Raven problems in industrial areas
by Cat Urbigkit, Pinedale Online!
October 14, 2012
The Fall 2012 issue of Human–Wildlife Interactions, a peer-reviewed journal focused on human/wildlife conflicts published by the Jack Berryman Institute of the University of Utah, includes a paper by USDA Wildlife Services Supervisory Wildlife Biologist Rod Merrell of Rock Springs. Merrell’s paper outlined some successful methods to mitigate conflicts with ravens in industrial areas.
Common ravens are federally protected under the Migratory Bird Treaty Act, so when ravens cause problems, solutions generally involve federal wildlife officials. Industrial companies have unique challenges when it comes to ravens at their facilities (including coal and trona mines, gas facilities, and power plants) since shooting, harassment and destruction of nests are not allowed without a special permit from the U.S. Fish & Wildlife Service.
Nesting ravens can be very aggressive towards workers coming near their nests, which can be built on catwalks, stairwells, derricks and smoke stacks, but most raven complaints at industrial facilities involve roosting ravens. While a few ravens aren’t often much of an issue, Merrell is called to respond to cases involving 150-300 roosting birds and the health and safety issues caused by their fecal material deposited on equipment, handrails, stairs, and other surfaces that workers routinely contact.
Merrell’s five-page paper discusses methods he has personally used to mitigate raven conflicts, from the use of lasers, hazing, scarecrows, sirens, propane cannons, avicides, shooting, and effigies. The paper acknowledges that ravens are intelligent birds with remarkable eyesight, and an acute sense of smell.
Merrell reports, "Based on my experience, effigies are the most effective means to keep ravens from roosting on towers, tanks, cable trays, and other elevated structures." After experimenting with a variety of effigies (including fake ravens used as movie props, which were quickly "torn to pieces" by ravens), Merrell recommends the use of actual dead ravens, hung upside down where the wind will create some movement. His paper goes into specifics about the placement of effigies (and how they must be properly disposed of according to federal permit guidelines when no longer needed).
Merrell also acknowledges that breaking up a roost is a process, "often time- consuming, frustrating, and requiring follow-up," and no single technique will resolve the problem.
"One must reinforce danger with other tools and techniques or the ravens will habituate to the natural effigies with time," he wrote.
Click on the link below to access his paper, "Some successful methods to mitigate conflicts caused by common ravens in an industrial environment."