Breeding Ecology of Great Crested Grebe Podiceps cristatus

—Breeding-site Tenacity and Production of Second Brood

Abstract

Observation of the breeding Great Crested Grebe Podiceps cristatus was carried out at two small man-made irrigation ponds, Shin Pond and Mochinosawa Pond, in Aomori Prefecture. A pair of grebes bred every year at Shin Pond from 2006 to 2009, and at Mochinosawa Pond from 2008 to 2009, respectively. The apparently same pair bred in Shin Pond for four successive years. Pairs in both sites attempted second broods within a breeding season. The absence of conspecific competition for diet or nesting-sites, and the presence of abundant fish in these two sites might facilitate these attempts at second broods.