Reducing light-induced mortality of seabirds: High pressure sodium lights decrease the fatal attraction of shearwaters

Abstract

The use of artificial light at night and its ecological consequences are increasing around the world. Light pollution can lead to massive mortality episodes for nocturnally active petrels, one of the most threatened avian groups. Some fledglings can be attracted or disoriented by artificial light on their first flights. Studies testing the effect of artificial light characteristics on attractiveness to seabirds have not provided conclusive results and there is some urgency as some endangered petrel species experience high lightinduced mortality. We designed a field experiment to test the effect of three common outdoor lighting systems with different light spectra (high pressure sodium, metal halide and light emitting diode) on the number and the body condition of grounded fledglings of the short-tailed shearwater Ardenna tenuirostris. A total of 235 birds were grounded during 99 experimental hours (33 hours for each treatment). 47% of birds were grounded when metal halide lights were on, while light emitting diode and high pressure sodium lights showed lower percentages of attraction (29% and 24%). Metal halide multiplied the mortality risk by a factor of 1.6 and 1.9 respectively in comparison with light emitting diode and high pressure sodium lights. No differences in body condition were detected among the birds grounded by the different lighting systems. We recommend the adoption of high pressure sodium lights into petrel-friendly lighting designs together with other light mitigation measures such as light attenuation, lateral shielding to reduce spill and appropriate orientation.

Rapid assessment of lamp spectrum to quantify ecological effects of light at night

“…Analysis of birds grounded from Rodríguez et al. (), comparing Actinic Power per Lux with CCT, brightness, and lamp type as explanatory variables…”

“…Quantification of actinic power can be used to develop hypotheses to test in the field, such as the comparison of lamp types undertaken by Rodríguez et al. () that we revisited. Furthermore, it allows the rapid and easily updatable comparison of new lamp types so that the most promising spectral configurations for a particular situation can be identified and tested in the field.…”

“…To test this approach with experimental data, we compared the results of the light hazard for shearwaters in an experiment comparing light attraction of short‐tailed shearwaters for metal halide, high pressure sodium, and 4536 K LED lamps (Rodríguez et al., ). We modeled relative attraction using the same approach of generalized linear mixed models with night as a random factor and actinic power, lamp type, brightness, and CCT each in separate models as an independent factor.…”

“…Conservation scientists need to keep up with the changing array of outdoor lighting options to provide guidance to officials and managers around the world who are faced with the obvious economic choice of switching to high-efficiency lighting such as LEDs (Hecht, 2016). Such a switch can be catastrophic for the effects on other species, or it can be a benefit, depending on the spectrum, duration, direction, and intensity of the new lamps (Gaston et al, 2012;Longcore et al, 2015;Rodríguez, Dann, & Chiaradia, 2017a). The same applies to sky glow (Kinzey et al, 2017).…”

“…Finally, we calculated photometric indices for each light source that are important to lighting engineers and end users. These include the correlated color temperature (CCT), color rendering index (CRI), To test this approach with experimental data, we compared the results of the light hazard for shearwaters in an experiment comparing light attraction of short-tailed shearwaters for metal halide, high pressure sodium, and 4536 K LED lamps (Rodríguez et al, 2017a).…”