A path forward in the investigation of seabird strandings attributed to light attraction

Abstract

A variety of anthropogenic threats cause mortality and population declines of procellariiform seabirds. Globally, fledglings of many colonial procellariiforms become stranded in towns and cities during their first flights from the nest, which occur at night. Since the 1960s, when the phenomenon became widely known, these strandings have been largely attributed to attraction toward artificial lights at night (ALAN). Artificial light attraction has been blamed due to the predictable, annual nature of strandings; the large numbers of birds found in lighted areas during stranding events; and the inexperience of fledglings in interpreting sensory stimuli. However, up‐to‐date, few alternative hypotheses to that of light attraction have been suggested, and few if any have been explored experimentally. In this paper, we do not seek to refute the light attraction hypothesis. Instead, our objectives are threefold. We wish to (1) highlight the current evidence for light attraction in procellariiforms; (2) identify where evidence may be lacking or subject to confirmation bias; and (3) suggest alternative hypotheses and possible experimental approaches to study them. Given the imperiled nature of many of the affected species and the need to explore and address this source of mortality, our goal in this review is to accelerate and diversify research efforts on this topic.

Small tube-nosed seabirds fledge on the full moon and throughout the lunar cycle

“…From a conservation perspective, these results indicate that Leach's storm-petrel fledgling monitoring and rescue programmes should concentrate efforts beginning early in the night throughout mid-September to mid-November. Storm-petrels do not appear to base their fledging decision on moon conditions, however, other factors like wind speed, wind direction, fog, and the brightness and colour of anthropogenic light may influence the likelihood of birds stranding, creating the possibility for mass strandings even during a full moon [4]. Long-term studies of mass-stranding events of all seabird species (i.e.…”

“…Seabirds are one of the most at-risk groups of birds, and attraction to anthropogenic light is a risk for at least 73 seabird species, mainly procellariiforms [1][2][3][4]. Globally, thousands of seabirds strand annually around brightly lit coastal and offshore structures [2][3][4][5][6][7].…”

“…Seabirds are one of the most at-risk groups of birds, and attraction to anthropogenic light is a risk for at least 73 seabird species, mainly procellariiforms [1][2][3][4]. Globally, thousands of seabirds strand annually around brightly lit coastal and offshore structures [2][3][4][5][6][7]. Stranded seabirds are subject to predation, dehydration, starvation, collisions with structures or vehicles, and oiling or injury by machinery [2].…”

Navigating the Night: Effects of Artificial Light on the Behaviour of Atlantic Puffin Fledglings

“…The existence of such "hotspots" has been taken as anecdotal evidence in support of the light attraction hypothesis of stranding in puffins, although it is unclear to what degree this pattern may be driven by a spatial bias in non-systematic search effort (e.g., toward well-lit areas, where people are also presumably more comfortable searching at night). Furthermore, while hundreds of puffins are stranded annually, this represents only a very small proportion of the total number of individuals fledging from the colonies (Wilhelm et al 2021), providing support to the natural random dispersal hypothesis which suggest that young birds become stranded because of their inexperience in navigating a new environment (Brown et al, 2023). To date, no experimental study has been conducted to directly test the light attraction hypothesis and confirm the role of ALAN in causing Atlantic Puffin strandings.…”

Moonlight diminishes seabird attraction to artificial light

“…Since then two non‐mutually exclusive hypotheses have been proposed by several authors as explanations: (1) reduction of strandings because birds are less attracted and disorientated by light pollution during full moon nights; and (2) reduction of fledging activity, that is, chicks avoid departing the colony during nights with increased moonlight (a possible anti‐predator behavior) (Chevillon et al, 2022; Deppe et al, 2017; Le Corre et al, 2002; Reed et al, 1985; Rodríguez & Rodríguez, 2009; Syposz et al, 2018; Telfer et al, 1987). In a recent review paper, Brown et al (2023) identified the need for additional research “to confirm if fewer strandings observed around the full moon are due to reduced fledging activity at the colony (as opposed to the hypothesis that bright moonlight diminishes the attractiveness of point sources of artificial light).” Here, we argue that evidence supports the first hypothesis, that is, fledglings are less attracted and disorientated by light pollution during full moon nights, with evidence lacking to support the reduction of fledging activity hypothesis.…”