Bird Electrocutions in

Richard E. Harness Certified Wildlife Biologist

EDM International, Inc. 4001 Automation Way

Fort Collins, CO 80525, USA rharness@edmlink.com

Abstract - In December 2011 we visited distribution pole lines in the Thar Desert in western India to access their risks to raptors. We inspected 624 concrete poles and detected 160 bird carcasses at pole bases. Although power lines can provide positive benefits for birds, the trend to use concrete poles with metal crossarms outweighs positive benefits. If concrete poles are to be used in raptor habitat, alternative construction methods should be substituted, such as the use of suspended insulators.

Index Terms—Common kestrel, concrete pole, raptor, electrocution, India, power line, rural electrification, steel crossarm, white-eyed buzzard.

I. INTRODUCTION

Despite a wealth of information on avian interactions with power lines, problems persist throughout the world [1]. This study was initiated to determine if 11 kV distribution power lines in rural India are contributing to avian electrocutions and, if so, at what level. A secondary goal was to identify if any power line configurations are more problematic than others.

II. METHODS

A. Study Area Power pole inspections concentrated on 11 kV distribution

lines located in the western state of Rajasthan, India. India's government set an ambitious goal to provide electric power to all households by 2012 [2]. Although this goal has not been obtained, there is a concerted effort to provide power to all rural areas, and in the study area the India Planning Commission reports 98% of all villages in Rajasthan were electrified as of 2004 [2].

The survey areas included power lines near Tal Chappar and Bikaner, areas supporting an estimated 250 bird species [3]. Rajasthan contains sites recognized by the Bombay Natural History Society, Mumbai, as International Birdlife Areas and identified as high priority areas for avifaunal conservation [4]. Survey areas were selected due to their proximity to Jorbeer, a dumping site for cattle carcasses, which attracts numerous wintering raptors including four eagle species and six vulture species [5].

The study area is located within the Thar Desert, which has an average annual rainfall of 100-400 mm and temperatures range from a minimum of -2°C in winter to a maximum of

Western Rajasthan, India

Dr. Pranay Rao Juvvadi General Secretary

Raptor Conservation Foundation Hyderbad-500 016

1-10-63/4, Chikoti Gardens, Begumpet, Andra Pradesh, India

raptorconserve@yahoo. com

51°C in summer [6]). The vegetation is mainly composed of dry open grassland or grassland interspersed with trees and thorny drought resistant bushes growing in sandy soils [7].

B. The Mechanics of an Electrocution Animals are not hurt or injured by voltage alone as

evidenced by birds perching on an energized wire without incident. Injury (shock) or death (electrocution) occurs when an animal becomes a pathway for current to flow from a higher potential (or voltage) to a lower potential (often a ground). In the case of a distribution power line, high potentials exist on the three-phase conductors, and low potential exists on any conducting part of the structure connected to an earth ground. The other case of potential differences occurs between different phase conductors, where one phase of voltage can "appear" as a lower potential to another phase of voltage. In summary, anywhere a bird can create a path between high voltage and ground (or another phase of high voltage) shock or electrocution can occur [8].

C. Power Line Materials In this study area all poles are constructed with concrete

with an internal support of grounded metal. The poles in this study area also deploy metal crossarms. This is significant because the materials used to support power lines have varying insulating properties. For example, wood poles are better insulators than concrete poles [9] and in a study of 10 kV power poles in the Mongolian steppe, bird carcass detections were compared between power lines constructed with wooded poles to those constructed with concrete poles and steel crossarms (comparable to the poles in this study area). In similar Mongolian habitat, bird carcass detection was significantly higher under concrete poles with grounded metal crossarms than at wood poles [10]. Non-wood poles are commonly used in distribution line construction in Europe and other parts of the world, and Janss and Ferrer [11] report differences in electrocution for different materials, requiring different mitigating methods.

D. Survey Routes and Habitat Assessment December 2011 two biologists drove rural roads south of

Bikaner, India, searching for 1 lkV distribution power lines to inspect. Sites were chosen in open country restricted to power line corridors with public access, thus generally parallel to roads. Using convenience sampling, 10 rural line sections of

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energized power lines (493 total poles) were identified. Three un-energized sections (131 total poles) were identified as controls.

Over 6 days two biologists walked each identified pole section. Whenever possible, surveyors walked parallel to each other, directly under the primary wires to detect possible bird collisions. Access to the power lines was good and vegetation was typically less than 10 centimeters tall, allowing easy detection of any bird carcasses.

At each pole surveyors looked for bird carcasses out to a radius of 7.6 m around each pole base [12] and collected a GPS waypoint. Using standardized data sheets, at each pole the following utility data were recorded: • Power pole configuration (specific physical arrangement

of the primary wires) • Height of the center pin insulator (high, low, or none) • Equipment type and number:

o Transformer o Switch o Jumper

At each pole surveyors visually determined the dominant habitat type. The habitat category was based on the dominant habitat and included shrub, grass, and row crop. Crop data did not differentiate between type or crop stage.

Surveyors also noted any land use features located within a 50 meter radius of each pole. This included the presence of any natural feature, such as ponds, and manmade features such as rural residential buildings, rural industrial parks, dirt roads, and paved secondary roads.

Lastly, signs of bird usage including presence of whitewash, nesting materials and/or prey remains were noted. All carcasses were photographed and categorized when possible to species, sex and age. Any superficial burn marks on the bird carcasses were noted but necropsies were not performed, which we address in the Discussion section.

III. RESULTS

Every energized power pole encountered was concrete with an internal system of grounded metal supports. Each pole also supported three energized 11 kV primary wires with different framing arrangements. The most common energized configuration was a three-phase tangent pole without any equipment (83%, n=407) (Fig. 1). These poles consisted of three energized wires, each sitting on a pin insulator. The typical tangent pole had a metal crossarm supporting two of the conductors on outside pins (Fig. 1). The third wire was typically mounted on the pole top.

Fig. 1. Typical 11 kV tangent concrete pole with grounded metal crossarm

Upon closer examination it was noted there was variation on the height of the center pin on the 407 tangent units. The typical configuration (n=267) consisted of a mounting plate spaced close to the pole top, providing approximately 15 cm of separation from the top of the grounded mounting plate to the energized conductor (Fig. 2a). The remaining units (n=140) had a metal extension bracket providing approximately 46 cm of separation from the top of the grounded mounting plate to the energized conductor (Fig. 2b).

Fig. 2. a) Typical 11 kV tangent with low mounted pin, and b) typical 11 kV tangent with high mounted pin

The next pole classification consisted of poles with exposed primary jumpers, but without any equipment (n=65). These jumper configurations were used to turn angles (Fig. 3) and to support lateral taps (Fig. 4). The number of exposed energized jumpers was recorded at each pole.

Fig. 3. Typical 11 kV double deadend pole with grounded metal crossarms and 3 exposed jumpers

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j m \ Fig. 4. Typical 11 kV double deadend three-phase lateral tap pole with

grounded metal crossarms and 6 exposed jumpers

The final pole classification consisted of equipment poles with exposed primary jumpers (n=21). Transformer banks were served by 19 of these poles (Fig. 5). The remaining 2 equipment poles consisted of switch poles (Fig. 6). The number of exposed energized jumpers was recorded at every pole type.

Fig. 5. Typical 11 kV three-phase transformer bank with grounded metal crossarms and 9 exposed jumpers

Fig. 6. Typical 11 kV three- phase switch with grounded metal crossarms and 9 exposed jumpers

In total, 159 bird carcasses were detected under 493 energized poles (Table 1). Thirty poles (6%) had multiple carcasses, ranging from 2 to 5 birds. One pole had 10 carcasses. Both large and small birds were detected, ranging from Indian rollers (Coradas benghalensis) (Fig. 7) to tawny eagles (Aquila rapax). This equates to an overall carcass detection value of .32 birds/pole (1 carcass for every 3.1 poles). In contrast, only one house crow (Corvus splendens) was detected under 131 de-energized poles (Table 1).

TABLE 1. BIRD CARCSSES DETECTED UNDER 4 9 3 ENERGIZED AND 131

DE-ENERGIZED POWER LINES

Unit No. Bird Carcasses Rate Tangent: Low Pin 267 89 0.33 Tangent: High Pin 140 04 0.03 Deadend: No Equipment 65 44 0.68 Transformer Pole 19 19 1.00 Switch Pole 2 3 1.50 De-energized Pole 131 1 0.01

624 160

Fig. 7. Indian roller perched on an energized jumper with approximately 15 cm of ground clearance

Pole configurations were compared to determine how carcass detection numbers varied. As previously noted, the most common configuration on the landscape consisted of three-phase tangent units without any equipment (Fig. 1). This configuration comprised 83% of all energized poles (n=407) and was associated with 93 bird carcasses (58%). This configuration had 267 poles with the center pin mounted low (Fig. 2a), which was associated with 96% of the birds found under all tangents (n=89, 0.33 carcasses/pole). The remaining tangents (n=140) had the center pin mounted high (Fig. 2b) and were associated with only four detected carcasses (.03 carcasses/pole).

Configurations with jumpers (both with and without equipment) comprised the remaining 17% of energized poles (n=86) and were associated with 66 bird carcasses (42%). Collectively, jumper configurations were associated with the highest detection value of 0.77 carcasses per pole, versus 0.22 carcasses per pole for tangents.

Further investigation compared jumper configurations with and without equipment (transformers and switches). Angle/tap jumper poles without equipment (n=65) were associated with

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44 carcasses while equipment jumper poles (transformers and switches) (n=21) were associated with 22 carcasses. Three un-energized line sections (the study control) were also inspected (n=131 poles) yielding one carcass, a house crow (Corvus splendens).

IV. DISCUSSION

The number of suspected electrocutions in this study is high compared to other published work (1 carcass for every 3.1 poles). However, to accurately determine the rate of birds being electrocuted, one needs to regularly patrol the lines and necropsy every bird, plus adjust numbers to account for biases due to scavenging, crippling, and carcass detection.

In this survey, none of these were done except to note when burn marks were present. It is certain some carcasses were scavenged as we noted hundreds of feral domesticated dogs (Canus familiarus) in the Jorbeer area along with hundreds of vultures and other opportunistic feeding birds. Other animals noted likely to scavenge were the Indian fox (Vulpes bengalensis), caracal (Caracal caracal) and Indian wild boar (Sus Ser of a). The lack of accounting for such scavenging would underestimate the number of detected carcasses.

Crippling bias could be estimated from other studies, but again, ignoring this results in a conservative scope as opposed to overinflating the issue. Due to the low ground cover, the observer detection bias would be expected to be very low and for the same reasons as above, tends to push the results towards being more conservative.

The biggest concern is the uncertainty these birds were all electrocuted. Burn marks were detected on the heads and backs of three common kestrels {Falco tinnunculus) and two Indian rollers (Coradas benghalensis), so one can be confident such small birds can be electrocuted (Fig. 8). An electrocuted Eurasian eagle owl (Bubo bubo), Indian peafowl (Pavo cristatus), and house crow (Corvus splendens) were also noted hanging from energized poles.

j M B S W E — i i S T a B K S B I

Fig. 8. Indian roller with electrocution burn marks

To help address this problem we surveyed 131 de-energized poles in similar habitat. This was done to establish

a benchmark against the energized lines. We hypothesized that if birds are dying due to causes other than electrocution (i.e. disease, starvation, prédation, shooting, etc.), values between energized and de-energized lines should be similar. However, we detected only one carcass under 131 de-energized poles, whereas, we would have expected 42 carcasses using the recorded value of .32 detected carcasses per energized pole. Additionally, if birds found under energized lines were not being electrocuted, one might expect the distribution of carcasses to be randomized in relation to pole configuration. This is not the case as certain configurations have significantly elevated detection rates. For example, tangent units with their center pin mounted high have 10 times fewer detected carcasses than similar units with their center pins mounted low. Likewise, transformer poles have significantly elevated detection rates (1.00 carcass per pole) over all other configurations.

Lastly, because the surveys were restricted to public access along public roads, many line sections across undisturbed habitat were not inspected. This likely resulted in more urban tolerant species, such as the house crow, being detected than other species less tolerant to human disturbance.

V. CONSERVATION IMPLICATIONS AND SOLUTIONS

Power lines can play a positive role for raptors by providing areas to hunt from and to nest upon [8]. However, as demonstrated in this paper, the trend to use concrete poles with metal crossarms outweighs positive benefits. Every pole inspected has the potential to kill both small and large birds and the detected carcass value for this study was high (.32 birds/pole).

Correcting the power lines in this region is important as electrocutions can be a restrictive factor for some raptor populations [13]. Vulture numbers have been declining in India and three of the six vulture species in our study area near Jorbeer are of conservations concern with the Egyptian vulture (Neophron percnopterus) listed as endangered, the red-headed vulture (Sarcogyps calvus) listed as critical, and the cinereous vulture (Aegypius monachus) listed as near threatened [14].

Although no vulture electrocutions were detected, vulture electrocutions are a persistent problem globally [15] and, furthermore, one of the control lines near the carcass dump is presently de-energized but numerous Egyptian vultures were seen along this line section which will be energized in the future.

There are two ways to approach remedying these poles, using insulation or isolation. The preferred method is to install insulator covers (Fig. 9). Although these units are relatively expensive, they will allow birds to continue using the structures. Each structure would require three conductor covers (the center phase could utilize a perch discourager as an alternative). Furthermore, all jumpers should be insulated and all transformer bushings covered. Switches also should be insulated or isolated.

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Insulator Cover Side Profile 3 - Required

Fig. 9. Retrofitting using insulator covers-preferred method

If concrete poles are to be used in future new construction, alternative construction methods must be substituted and framing should be changed to prevent electrocutions [16]. In Russia, new steel pole lines are being constructed using suspension insulators (Fig. 10). According to Transmission and Distribution World [17], this configuration is reliable and allows for increased span lengths. This configuration will accommodate both small and large birds and will safely allow nesting.

j SteeL Crossarm

- Concrete

Fig. 10. Alternative 11 kV raptor-safe framing

VI. REFERENCES [1] R. N. Lehman, "Raptor electrocution on power lines: current issues and

outlook," Wildlife Society Bulletin 29:804-813, 2001. [2] V. Modi, "Improving electricity services in rural India: An initial

assessment of recent initiatives and some recommendations," CGSD Working Paper No. 30 December 2005. Working Papers Series. Center on Globalization and Sustainable Development, The Earth Institute at Columbia University, www.earth.columbia.edu.

[3] A. R. Rahmani, Wildlife in the Thar, World Wide Fund for Nature, New Delhi, India, 1997, 100 p.

[4] M. Z. Islam and A. R. Rahmani, Important bird areas: priority sites for conservation, Indian Bird Conservation Network, Bombay Natural History Society and Birdlife International, UK, XVIII, 1133 p. 2004.

[5] P. Sharma and K. S. G. Sundar, "Counts of Steppe Eagles Aquila nipalensis at a carcass dump in Jorbeer, Rajasthan, India," Forktail 25:160-163,2009.

[6] K. K. Sharma and S. P. Mehra, "The Thar of Rajasthan (India): Ecology and conservation of a desert ecosystem", in C. Sivaperuman, Q. H. Baqri, G. Ramaswamy and M. Naseema [eds], Faunal ecology and conservation of the Great Indian Desert, Springer-Verlag Berlin Heidelberg, 2009.

[7] R. K. Gupta, "Plant life in the Thar", in R.K. Gupta and I. Prakash (eds) Environmental analysis of the Thar Desert, English Book Depot, DehraDun. 1975.

[8] Avian Power Line Interaction Committee (APLIC), Suggested Practices for Avian Protection on Power Lines: The State of the Art in 2006, Edison Electric Institute, APLIC, and the California Energy Commission, Washington, D.C. and Sacramento, CA., 2006.

[9] R. Harness, "Raptor electrocutions and distribution pole types," North American Wood Pole Coalition: 1-19, 2000. [Online] Available: http ://products .construction. com/s wtscontentfiles/1475/593092.pdf

[10] R. Harness, S. Gombobaatar, and R. Yosef, "Mongolian distribution power lines and raptor electrocution," in 2008 Proc. of the Rural Electric Power Conference, Institute of Electrical and Electronics Engineers, New York, N.Y. IEEE 52: 1-6, 2008. [Online] Available: http://ieeexplore.ieee.org/xpl/topAccessedArticles.jsp ?reload=true&pu number=4511478

[11] G. F. E. Janss and M. Ferrer, "Mitigation of raptor electrocution on steel power poles," Wildlife Society Bulletin 27: 263-273, 1999.

[12] R. E. Harness, "Effectively Retrofitting Power Lines to Reduce Raptor Mortality," Avian Interactions with Utility Structures, in Proceedings of a workshop held in Charleston, South Carolina, December 2-3, 1999, Technical Report, 29-45.

[13] M. Ferrer, M. De La Riva, and J. Castroviejo, "Electrocution of raptors on power lines in southwestern Spain," Journal of Field Ornithology 62(2): 181-190, 1991.

[14] M. L. Thakur and S. K. Narang, "Population status and habitat-use pattern of Indian white-backed vulture (Gyps bengalensis) in Himachal Pradesh, India," Journal of Ecology and the Natural Environment Vol. 4(7), pp. 173-180,2012.

[15] M. D. Anderson, Karoo large terrestrial bird powerline project, Report No. 1. Unpublished report to Eskom, 2002.

[16] R. Harness, "Steel distribution poles - Environmental implications," pp. D1 1-5 in 1998 Rural Electric Power Conference, St. Louis, Missouri, April 26-28, Institute of Electricity and Electronic Engineers, Inc., New York, 1998.

[17] Y. Hunger, A. Zevin, G. Shwarz, and S. Golubev, "Russia rethinks distribution-Changes in design materials and applications result in a more reliable network," Transmission & Distribution World, September 2006.

The proposed measures in the conclusions will not only protect birds but will provide a more reliable electric system by reducing the number of annual electric outages caused by bird and nesting material contacts. These modifications will simplify utility maintenance activities while contributing to bird conservation.

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