Attraction of petrels to artificial lights in the Canary Islands: effects of the moon phase and age class

Abstract

The extent and intensity of artificial night lighting has increased with urban development worldwide. The resulting light pollution is responsible for mortality among many Procellariiformes species which show nocturnal activity on their breeding grounds. Here, we report light‐induced mortality of Procellariiformes during a 9‐year study (1998–2006) on Tenerife, the largest island of the Canary archipelago. A total of 9880 birds from nine species were found grounded, the majority being Cory’s Shearwaters Calonectris diomedea (93.4%). For this species the majority of grounded birds were fledglings (96.4%), which fall apparently while leaving their nesting colony for the first time; for the smaller species (storm‐petrels) adult birds were more often grounded than fledglings. For almost all species, grounding showed a seasonal pattern linked with their breeding cycle. Certain phases of the moon influenced grounding of Cory’s Shearwater, with the extent of grounding being reduced during phases of full moon. The percentage of fledglings attracted to lights in relation to the fledglings produced annually varied between species and years (0–1.3% for the Madeiran Storm‐petrel Oceanodroma castro; 41–71% for Cory’s Shearwater). Mean adult mortality rates also varied between species (from 0.4% for the European Storm‐petrel Hydrobates pelagicus and the Cory’s Shearwater, to 2.3% for the Manx Shearwater Puffinus puffinus). Here we show that light‐induced mortality rates are of concern, at least for petrels and small shearwaters. Thanks to efforts involving civil cooperation, 95% of grounded birds have been returned to the wild. To minimize the impact of artificial lights on petrels we recommend several conservation measures: continuing rescue campaigns, alteration of light signatures and reduction of light emissions during the fledging peaks. Furthermore, we recommend that a monitoring program for petrel populations be implemented, as well as further studies to assess the fate of released fledglings and continued research to address why petrels are attracted to lights.

Using observed seabird fallout records to infer patterns of attraction to artificial light

“…Fallout caused by attraction to artificial light is thought to be a contributing factor to the decline of several procellariid and hydrobatid species (Ainley et al 2001, Le Corre et al 2002, Rodriguez & Rodriguez 2009, Fontaine et al 2011, Rodriguez et al 2012b, and our findings further underscore the severity of the threat that anthropogenic light poses to these birds. Annual public participation in the rescue of fledglings downed by lights has resulted in thousands of birds reaching the ocean that would otherwise not have arrived there, and reduction in light use through awareness campaigns has undoubtedly prevented many instances of light-induced mortality (e.g.…”

“…Annual public participation in the rescue of fledglings downed by lights has resulted in thousands of birds reaching the ocean that would otherwise not have arrived there, and reduction in light use through awareness campaigns has undoubtedly prevented many instances of light-induced mortality (e.g. Ainley et al 2001, Le Corre et al 2002, Rodriguez & Rodriguez 2009, Fontaine et al 2011, Rodriguez et al 2012b). Methods to reduce overall light output, including attaching shields to bright light sources (which prevents direct upward radiation; Reed et al 1985) and simply decreasing total light output (King & Gould 1967, Miles et al 2010, have been shown to reduce total fledgling fallout in local areas.…”

“…Although rescue efforts for downed fledglings appear to save many birds annually, it is estimated that some birds still perish due to fallout because they are never found (Ainley et al 2001). Furthermore, it is unknown whether the experience of fallout leaves rescued fledglings unscathed enough to survive their first few weeks of pelagic life (Ainley et al 2001, Le Corre et al 2002, Rodriguez & Rodriguez 2009, Rodriguez et al 2012a. Thus, while the continuation of these rescue and light reduction efforts is crucial, populations could still be declining due to the effects of anthropogenic light despite these measures, albeit at a slower rate.…”

“…Fledglings of certain seabird species, particularly in the families Procellariidae (shearwaters and petrels) and Hydrobatidae (storm-petrels), are attracted to artificial light on their maiden flights to the ocean (Harrow 1965, Imber 1975, Reed et al 1985, Telfer et al 1987, Le Corre et al 2002, Salamolard et al 2007, Rodriguez & Rodriguez 2009, Miles et al 2010, although the cause of this attraction remains unknown. As these birds approach light sources, they can become disoriented and fall to the ground following physical exhaustion or collision with manmade structures and vegetation, a phenomenon known as 'fallout.'…”

“…As these birds approach light sources, they can become disoriented and fall to the ground following physical exhaustion or collision with manmade structures and vegetation, a phenomenon known as 'fallout.' While many of these downed birds are found alive and are released each year through public rescue efforts, recent studies suggest that light-induced mortality may still significantly decrease long-term population recruitment (Ainley et al 2001, Le Corre et al 2002, Rodriguez & Rodriguez 2009, Fontaine et al 2011, Griesemer & Holmes 2011, Rodriguez et al 2012b.…”