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

Humans have erected vertical structures, such as power poles, fence lines, windmills, and oil rigs, throughout much of the sage-grouse’s historic range of the sage-grouse.

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. Previous research has shown that man-made vertical structures may lead to an increase in raptor and corvid visitation to an area by allowing access to habitats that do not naturally support vertical structures. Man-made vertical structures increase the availability of perching, nesting, and roosting sites. Biologists believe that this has resulted in an increase in foraging and predation efficiency.

Fragmentation Divides suitable habitat. Increases isolation of populations. Abandonment of sites. Powerlines may not only lead to increased predation but also increased fragmentation of habitats and populations. This fragmentation is deceptive because it subdivides suitable habitat in a way that could be imperceptible with only a broad view of the landscape. The habitat can be of the same quality on either side of the powerline, but the powerline acts as a barrier that the grouse might not cross. This can increase the isolation of populations and could result in sage-grouse abandoning sites.

Management Need Evaluation of effects of human infrastructure such as power lines on population. Sage-grouse evolved in a habitat free of vertical structures. But little is known about what effect the increase in man-made vertical structures has on sage-grouse populations. This has resulted in a need for evaluation.

Conservation Strategy Retrofitting structures with perch discouragers to deter raptors and corvids from perching. As a step towards addressing the issue of power poles on sage-grouse populations, Conservation Plans for Gunnison Sage-grouse have identified the strategy of 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. To address this conservation strategy the study we conducted tested the efficacy of five types of perch discouragers with the objective of determining which of the five perch deterrents may be more effective in preventing or reducing perching by raptors and corvids, or if none of them are effective.

Study Site Gunnison Sage-grouse Conservation Study Area, San Juan County, Utah. The discouragers were be placed on an existing utility line located within the Gunnison Sage-grouse Conservation Study Area in San Juan, County Utah.

Study Site The power line is located on the northern edge of the Study Area and runs near both winter and summer ranges of the grouse.

Discouragers One Fire Fly Two Fire Flies The five types of discouragers consist of two arrangements of a hazing deterrent and three physical discouragers. The hazing deterrent is the Fire Fly. This is a plastic piece covered with a reflective material that spins in the wind. The study uses two arrangements of the fire fly. The photo on the left shows the one fire fly arrangement with the device located on the insulator cover on top of the pole. The photo on the right shows the two fire fly arrangement with the devices located on the cross arm of the pole. One Fire Fly Two Fire Flies

Discouragers Cones Triangles (Kaddas) Cones and triangles are two of the physical deterrents. Cones (Kaddas) Triangles

Discouragers Spikes No treatment (Mini-zena) Spikes are the third physical deterrent placed on the poles. The untreated or control poles are not fitted with a discourager. Spikes (Mini-zena) No treatment

Study (2007-2008) 7.5 miles of power line with 84 poles. The study power line was 7.5 miles long and consisted of 84 poles. The line runs through CRP fields, agriculture, range, and sagebrush habitats.

Methods Divided into 14 blocks of 6 poles. Each block contained one of each discourager and a control. Treatments and control were randomly assigned. The power line was divided into 14 blocks, each block contained 6 poles. Each block contained one of each discourager and a control that 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. The surveys took place during the winters of 2007 and 2008. The surveys began in mid-January and finished the end of April. The line was surveyed twice a day, in the morning and late afternoon, five days a week. The entire line was walked once a week to look for evidence of depredation events and electrocutions. Any castings and pellets were collected to analyze for grouse remains. This also served as a way of finding signs of sage-grouse activity along the power line.

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. The starting points, either the east or west end of the power line, was randomly selected each time. Alternate routes were taken to the starting points to prevent the disruption of the birds. Five minutes was spent making observations at the starting point, and at each mile point. Observations were also made while driving.

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. The observations made during the surveys consisted of the species, number of individuals, feeding forays, mortalities, and perching location. Often the vehicle and a bird would leap frog down the power line. The bird was counted more than once if it continued down the line perching on different poles.

Methods Exact positions of birds on study poles. If a bird was perched on a study pole, the specific position on the pole was noted, whether it was perched on the cross arm, cross arm insulator, or top insulator cover. This is where the study got a little confusing. Each pole has a top insulator cover on it. This insulator cover provides a safe perching site on the pole. So we set out to test which perch discouragers were most effective at preventing perching, but the birds were also provided with a safe perching site.

Results No signs of electrocutions. One dead grouse on the road. Observations of grouse near road. The powerline was walked once a week and all raptor castings and pellets were collected. Analysis of the pellets indicated that lagomorphs were the dominate prey species. No electrocutions of raptors, corvids, or grouse were found. One dead grouse was found on the road, but it was not possible to figure out the cause of death. Both winters, my technician saw a group of grouse crossing the road, but only once each year. It was not a regular occurrence. There were no other signs of grouse (tracks or pellets) found. But we only searched directly under the line, so this can not be used to determine sage-grouse use of the area.

Results 2007 2008 Golden Eagle 278 Common Raven 39 Red-tailed Hawk 35 Rough-legged Hawk 15 Northern Harrier 8 Unknown 2 Ferruginous Hawk 1 Golden Eagle 230 Common Raven 23 Rough-legged Hawk 9 Ferruginous Hawk 3 Bald Eagle 2 Unknown 1

2007 Results

2007 Results GOLDEN EAGLE Total: 278 perching events. Cross Arm: 122 Insulator Cover: 156

2008 Results

2008 Results GOLDEN EAGLE Total: 231 perching events. Cross Arm: 112 Insulator Cover: 119

Results Here is the 1FF arrangement with Golden Eagles perched on each part of the pole.

Discussion- Problems We encountered a few problems along the way. The first was the issue of the top insulator cover providing a safe perching site. Another problem we encountered was with the Fire Flies. They had a tendency to break. By the end of the 2007 surveys, the majority of them were broken. The reflective tags broke, and sometimes the entire rod broke off. The broken Fire Flies were not replaced before the beginning of the 2008 surveys and so we were not able to start fresh.

Discussion- Problems Another problem occurred due to miscommunication as information was passed down the ranks to the line crew. Several of the poles for the 2007 survey had both cones and fire flies on them because the line crew didn’t take off the cones that were previously mounted on some of the poles. When they did finally take them down they still left a few poles with both treatments. Here are photos of cones with the broken one FF arrangement and cones with a broken 2FF arrangement.

Discussion Even though we encountered problems with the study design, it was quite easy to come to certain conclusions. So what conclusions can we draw from this study at this point. Well, with the current structure of power poles, perch discouragers are not effective in preventing or reducing perching by raptors and corvids. The requirement of a top insulator cover defeats the purpose.

Discussion The end insulators on the cross arms also provide a safe perching site.

Conclusions Perch discouragers were originally designed to prevent electrocutions by forcing birds to perch on safe parts of the pole where they would not be able to touch two phases at the same time. But as a device to stop perching events they are not effective when safe perch sites, such as insulators, are provided. In the future, if perch discouragers are to be used to prevent perching events, it will be necessary to modify pole structure or else create new perch discouragers that will also treat the insulators.

Acknowledgments Advisor: Dr. Terry Messmer Funding: PacifiCorp Avian Power Line Interaction Committee. Bureau of Land Management Field Technician Erin Colin.

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