期刊
JOURNAL OF ANIMAL ECOLOGY
卷 87, 期 5, 页码 1286-1298出版社
WILEY
DOI: 10.1111/1365-2656.12856
关键词
bio-logging; multidimensional nutritional niche framework; multivariate ellipse-based Bayesian approach; niche theory; nutritional landscapes; seabirds
资金
- Faculty of Veterinary Science DVC compact fund (The University of Sydney)
- Massey University Animal Ethics committee [13/65]
- New Zealand Department of Conservation [35189-FAU]
- Loxton research fellowship from the Sydney School of Veterinary Science, The University of Sydney
Our understanding of the niche concept will remain limited while the quantity and range of different food types eaten remain a dominant proxy for niche breadth, as this does not account for the broad ecological context that governs diet. Linking nutrition, physiology and behaviour is critical to predict the extent to which a species adjusts its nutritional niche breadth at the levels of prey (prey composition niche, defined as the range of prey compositions eaten) and diet (realized nutritional niche is the range of diets composed through feeding on the prey). Here, we studied adult chick-rearing Australasian gannets Morus serrator to propose an integrative approach using sea surface temperature anomalies (SSTa), geographic location and bathymetry over different years, to explore their relationship with the nutritional composition of prey and diets (i.e. prey composition and nutritional niche breadth), habitat use and foraging behaviour. We found that gannets feed on prey that varied widely in their nutritional composition (have a broad prey composition niche), and composed diets from these prey that likewise varied in composition (have a broad realized nutritional niche), suggesting generalism at two levels of macronutrient selection. Across seasons, we established nutritional landscapes (hereafter nutriscapes), linking the nutritional content of prey (wet mass protein-to-lipid ratioP:L) to the most likely geographic area of capture and bathymetry. Nutriscapes varied in their P:L from 6.06 to 15.28, over time, space and bathymetry (0-150m). During warm water events (strong positive SSTa), gannets expanded their foraging habitat, increased their foraging trip duration and consumed prey and diets with low macronutrient content (wet mass proportions of P and L). They were also constrained to the smallest prey composition and realized nutritional niche breadths. Our findings are consistent with previous suggestions that dietary generalism evolves in heterogeneous environments, and provide a framework for understanding the nutritional goals in wild marine predators and how these goals drive ecological interactions and are, in turn, ultimately shaped by environmental fluctuations.
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