Is there sexual segregation in habitat selection by Black-browed Albatrosses wintering in the south-west Atlantic?

ABSTRACT

Sexual segregation in habitat use occurs when sexes differ in their use of the physical environment and is widely reported among seabirds. The Black-browed Albatross (Thalassarche melanophris) is one of the most abundant seabird species in the south-west Atlantic, but whether the sexes differ in their habitat selection during winter remains unknown. Here, we tested for sexual segregation in adult and immature Black-browed Albatrosses during winter. Movement data from 21 satellite-tracked Black-browed Albatrosses across the south-west Atlantic Ocean between 2011 and 2015 were used to determine suitable foraging habitat for males (n = 7) and females (n = 14) using habitat selection models. Sexual segregation was then assessed using an index of niche overlap for immature and adult age classes. Variables with the highest importance in habitat selection models across all groups were depth and sea surface temperature. The highest probabilities of occurrence were in shallow waters and intermediate surface temperatures. No sexual segregation was found which may be because of the large abundance of prey in the region and moderate energy requirements during the non-breeding season. These results are relevant for spatially explicit conservation management in this region, including the designation of marine protected areas. Indeed, bycatch in fisheries is a major threat to seabirds in this area, and foraging behaviour and performance in winter of this keystone species will influence their future reproductive performance.

KEYWORDS:

• Sexual segregation
• foraging habitat selection
• Black-browed Albatross
• south-west Atlantic Ocean
• oceanographic variables
• non-breeding season
• immatures

Acknowledgements

The authors thank the Instituto de Investigaciones Marinas y Costeras (Universidad Nacional de Mar del Plata – Consejo Nacional de Investigaciones Científicas y Técnicas) and Instituto Antártico Chileno. We are grateful to Teresa Ravasi, Germán García, Rocío Mariano-Jelicich, Carolina Block, Julián Bastida and Maximiliano Hernandez who helped in the fieldwork, and also the Captain and crew of the vessels involved in trials Ur-Ertza, Raptor, Stuka and Capitán Porreti. We also thank Cristian Marinao for providing advice with statistical analysis. We are grateful to the Agreement on the Conservation of Albatrosses and Petrels for providing secondment to the lead author. We would like to thank Flounder Pesca Deportiva for donating equipment for fieldwork. We are grateful to three anonymous reviewers and journal editors who helped to improve the manuscript, as well as Peter Lowther through the Association of Field Ornithologists’ programme for editorial assistance.

Disclosure statement

No potential conflict of interest was reported by the author.

Location information

The study area covered the following extent: 21.96° - 54.04° S, 70.04° - 43.86° W.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by the [Universidad Nacional de Mar del Plata] under Grant [15/E795-EXA842/17]; [Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina] under Grant [PIP-CONICET 00070]; and [Agencia Nacional de Promoción Científica y Tecnológica] under Grant [PICT 2013‐0711 and PICT 2017‐0573]. The authors thank Seaworld & Busch Gardens Conservation Fund, Mohamed Bin Zayed and Phil and Marsha Dowd for additional funding.