Mates but not sexes differ in migratory niche in a monogamous penguin species
Thiebot, J.; Bost, C.; Dehnhard, N.; Demongin, L.; Eens, M.; Lepoint, G.; Cherel, Y.; Poisbleau, M. (2015). Mates but not sexes differ in migratory niche in a monogamous penguin species. Biol. Lett. 11(9): 20150429. https://dx.doi.org/10.1098/rsbl.2015.0429
In: Biology Letters. Royal Society Publishing: London. ISSN 1744-9561; e-ISSN 1744-957X, more
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 (d13C and d15N values) but a segregation of the feeding habitats (d13C 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.
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