Flock-fishing in the Great Crested Grebe Podiceps cristatus

摘要

Flock-fishing, i.e. when a tight group of birds moves in a coordinated way under more or less synchronous diving, is common in cormorants Phalacrocorax spp. and mergansers Mergus spp., but is said in the major handbooks not to occur in Great Crested Grebes Podiceps cristatus. The present communication reports repeated observations of such flock-fishing at a South Swedish lake during summer. Great Crested Grebes' dispersion in relation to diving activity within large aggregations on a nearby lake in late autumn - early winter is also described.