TY - ECHAP
AU - Samba Kumar
AU - Ullas Karanth
AU - James Nichols
AU - Srinivas Vaidyanathan
AU - Beth Gardner
AU - Jagdish Krishnaswamy
AB - 1. Understanding the influence of natural factors and anthropogenic impacts on populations of wild ungulates is of fundamental importance to their management. However, the spatial and observation processes involved in field studies often obscure our understanding of the underlying ecological process, which is the real determinant of the distribution and abundance of ungulates. Modern hierarchical modeling approaches enable rigorous assessment of the influences of ecological, spatial and observation processes. In this chapter, using the models developed in Chap. 2, we investigate ungulate-habitat relationships in a tropical deciduous forest landscape in the Western Ghats, India. We confront the hierarchical spatial model with carefully gathered field survey data on ungulates as well as remotely-sensed data. 2. Our focus is on discerning the patterns of spatial variation in the density of five threatened tropical forest ungulate species. These study species differed in terms of body size, diet and social grouping behaviors. We hypothesized a priori, based on prior knowledge, the ecological determinants of the association between abundance and habitat characteristics for each species. These hypotheses were tested using our models. 3. We obtained count data on ungulates from 77 samplers (spatially replicated line transects) systematically placed with a random start. These transects covered an area of 1400 km2 spanning the study landscape. We used model-based analyses to investigate the influence of forest vegetation type, availability of palatable forage, topographic features, proximity to water, human disturbances and effectiveness of protection, on patterns of species abundances. We employed a Poisson-regression model under the class of Generalized Linear Mixed Models, within a Bayesian analytical framework. The models were confronted against survey data to assess the relative influence of hypothesized ecological determinants of abundance patterns. 4. Our results showed that different predictor variables did influence each study species as we had hypothesized. However, the strength of inferences among these relationships varied. The patterns of ungulate abundance distributions generally reflected how local and landscape level influences met expected habitat requirements of each species. 5. For sambar, chital and wild pig, forest vegetation type mattered most. For gaur, a terrain feature (topography) was the most influential determinant of abundance patterns. Muntjac was most vulnerable to human disturbances. No single habitat covariate could alone adequately explain the abundance patterns of any of these species. Different combinations of habitat variables, however, could describe observed abundance patterns satisfactorily. Protection effectiveness against hunting and habitat disturbance was a critically important determinant of abundance for all species. 6. Management actions focused at reducing hunting and habitat impacts of humans are critically important for recovering, maintaining and increasing densities and the carrying capacity for ungulates in tropical forests. Thus, effectively protected areas, such as the one we studied, have a central role in conservation of populations of these and other threatened ungulate species in India. However, such protected areas comprise <5% of India’s geographical area. Extensive tropical deciduous forests, currently remaining outside the protected areas in India, can still offer great opportunities for recovery of threatened wild ungulates. Rigorous evidence presented here directly supports an overall conservation strategy based on expanding coverage of effective field protection across the country.
BT - Spatial Dynamics and Ecology of Large Ungulate Populations in Tropical Forests of India
CY - Singapore
DA - 01/2021
DP - Springer Link
LA - en
N2 - 1. Understanding the influence of natural factors and anthropogenic impacts on populations of wild ungulates is of fundamental importance to their management. However, the spatial and observation processes involved in field studies often obscure our understanding of the underlying ecological process, which is the real determinant of the distribution and abundance of ungulates. Modern hierarchical modeling approaches enable rigorous assessment of the influences of ecological, spatial and observation processes. In this chapter, using the models developed in Chap. 2, we investigate ungulate-habitat relationships in a tropical deciduous forest landscape in the Western Ghats, India. We confront the hierarchical spatial model with carefully gathered field survey data on ungulates as well as remotely-sensed data. 2. Our focus is on discerning the patterns of spatial variation in the density of five threatened tropical forest ungulate species. These study species differed in terms of body size, diet and social grouping behaviors. We hypothesized a priori, based on prior knowledge, the ecological determinants of the association between abundance and habitat characteristics for each species. These hypotheses were tested using our models. 3. We obtained count data on ungulates from 77 samplers (spatially replicated line transects) systematically placed with a random start. These transects covered an area of 1400 km2 spanning the study landscape. We used model-based analyses to investigate the influence of forest vegetation type, availability of palatable forage, topographic features, proximity to water, human disturbances and effectiveness of protection, on patterns of species abundances. We employed a Poisson-regression model under the class of Generalized Linear Mixed Models, within a Bayesian analytical framework. The models were confronted against survey data to assess the relative influence of hypothesized ecological determinants of abundance patterns. 4. Our results showed that different predictor variables did influence each study species as we had hypothesized. However, the strength of inferences among these relationships varied. The patterns of ungulate abundance distributions generally reflected how local and landscape level influences met expected habitat requirements of each species. 5. For sambar, chital and wild pig, forest vegetation type mattered most. For gaur, a terrain feature (topography) was the most influential determinant of abundance patterns. Muntjac was most vulnerable to human disturbances. No single habitat covariate could alone adequately explain the abundance patterns of any of these species. Different combinations of habitat variables, however, could describe observed abundance patterns satisfactorily. Protection effectiveness against hunting and habitat disturbance was a critically important determinant of abundance for all species. 6. Management actions focused at reducing hunting and habitat impacts of humans are critically important for recovering, maintaining and increasing densities and the carrying capacity for ungulates in tropical forests. Thus, effectively protected areas, such as the one we studied, have a central role in conservation of populations of these and other threatened ungulate species in India. However, such protected areas comprise <5% of India’s geographical area. Extensive tropical deciduous forests, currently remaining outside the protected areas in India, can still offer great opportunities for recovery of threatened wild ungulates. Rigorous evidence presented here directly supports an overall conservation strategy based on expanding coverage of effective field protection across the country.
PB - Springer
PP - Singapore
PY - 2021
SN - 978-981-15-6934-0
SP - 83
EP - 165
T2 - Spatial Dynamics and Ecology of Large Ungulate Populations in Tropical Forests of India
TI - Model-Based Assessment of Ungulate-Habitat Relationships
UR - https://doi.org/10.1007/978-981-15-6934-0_3
Y2 - 2020/11/15/07:40:47
ER -