Avian collisions with power lines: a global review of causes and mitigation with a South African perspective

Abstract

SummaryMany large terrestrial and wetland birds and some smaller, fast-flying species are prone to colliding with overhead wires associated with power infrastructure. A high proportion of these are threatened species and for some, collision with power lines and other man-made structures is a significant and damaging source of anthropogenic mortality. We review the existing literature on the nature, scale and impact of this problem worldwide, with particular emphasis on the South African situation, and focus on the evidence for and against various line configurations and devices proposed to mitigate the negative effects of overhead lines on bird populations. Cranes, bustards, flamingos, waterfowl, shorebirds, gamebirds and falcons are among the most frequently affected avian groups, and collision frequency is thought to be an influential factor in ongoing population declines in several species of cranes, bustards and diurnal raptors. The bulk of the research on this issue has been done in North America, Scandinavia, southern Europe and South Africa. Few comprehensive experimental studies on ways to reduce avian collisions with power lines have been carried out, although most of these have yielded quite clear results. Mitigation options considered include reviewing the placement of proposed new lines, removing the earth-wire which is usually the highest, thinnest and most problematic component in an overhead power line configuration, or else fitting this wire with markers -brightly coloured 'aviation' balls, thickened wire coils, luminescent, shiny or hinged flashing or flapping devices. All of these options reduce bird collision frequency overall by at least 50-60%, although the efficacy of line marking may be much lower for certain species (e.g. bustards). There remains considerable uncertainty about the best-performing marking device (perhaps because performance may vary with both local conditions and the species involved in each instance), and a durable, all-purpose device, that is effective both during the day and at night, has not yet been developed. We conclude by outlining a proposed experimental evaluation of the full array of collision mitigation options, to select the best approaches for use under South African conditions.

Electrocution and collision of birds with power lines in Saudi Arabia

“…The issue of collision and electrocution probably needs more investigation, as some could argue that the size, length of wing and position of the carcasses do not always indicate the actual cause of death. JENKINS et al (2010) suggested that the vulnerability of a species to collision with power lines is defined by a combination of the exposure to collision risk and the susceptibility of the species to collision. Studies from other areas suggested that large birds are more susceptible to collision along with the vegetation cover, density of predators, the size of the bird and the terrain of the area (CURRY & KERLINGER 2002, DIETER et al 2000, RUGGE et al 2003.…”

Avian mortalities due to transmission line collisions: a review of current estimates and field methods with an emphasis on applications to the Canadian electric network

“…Many species of birds are especially vulnerable to collisions with high voltage transmission lines because of the height of these structures with respect to flight altitude, and because of their low visibility, whereas many species are potentially less vulnerable to collisions with distribution lines-the network of lower voltage lines that carry electricity to customers from load centers (Morkill and Anderson 1991, Jenkins et al 2010, APLIC 2012. Specifically, the shield wires, typically the highest wire found on transmission lines, are usually smaller in diameter than conductor wires, which renders them less visible (Brown et al 1987, Faanes 1987.…”

Comportamento de voo de aves em resposta ao uso de sinalizadores em linhas de transmissão de energia elétrica

“…Segundo Jenkins et al (2010), o número de linhas de energia elétrica no mundo aumenta a uma taxa de 5% a cada ano. Essas linhas acabam por formar redes extensas que atravessam diferentes habitat, entre eles alguns de extrema relevância para a avifauna, como corredores ou rotas de voo regulares entre áreas de alimentação e dormitório, caracterizados por grande tráfego de aves (Scott et al, 1972;Crivelli et al, 1988).…”

“…Embora a preocupação com interações entre aves e LTs date desde o século passado (Michener, 1928), o número de publicações tem aumentado principalmente nas últimas quatro décadas, abrangendo diferentes países na Europa (Scott et al, 1972;Alonso et al,1994;Janss & Ferrer, 1998;Janss, 2000;Bevanger & Broseth, 2001;Rubolini et al, 2005;Barrientos et al, 2012;Martínez et al, 2016), África (Shaw et al, 2010;Jenkins et al, 2010;Krüger et al, 2015), América do Norte (Brown & Drewien, 1995;Savereno et al, 1996;Rioux et al, 2013;Sporer et al, 2013) e América do Sul (De La Zerda & Rosseli, 2003;Raposo, 2013). No Brasil, trabalhos sobre colisão de aves com estruturas de LTs ainda são escassos e limitados a estudos de licenciamento de impacto ambiental (Raposo, 2013).…”

“…Levando-se em consideração custo e garantia de um fornecimento de energia seguro e contínuo, a sinalização desses cabos tem sido indicada como a forma mais apropriada para a mitigação da mortalidade de aves (Alonso et al, 1994;Jenkins et al, 2010). Esses dispositivos de sinalização visam aumentar a visibilidade dos cabos pelas aves, proporcionando mais tempo para as mesmas evitarem a colisão (Alonso et al, 1994;Janss, 2000).…”