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.

Anurans of select green spaces of Davao City, Mindanao Island, Philippines

“…This observation may connote that endemic anurans have a greater affinity to forested habitats or those with thicker vegetation than with more open habitats (Solania and Fernandez-Gamalinda 2018;Delima-Baron et al 2021). The presence of the endemic F. vittigera, F. moodiei, and L. leytensis in green spaces near city centers supports previous accounts of the habitat generalist nature of these species as they can thrive in low elevation, agricultural, and highly disturbed habitats (Delima et al 2006;Brown et al 2013;Gersava et al 2020).…”

“…To date, published literature on anurans in green spaces of Davao City is still sparse. Although existing studies on anurans of the city were already published (Ibañez et al 2012;Apayor-Ynot et al 2017;Dacalus et al 2017;Baron et al 2019;Jabon et al 2019;Gersava et al 2020), data from these accounts were from surveys conducted on a single location within Davao City. In contrast, the present study provides data on anurans in green spaces previously not surveyed and has included several locations.…”

“…In the Philippines, accounts of anurans in non-forested habitats are available, but these are direct comparisons to species found in forested areas close to surveyed non-forested areas (Aureo and Bande 2019;Cruz et al 2019). Philippine data on anurans documented from urban green spaces in highly urbanized localities are limited to current writing (Apayor-Ynot et al 2017;Jabon et al 2019;Gersava et al 2020;Duco et al 2020).…”

Diet of the Nonnative Southeast Asian Treefrog Polypedates leucomystax on Okinawajima, Ryukyu Archipelago, Japan

“…For instance, while orthopterans emerged as the most numerous and frequently consumed prey category in Okinawajima and Vietnam (as "Polypedates cf. leucomystax": Le et al, 2018), they were over- taken by hymenopterans (mostly Formicid ants) in the Philippines, Malaysia, and Singapore (Berry, 1965;Almeria and Nuñeza, 2013;Yap, 2015;Gersava et al, 2020). As Katsube and Ota (2007) proposed, the prevalence of these prey types could reflect their high abundance in the primary habitats of this frog in Okinawajima (secondary forests, shrubs, and harvested areas).…”

Amphibians in the natural and human-modified ecosystems at the Center for Ecological Development and Recreation (CEDAR), Bukidnon, the Philippines

“…Biodiversity loss is drastically increasing worldwide, and amphibians represent the most threatened vertebrate class in terms of population and species declines (Collins and Storfer, 2003;Collins, 2010;Luedtke et al, 2023). These declines are mainly due to human-influenced activities such as habitat loss and degradation, as well as disease epidemics, and climate change (Brook et al, 2003;Stuart, 2004;Gallant et al, 2007;Alcala et al, 2012;Luedtke et al, 2023). In the Philippines, amphibian population declines are largely attributed to over-exploitation, habitat fragmentation, and habitat destruction (Stuart, 2004;Alcala et al, 2012).…”