Comparative isotopic niches of syntopic Imperial Cormorant and Rock Shag at two different colonies in central Patagonia, Argentina

GATTO, ALEJANDRO; YORIO, PABLO

Congreso; 6th World Seabird Twitter Conference; 2020

World Seabird Union

Following the competitive exclusionprinciple, two closely-related species living in sympatry can only coexist if ecologicalniche partitioning occurs. Imperial Cormorant (Leucocarbo atriceps) and Rock Shag (L. magellanicus) often breed in mixed-species colonies. Isotopicniche assessment of both species was performed during two breeding seasons in two different colonies were they breed syntopically,where whole blood samples were obtained from breeding adults of both species duringthe early chick stage. The isotopic niche overlap between species was small orinsignificant, suggesting niche partitioning, and the isotopic niche width inthe different colonies and seasons was significantly smaller in the ImperialCormorant than in the Rock Shag. Further studies are needed at additionalcolonies where these species breed alone and with other cormorant species, consideringthat the metacommunity framework predicts that the combination of species in metapopulationcontexts could be sometimes achieved through pairs of species with similarresource utilization.