What we know and what we should know to mitigate seabird mortality induced by light pollution

Abstract

**Abstract:** Artificial night lighting and its consequent light pollution cause high mortality events on burrow nesting seabirds, particularly petrels and shearwaters. Mainly fledglings are attracted and disorientated by artificial lights during their naïve nocturnal flights from their natal nests towards the sea. Light forces them to land, and once grounded, they are vulnerable to fatal injuries, vehicle collisions or predators. Here, I review the current state of knowledge of seabird mortality induced by light pollution to identify information gaps and propose measures to address the problem. Specifically, I focus on 1) what have we learned after more than 40 years rescuing birds on archipelagos around the world; and 2) what we should know to assess and mitigate this emerging source of mortality. More than 56 species, more than one-third of them threatened, are subject to grounding by lights worldwide. Rescue programmes of grounded birds are the most relevant and extended measures to mitigate light-induced mortality, despite being a palliative action. Thanks to rescue campaigns, around 90% of collected birds are released into the wild. However, this figure seems overestimated as many grounded birds are never found or reported, being 60% a more accurate estimate. Why seabirds are attracted and grounded by lights is still poorly understood. The main body of knowledge comes from rescue programmes typically conducted by volunteers and citizen, thus information is strongly biased and fragmented, and leads to inaccurate impact estimates. More research is needed to understand and finally propose actions to mitigate light-induced mortality. Briefly, the most urgent actions are: 1) estimation of mortality and population effects; 2) assessment of threshold light levels and safe distances to pollution sources; 3) assessment of the fate of rescued birds; 4) improvement of rescue campaigns; and 5) research on and development of seabird-friendly lights to minimise attraction. In lines with these actions, I will present some unpublished results of my research to illustrate how we proceed and advance to reduce light pollution effects on seabirds. **Authors:** Airam Rodriguez¹ ¹Estacion Biologica de Doñana CSIC