Capelin Selection by Common and Brunnich's Guillemots during the Prelaying Season

Abstract

During the prelaying season common uria aalge and brunnich''s guillemot U. fomvia off Finnmark, northern Norway fed exclusively on capelin Mallotus villosus. In mixed flocks common guillemotis took smaller fish than brunnich''s guillemots. In the absence of common guillemots, brunnich''s guillemots fed on a wider size spectrum and also included the small fish otherwise eaten by common guillemots. A comparison of the size distribution of fish eaten and those caught in trawl net samples suggested that common guillemots fed mainly on maturing female capelin in the upper water masses, whereas brunnich''s guillemots dove deeper and fed on mature and spent male and female capelin caught near the bottom.