Nest-site selection of kittlitz’s murrelets brachyramphus brevirostris on Kodiak Island, Alaska

Abstract

We studied aspects of nest-site selection by Kittlitz’s Murrelet Brachyramphus brevirostris on Kodiak Island, Alaska, during 2008–2011. We discovered 54 Kittlitz’s Murrelet nests on the surface of mountain slopes between 188 and 454 m above sea level, in an area devoid of glaciers. Nests were dispersed across the landscape, with an annual average of 0.09 nests/ha of habitat searched. Four nests were reused in separate study years, and 10 additional nests were located within 60 m of a nest site active in a previous study year. Nest scrapes were most often shallow, circular depressions in gravel situated among larger rocks and immediately downslope of one or more prominent moderate-to large-sized rocks. We compared the habitat characteristics of plots centered on nest sites (nest plots) with those of randomly selected locations within 150 m of nests (near-nest plots) and within the entire area where nest searching was conducted (random plots). Mean percent vegetation cover on nest plots was less than half that of near-nest and random plots (6.6%, 14.0%, 16.3%, respectively). The percent cover of rocks 10–30 cm diameter was higher, and percent cover of rocks >30 cm diameter was lower at nest plots compared with near-nest and random plots. Nest plots were located on steeper slopes (mean 29°) than near-nest and random plots (27° and 25°, respectively) and farther from edges of continuous vegetation (mean 79 m) than near-nest and random plots (mean 64 m and 63 m, respectively). Nest survival was unrelated to selected habitat variables, although our sample size may have been too small to detect an effect. The high dispersion of active nests and sparse vegetation in areas surrounding nest sites suggest that nest-site preference by Kittlitz’s Murrelets may reflect an ecological strategy to minimize nest predation.