Intra- and inter-specific spatial segregation between the Black-browed Albatross and the White-chinned Petrel in waters of the Southwest Atlantic during the non-breeding season

Seabirds are useful tools for studying the segregation of the habitat use. The general aim of the present study is to evaluate the intra- and inter-specific spatial segregation in Black-browed Albatross (BBA, Thalassarche melanophris) and White-chinned Petrel (WCP, Procellaria aequinoctialis) during the non-breeding season in waters of the Southwest Atlantic. Satellite transmitters (n=25) were deployed during the period 2011-2015. In order to determine the segregation, Kernel analysis (core area: 50%) and Generalized Linear Models using an overlap index considering age and sex (UDOI=0 no overlap; UDOI≥1 total overlap) were performed. The BBA used areas in Río de la Plata, El Rincón and at south of Península Valdés while the WCP in addition to the first two areas also used an area in Brazil. There were no significant differences that indicated inter-specific segregation (UDOI50%WCP/BBA=0.013±0.026; P>0.05). In relation to intra-specific segregation in BBA, adult birds had a more extensive distribution than juveniles. Adult females used more pelagic areas than males and juvenile females. The core areas corresponded to El Rincón and Río de la Plata, although adult individuals also made use of areas located further south. With respect to UDOI, only significant differences were found in age group, where segregation was greater between adults and juveniles than between juvenile individuals (UDOI50%JA=0.017±0.029; UDOI50%JJ=1.25±2.43; P<0.05). The results presented here are of great relevance for the establishment of conservation measures considering that by-catch is one of the main threats for both species.