Drivers of interspecific spatial segregation in two closely related seabird species at a pan-Atlantic scale

Aim. Ecologically similar species living in sympatry are expected to segregate to reduce the effects of competition where such resources are limiting. Segregation from heterospecifics commonly occurs in space, but it is often unknown whether segregation has underlying environmental causes. Indeed, species could segregate because of different fundamental environmental requirements (i.e., ‘niche divergence’), because competitive exclusion at sympatric sites can force species to either change the habitat use they would have at allopatric sites (i.e., ‘niche displacement’) or to avoid certain areas, independently of habitat (i.e., ‘spatial avoidance’). Testing these hypotheses requires the comparison between sympatric and allopatric sites. Understanding the competitive mechanisms that underlie patterns of spatial segregation could improve predictions of species responses to environmental change, as competition might exacerbate the effects of environmental change. Location. North Atlantic an..., The data consists in common guillemots (Uria aalge) and Brünnich’s guillemots (U. lomvia) GPS tracking data from multiple colonies. Details on data collection methodologies are available in the associated publication in Journal of Biogeography (https://doi.org/10.1111/jbi.15042)., , # Drivers of interspecific spatial segregation in two closely related seabird species at a pan-Atlantic scale

[https://doi.org/10.5061/dryad.5dv41nsf9](https://doi.org/10.5061/dryad.5dv41nsf9)

Datasets and codes for running the analyses in [https://doi.org/10.1111/jbi.15042](https://doi.org/10.1111/jbi.15042). Common guillemots (*Uria aalge*) and Brünnich's guillemots (*U. lomvia*) were fitted with GPS loggers at 20 colonies across the North Atlantic and Arctic during the breeding season to study at-sea foraging habitat use. Overlap analyses were run to estimate the levels of spatial segregation between the two species at sympatric sites. Habitat models were run to evaluate the habitat preferences of each species separately, and test three hypotheses to explain the observed spatial segregation: niche divergence (different fundamental environmental requirements for the two species), niche displacement (competitive exclusion at sympatric sites forcing species to change the habitat use t...