Why do Eared Grebes Leave Hypersaline Lakes in Autumn?

Abstract

Jehl (1988) observed that the departure of Eared Grebes Podiceps nigricollis from Mono Lake, California, a major fall staging area, did not occur in relation to time of year or weather but was initiated after the density of brine shrimp (Artemia monica)-the major prey-fell below a predictable threshold. Although Caudell and Conover (2006) found no such relationship at Great Salt Lake, the other major staging area, reevaluation of their data indicates that the threshold concept applies there as well. Substantial differences in the staging ecology of Eared Grebes at the two lakes remain to be demonstrated.