Landscape Correlates of Large Mammal Occupancy in Chitwan Annapurna Landscape, Nepal

Abstract

Human activities and natural processes are causing landscape change and biodiversity loss. Large mammals are among the most threatened animals by land use and land cover change (LULCC). They are under the pressure of habitat loss and alternation, especially in the areas outside the protected area system. Chitwan Annapurna Landscape (CHAL) is a north-south linkage between Chitwan National Park and Annapurna Conservation Area in central Nepal that provide a safe passage of forest corridor for wildlife. This study attempted to: 1) characterize the spatio-temporal pattern of land use and land cover change in central part of CHAL; 2) evaluate the relative abundance of large mammals and their interaction with people; 3) examine the impacts of environmental correlates on the occupancy of large mammals, and 4) identify the landscape level connectivity for the large mammals. The LULCC in the area was characterized by supervised classification of Landsat images for 2000, 2010 and 2020. Relative abundance of large mammals in four different blocks (A–D) of the study area was done by line-transect (n = 150, average length = 3.18 ± 0.11 km) survey. Interaction of human with large mammals were assessed through the questionnaire survey among 600 respondents. The occupancy of the large mammals was evaluated using the program PRESENCE. Potential distribution of the large mammals and their environmental correlates were identified by species distribution modelling using maximum entropy algorithm. Important landscape patches in the study area were identified and least-cost path approach with circuit theory was used to pinpoint the linkages among those patches. The Kernel density estimation method was used to identify the hotspots for the connection of isolated population of the mammals in the patches. The LULCC results revealed that forest is dominant feature of the study area. Overall forest increased by 360.52 km 2 and cropland, grassland and barren area decreased by 329.45 km 2 , 46.78 km 2 and 12.18 km ix

2 respectively from 2000 to 2020. A total of 18 species of large mammals were enumerated from primary field data. Chital was the most abundant species in lowland (block A) and northern red muntjac in mid-hills (blocks B, C and D). Among the carnivores, tiger was recorded only from the lowlands while leopards were reported throughout the landscape, and Himalayan black bear was reported in blocks B, C and D. Land cover types, anthropogenic disturbances, and coverage of invasive and alien plant species (IAPS) have been identified to affect the abundance of large mammals. The human-large mammal conflict is a serious problem in this landscape with an estimated annual loss of US$ 12.02 and 74.60 per household from crop damage and livestock depredation, respectively. The highest estimated occupancy (ψ = 0.944 ± 0.048) was found for leopard whereas the lowest occupancy was for Himalayan goral (ψ = 0.038 ± 0.011). Species distribution model predicted 30.29% of the study area as suitable habitats for northern red muntjac, 6.45% for chital, 2.6% for sambar, 14.55% for wild pig, 15.55% for Himalayan goral, 34.88% for rhesus macaque, 34.65% for langur, 5.79% for Himalayan black bear and 29.94% for leopard. A total of 15 habitat patches were identified in the central part of CHAL on the basis of suitable habitats of mammals. The study found a poor connectivity among the patches for chital and sambar, a strong connectivity for muntjac, leopard, rhesus macaque and langur in the lowland to mid-hill and a strong connectivity for Himalayan black bear and Himalayan goral in mid-hills. The heterogeneity and dynamics in the landscape pattern in CHAL mainly attributed forest change due to migration of people from rural to urban and lowland areas. Landscape conservation efforts in the CHAL should maintain the contiguity of forest patches. This research provides the baseline information of large mammals in the CHAL and how they are responding to changes in the landscape. It reveals the role of fragmented landscape for supporting large mammal assemblages and conserving biodiversity.