Details:

Creators:
Coates, Robert W. ; Delwiche, Michael J. ; Gorenzel, W. Paul ; Salmon, Terrell P.
Coates, Robert W. ; Delwiche, Michael J. ; Gorenzel, W. Paul ; Salmon, Terrell P. Less -
Corporate Creators:
University of California, Davis. Dept. of Biological and Agricultural Engineering
Subject/TRT Terms:
[+]
Bird Pests Bridges California Control Maintenance And Repair Swallows
Publication/ Report Number:
CA05-0926
Resource Type:
Tech Report
Geographical Coverage:
California
Corporate Publisher:
California. Dept. of Transportation. Division of Research and Innovation
Abstract:
Cliff swallows (Petrochelidon pyrrhonota) are colonially breeding migratory birds that frequently nest on highway

structures. Protected by the Migratory Bird Treaty Act of 1918, nesting control methods cannot harm swallows or active

nests. This causes problems and delays for structures and maintenance divisions of many departments of transportation.

Two aversion strategies, bioacoustic deterrents and surface modifications, were evaluated for their effect on cliff swallow

nesting behavior. The bioacoustic deterrents (BC) consisted of sonic devices that broadcast 8 unique recordings of alarm

and distress calls. Surface modification consisted of plastic sheeting with a low coefficient of friction. In year 1, surface

modifications with high density polyethylene (HDPE) sheeting were mounted on the vertical surfaces at typical nesting

locations. Twenty-eight bridges in the Sacramento Valley of California were used to test the aversion strategies, using a 22

factorial design with 7 replicates. In year 2, silicone-based paint and polytetrafluoroethylene (PTFE, commonly called

Teflon) sheeting were evaluated as surface modifications. Nine bridges were divided into three treatment groups: control

(no treatment), silicone paint, and PTFE. In year 3, 15 bridges were divided into three treatment groups: control (no

treatment), PTFE, and PTFE+BC. Each year, completed nests were counted on a weekly basis for several months. In year 1,

both broadcast calls and HDPE treatments reduced the number of nests built at a site, but neither treatment nor the

combination completely stopped nesting. In year 2, swallows were able to complete nests on silicone paint, but did not

successfully complete any nests on PTFE. Silicone paint was determined to be an ineffective surface modification. In year

3, nests were completed at all control sites, and several PTFE and PTFE+BC sites. Nests built at sites with PTFE or

PTFE+BC were never started on the PTFE sheeting itself, but instead on the bare concrete and next to the sheeting or at a

location where sheeting had peeled away from the surface. Altogether, these tests indicated that only PTFE was wholly

effective in preventing cliff swallows from building on a treated surface, however nests were still completed at non-covered

locations on the bridge surface or at locations of failed sheeting attachment. Broadcast calls (BC) reduced the number of

completed nests by delaying the onset of building, but did not stop nest construction altogether.


Format:
PDF
Funding:
65A0220
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:787834529ec171bc82a14a0887a8d68c5d988e99b24a839966bc43612534aa4a
Download URL:
https://rosap.ntl.bts.gov/view/dot/27617/dot_27617_DS1.pdf
File Type:

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