Native and invasive alien anuran species in urbanized areas in Davao City, Philippines, with preliminary study of feeding biology

Abstract

This article presents the anuran species in urbanized areas, diet overlaps between native and invasive alien anuran species, and its implications on conservation and ecological health in urban environment. Visual encounter technique following the road as a transect was done to determine the diversity of anurans, and stomach content extraction was employed to analyze its diet composition. Results revealed a very low anuran diversity (Shannon-Weiner; 1.165), which is dominated by invasive alien anuran species. Jackknife 1 species richness estimator indicated that 77-100% of the anuran species in the area were already detected which includes three invasive; Rhinella marina (Linnaeus, 1758), Kaloula pulchra Gray, 1831, Hoplobatrachus rugulosus (Wiegmann, 1834), and two natives; Polypedates leucomystax (Gravenhorst, 1829), Limnonectes leytensis (Boettger, 1893). Additionally, assessing the diet of 33 randomly selected anuran samples revealed that Formicidae dominated their food item. Invasive anurans also showed more diverse diet composition compared to native frogs, in which diet overlaps were observed. In conclusion, the study supports the idea that urbanization decreases anuran diversity and supports the dominance of invasive anurans which compete for food with their native and endemic counterparts. Additionally, it is important to manage invasive anurans that dominates urban ecosystem which might affect the native and endemic species in the area and possibly in nearby pristine environment.