Noise pollution does not significantly affect distributions of red-wattled lapwing Vanellus indicus and pied king-fisher Ceryle rudis in a riverine ecosystem

Riverine ecosystems are increasingly threatened by anthropogenic activities from encroaching human populations. Noise pollution can disturb the density, behavior, and distribution of bird species, but interactions with other environmental factors and underlying mechanisms remain unclear. In this study, we investigated the influence of noise intensity on the presence and abundance of red-wattled lapwing Vanelus indicus and pied king-fisher Ceryle rudis along the Maroon river in Behbahan city, Khuzestan Province, southwestern Iran. We considered sampling date, vegetation density, daytime, daily temperature, and study site as covariates as well. Results of the generalized linear model indicated that noise intensity had no significant effect on the presence and abundance other either bird species. However, we did find that the distribution of V. indicus was significantly influenced by sampling date (P = 0.031) and vegetation density (P < 0.001). Additionally, we found that higher daily temperatures significantly increased both presence (P = 0.042) and abundance (P = 0.044) of V. indicus. For C. rudis, we observed that there were significant differences in presence (P < 0.001) and abundance (P = 0.009) across different study sites with significantly more at the Sang-Shekan study site upstream of the Maroon river. Presence (P < 0.001) and density (P < 0.001) of C. rudis decreased significantly later in the study season. Further research is needed to understand the potential resiliency of V. indicus and C. rudis against noise pollution, which may help inform future conservation and management strategies.