Electrical transmission line development has been expanding globally by 5% per year, leading to increases in avian collisions with lines. Canadian estimates of transmission line collision mortalities range from 2.5 to 25.6 million birds per year, with the majority of mortalities attributed to collisions with overhead shield wires, and by susceptible birds that are young, large-bodied, with low maneuverability, or in open habitats. In this study, avian mortality was estimated for a ~4900 ha area in the mixed-grass prairie of southeastern Alberta following construction of two major transmission lines. We surveyed seven 500 m transects 7–10 times during both the breeding and migration seasons, where transects were categorized into road (n = 2), transmission line (n = 2), wetland (with transmission lines above; n = 1), or control (n = 2) areas. During the 2016 breeding season (5 May–24 June), we detected 23 mortalities under transmission lines, 7 mortalities beside roads, and no mortalities in controls. In the 2017 spring migration season (31 March–5 May), we detected 24 mortalities under transmission lines, 3 mortalities beside roads, and no mortalities in controls. Mortality rates were adjusted with biases estimated from detectability and scavenging trials. Scavenging rates were high (82% of carcasses were scavenged within 5 days) and detectability of deceased birds was positively related to body size. Overall, linear disturbances within the study area, including 37.7 km of highways and transmission lines, contributed to an estimated 75 deaths/km of linear disturbance during one migration and one breeding season (~50 deaths/km of transmission line and ~25 deaths/km of road; ~1904 bird mortalities total). These findings point to the need for mitigation to reduce bird mortality, thereby minimizing the long-term impact of linear disturbances, such as transmission lines and roads, on associated bird communities.

中文翻译：

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草原鸟类死亡率随输电线路增加

全球输电线路的发展每年以 5% 的速度增长，导致鸟类与线路发生碰撞的情况有所增加。加拿大对输电线路碰撞死亡率的估计范围为每年 2.5 至 2560 万只鸟，其中大部分死亡归因于与架空屏蔽线的碰撞，以及年轻、体型大、机动性低或在开阔栖息地的易感鸟类. 在这项研究中，在两条主要输电线路建设后，估计了阿尔伯塔省东南部混合草草原约 4900 公顷的鸟类死亡率。在繁殖和迁徙季节，我们对 7-10 次 500 m 样带进行了 7-10 次调查，其中样带分为道路（n = 2）、输电线路（n = 2）、湿地（上面有输电线路；n = 1）、或控制 (n = 2) 区域。在 2016 年的繁殖季节（5 月 5 日至 6 月 24 日），我们在输电线路下检测到 23 人死亡，在道路旁检测到 7 人死亡，对照组没有死亡。在 2017 年春季迁徙季节（3 月 31 日至 5 月 5 日），我们检测到输电线路下 24 人死亡，路边死亡 3 人，对照组无死亡。死亡率根据可检测性和清除试验估计的偏差进行了调整。清除率很高（82% 的胴体在 5 天内清除），死鸟的可检测性与体型呈正相关。总体而言，研究区域内的线性扰动，包括 37.7 公里的高速公路和输电线路，在一个迁徙和一个繁殖季节导致估计有 75 人死亡/公里的线性扰动（约 50 人死亡/公里输电线路和约 25 人死亡/公里）公里的道路；~1904 只鸟的总死亡率）。这些发现表明需要采取缓解措施来降低鸟类死亡率，从而最大限度地减少线性干扰（如输电线路和道路）对相关鸟类群落的长期影响。