Fatal Attraction of Short-Tailed Shearwaters to Artificial Lights

Light pollution is increasing around the world and altering natural nightscapes with potential ecological and evolutionary consequences. A severe ecological perturbation caused by artificial lights is mass mortalities of organisms, including seabird fledglings that are attracted to lights at night on their first flights to the sea. Here, we report on the number of fledging short-tailed shearwaters Ardenna tenuirostris found grounded in evening and morning rescue patrols conducted at Phillip Island, Australia, during a 15-year period (1999–2013). We assessed factors affecting numbers of grounded birds and mortality including date, moon phase, wind direction and speed, number of visitors and holiday periods. We also tested experimentally if birds were attracted to lights by turning the lights off on a section of the road. Of 8871 fledglings found, 39% were dead or dying. This mortality rate was 4–8 times higher than reported elsewhere for other shearwater species, probably because searching for fledglings was part of our systematic rescue effort rather than the opportunistic rescue used elsewhere. Thus, it suggests that light-induced mortality of seabirds is usually underestimated. We rescued more birds (dead and alive) in peak fledging, moonless and windy nights. Mortality increased through the fledging period, in the mornings and with increased traffic on holiday periods. Turning the road lights off decreased the number of grounded birds (dead and alive). While moon, wind and time are uncontrolled natural constraints, we demonstrated that reduction of light pollution and better traffic management can mitigate artificial light-induced mortality.全球光污染问题日益加剧，正改变自然夜景观，并可能带来生态与进化层面的潜在后果。人工光照所引发的严重生态扰动之一，便是造成大量生物死亡，其中包括在首次跨海飞行夜间被灯光吸引的海鸟雏鸟。本研究统计了1999年至2013年共15年间，在澳大利亚菲利普岛开展的昼夜救援巡护中发现的落地短尾鹱（Ardenna tenuirostris）雏鸟数量。我们评估了影响落地雏鸟数量与死亡率的各类因素，包括日期、月相、风向与风速、游客数量以及假期时段。此外，我们还通过关闭某段道路的灯光开展对照实验，以验证鸟类是否会被灯光吸引。本次研究共发现8871只雏鸟，其中39%已死亡或濒临死亡。该死亡率是其他地区报道的其他鹱类鸟类死亡率的4至8倍，这大概率是因为本研究的雏鸟搜寻属于系统性救援行动，而非其他地区采用的偶发救援。由此可见，光污染引发的海鸟死亡率通常被低估。在雏鸟离巢高峰期、无月夜以及大风夜间，我们救援到的死体与活体雏鸟数量更多。死亡率在整个雏鸟离巢期内呈上升趋势，且在晨间以及假期时段车流量增加时会升高。关闭道路灯光可减少落地雏鸟（死体与活体）的数量。尽管月相、风速与时间属于无法人为控制的自然限制因素，但本研究证实，减少光污染与优化交通管理可有效缓解人工光照引发的海鸟死亡问题。