Effects of Land Use and Land Cover on Occurrence of Barn Owl (Tyto Alba Scopoli, 1769) in Kathmandu Valley, Nepal

Abstract

Barn owl is a flagship and an indicator species of healthy grassland, and closely associated with agricultural area. Study on its presence and abundance is very important in order to understand the state of the ecosystem. No study has been done on Barn owl in Nepal and the effects of Land Use and Land Cover (LULC) on its occurrence remain unknown. This study was designed to assess the effects of the LULC on the occurrence of Barn owl in Kathmandu valley from July till December 2014 with monitoring till February 2015. Post-earthquake scoping survey was conducted from mid May till July 2015. Sampling design resulted total 17 plots of 1.5 km radius and 68 sub-plots of 250 m radius. Survey was conducted within the plots at day time with intensive survey in sub-plots. Sub-plots with inconclusive evidence of occurrence were surveyed with both visual and aural survey aided with play-back recordings for an hour before and after sunset. LULC mapping was done on IKONOS image in ArcGIS. A total of 261.95 km of major roads, 187.68 km rivers and 216 temples were digitized. Plot-level mapping resulted 52% grass cover, 41% built-up, 6% tree cover and 1 % water body. Site-level LULC revealed total 4.86 km 2 of built-up, 7.62 km2 of grass cover, 0.78 km2 of tree cover and 0.08 km2 of water body. Barn owl was recorded in 11 plots out of 17 plots. Barn owls occurred in 69 sites including 50 sites within the plots that constituted 54% Temporary Rest Site (TRS), 20% Active Roost Site (ARS), 14% Occupied Breeding Site (OBC), 8% site with death record and 2% with live Barn owl in captive stage. Majority of the sites (51%) used by Barn owl were buildings for both ARS and OBS. One-way ANOVA revealed that the occurrence of Barn owl was significantly affected by built-up level [F(2,14)= 5.049, p<0.05]. Occupancy modeling in program PRESENCE revealed tree cover had greater weight in determining occupancy at plot-level. Barn owl occupancy was highly positively correlated with temple (1.55 ± 1). Built-up has strong positive association with occupancy of Barn owl at both plot-level (1.25 ± 0.69) and sub-plot level (8.871 ± 5.177). The earthquake has negatively affected the potential sites of Barn owl. Rapid urbanization may result decrease in suitable cavities for Barn owls, affect breeding success and prey abundance which should be studied in detail to understand the pattern of occupancy, and attributes supportive for their survival in complex urban area like Kathmandu valley.