The diet of the diving petrelsPelecanoides georgicusandP. urinatrixwas studied during 1986 (P. georgicus) and 1987 (both species) by lavaging adults as they returned to feed chicks on Bird Island, South Georgia. The diet of both species was dominated by crustaceans, in particular euphausiids (mainlyEuphausia superbaand someThysanoessa), which contributed 47–76 of the biomass of crustaceans in the diet ofP. georgicus, and copepods, which contributed 71 of the biomass of crustaceans in the diet ofP. urinatrix.Calanoides acutuswas the most numerous copepod in the diet of both species; however,Rhincalanus gigaswas more common inP. urinatrixthan inP. georgicus. The dominant amphipod in the diet ofP. georgicus,Primno macropa, was absent from the diet ofPelecanoides urinatrix, in whichThemisto gaudichaudii(rare inPelecanoides georgicus) dominated. Dietary differences were maintained in the period (2 weeks of a total of 10 weeks) when both species were simultaneously rearing chicks. Knowledge of the prey species and of the diving abilities and foraging habits of diving petrels suggests that at South GeorgiaPelecanoides urinatrixfeeds closer inshore and dives deeper thanPelecarnoides georgi
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