Patch size does not always indicate bird species diversity: case in peri-urban tropical habitat in Riau, Indonesia

Larger patches generally are inhabited by higher species richness, including birds, as predicted by the island biogeography theory. The objective of this research was to reveal the response of bird species richness in different patch sizes in peri-urban habitat. The study site area was five patches (2 large patches near human activities, remote large patch with a small lake, small patch, corridor patch) of disturbed secondary shrub-forest in Riau University, Sumatra. Birds were observed using the standard point-counts in early morning and late afternoon (8 points/patch, 3 replicates, total 40 observation-hour) in March-April 2021. Species richness (S), Shannon-Wiener diversity indices (H’), Chao species prediction, and Bray-Curtis similarity indices (B) were calculated. Total of 979 individual birds were observed, consisted of 68 species from 28 families with B ranged from 0.573 to 0.846. Large patch with lake in remote area had the highest species richness (S:39 species, Chao:54) and H’ (3.097). However, two large patches closed to human activities had the lowest number of species (S:27, Chao:30, H’:2.908, and S:23, Chao:32, H’:2.938, respectively), even lower than small patch (S:30, Chao:40, H’:2.925) or corridor patch (S:34; Chao:51, H’:2.724). Clearly human disturbance and micro-habitat diversity affect species richness in a local scale.