Volume 48, No. 1

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Nocturnal copulation in Glaucous-winged Gulls Larus glaucescens


1Department of Biology, Pacific Union College, Angwin, California 94508, USA *(
2Department of Biology, Andrews University, 4280 Administration Drive, Berrien Springs, Michigan 49104-0410, USA


HAYES, F.E. & HAYWARD, J.L. 2020. Nocturnal copulation in Glaucous-winged Gulls Larus glaucescens. Marine Ornithology 48: 55 - 59

Received 30 August 2019, accepted 21 November 2019

Date Published: 2020/04/15
Date Online: 2019/03/05
Key words: behavior, cathemeral, Laridae, life history, mating, nocturnality, reproduction


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.


ALLISON, N.L. & DESTEFANO, S. 2006. Equipment and techniques for nocturnal wildlife studies. Wildlife Society Bulletin 34: 1036-1044.

ANONYMOUS. 2013. Statistix 10 User's Manual. Tallahassee, USA: Analytical Software.

ATKINS, G.J., REICHERT, A.A., HENSON, S.M. & HAYWARD, J.L. 2017. Copulation call coordinates timing of head-tossing and mounting behaviors in neighboring Glaucous-winged Gulls (Larus glaucescens). Wilson Journal of Ornithology 129: 560-567.

BARROWS, E.M. 2011. Animal Behavior Desk Reference: A Dictionary of Animal Behavior, Ecology, and Evolution. Boca Raton, USA: CRC Press.

BELL, D.A. 1996. Genetic differentiation, geographic variation and hybridization in gulls of the Larus glaucescens-occidentalis complex. The Condor 98: 527-546.

BROOKE, M.D.L. & PRINCE, P.A. 1991. Nocturnality in seabirds. Proceedings of the International Ornithological Congress 20: 1113-1121.

BURGER, J. & STAINE, K.J. 1993. Nocturnal behavior of gulls in coastal New Jersey. Estuaries 16: 809-814.

FETTEROLF, P.M. 1979. Nocturnal behaviour of Ring-billed Gulls during the early incubation period. Canadian Journal of Zoology 57: 1190-1195.

FOOTTIT, R.G. & BUTLER, R.W. 1977. Predation on nesting Glaucous-winged Gulls by river otter. Canadian Field-Naturalist 91: 189-190.

GALUSHA, J.G. & HAYWARD, J.L. 2002. Bald Eagle activity at a gull colony and seal rookery on Protection Island, Washington. Northwestern Naturalist 83: 23-25.

GARTHE, S. & HÜPPOP, O. 1996. Nocturnal scavenging by gulls in the southern North Sea. Colonial Waterbirds 19: 232-241.

HAILMAN, J.P. 1964. The Galápagos Swallow-tailed Gull is nocturnal. Wilson Bulletin 76: 347-354.

HAYES, F.E., TURNER, D.G., ZIMMERLY, N.D. & PERALTA, M.B. 2018. Nocturnal courtship, copulation, and egg-laying in the western grebe (Aechmophorus occidentalis) and Clark's grebe (A. clarkii). Journal of Ethology 36: 65-75.

HAYWARD, J.L. JR., AMLANER, C.J. JR., GILLET, W.H. & STOUT, J.F. 1975. Predation on nesting gulls by a river otter in Washington State. Murrelet 6: 9-10.

HAYWARD, J.L., GALUSHA, J.G. & HENSON, S.M. 2010. Foraging-related activity of Bald Eagles at a Washington seabird colony and seal rookery. Journal of Raptor Research 44: 19-29.

HAYWARD, J.L., HENSON, S.M., BOVÉ, J., BOVÉ, C. & GREGORY, C.J. 2017. Daily and annual habitat use and habitat-to-habitat movement by Glaucous-winged Gulls at Protection Island, Washington. Northwestern Naturalist 98: 180-189.

HAYWARD, J.L. & VERBEEK, N.A. 2008. Glaucous-winged Gull (Larus glaucescens). In: POOLE, A. (Ed.). Birds of North America Online. Ithaca, US: Cornell Laboratory of Ornithology. [Available online at: Accessed 06 June 2019].

HÉBERT, P.N. & MCNEIL, R. 1999. Nocturnal activity of Ring-billed Gulls at and away from the colony. Waterbirds 22: 445-451.

HENSON, S.M., DENNIS, B., HAYWARD, J.L., CUSHING, J.M. & GLUSHA, J.G. 2007. Predicting the dynamics of animal behaviour in field populations. Animal Behaviour 74: 103-110.

HENSON, S.M., DESHARNAIS, R.A., FUNASAKI, E.T., GALUSHA, J.G., WATSON, J.W. & HAYWARD, J.L. 2019. Predator-prey dynamics of Bald Eagles and Glaucous-winged Gulls at Protection Island, Washington, USA. Ecology and Evolution 9: 3850-3867. 

HENSON, S.M., WELDON, L.M, HAYWARD, J.L., GREENE, D.J., MEGNA, L.C. & SEREM, M.C. 2012. Coping behavior as an adaptation to stress: post-disturbance preening in colonial seabirds. Journal of Biological Dynamics 6: 17-37.

HOWELL, T.R., ARAYA, B. & MILLIE, W.R. 1974. Breeding biology of the Gray Gull. University of California Publications in Zoology 104: 1-57.

JAMES-VEITCH, E. & BOOTH, E.S. 1954. Behavior and life history of the Glaucous-winged Gull. Walla Walla College Publications of the Department of Biological Sciences and the Biological Station 12: 1-30.

JOHNSON, M., BECKMANN, J.P. & ORING, L.W. 2002. Temperate breeding shorebirds copulate at night. Wader Study Group Bulletin 97: 45-46.

JOHNSON, M., BECKMANN, J.P. & ORING, L.W. 2003. Diurnal and nocturnal behavior of breeding American Avocets. Wilson Bulletin 115: 176-185.

LA, V.T. 2011. Diurnal and nocturnal birds vocalize at night: a review. The Condor 114: 245-257.

LEOPOLD, F., PHILIPPART, C.J.M. & YORIO, P. 2010. Nocturnal feeding under artificial light conditions by Brown-hooded Gull (Larus maculipennis) in Puerto Madryn harbour (Chubut Province, Argentina). El Hornero 25: 55-60.

MARTIN, G. 1990. Birds by Night. London, UK: Poyser.

MARTIN, K.L.M. & RAIM, J.G. 2014. Avian predators target nocturnal runs of the beach-spawning marine fish, California grunion, Leuresthes tenuis (Atherinopsidae). Bulletin of the Southern California Academy of Science 113: 187-199.

MCALLISTER, N.M. 1958. Courtship, hostile behavior, nest-establishment and egg laying in the Eared Grebe (Podiceps caspicus). The Auk 75: 290-311.

MCNEIL, R., DRAPEAU, P. & GOSS-CUSTARD, J.D. 1992. The occurrence and adaptive significance of nocturnal habits in waterfowl. Biological Reviews 67: 381-419.

MCNEIL, R., DRAPEAU, P. & PIEROTTI, R. 1993. Nocturnality in colonial waterbirds: occurrence, special adaptations, and suspected benefits. In: POWER, D.M. (Ed.). Current Ornithology. Vol. 10. New York, USA:Plenum Press.

MCWILLIAMS, K.M., SANDLER, A.G., ATKINS, G.J., HENSON, S.M. & HAYWARD, J.L. 2018. Courtship and copulation in Glaucous-winged Gulls, Larus glaucescens, and the influence of environmental variables. Wilson Journal of Ornithology 130: 270-285.

MEGNA, L.C., MONCRIEFF, A.E., HAYWARD, J.L. & HENSON, S.M. 2014. Equal reproductive success of phenotypes in the Larus glaucescens-occidentalis complex. Journal of Avian Biology 45: 410-416.

MONCRIEFF, A.E., MEGNA, L.C. & HAYWARD, J.L. 2013. Mating patterns and breeding success in gulls of the Larus glaucescens-occidentalis complex, Protection Island, Washington, USA. Northwestern Naturalist 94: 67-75.

MOYNIHAN, M. 1955. Some aspects of reproductive behavior in the Black-headed Gull (Larus ridibundus ridibundus L.) and related species. Behaviour Supplement 4: 1-201.

MOYNIHAN, M. 1962. Hostile and sexual behavior patterns of South American and Pacific Laridae. Behaviour Supplement 8: 1-365.

NELSON, D.A. 1989. Gull predation on Cassin's Auklet varies with the lunar cycle. The Auk 106: 495-497.

NEWTON, I. 2008. The Migration Ecology of Birds. London, UK: Academic Press.

NOCERA, J. & KRESS, S.W. 1996. Nocturnal predation on Common Terns by Great Black-backed Gulls. Colonial Waterbirds 19: 277-279.

ORO, J.D., RUIZ, X., JOVER, L., PEDROCCHI, V. & GONZÁLEZ-SOLÍS, J. 1997. Diet and adult time budgets of Audouin's Gull Larus audouinii in response to changes in commercial fisheries. Ibis 139: 631-637.

PUGH, A.R. & PAWSON, S.M. 2016. Artificial light at night potentially alters feeding behaviour of the native Southern Black-backed Gull (Larus dominicanus). Notornis 63: 37-39.

SALZER, D.W. & LARKIN, G.J. 1990. Impact of courtship feeding on clutch and third-egg size in Glaucous-winged Gulls. Animal Behaviour 39: 1149-1162.

SANDLER, A.G. 2013. Features of Copulation and the Copulation Call in Glaucous-winged Gulls (Larus glaucescens). MSc thesis. Berrien Springs, USA: Andrews University.

SOUTHERN, L.K. & SOUTHERN, W.E. 1979. Absence of nocturnal predator defense mechanisms in breeding gulls. Proceedings of the Colonial Waterbird Group 2: 157-162.

SOUTHERN, L.K., PATTON, S.R. & SOUTHERN, W.E. 1982. Nocturnal predation on Larus gulls. Colonial Waterbirds 5: 169-172.

TINBERGEN, N. 1959. Comparative studies of the behaviour of gulls (Laridae): a progress report. Behaviour 15: 1-70.

TINBERGEN, N. 1960. The Herring Gull's World: A Study of the Social Behavior of Birds. New York, USA: Harper & Row.

VERBEEK, A.M. & MORGAN, J.L. 1978. River otter predation on Glaucous-winged Gulls on Mandarte Island, British Columbia. Murrelet 59: 92-95.

VERMEER, K. 1963. The breeding ecology of the Glaucous-winged Gull (Larus glaucescens) on Mandarte Island, B.C. Occasional Papers of the British Columbia Provincial Museum 13: 1-104.

YORIO, P., SUÁREZ, N., QUINTANA, F. & GATTO, A. 2005. Nocturnal activity in breeding Olrog's Gulls (Larus atlanticus). Ornitología Neotropical 16: 123-126.

ZAR, J.H. 2010. Biostatistical Analysis, 5th Edition. Upper Saddle River, USA: Pearson.

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