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Marine Ecology Progress Series

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MEPS 549:217-229 (2016)  -  DOI:

Niche partitioning by three Pterodroma petrel species during non-breeding in the equatorial Pacific Ocean

M. J. Rayner1,2,*, N. Carlile3, D. Priddel3, V. Bretagnolle4, M. G. R. Miller5, R. A. Phillips6, L. Ranjard7, S. J. Bury8, L. G. Torres9

1Auckland Museum, Private Bag 92018, Auckland, 1141, New Zealand
2School of Biological Sciences, University of Auckland, 3A Symonds Street, Auckland, PB 92019, New Zealand
3Office of Environment and Heritage, PO Box 1967, Hurstville, NSW 2220, Australia
4Centre National de la Recherche Scientifique, Centre d’Etudes Biologiques de Chizé, 79360 Beauvoir-sur-Niort, France
5Centre for Tropical Environmental and Sustainability Science, James Cook University, PO Box 6811, Cairns, Queensland, 4870, Australia
6British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, UK
7Research School of Biology, The Australian National University, Canberra, ACT 0200, Australia
8National Institute of Water and Atmospheric Research, Greta Point, Private Bag 14-901, Kilbernie, Wellington 6011, New Zealand
9Marine Mammal Institute and Department of Fisheries and Wildlife, Hatfield Marine Science Center, Oregon State University, Newport, Oregon 97365, USA
*Corresponding author:

ABSTRACT: Niche divergence is expected for species that compete for shared resources, including migrants that occupy similar regions during the non-breeding season. Studies of temperate seabirds indicate that both spatial and behavioural segregation can be important mechanisms for reducing competition, but there have been few investigations of resource partitioning by closely related taxa in low productivity, tropical environments. We investigated niche partitioning in 3 gadfly petrel taxa, Pterodroma leucoptera leucoptera (n = 22), P. leucoptera caledonica (n = 7) and P. pycrofti (n = 12), during their non-breeding season in the eastern tropical Pacific Ocean by combining tracking data from geolocator-immersion loggers with remotely sensed environmental data in species distribution models (SDMs), and by comparing feather stable isotope ratios. The 3 taxa showed spatial partitioning: two foraged in the North Equatorial Counter Current and one in the South Equatorial Current. This reflected differences in their realised habitat niches, with significant taxon-specific responses to thermocline depth, sea surface temperature and bathymetry. There were also differences among taxa in activity patterns, and all birds spent a much larger proportion of time in flight at night than during the day, suggesting predominance of nocturnal foraging behaviour. Comparison of stable isotope ratios in feathers suggests that P. l. leucoptera and P. pycrofti mainly consume vertically migrating mesopelagic fishes, whereas the diet of P. l. caledonica also includes some lower trophic levels including crustaceans and squid. Unique insights can be gained from studies of the foraging ecology of tropical pelagic seabirds, in comparison with temperate and polar waters, and are urgently required for understanding and protecting tropical avifauna in key marine habitats.

KEY WORDS: Species distribution models · Stable isotope analysis · Niche · Foraging ecology · Seabirds · Tropical Pacific

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Cite this article as: Rayner MJ, Carlile N, Priddel D, Bretagnolle V and others (2016) Niche partitioning by three Pterodroma petrel species during non-breeding in the equatorial Pacific Ocean. Mar Ecol Prog Ser 549:217-229.

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