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Jeanniard-du-Dot T, Thomas AC, Cherel Y, Trites AW, Guinet C
Combining hard-part and DNA analyses of scats with biologging and stable isotopes can reveal different diet compositions and feeding strategies within a fur seal population
You are what you eat: animals' diet in the wild is key to their health, condition and demographic performances, but remains extremely difficult to assess in marine species. Jeanniard-du-Dot and co-workers have combined 3 methods of diet estimation (hard parts and DNA from scats; blood stable isotopes) with individual foraging behaviours (tracks, dives) to determine fine scale variations in diet composition of northern fur seals. They found that methods based on scats tend to be biased towards animals feeding closest to land and underestimate some dietary specializations within the population. Consequently, the combination of multiple methods helps identify and quantify specialist groups within a population in relation to their foraging distribution, thus providing a wider spatio-temporal ecological context for dietary analysis.