Mortality Census of the Road-Killed Butterflies in Mahendra Highway, Nepal

Increasing roads become the serious conservation threats to the animal populations. The most direct effect of roads on them is deadly collision with vehicles, leading to high levels of injury or death. Estimates of detectability of road-killed higher vertebrates have been determined but not for the invertebrates like butterflies, although they are frequently killed insects group on roads. This is the first comprehensive mortality census of road-killed butterflies in Nepal. The main aim of this study was to estimate the detectability of road-killed butterflies in Mahendra Highway, the busiest highway in Nepal. We established eight transects, each of 500 m long within the randomly selected forest and human settlement landscapes. Pearson’s correlation was calculated to test the link between the number of road-killed and living butterflies. All together 1000 butterfly individuals were counted throughout the study periods including road-killed and living butterflies. Among them, 364 butterflies were counted raodkilled whereas 636 butterflies were living. Forest landscape contributed higher number in both road-killed and living butterflies than human settlement landscape. Also, the number of butterflies killed on the roads were significantly correlated with number of living butterflies on the road. Our results indicate that road has the significant impact on loss of butterfly population. Also, higher the number of living butterflies more will be road mortality. The public awareness and maintaining the habitats with high forbs cover, gardening, avoid depositing asphalts, etc. in the vicinity of road can denigrate the rate of road mortality of butterflies.