Influence of Covariates:
Summed AIC weight from the most competitive (ΔAIC<2) eight
models showed that termites are most important covariates followed by
fruit, disturbance, tree cover, TRI and EVI (Figure 2) . The
averaged strength of positive influence of covariates in habitat
occupancy was higher for termites followed by fruit, disturbance, TRI
and EVI while it was negative for tree cover. The 95% confidence
interval (CI) of averaged beta coefficients occupancy covariates
overlapped zero except for termites indicating high confidence on the
magnitude and direction of influence by termites but less confidence on
similar influence by other variables (Figure 3) .
Food resources of sloth bears particularly termites followed by fruits
had relatively strong influence on sloth bear occupancy. This is
expected because sloth bears are opportunistic omnivores specialized for
myrmecophagous diet particularly termites. Studies on feeding ecology
also shows that termites are most frequent in diet throughout year while
fruits dominate according to seasonal availability (Yoganand et al.
2005; Palei et al. 2014, 2020; Bargali et al.2004; Ramesh et al. 2012;
Rather et al. 2020; Philip et al. 2021). In Chitwan, fruits are
available for short duration from April-August while termites
increasingly dominate the sloth bear’s occurring in 52% of scats in
1970s (Laurie and Seidensticker, 1977), 81% during 1990s (Joshi et. al
1997) and 92% in 2010s (Khanal and Thapa 2014). Sloth bears had
negative association with tree cover indicating its preference for open
grassland habitat. During the dry season, the soil in upland Sal forest
habitat becomes stiff (Mall & Karki, 2016) and termites excavate deeper
into the ground to keep up with lowering water table (Mugendi D.G 2020;
Ahmed et al. 2018; Kalumanga, 2016; Dangerfield et.al.1998). While water
table is relatively higher in alluvium grasslands and the soil is
relatively loose making it favourable for sloth bears to obtain
termites. Correlation analysis with tree cover indicated that not
termites mounds (r=0.02) but fruits were more abundant in grasslands (r=
-0.28) during this period. Axelsson and Andersson E.P. 2012 and
Chakraborty and Singh 2020 also observed that termite mounds were higher
in forested areas compared to edge or open habitats. However, Garshelis
et al (1999) also showed that mound digging by sloth bears was higher in
grasslands despite high density of mounds in the forest. They also
reported high ratio of diggings to obtain underground colonies of
termites during the dry season. Thus, the preference for habitats with
open tree cover during the dry season may be due to the better
accessibility of food resources.
We expected that disturbance would have negative influence on habitat
occupancy by sloth bears but in contrast the averaged beta coefficient
for the covariate indicated otherwise. Understanding effects and impact
of disturbance on species is challenging as it is driven by multiple
factors such as individual behavior, evolutionary history as well as the
frequency, duration and scale of disturbance events (Graham et al.2021;
Iwasaki & Noda, 2018; Sousa W.P. 1984). In relatively intact landscape
such as in western ghats, India, sloth bears have shown to avoid
disturbance (Das et al. 2014; Puri et al. 2015; Babu et al. 2015) while
in human dominated landscapes they have been reported to tolerate some
degree of disturbance (Bargali et al. 2012) often consuming cultivated
crops (Palei et al. 2019), human food waste (Prajapati et al. 2021) and
causing conflicts with humans (Debata et al. 2017; Dhamorikar et al.
2017). Human-sloth bear conflict is common throughout the year in
chitwan national park suggesting that sloth bears perceive humans as
threats (Acharya et al.2016; Silwal et al.2016; Lamichhane et al. 2018).
However, sloth bears might be using disturbed habitat in moderation for
requirements such as food, water and shelter as suggested by weak but
positive correlation of disturbance with terrain ruggedness, vegetation
productivity and termites (Figure 2). Rugged terrain provides
sloth bears with resting and denning refuge (Baskaran et al. 2015;
Bargali et al. 2012; Akhtar et al. 2007) sites and cover to hide their
cubs from potential predators like tigers. We used coefficient of
variation in terrain ruggedness and enhanced vegetation productivity
across our grids as it better represented the heterogeneity in the
habitat. They were positively related but did not have enough variation
to produce significant effect on the sloth bear occupancy. The weak
association of covariate might be because our study was more localized
while these variables are more adequately captured at a larger scale
(Rather et al. 2021; Srivathsa et al. 2017).