Modeling artificial light viewed by fledgling seabirds

Abstract

Abstract. Artificial light is increasing in coverage across the surface of our planet, impacting the behavioral ecology of many organisms. Attraction to sources of artificial light is a significant threat to certain fledgling shearwaters, petrels (Procellariidae), and storm-petrels (Hydrobatidae) on their first nocturnal flights to the sea. Disorientation by light can cause these birds to crash into vegetation or manmade structures, potentially resulting in death from physical injury, starvation, dehydration, predation by introduced predators, or collisions with vehicles. We developed a GIS-based method to model the intensity of artificial light that fledgling procellariids and hydrobatids could view en route to the ocean (to estimate the degree of threat that artificial light poses to these birds) and present two models for the island of Kauai as examples. These models are particularly relevant to the federally threatened Newell's Shearwater, or`A`o (Puffinus newelli ), of which .30,000 fledglings have been collected in response to disorientation by lights on Kauai during the past 30 years. Our models suggest that there are few to no portions of Kauai from which young birds could fledge and not view light on their post-natal nocturnal flights, which is concerning given evidence of a Newell's Shearwater population decline. In future work using this technique, night light intensity layers could be altered to model the effects of modified coastal light conditions on known and potential procellariid and hydrobatid breeding locations. Furthermore, certain methods presented herein may be applicable to other seabirds and additional taxa in which attraction to anthropogenic light poses a serious threat, including migratory passerines and hatchling marine turtles. Components of this modeling approach could potentially be used to spatially estimate effects of other point-source threats to ecological systems, including sound and air pollution.

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

“…Despite whether pixel values represent the actual light intensity being emitted by lights or the numbers of lights within the pixel area (or both), this satellite layer is suitable for research investigating the threat that light may pose to fledgling seabirds (e.g. Troy et al 2011), as well as the relationship between light and seabird fallout (e.g. Rodrigues et al 2012, Rodriguez et al 2012b), on a large scale.…”

“…In addition, from a stationary perspective (i.e. without considering bird movement), it was recently shown that light could not be viewed from approximately 30% of the island of Kauai (Troy et al 2011), and these dark locations mostly included regions in the interior and northwestern portion of the island where many known Newell's shearwater activity sites are located. Given this additional information concerning viewable light on Kauai, the expected behavior of the species in the absence of light, and the results of this study, it appears likely that many birds could successfully reach the coastline and ocean, where they are then exposed to a range of light intensities emanating from multiple fallout sectors (spanning a large portion of the island) and are more likely to be attracted to sectors with greater light intensities and/or greater densities of light sources.…”

Population size, breeding biology and on-land threats of Cape Verde petrel (Pterodroma feae) in Fogo Island, Cape Verde

“…Light-induced mortality occurs in several gadfly petrels, especially in fledglings [21,22], suggesting that Cape Verde petrels could also be sensitive to light pollution. Indeed, fledglings have been collected in Chã das Caldeiras near light sources in at least three occasions over the last decade (Fogo Natural Park authorities’ personal communication), despite no public lights or infrastructures with important sources of light in the village.…”

“…Light-induced mortality is known to occur in other gadfly petrels, especially in fledglings [21,22], pointing out the possibility to also occur in Cape Verde petrels. To identify where conservation actions should be applied in the future to avoid high light pollution levels, and thus reduce the probability of light-induced mortality in the study species, we deployed 15 GPS devices on 9 breeding adults over the chick-rearing period of 2015.…”

“…Among shearwaters and petrels, fledglings are often disoriented and grounded by artificial light during their first flight to the sea, exposing them to collision and predation, ultimately inducing relevant levels of mortality in several species [20]. This phenomenon has also been reported in gadfly petrels species, for instance in the Barau's ( Pterodroma baraui ) and Hawaiian ( Pterodroma sandwichensis ) petrels, pointing out the sensitivity of this group of birds to this problem [21,22]. …”