Bird Strike Committee Proceedings
Accessibility Remediation
If you are unable to use this item in its current form due to accessibility barriers, you may request remediation through our remediation request form.
Date of this Version
10-24-2002
Document Type
Article
Abstract
Successful operation of the FAA’s Low-Level Windshear Alert System (LLWAS) depends largely on birds not perching on the wind-sensing units which are installed atop poles 40-45 m tall. Because new LLWAS units will be erected at airports throughout North America, anti- perching devices must deter numerous avian species ranging widely in body size and behavioral pattern. To determine the most promising devices, we conducted pen trials with brown-headed cowbirds, fish crows, barred owls, great horned-owls and black vultures. Birds were given free access to an unmodified sensor unit mounted on a tripod for 24 hours, during which the only alternative perch was a tree branch at ground level. This was followed by 24 h with a perching deterrent installed on the sensor unit. Trials were video-taped 10 hours daily and the sensors were connected to a computer so that failures in acquisition of wind data due to perching activity were continuously recorded. Smaller birds (cowbirds, crows) tended to perch on the 3 arms of the sensor units and were mostly deterred by “Bird Spinners”, metal bushings slipped onto the sensor arms that turned freely and prevented the birds from obtaining a stable perch. Owls and vultures were not affected by “Bird Spinners”, but “AgSpikes” (sharp, stout spikes emanating from a central base) reduced perching 95-98%. With the “AgSpikes” or “AgCone” (a smooth, solid aluminum cone) installed, owls and vultures attempted to perch but departed when they were not able to obtain a comfortable, stable grip. Commercial bird spikes and a monofilament web attached to the sensor arms were each ineffective regardless of species. It appears that a single perch deterrent device will not suffice for all birds, but a combination of “Bird Spinners” with “AgSpikes” or “AgCone” should be appropriate for most situations. Verification of these findings with field testing is needed.