Impact of Human Recreational Disturbances on the Distribution of Avifauna in the Sinhararja Forest Reserve, Sri Lanka

Abstract

Sri Lanka’s protected areas are increasingly becoming prime tourism destinations for bothinternational and domestic tourists. Ironically, most nature-based tourism activities areconcentrated on few well-known National Parks and Forest Reserves in the country. As aresult, these sites are continuously subjected to increased visitor pressure. Conservationistsfrequently cite human recreational disturbances of wildlife as one of the key issues inbiodiversity conservation, especially in protected areas open for public visitation. Behaviourof birds has been found to be often influenced by human recreational activities; yet scientificevidences to assess the degree of this threat are limited in literature, especially in the SriLankan context. This study investigated the effects of human recreational disturbances on the distribution of39 species of birds along a highly visited nature trail in Sinhararja World Heritage Forest, SriLanka, from May to November, 2013. The study employed eighteen 25 m fixed-radius pointcounts laid perpendicular to the nature trail (six counts along the nature trail, and six countseach100m and 200 m perpendicular to the trail). Each point count was visited at least 18times during the study period at different times of the day. Point counts recorded 37 breedingresident species of which 17 were endemic, while there were two migrant species. Humanrecreational disturbances were defined in terms of visitor group size (visual disturbance) andtheir relative noise level (noise disturbance). Accordingly, four disturbance levels (no humandisturbance, low human disturbance, medium human disturbance and high humandisturbance) were derived using a two-step clustering procedure. The relationship betweendisturbance levels and abundance of birds was statistically tested Results revealed a significant negative correlation between visitor numbers and abundance ofbirds in point counts on the trail (Spearman's rho = -0.20, p=0.045), and a significantpositive correlation between the same variables in plots 200m away from the trail at 0.05significance level (Spearman's rho = 0.19, p=0.049). This in general, suggests a possibleavoidance of edge habitats by birds at the human presence and flushing into the forest.Regardless of the disturbance type, mean number of birds recorded was highest in plots onthe trail (mean =14.20 ± SD or SE 1.98) followed by plots 200 m away from the trail (mean=10.11± SD or SE 2.00). Null hypothesis of “bird counts at various distances from the trailare independent of disturbance levels” was tested using Chi-square test for each species. Outof 22 species with sufficient data available for analysis, Ashy-headed laughing thrush(Garrulax cinereifrons) found to shift away from the trail as disturbance levels increased (χ2-=6.41, p=0.041). For the most species recorded in the study, non-significance for Chi-squaretest suggests that these species may have become habituated to low-intensity and predictablehuman recreational disturbances.