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
closed completely, a common practice for bird control around
lines, site made too narrow, small, or otherwise less suitable
for normal passage or use. [example: pigeons (rock doves) at
stadium site] .
and potential applications:
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.
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.
lines interfere behaviorally with rapid escape when there is
varies by species and site.
from 6 to 12 inches (certain swallow applications around structures)
to 50 to 80 feet (some gulls and some waterfowl on reservoirs).
generally repel adult birds more strongly than juveniles.
spacing: 1 or 2 feet apart at feeding sites
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.
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.
not repelled: Pigeons, European starlings, other backyard
hoop device (Magic Halo):
device over backyard feeders repelled House sparrows (88-94%
in winter; 84% of males and 67% of females/juveniles in summer).
birds were not repelled
applications, behavioral exclusion:
device at backyard feeders
at feeding sites (spacing: 1 or 2 feet apart)
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
effective: Lines at house sparrow nesting sites do not prevent
Swallows and Cliff Swallows nesting on structures -
and preliminary trials in Nebraska and other states indicate
that lines spaced about 6 to 12 inches apart prevent nesting
use reported in and around buildings on porches, light fixtures,
eaves, and similar sites.
and waterfowl -
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.
D. A., R. J. Johnson, and K. M. Eskridge. 1991. Monofilament
lines repel house sparrows from feeding sites. Wildl. Soc.
W. F., and K. P. Burnham. 1993. Effectiveness of nylon lines
for deterring rock doves from landing on ledges. Wildl. Soc.
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.
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.
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.
D. H., D. A. Agüero, R. J. Johnson, and K. M. Eskridge.
1991. Monofilament lines fail to protect grapes form bird damage.
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