The Common Loon (Gavia immer) is a highly aquatic, migratory bird distributed across North America, Greenland, and Iceland. The common loon is 66 cm to 91 cm in length and weighs between 2.5 kg and 6.1 kg. They have an average wingspan of 130 cm to 140 cm (McIntyre and Barr, 1997).
The geographic location of the common loon during the breeding season is in forested areas surrounding freshwater, oligotrophic lakes in the northern region of North America, Greenland, and Iceland. During the winter months, the common loon migrates to coastal marine habitats in the southern portion of North America. Migration for the winter occurs between September and December and migration for the summer occurs between March and June. Migration groups can be composed of thousands of irregularly spaced individuals, a small group of individuals, or a single individual (McIntyre and Barr, 1997).
The common loon is high specialized for swimming and diving (Perrins and Middleton, 1985; McIntyre and Barr, 1997). Individuals spend most of their lives in the air or in water and only come to land to copulate, nest, or when ill (McIntyre and Barr, 1997). Although most dives underwater last under a minute, the common loon is capable of remaining underwater for several minutes (Perrins and Middleton, 1985).
The species diet primarily consists of live fish, although other aquatic vertebrates and vegetation are also consumed. Predators of the common loon most commonly attack young and include crows, ravens, gulls, skunks, weasels, bald eagles, and snapping turtles (McIntyre and Barr, 1997).
The common loon is monogamous and mates typically remain together throughout the breeding season. Mate replacement occurs after the death of one individual. The age at first breeding varies between four and seven years of age and breeding is annual. Adults are highly aggressive in territorial defense. Both sexes are capable of severely injuring or even killing conspecifics that invade their territory (McIntyre and Barr, 1997).
Clutch size is two eggs and the incubation period is about 28 days (McIntyre and Barr, 1997). Both parents participate in incubation of the eggs. Young are precocial, or well-developed, after hatching. Young eat fresh food caught by the parents as opposed to food that has been regurgitated. Additionally, young are capable of leaving the nest and even diving the day after hatching (Perrins and Middleton, 1985)!
Additional Information on the Skull
Click on the thumbnails below for labeled images of the skull in standard anatomical views.
Literature
Baumel, J. J., A. S. King, J. E. Breazile, H. E. Evans, and J. C. Vanden Berge (eds.). 1993. Handbook of Avian Anatomy: Nomina Anatomica Avium, Second Edition. Publication of the Nuttall Ornithological Club, number 23. Nuttall Ornithological Club, Cambridge, Massachusetts, 779 pp.
McIntyre, J. W. and J. F. Barr. 1997. Gavia immer. The Birds of North America: Life Histories for the 21st Century 313:1-32
Perrins, C. M. and A. Middleton. 1985. The Encyclopedia of Birds. Facts on File, Inc., New York, NY. pp 447.
Links
Gavia immer page on the Animal Diversity Web (University of Michigan Museum of Zoology)
Gavia immer on the USGS Patuxent Bird Indentification InfoCenter.
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