Consistent offshore artificial light at night near the last breeding colony of a critically endangered seabird

Abstract Artificial light at night (ALAN) is considered a major threat to biodiversity, yet impacts of offshore ALAN on seabirds remain poorly understood. Particularly understudied are deck strikes (collisions of seabirds with vessels due to ALAN‐induced disorientation). To infer deck strike risks to the critically endangered Whenua Hou Diving‐petrel (Pelecanoides whenuahouensis; WHDP), we estimated nightly vessel counts and associated probability of floodlight use in close proximity of their only breeding colony, number of WHDP commutes, duration of phenophases, and ultimately the cumulative exposure to floodlights using a Bayesian framework. The estimated nightly number of vessels was 0.76 (0.64–0.89), 31% (21%–38%) of which used floodlights. WHDPs were potentially exposed to 28.9 (19.7–39.7) floodlights per breeding period. There was no evidence for inter‐annual variation in vessel counts, floodlight use, or WHDP activity, despite varying environmental conditions. WHDP activity, and therefore risk, was highest during courtship and post‐guard. Yet, there was potential for deck strikes throughout the breeding period, which could impact WHDPs. We identify key research questions (likelihood of a deck strike occurring, survival of deck‐struck birds, and post‐release survival of deck‐struck birds). In the meantime, small behavioral changes of vessel operators could be a successful approach to protecting seabirds from offshore ALAN. Tuhinga whakarāpopoto Ko te rama tāwhai ite pō (ALAN) he mea whakamōrearea i te rerenga rauropi, engari ko ngā pānga ote ALAN ki ngā manu moana ki tai kāore anō kia āta whakamāramatia. Ko ngāāhuatanga kāore anō kia āta tātari ko te tukinga kāraho (ko te tūtukinga o ngāmanu moana e tāhurihuri ana ki ngā waka, nā te ALAN). Ki te whakapae atu i temōreareatanga o te tukinga kāraho ki te Kuaka Whenua Hou (Pelecanoideswhenuahouensis; WHDP) he manu e ngaro haere ana tōna whare ora, i whakatau tatate tini o ngā waka e tere i te pō me te tūponotanga e hāngai ana ki tewhakamahinga o te tūrama raharaha e pātata ana ki pūrei kōhanga anake ō rātou,te maha o ngā rerenga o ngā WHDP, te roa o te tauwāhi mātai, ā, i te otinga kuawhakamahia te anga ‘Bayesian’ ki te ine i ngā pānga tapeke o ēnei manu ki ērārama. Ko te whakatau tata o te maha o ngā waka i ia pō ko te 0.76 (0.64‐.089),31% (21%‐38%) o ēnei i whakamahia ngā tūrama rarharaha. I hōrakerake ai pea ngāWHDP kia 28.9 (19.7‐39.7) ngā wā i ia wā whakatipu. Kāore he taunakitanga i tererekētanga o te maha o ngā waka, te whakamahinga o te tūrama raharaha, te mahio te WHDP i waenga i ngā tau, ahakoa he rerekē ngā āhuatanga o te taiao. Ko temahi a ngā WHDP, waihoki ko te pānga o te mōrearea ki a rātou hoki, kua pikiake i te wā o te whakaipoipo, ā, mō muri hoki i tā rātou tūtei hua. Arā tonu tepitomata ka tukia pea te kāraho i te wā katoa o te wa whakatīpu, mā reira e pākino ai ki ngā WHDP. Ka tūtohutia e mātou ngā pātai rangahau matua (tetingatanga o te tukinga kāraho, te oranga tonutanga rānei o te manu kua tukia kite kāraho, me te oranga tonutanga o te manu kua whakamātūtū, ā, kua whakahokiakētia ki tōna ao). Āianei, mā te paku panonihanga o ngā whanonga hautū waka ongā kaihautū waka ka tiaki pai ngā manu moana i te ALAN ki tai.