Introduction :
Large mammals around the world face serious threats and experience massive decline in their populations and geographic ranges (Ceballos et al. 2015, 2017; Ripple et al. 2014; Karanth, 2009; Ceballos & Ehrlich 2002). Protected areas (PAs) have become the last refuge of many threatened mammals and have contributed to conservation of some flagship species yet their effectiveness to halt decline of other sympatric species remains questioned (UNEP-WCMC & IUCN, 2021; CBD, 2020; Li et al.2020; Geldmann et al. 2019; Schulze et al. 2018; Barnes et al. 2016; Ceballos et al. 2015; Geldmann et al. 2013; Hoffmann et al. 2010). Increasing pressure on the environment has compromised the intactness of natural habitat and species ability to procreate and persist in a healthy population (Crooks et al. 2017; Wilson et al. 2016). Extinction risk of mammals in small, degraded, and isolated habitats increase in long run through population decline and loss of genetic diversity (Frankham et al. 2002, 2010).
The sloth bear Melursus ursinus is an endemic mammal of the Indian sub-continent occurring in a wide range of habitats including dry or moist forest, savannah, scrublands and grasslands (Dhariya et al. 2020; Garshelis et al.1998). However, their populations have declined by almost 50 % over the last three decades and are categorized as “vulnerable” in IUCN Red List (Dhariya et al. 2020). They have become extinct from entire country in Bangladesh (Islam et al.2013) and possibly from Bhutan and locally from different habitat patches of India and Nepal (Dhariya et al. 2020; Garshelis et al 1998). They were once present along continuous strip of forest and grasslands in the southern Nepal until 1950s when expansion of human settlement and agriculture confined them primarily in few protected areas (Amin et al. 2018; Jnawali et al. 2011). While distribution, habitat use, population and conservation ecology of sympatric co-predators’ tiger and leopard is well explored (Subedi et al. 2021; Thapa et al 2021; Lamichhane et al. 2019; 2017; Dhungana et al. 2019, 2018; Kafley et al. 2019; Pokheral et al. 2019; Karki et al. 2015; Barber-Meyer et al. 2013; Bhattarai et al. 2012; Carter et al.2012; Smith 1984), similar studies for sloth bears are limited (Lamichhane et al. 2016; Laurie & Seidensticker, 1977; Garshelis et al. 1999; Joshi et al. 1995,1997,1999) to from a conclusive view on its current conservation status.
Information on the species spatial distribution pattern in the wild and factors that influence this pattern are critical for setting conservation priorities and site-specific management actions for securing these population over time. Primarily, species distribution and habitat use are determined by the availability and spatial variation of food resources and the extent of natural and anthropogenic threats (Ceballos & Ehrlich, 2002; Schipper et al. 2008). Unlike other carnivores, bears exhibit a different set of morphological specializations for diet (Sacco et al. 2004). Sloth bears are specially adapted for myrmecophagy with the composition of diet varying with temporal and spatial availability of the food resources particularly termites and fruits (Philip et al.2021; Palei et.al. 2014, 2020; Rather et.al. 2020; Mewada et al. 2019,2015; Baskaran et al.2015; Khanal & Thapa, 2014; Sukhadiya et al. 2013; Baskaran & Desai.2010; Bargali et.al. 2004; Joshi et.al,1997; Laurie & Seidensticker,1977). In fruit rich areas, sloth bears play important role in the dispersal of seed and regeneration of fruit plants (Sreekumar & Balakrishnan, 2002) thus playing important role in maintenance of forest structure and composition. They largely prefer habitats away from human disturbance (Joshi et al. 1999; Babu et.al 2015, Ghimire & Thapa,2014; Ratnayeke et.al.2007) but they have also been reported to tolerate some degree of disturbance in human-dominated landscapes (Puri et.al 2015, Bargali et al. 2012; Akhtar et al.2004, 2007). Prevalence of human-sloth bear conflict in India (Rajpurohit & Kruasman, 2000; Debata et al. 2012,2017; Garcia et al. 2016; Dhamorikar et al. 2017; Bargali et al. 2005; Ratnayeke et al 2014; Ahmed et al.2012; Sharp et al.2020; Ketting et al.2020) and Nepal (Pokharel et al. 2020; Ruda et al. 2020; Silwal et al. 2019; Lamichhane et al. 2018; Acharya et al.2016) is one of the threats to its survival. Additionally, removal of the individuals through poaching or live capture for use as ‘dancing bears’ is not common but can be detrimental enough for a population that is already small, isolated and threatened.
Direct observation of sloth bears is difficult because of their rare, elusive, and aggressive nature. We use occupancy analysis which is widely used in recent years and have evolved as a strong, flexible, and viable method for estimating species distribution and occupancy dynamics while accounting for possible non-detection as well as incorporating predictor variables measured remotely or during the observation process in field (MacKenzie et al.2002,2003, 2004, 2017; Bailey et al. 2014; MacKenzie & Nichols 2004; MacKenzie & Royle, 2005). We employed single-season occupancy model for understanding the distribution and occupancy dynamics of the sloth bears and its ecological, environmental, and anthropogenic determinants.