Comparison of isotopic niche metrics between study species, sexes, and seasons (Nov.-May vs. Jun.-Oct.).

Carbon range, the distance between max. and min. δ¹³C values; (2) nitrogen range, the distance between max. and min. δ¹⁵N values; (3) total area (TA), as the convex hull area encompassed by all values in a δ¹³C – δ¹⁵N bi-plot space; (4) standard ellipse area (SEA); (5) standard ellipse corrected for sample size (SEA_C), depicting the area with 40% probability of containing a subsequently sampled datum; (6) mean distance to centroid (CD), as the average Euclidean distance of each isotopic value to the δ¹³C - δ¹⁵N centroid, where the centroid is the mean δ¹³C – δ¹⁵N value for all values in the food web; (7) mean nearest neighbour distance (NND), as the mean of the Euclidean distances to each value nearest neighbour in bi-plot space, and thus a measure of the overall density of ‘values packing’; (8) SD nearest neighbour distance (SDNND), as a measure of the evenness of ‘values packing’ in bi-plot space that is less influenced than NND by sample size.

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