IUCN threat status:

Least Concern (LC)

Comprehensive Description

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Comprehensive Description

The Pacific loon, or Gavia pacifica, is part of the Gaviidae family and is one of the most abundant loons in North America. Males are slightly larger than females, but overall length for both sexes is between 58-74 cm, with a wingspan of 110-128 cm, and a weight between 1000-2500 g. (All About Birds 2017). G. pacifica’s body is stout and duck-like in structure. The nape, especially in breeding plumage, is grayer in contrast with the back, which is blacker, indeed blacker than other loons. During breeding season, the back is interrupted with patches of white. The bird’s flanks and underwings are snowy white (Russell 2002). Differences between the Pacific loon and the Common loon (Gavia immer) are that the Pacific loon is slightly smaller and its bill is straighter, thinner, and blacker than that of the Common loon (Alden 1998).

The native range of G. pacifica includes Alaska, Canada, and the West coast of the United States However, this bird has a very wide range and can be seen all around the Pacific Ocean including in Russia, Japan, Mexico and Korea.  Breeding occurs on and around freshwater lakes in the arctic tundra, where G. pacifica spend the summer months (All About Birds 2017). The habitat that is ideal for G. pacifica is the ocean and associated bays and estuaries, where they winter and also rest during migration (Alden 1998).

The behavior of G. pacifica is sociable and they move in large numbers (in the thousands) when food is plentiful. During mating season, they are heavily aggressive and very territorial. They are very defensive of their nesting territories and have been observed to kill harmless birds like ducklings that come close to their nests (Kaufmann 2017). G. Pacifica hunts for its food by diving, propelled mainly by its feet, pursuing fish, crustaceans, and insects.  Its diet varies seasonally -it is known to feed on plant material and mollusks during its breeding season, while mostly eating small fish during the winter (Kaufmann 2017).

After a ritualized courtship that includes bill dipping and splash diving from both the male and female. G. pacifica mate for life and have an average generation length of 9.8 years (BirdLife International 2016). Nests are made on the ground and can be identified by a simple depression or dip with scant lining. If the nest is formed near water however, it will typically be bowl shaped and filled with grasses and aquatic plants. G. pacifica raises one brood per year (All About Birds 2017).  Numbers of G. pacifica are stable; however they are vulnerable to pollution, especially in offshore wintering areas (Kaufmann 2017). 

Unreviewed

Creative Commons Attribution 3.0 (CC BY 3.0)

© Authors: Grace Stewart and Iran Carranza; Editor: Dr. Gordon Miller; Seattle University EVST 2100 - Natural History: Theory and Practice, Spring 2017.

Supplier: seattleu_natural_history

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