lines repel house sparrows from feeding sites. Wildl. Soc. Bull. 19:416-422.  

Andelt, W. F., and K. P. Burnham. 1993. Effectiveness of nylon lines for deterring rock doves from landing on ledges. Wildl. Soc. Bull. 21:451-456.  

Kessler, K. K., R. J. Johnson, and K. M. Eskridge. 1994. Monofilament lines and a hoop device for bird management at backyard feeders. Wildl. Soc. Bull. 22:461-470.  

Pochop, P. A., R. J. Johnson, and K. M. Eskridge. 1993. House Sparrow response to monofilament lines at nest boxes and adjacent feeding sites. Wilson Bull. 105:504-513.  

Pochop, P. A., R. J. Johnson, D. A. Agüero, and K. M. Eskridge. 1990. The status of lines in bird damage control - a review. Proc. Vertebr. Pest Conf. 14:317-324.  

Steinegger, D. H., D. A. Agüero, R. J. Johnson, and K. M. Eskridge. 1991. Monofilament lines fail to protect grapes form bird damage. HortScience 26:924.

*reprinted with permission from Ron J. Johnson, University of Nebraska - Lincoln, by Soni Cochran, Extension Associate, University of Nebraska Cooperative Extension in Lancaster County (1997)

( June 5, 2002 )