Ardea
Official journal of the Netherlands Ornithologists' Union

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Vermeer K. (1979) Nesting requirements, food and breeding distribution of Rhinoceros Auklets Cerorhinca monocerata and Tufted Puffins Lunda cirrhata. ARDEA 67 (3-4): 101-110
The nesting preferences, food habits of the young, and breeding populations of Rhinoceros Auklets and Tufted Puffins were determined at Triangle Island, British Columbia in 1975 and 1976. Tufted Puffins nested predominantly in tufted hairgrass, on steep slopes and cliff tops. The nesting pattern of puffins suggests that they benefit from high elevations and steep slopes for taking off. In contrast, Rhinoceros Auklets nested at a wide range of slope gradients, and in vegetation other than hairgrass. Rhinoceros Auklets and Tufted Puffins showed latitudinal differences in principal food items along the eastern Pacific, except for sandlance which was important for both species at all localities. Rhinoceros Auklet and Tufted Puffin principal prey on Triangle Island consisted of sandlance, Pacific sauries and rockfishes. Bluethroat argentines occurred in the diet of both birds only in 1978. Rhinoceros Auklets fed more on Pacific sauries and Tufted Puffins on sandlance. Possible factors determining differences in Rhinoceros Auklet and Tufted Puffin breeding distributions have been discussed. In the north-eastern Pacific, Tufted Puffins were most numerous in Alaska, but Rhinoceros Auklets breed mainly from south-eastern Alaska to Washington. In British Columbia, Tufted Puffins occur mostly offshore but Rhinoceros Auklets are numerous inshore and offshore. Distribution differences between the species can be explained by differences in nocturnal and diurnal behaviour, different predation pressures and nesting flexibilities. Triangle Island had 25,000 breeding pairs of Tufted Puffins in 1975 and 15,000 pairs of Rhinoceros Auklets in 1976. Triangle Island has the largest Tufted Puffin colony in British Columbia.


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