From video recordings to whisker stable isotopes: a critical evaluation of timescale in assessing individual foraging specialisation in Australian fur seals

Kernaléguen, Laëtitia, Dorville, Nicole, Ierodiaconou, Daniel, Hoskins, Andrew J., Baylis, Alastair M. M., Hindell, Mark A., Semmens, Jayson, Abernathy, Kyler, Marshall, Greg J., Cherel, Yves and Arnould, John P. Y. 2016, From video recordings to whisker stable isotopes: a critical evaluation of timescale in assessing individual foraging specialisation in Australian fur seals, Oecologia, vol. 180, no. 3, pp. 657-670, doi: 10.1007/s00442-015-3407-2.

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Title From video recordings to whisker stable isotopes: a critical evaluation of timescale in assessing individual foraging specialisation in Australian fur seals
Author(s) Kernaléguen, Laëtitia
Dorville, Nicole
Ierodiaconou, DanielORCID iD for Ierodiaconou, Daniel orcid.org/0000-0002-7832-4801
Hoskins, Andrew J.
Baylis, Alastair M. M.
Hindell, Mark A.
Semmens, Jayson
Abernathy, Kyler
Marshall, Greg J.
Cherel, Yves
Arnould, John P. Y.ORCID iD for Arnould, John P. Y. orcid.org/0000-0003-1124-9330
Journal name Oecologia
Volume number 180
Issue number 3
Start page 657
End page 670
Total pages 14
Publisher Springer
Place of publication Berlin, Germany
Publication date 2016-03
ISSN 1432-1939
Summary Estimating the degree of individual specialisation is likely to be sensitive to the methods used, as they record individuals' resource use over different time-periods. We combined animal-borne video cameras, GPS/TDR loggers and stable isotope values of plasma, red cells and sub-sampled whiskers to investigate individual foraging specialisation in female Australian fur seals (Arctocephalus pusillus doriferus) over various timescales. Combining these methods enabled us to (1) provide quantitative information on individuals' diet, allowing the identification of prey, (2) infer the temporal consistency of individual specialisation, and (3) assess how different methods and timescales affect our estimation of the degree of specialisation. Short-term inter-individual variation in diet was observed in the video data (mean pairwise overlap = 0.60), with the sampled population being composed of both generalist and specialist individuals (nested network). However, the brevity of the temporal window is likely to artificially increase the level of specialisation by not recording the entire diet of seals. Indeed, the correlation in isotopic values was tighter between the red cells and whiskers (mid- to long-term foraging ecology) than between plasma and red cells (short- to mid-term) (R (2) = 0.93-0.73 vs. 0.55-0.41). δ(13)C and δ(15)N values of whiskers confirmed the temporal consistency of individual specialisation. Variation in isotopic niche was consistent across seasons and years, indicating long-term habitat (WIC/TNW = 0.28) and dietary (WIC/TNW = 0.39) specialisation. The results also highlight time-averaging issues (under-estimation of the degree of specialisation) when calculating individual specialisation indices over long time-periods, so that no single timescale may provide a complete and accurate picture, emphasising the benefits of using complementary methods.
Language eng
DOI 10.1007/s00442-015-3407-2
Field of Research 060201 Behavioural Ecology
060205 Marine and Estuarine Ecology (incl Marine Ichthyology)
Socio Economic Objective 970106 Expanding Knowledge in the Biological Sciences
HERDC Research category C1 Refereed article in a scholarly journal
ERA Research output type C Journal article
Copyright notice ©2016, Springer
Persistent URL http://hdl.handle.net/10536/DRO/DU:30077890

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