Nocturnal copulation in Glaucous-winged Gulls Larus glaucescens

Gulls (Laridae) are primarily diurnal, although many species forage opportunistically at night, and several species copulate at night. We used trail cameras to study time-of-day variation in the rate of copulation by Glaucous-winged Gulls Larus glaucescens in a breeding colony (1500+ pairs) at Prote...

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Bibliographic Details
Published inMarine ornithology Vol. 48; no. 1; p. 55
Main Authors Hayes, Floyd E, Hayward, James L
Format Journal Article
LanguageEnglish
Published Honolulu Pacific Seabird Group 01.04.2020
Subjects
Biological fertilization
Breeding
Cameras
Colonies
Laridae
Larus glaucescens
Reproductive behaviour
Seabirds
Sleep
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Summary:Gulls (Laridae) are primarily diurnal, although many species forage opportunistically at night, and several species copulate at night. We used trail cameras to study time-of-day variation in the rate of copulation by Glaucous-winged Gulls Larus glaucescens in a breeding colony (1500+ pairs) at Protection Island, Washington, USA, from 31 May to 07 June 2018. Copulations (n = 353) occurred at a significantly higher rate during the day (0.82/camera-h) than at night (0.51/camera-h), with 76.3 % of copulations during the day and 23.7 % at night (daylight comprised 66.1 % and darkness comprised 33.9 % of the study period). The copulation rate peaked shortly before and after dawn, with a second peak before sunset. Copulation rate was lowest during the middle of the day and middle of the night. Glaucous-winged Gulls sleep intermittently during both day and night and have sufficient energy to sustain sporadic copulations during the night, which appears to be a normal part of their reproductive behavior. The most likely advantage of this pattern is an increased opportunity for fertilization with a mate.
ISSN:1018-3337
2074-1235