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Foraging niche separation in sympatric temperate-latitude fur seal species
journal contribution
posted on 2017-02-01, 00:00 authored by A J Hoskins, N Schumann, D P Costa, John ArnouldJohn ArnouldTo reduce interspecific competition, sympatric species must segregate their re - sources in a variety of dimensions. Otariid seals (fur seals and sea lions) breed sympatrically in several regions and, where this occurs, differences in lactation length and body size (which in - fluence foraging behaviour and diet) are apparent. However, congeneric Australian fur seals Arctocephalus pusillus doriferus (AUFS) and New Zealand fur seals A. forsteri (NZFS) breed sympatrically on several islands within south-eastern Australia, and display complete overlap in breeding period. How these populations segregate resources is unknown. We assessed the for - aging ecology and diet of adult females of both species breeding on Kanowna Island, south-eastern Australia. Foraging locations and diving behaviour differed between species, with AUFS diving deeper (consistent with benthic foraging; 70.6 ± 2.3 m [SD]), while NZFS predominantly dived to shallow depths (16.9 ± 3.7 m), suggesting an epipelagic foraging mode. A bimodal pattern in foraging range was observed in NZFS, with animals either foraging near the colony (15.7 ± 13.0 km) or travelling beyond the continental shelf (363.4 ± 17.2 km), while AUFS foraged within 79.8 ± 8.8 km of the colony. Although dietary composition was similar, the relative importance of prey differed. NZFS predominantly consumed pelagic species, while AUFS primarily consumed a variety of be nthic/demersal species (niche overlap 0.39). These differences coincide with the divergence in population demography of the 2 species (AUFS exhibit lower, more stable fecundity compared to NZFS) and are consistent with predictions that foraging mode influences life history traits in otariid seals.
History
Journal
Marine ecology progress seriesVolume
566Pagination
229 - 241Publisher
Inter-ResearchLocation
[Oldendorf/Luhe, Germany]Publisher DOI
ISSN
0171-8630Language
engPublication classification
C Journal article; C1 Refereed article in a scholarly journalCopyright notice
2017, Inter-ResearchUsage metrics
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Keywords
Benthic divingPelagic divingSpatial distributionDiet overlapAustralian fur sealNew Zealand fur sealScience & TechnologyLife Sciences & BiomedicinePhysical SciencesEcologyMarine & Freshwater BiologyOceanographyEnvironmental Sciences & EcologyNEW-ZEALANDANOLIS LIZARDSCLIMATE-CHANGEHABITAT USEFISH PREYBODY-SIZEDIETLIONSLOCATIONSZoologyOceanographyEcology
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