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Raptor and Corvid Use of Utility Poles: An Assessment of the Efficacy of Perch Deterrents Presented by: Phoebe R. Prather Advisor: Dr. Terry A. Messmer Jack H. Berryman Institute Utah State University Previous Research • Man-made vertical structures are believed to lead to increased: • • • • Raptor and corvid visitation. Access to habitats. Availability of perch, nesting, and roosting sites. Foraging and predation efficiency. Fragmentation • Divides suitable habitat. • Increases isolation of populations. • Abandonment of sites. Management Need • Evaluation of effects of human infrastructure such as power lines on population. Conservation Strategy • Retrofitting structures with perch discouragers to deter raptors and corvids from perching. Study Objective • Test the efficacy of five types of perch discouragers on reducing the number of perching events of raptors and corvids. Study Site • Gunnison Sagegrouse Conservation Study Area, San Juan County, Utah. Study Site Discouragers One Fire Fly Two Fire Flies Discouragers Cones (Kaddas) Triangles Discouragers Spikes (Mini-zena) No treatment Study (2007-2008) • 7.5 miles of power line with 84 poles. Methods • Divided into 14 blocks of 6 poles. – Each block contained one of each discourager and a control. – Treatments and control were randomly assigned. Methods - Surveys • Began mid-January, finish end of April. • Surveyed twice a day, five days a week. • Entire line walked once a week. – Evidence of depredation events and electrocutions. Methods - Survey Protocol • Starting point (east or west) randomly selected. • Alternate routes taken to starting point. • Five minutes spent at starting point and each mile point. Methods - Survey Protocol • Observations: – Species and numbers of individuals within a quarter mile of either side of the powerline. • Flying, on ground, perched on trees, fences or poles of a different line. – Species and numbers of individuals perched on the study poles. • Individual counted more than once if continued down the line perching on different poles. Methods – Exact positions of birds on study poles. Results • No signs of electrocutions. • One dead grouse on the road. • Observations of grouse near road. Results 2007 Golden Eagle 2008 278 Golden Eagle Common Raven 39 Common Raven Red-tailed Hawk 35 Rough-legged Hawk Rough-legged Hawk 15 Ferruginous Hawk Northern Harrier 8 Bald Eagle Unknown 2 Unknown Ferruginous Hawk 1 230 23 9 3 2 1 2007 Results Golden Eagles 70 Perching Events 60 50 40 30 20 10 0 1FF control triangles cones Treatment spikes 2FF GOLDEN EAGLE 2007 Results Perching Events Cross Arm 45 40 35 30 25 20 15 10 5 0 •Total: •278 perching events. control spikes cones triangles 1FF 2FF 1FF 2FF Treatments Perching Events Insulator Cover 45 40 35 30 25 20 15 10 5 0 control spikes cones triangles Treatments •Cross Arm: 122 •Insulator Cover: 156 2008 Results Golden Eagles 90 80 Perching Events 70 60 50 40 30 20 10 0 1FF 2FF control cones Treatment spikes triangles GOLDEN EAGLE 2008 Results Perching Events Cross Arm 70 60 50 40 30 20 10 0 Total: 231 perching events. control spikes cones triangles 1FF 2FF 1FF 2FF Treatment Perching Events Insulator Cover 70 60 50 40 30 20 10 0 control spikes cones triangles Treatments Cross Arm: 112 Insulator Cover: 119 Results Discussion- Problems Discussion- Problems Discussion Discussion Conclusions Acknowledgments • Advisor: Dr. Terry Messmer • Funding: – PacifiCorp – Avian Power Line Interaction Committee. – Bureau of Land Management • Field Technician Erin Colin. Questions?