Nightly colony attendance patterns of provisioning Cassin's Auklet Ptychoramphus aleuticus are consistent and synchronous

We conducted a multi-year (1999-2001) radio telemetry study to determine patterns of colony attendance among breeding Cassin's Auklets Ptychoramphus aleuticus during the chick-rearing period on Triangle Island in British Columbia, Canada. A total of 1 625 detections were obtained for 80 individ...

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Bibliographic Details
Published inMarine ornithology Vol. 48; no. 2; p. 263
Main Authors Tranquilla, Laura Mcfarlane, Ryder, John L, Blight, Louise K, O'Hara, Patrick D, Bertram, Douglas F
Format Journal Article
LanguageEnglish
Published Honolulu Pacific Seabird Group 01.10.2020
Subjects
Animal behavior
Birds
Breeding
Colonies
Duration
Egg production
Females
Foraging
Individual rearing
Predators
Prey
Ptychoramphus aleuticus
Radio telemetry
Seabirds
Telemetry
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Summary:We conducted a multi-year (1999-2001) radio telemetry study to determine patterns of colony attendance among breeding Cassin's Auklets Ptychoramphus aleuticus during the chick-rearing period on Triangle Island in British Columbia, Canada. A total of 1 625 detections were obtained for 80 individual birds (24-28 birds per year), each detected 20.3 times on average. We found that colony attendance (arrival times, departure times, in-burrow shift duration) and foraging trip duration (i.e., time away from the colony) were remarkably synchronous among individuals and years. On average, birds arrived in a pulse after darkness, with 67% of returns between 23h15 and 00h15 and a peak (22% of all returns) between 23h30 and 23h45. Birds departed synchronously en masse before sunrise, with 86% of departures between 03h15 and 04h15 and a peak (38% of all departures) between 03h45 and 04h00. Overall, parents visited the colony every 19.8 hours (median) and stayed for roughly four hours during the chick-rearing period. At the beginning of the season, female foraging trip duration was longer than that of males, though this decreased with day of year, suggesting that females may aim to recover condition immediately following egg production via increased foraging time. Most breeders routinely visited the colony every night despite the risk posed by avian predators. Understanding patterns of colony attendance is important, given changing ocean conditions and prey availability in the vicinity of the world's largest colony for this species.
ISSN:1018-3337
2074-1235