Mates but not sexes differ in migratory niche in a monogamous penguin species

• Published in: Biology Letters
• Main Authors: Thiebot, Jean-Baptiste, Bost, Charles-André, Dehnhard, Nina, Demongin, Laurent, Eens, Marcel, Lepoint, Gilles, Cherel, Yves, Poisbleau, Maud
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 2015
• Subjects: Rockhopper penguin
• Online Access: http://dx.doi.org/10.1098/rsbl.2015.0429; https://royalsocietypublishing.org/doi/pdf/10.1098/rsbl.2015.0429; https://royalsocietypublishing.org/doi/full-xml/10.1098/rsbl.2015.0429

Strong pair bonds generally increase fitness in monogamous organisms, but may also underlie the risk of hampering it when re-pairing fails after the winter season. We investigated whether partners would either maintain contact or offset this risk by exploiting sex-specific favourable niches during winter in a migratory monogamous seabird, the southern rockhopper penguin Eudyptes chrysocome . Using light-based geolocation, we show that although the spatial distribution of both sexes largely overlapped, pair-wise mates were located on average 595 ± 260 km (and up to 2500 km) apart during winter. Stable isotope data also indicated a marked overlap between sex-specific isotopic niches ( δ 13 C and δ 15 N values) but a segregation of the feeding habitats ( δ 13 C values) within pairs. Importantly, the tracked females remained longer (12 days) at sea than males, but all re-mated with their previous partners after winter. Our study provides multiple evidence that migratory species may well demonstrate pair-wise segregation even in the absence of sex-specific winter niches (spatial and isotopic). We suggest that dispersive migration patterns with sex-biased timings may be a sufficient proximal cause for generating such a situation in migratory animals.