Light-induced mortality of seabirds is a poorly understood phenomenon, largely because of the challenge to track seabirds at night from their nests to the grounding light-polluted locations. New tracking technologies can inform about this phenomenon. Here, we used GPS transmitters with remote download to track the flights of Cory’s shearwater Calonectris borealis fledglings from an inland experimental releasing site to the ocean. We released birds assigned to three experimental groups: GPS tagged, tape-labelled, and control birds. We assessed how both intrinsic (such as body mass, body condition, body size, and down abundance) and extrinsic (i.e., flight descriptors, such as distance, straightness, and flight duration, wind speed, or moon luminance) factors influenced light-induced groundings by using two datasets: one including the three groups and another including just the GPS tagged birds (as GPS devices provide unique information). GPSs with remote data download provided information on birds reaching the ocean, this being a substantial improvement to previous studies requiring recapture of the individuals to retrieve the data. GPS tracks of birds reaching the ocean allowed us to know that some birds overflew coastal urban areas so light-polluted as the landing sites of grounded birds. We provide novel scientific-based information to manage seabird mortality induced by artificial lights.
More info at: Rodríguez A, et al. 2022. Tracking flights to investigate seabird mortality induced by artificial lights. Frontiers in Ecology and Evolution
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On O’ahu, Hawai‘i, fledgling wedge-tailed shearwaters leaving their nests for the first time are often disoriented by lights and may become grounded due to exhaustion or collision, exposing them to additional threats from road traffic and predation. Highway streetlights on O’ahu were changed from unshielded high-pressure sodium (HPS) to full-cutoff light-emitting diode (LED) streetlights in 2016. We conducted road surveys to locate road-killed shearwaters from 2012-2019 and compared mortality before and after the change in lighting. We also accounted for three potential environmental drivers of interannual variability in fallout: moon illumination, wind speed, and wind direction. While the effects of these environmental drivers varied across years, the interaction between moon illumination and wind speed was the most important predictor, suggesting that mortality related to fallout increases during nights with low moon illumination and strong winds. We did not find the change in streetlights to significantly affect the number of road-killed shearwaters observed in our surveys. However, due to potential species-specific disparities in the behavior and light attraction of petrels, similar studies are needed before energy saving LED lights are implemented throughout the Hawaiian archipelago. More info at: Urmston et al. 2022. Quantifying wedge-tailed shearwater (Ardenna pacifica) fallout after changes in highway lighting on Southeast Oʻahu, Hawaiʻi. Plos One |
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October 2023
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