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Johannesburg, South Africa

Shaw J.M.,University of Cape Town | Jenkins A.R.,University of Cape Town | Smallie J.J.,Wildlife and Energy Programme | Ryan P.G.,University of Cape Town

The Overberg wheatbelt population of Blue Cranes Anthropoides paradiseus in the Western Cape of South Africa is approximately half the global population of this vulnerable species. Blue Cranes are highly susceptible to collisions with overhead power lines, and a spatial model was developed to identify high-risk lines in the Overberg for proactive mitigation. To ground-truth this model, we surveyed 199 km of power lines. Although Blue Cranes were the most commonly killed birds found (54% of all carcasses), the model was unable to predict lines with high collision risk for Blue Cranes. Further Geographic Information System (GIS) modelling was undertaken to test a wider range of landscape and power-line variables, but only the presence or absence of cultivated land could usefully identify lines posing a collision risk. Modelling was limited by a lack of detailed spatial habitat data and recent information on Crane numbers and distributions. We used recent carcass counts to estimate a Blue Crane collision rate, corrected for sample biases, of 0.31/km power line per year (95% CI 0.13-0.59/km/year), which means that approximately 12% (5-23%) of the total Blue Crane population within the Overberg study area is killed annually in power-line collisions. This represents a possibly unsustainable source of mortality. There is urgent need for further research into risk factors and for mitigation measures to be more widely implemented. © 2010 The Authors. Journal compilation © 2010 British Ornithologists' Union. Source

Smallie J.,Wildlife and Energy Programme | Virani M.Z.,Peregrine Fund

A rapid risk assessment of the interactions between Kenya's large birds and electrical infrastructure was conducted around Magadi and Naivasha in Kenya in January 2009. Six out of the seven <132 kV distribution pole designs assessed pose an electrocution risk to medium and large-sized birds. Several sites of high bird collision risk were identified. Several of the observed >132 kV transmission tower structures were vulnerable to electrical faulting caused by birds. Of approximately 24 relevant bird species that are of conservation concern in Kenya, 17 (71 %) face a high risk of direct interactions with electrical infrastructure. Priority species for attention include the Egyptian Vulture Neophron percnopterus, White-headed Vulture Trigonoceps occipitalis, Lappet-faced Vulture Torgos tracheliotos, Grey-crowned Crane Balearica regulorum, Lesser Flamingo Phoeniconaias minor, White-backed Vulture Gyps africanus, Rüppell's Vulture Gyps rueppellii, Martial Eagle Polemaetus bellicosus, White Stork Ciconia ciconia, Secretarybird Sagittarius serpentarius, and various sit-and-wait raptors. These preliminary findings have national relevance given plans (already underway) for a rapid expansion of electrical infrastructure in Kenya; recommendations are made for a national response to this matter. Source

Jenkins A.R.,University of Cape Town | Shaw J.M.,University of Cape Town | Smallie J.J.,Wildlife and Energy Programme | Gibbons B.,African Crane Conservation Programme | And 2 more authors.
Bird Conservation International

Ludwig"s Bustard Neotis ludwigii, endemic to Africa"s south-west arid zone, is susceptible to collisions with overhead power lines. Limited data from the south-eastern part of its range suggest that this factor may threaten its survival. We estimated transmission line collision rates for Ludwig"s Bustard across its South African range to assess the effect of this mortality on the population. Conservatively, collision rates averaged at least 0.63 ± 0.12 fatal collisions per km of transmission line per year, with relatively little regional variation. Despite being less abundant, the larger males were more collision-prone than females, which might account for the female-biased population. Extrapolating collision rates across the range of the species suggests that 4,000-11,900 birds are killed annually on high-voltage transmission lines. Actual mortality on overhead lines is probably much greater, given biases in carcass detection (crippling, scavenging and habitat biases), as well as the fact that our estimate excludes mortality on lower voltage distribution lines and telephone wires. Given an estimated global population of 56,000-81,000 birds in the late 1980s, the demographic invariant method suggests that such mortality is unsustainable. This result supports the recent upgrading of the conservation status of Ludwig"s Bustard from "Least Concern" to "Endangered", and highlights the need for further research on this problem. Copyright © 2011 BirdLife International. Source

Jenkins A.R.,University of Cape Town | De Goede K.H.,Birds of Prey Programme | Sebele L.,Avisense Consulting | Diamond M.,Wildlife and Energy Programme
Bird Conservation International

In the Karoo region of South Africa, eagles nesting on high voltage power pylons are responsible for frequent short-circuits or faults, which reduce the quality of commercial power supply and escalate costs to the country's energy supplier, Eskom. Between 2002 and 2006 we conducted annual helicopter surveys of eagle nests on 1,400 km of power line and located 139 large nest structures, making up 96 eagle territories occupied by three species: Martial Eagle Polemaetus bellicosus (66 pairs), Verreaux's Eagle Aquila verreauxii (13 pairs) and Tawny Eagle Aquila rapax (17 pairs), and detailed 357 pair-years of breeding activity, including 241 breeding attempts. Roost sites and active nests were associated with line faulting, and more so at particular pylon configurations. We developed a three-step management plan to reduce eagle-related faulting while still accommodating eagles on the power lines: (i) all (potentially) problematic nests were relocated from high-risk positions above the power conductors, to specially provided platforms placed below the conductors; (ii) perch deterrents were installed above the conductors on all nest pylons and on high-risk pylons up to 10 structures on both sides of each nest tower; and (iii) the welfare of the eagles was monitored before and after management. In this way, line faulting was reduced on actively managed lines by > 75%, with no obvious deleterious effects on the eagle population. The study revealed that: (i) power lines can support substantial breeding populations of threatened large raptors, (ii) these birds can be a source of commercially significant line faulting, and (iii) nest relocations and perch deterrents are effective in reducing faulting without negatively impacting eagle populations. Copyright © BirdLife International 2013 Â. Source

Shaw J.M.,University of Cape Town | Jenkins A.R.,University of Cape Town | Ryan P.G.,University of Cape Town | Smallie J.J.,Wildlife and Energy Programme

Avian mortality on power lines in South Africa is currently recorded on the Central Incident Register (CIR), which is a collation of incidentally reported cases. The true scale of the problem is unknown, so we report here on a survey of representative power lines in the Overberg region of the Western Cape. On the 199 km surveyed, 123 birds of at least 18 species were found. Collisions were more common than electrocutions, apparently killing 88% of the birds found on distribution lines. Large terrestrial birds were the most numerous victims, with large numbers of Blue Cranes Anthropoides paradiseus and Denham's Bustards Neotis denhami killed. In comparison with mortality rates from the CIR, we estimate that only 2.6% of power-line mortalities are reported, emphasising the importance of systematic surveys in quantifying mortality and directing mitigation. Our survey highlights the general hazard that power lines pose to avifauna, and the urgent need for further research into the population impacts of the high incidence of collisions. © NISC (Pty) Ltd. Source

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