Document Type

Article

Publication Date

4-15-2020

Keywords

behavior, cathemeral, Laridae, life history, mating, nocturnality, reproduction

Abstract

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.

Journal Title

Marine Ornithology: Journal of Seabird Science and Conservation

Volume

48

Issue

1

First Page

55

Last Page

59

First Department

Biology

Acknowledgements

Retrieved 8/13/2020 from http://www.marineornithology.org/PDF/48_1/48_1_55-59.pdf

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