Aechmophorus clarkii  CLARK'S GREBEAechmophorus occidentalis  WESTERN GREBEPodiceps auritus  HORNED GREBEPodiceps grisigena  RED-NECKED GREBEPodiceps nigricollis  EARED GREBEPodilymbus podiceps  PIED-BILLED GREBETachybaptus dominicus  LEAST GREBE