Meta-Analysis of the Effectiveness of Marked Wire in Reducing Avian Collisions with Power Lines

Abstract

Collisions of birds with power transmission and distribution lines have been documented for many species, and cause millions of casualties worldwide. Attempts to reduce mortality from such collisions include placing bird flight diverters (i.e., wire markers in the form of, e.g., spirals, swivels, plates, or spheres) on static and some electrified wires to increase their visibility. Although studies of the effectiveness of such devices have yielded contradictory results, the implementation of flight diverters is increasing rapidly. We reviewed the results of studies in which transmission or distribution wires were marked and conducted a meta-analysis to examine the effectiveness of flight diverters in reducing bird mortality. We included in our meta-analysis all studies in which researchers searched for carcasses of birds killed by a collision with wires. In those studies that also included data on flight frequency, we examined 8 covariates of effectiveness: source of data, study design, alternate design (if marked and unmarked spans were alternated in the same line), periodicity of searches for carcasses, width of the search transect, and number of species, lines, and stretches of wire searched. The presence of flight diverters was associated with a decrease in bird collisions. At unmarked lines, there were 0.21 deaths/1000 birds (n =339,830) that flew among lines or over lines. At marked lines, the mortality rate was 78% lower (n =1,060,746). Only the number of species studied had a significant influence on effect size; this was larger in studies that addressed more species. When comparing mortality at marked and unmarked lines, we recommend use of the same time intervals and habitats and standardizing the periodicity of carcass searches.

Bird Collisions in a Railway Crossing a Wetland of International Importance (Sado Estuary, Portugal)

“…To collect baseline information for mitigating impacts, bird collision risk has been the subject of intensive research over the past two decades (Loss et al 2015), with many studies documenting bird mortality and its correlates in relation to roads (Santos et al 2016), wind farms (Barrios and Rodríguez 2004;Drewitt and Langston 2006), power lines (Barrientos et al 2011(Barrientos et al , 2012, and buildings (Loss et al 2015). Surprisingly, however, very few studies have analyzed bird collision in relation to railways, although these linear infrastructures extend over tens of thousands of kilometers across the world (see Chap.…”

“…Although the population-level consequences of such mortality are poorly known (but see, e.g., Carrete et al 2009;Borda-de-Água et al 2014), it is generally recognized under the precautionary principle that efforts should be made to reduce the number of birds killed each year as much as possible (Loss et al 2015). Information is thus needed on the bird species most vulnerable to collisions, and on the environmental and species-specific factors affecting such vulnerability (Barrios and Rodríguez 2004;Santos et al 2016), which are essential for developing management guidelines aimed at reducing collision risk (Barrientos et al 2011;May et al 2015).…”

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

“…Além disso, na hora da escolha do sinalizador mais apropriado, tamanho, cor (para maior contraste dos fios contra o fundo), preço, durabilidade, forma e densidade de dispositivos devem ser avaliados (Janss & Ferrer, 1998;Barrientos et al, 2011;, assim como as questões sensoriais e comportamentais de diferentes grupos e espécies de aves alvo (Bevanger, 1998). Provavelmente, um sistema de mitigação com múltiplos modelos de sinalizadores pode ser mais eficiente do que outros baseados em um único modelo.…”

Methods to Monitor and Mitigate Wildlife Mortality in Railways

“…Thus, specific mitigation measures should be taken whenever high levels of mortality are expected or identified. These measures are similar to those used to prevent collision and electrocution in powerlines (Bevanger 1994;Barrientos et al 2011). Additionally, the tubular poles often used to support the overhead wires can cause death if uncapped, especially among cavity nesting birds (Malo et al 2016).…”