**4. Discussion**

Barking deer and sambar are solitary species. Other than adult males which tend to be solitary, gaur and elephant usually live in small groups. Occasionally they form medium to large groups particularly at favoured feeding sites. Chital is the most gregarious ungulate and commonly form medium to larger groups. The social organisation of elephant and gaur are based around the family unit or the herd consisting of

#### *Population Density and Age-Sex Composition of Large Mammals in Tropical Forests, Southern… DOI: http://dx.doi.org/10.5772/intechopen.109567*

one or more related adult females and their offspring [20, 25–27]. In elephants the most cohesive unit is the family unit and it represents a tightly knit unit both socially and structurally [28]. At puberty, young females remain with the natal group, while the males leave the herd and they tend to form temporary groups with weak social bonds [29]. Little however is known about gaur social structure or about male dispersals.

We looked at the pattern of densities in relation to body size and diet [30] of individual species. Densities of smallest ungulates barking deer is lower than densities of considerably larger species such as chital, sambar and gaur. Because barking deer found in Moist deciduous forest and it selectively feeds on rich but scarce food items such as shoots and fruits [20]. Moist deciduous forest consists of only 33% of the different vegetation types of the study area. Their solitary nature and territorial spacing mechanisms may also contribute to their relatively low densities. Chital which are primarily grazers [22] are most abundant in the study area. Dry deciduous with extensive short grass clearing, Moist deciduous forest with and swamp microhabitat and Open grass lands in thorn forest support high density of chital in Mudumalai Tiger Reserve.

Sambar which is predominantly browsers [20] distributed relatively higher density in Moist deciduous forest in the Western part of the study area. They feed during evening and night hours and rest in large number in open swamp areas in Moist deciduous forest. As could be predicted from body size and diet of sambar are less abundant than chital. However densities of gaur a larger species are higher than sambar. Gaur are mixed feeders and they graze intensively in open swamp areas in Moist deciduous [31] and coarse grass in dry deciduous forest. They also seem to browse on the profuse secondary growth of Bamboo (*Bambusa arundanacia)* in Thorn forest in areas with less human disturbance [10].

Elephant density is higher than earlier estimate (2.4/km<sup>2</sup> ) [32]. Earlier studies in the year 1980s [25] indicated a much lower density (1/km<sup>2</sup> ) for the study area. Despite poaching reducing the male numbers and keeping them dispersed breeding is taking place and the population is increasing. The specialist folivore common langur is more abundant than generalist bonnet macaque in the study area. Wild pig that feed selectively on variety of plant and animal foods such as roots, tubers, fruits insects and carrion [33], found in relatively low density (0.4/km2 ) in the study area. The factors such as nocturnal feeding habitat and incidence of Anthrax in wild pig in the study area during the study period might reduce wild pig population density. Further monitoring and diseases control measures were taken by the forest department.

The adult sex ratios of ungulate species seem female biased. In ungulate species such as chital, sambar and gaur the males more solitary habits, proneness to injuries from intra-specific aggression, lack of alertness during rut and dispersal behaviour of makes them more vulnerable to predation [20, 24]. Whereas in elephant selective poaching of adult males especially tuskers caused skewed sex ratio (1:34). An earlier study in this area [25] had reported that the adult male to female ratios were far less skewed (1:4.7) than the current ratio of 1:34. This indicates that the adult male population has declined significantly from the mids 1980's. This decline in adult male population in elephants is largely due to poaching of males for their tusks [27].

The biomass of large herbivores is compared with other tropical forests (**Table 3**). MTR supported very high biomass density (15,198 kg/km2 ) than similar tropical forests in Southern India. It was almost equal to that of Nagarahole (14,744 kg/km2 [3]) and Bandipur National park (14,520 kg/km2 [24]) and more than Kanha (1592 kg/km2 [20]) and Pench (6013 kg/km<sup>2</sup> [34]) of Central India. Furthermore it was higher than Chitwan, Nepal [35]. Tropical humid forests were generally considered to be poorer habitats than Savannas in terms of supporting high biomass (Eisenberg, 1980) [30].


*a IGWS & NP- Indira Gandhi Wildlife Sanctuary and National Park.*

*b DDF-Dry deciduous forest; EG- Evergreen; GL-Grassland; MDF-Moist deciduous forest; TF-Thorn forest.*

*c The mean body weight of herbivores was used from other published sources [20, 23, 24, 35].*

#### **Table 3.**

*Comparison of wild biomass density of herbivores in different tropical sites.*

But several Savanna and Woodland habitats of Africa seem to support lower biomass densities than MTR [36–38]. For example the biomass estimates from the lowland rain forests of Gabon and Serengeti were considerably lower [38]. Whereas Manyara Lake park and Mara Plains in Kenya and Rwenzori Park in Uganda supported biomass densities higher than that of MTR [36].
