Similarity analysis of the diet composition among bird species and sampling sites through Non-metric Multidimensional Scaling (NMDS). Only species with at least three samples that provided valid data are represented. (a) Distribution plot in a two-dimensional space of the plant families (family name's ending “ceae” was removed from the graph to prevent label overlap) appearing in green, and invertebrate families appearing in red. Distribution plot of the samples by (b) species and (c) sites. The quality of the representation in space, or stress value, was 0.141. Numbers in brackets indicate the sample size.