USE OF AT-SEA DISTRIBUTION DATA TO DERIVE POTENTIAL FORAGING RANGES OF MACARONI PENGUINS DURING THE BREEDING-SEASON

Macaroni penguins are the main avian consumer of Antarctic krill in th e vicinity of South Georgia. The largest breeding colonies occur on sm all offshore islands to the northwest of the main island. To delimit t he foraging range of penguins from these colonies during the chick-rea ring period, we used a series of ship-based survey transects to estima te their distribution and abundance. The survey transects were positio ned so as to radiate from a point close to those islands with the larg est colonies. Spatial and temporal variations within the data are exam ined. Penguins were mostly over the continental shelf in water less th an 350 m depth and with more than 70 % of birds at distances less than 40 km from the main breeding site. To model the observed distribution of penguins, a theoretical at-sea distribution is developed together with a 'potential foraging footprint'. The results are compared with t hose from previous models based solely on the use of foraging trip dur ation and at-sea activity bud gets. The foraging 'footprint' is probab ly the best basis currently available for assessing the nature of inte ractions between macaroni penguins and the commercial fisheries for kr ill.