Yelkouan shearwaters nest on Mediterranean islands, and like several other burrow nesting seabirds they approach their colonies only under the cover of darkness to avoid natural predators. A study recently published in Journal of Ornithology examined how light pollution from large ships refuelling at sea affected a colony of Yelkouan shearwaters nesting in a cave on Malta. The authors tagged adult shearwaters and used a Radio Frequency Identification (RFID) system to measure the number of birds passing in and out of the cave during the breeding seasons 2017 to 2020. The authors also measured ambient light at the cliff face where the shearwaters breed and tracked ship activity during that time. The research showed that the presence of ships increased the brightness of the colony, with an effect similar to a full moon. As expected, the number of birds entering the colony was lower when the night was brighter and in the presence of ships. The authors suggest that colony attendance patterns adapted to the moon cycle are disrupted by artificial light, with potential effects on breeding success and colony recruitment. Moreover, despite some adult shearwaters attending nests in the presence of light pollution, the physiological impacts are unknown. The study advocates against nocturnal ship activity in front of shearwater breeding colonies and encourage the global shipping industry to adopt guidelines to reduce its environmental impact. More info at:
Austad M, et al. 2023. The effects of temporally distinct light pollution from ships on nocturnal colony attendance in a threatened seabird. Journal of Ornithology
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When juveniles of burrow-nesting seabirds leave their nests to start their first migration they are often curtailed from reaching the sea, grounded across urban areas after encountering light pollution. We set out to test the hypothesis that exposure to light during growth, or lack thereof, could be a main driving factor leading to the higher vulnerability observed in seabird juveniles, and why fallout is a predominantly burrow-nesting species event. We recorded chicks behavioural responses towards two contrastingly artificial lights, red and blue, and exposed each chick five times, from 3 weeks old to near fledging. We then analysed the effect of the chicks’ age (i.e., younger chicks would have worse visual ability than older chicks, and show less behavioural responses), and amount of exposure to artificial light during growth (i.e., chicks exposed to light more times would have their visual systems more trained, consequently display more behavioural responses). Our results showed that repetitive exposure to the artificial light stimuli increased the number of responses, but chick’s age did not have any effect on the responses. As burrow-nesters chicks will mostly grow in dark environments, which lack sufficient light stimuli to train their visual systems, our findings provide evidence of the untrained vision at fledging, and its contribution to the vulnerability towards light pollution. The effects that persistent light pollution close to these birds breeding colonies may have on their vulnerability should now be investigated.
More info at:
Atchoi E, et al. 2023. Ontogenetic exposure to light influences seabird vulnerability to light pollution. Journal of Exprimental Biology |
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