research
Rhinos in the Backyard?
Today, human-wildlife conflicts are increasing around the globe as people compete with wildlife for shared resources and space. Large tracts of land that were once contiguous habitats for wild animals are now being reduced by human intervention to isolated pockets. Wild animals often are forced to venture out of these pockets (usually protected areas) into the surrounding lands in search of better quality resources. For example, Indian rhinoceros, now confined to isolated "habitat island" parks, increasingly are in conflict with local people as they search outside the parks for higher quality food. Can you imagine having rhinos eating grass in your backyard?
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Addressing the issue
I spent last December 2000 May 2001 working in India s Kaziranga National Park (KNP) studying the relationship between habitat use and nutritional needs of Indian rhinos. The idea was that the knowledge gained would enable park managers to better understand why and when rhinos leave protected areas.
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| photo: © Gitanjali Banerjee 2001 |
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| KNP, located in northeast India, is unusual among protected areas that support rhinos in that it is relatively undisturbed, and human-rhino conflict in the surrounding area is low. Understanding the ecological requirements of the species in a more pristine habitat provides an important starting point for understanding rhino behavior. KNP is one of the last remnant patches of the tall wet grasslands that are as yet, free from harmful anthropogenic pressures. |
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photo: © Gitanjali Banerjee 2001 |
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The grasslands provide food for sizeable populations of endangered ungulates such as the Indian rhino, water buffalo, swamp deer, and hog deer. The nutritional value of the grass decreases as it ages. Therefore, park managers burn the tall grasslands each year to encourage the growth of new, high quality grass. This management regime provided me an opportunity to observe how a gradient in nutrient content of forage affected the behavior and distribution of rhinos and the other ungulates.
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| photo: © Gitanjali Banerjee 2001 |
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What I did
I aimed to determine how four large herbivore species -- rhino, water buffalo, swamp deer and hog deer achieve spatial and temporal separation across two seasons (winter and summer), and how seasonal variations in forage quality affected the habitat use patterns for each of the species. Each day in the field, I monitored animal locations, feeding patterns, and behavioral activities. I measured the grasslands for forage quality, and I collected samples for nutritional analysis. When the six months of fieldwork were completed, I returned to the Wildlife Institute of India, where I undertook the laboratory analysis of forage and conducted the data analyses.
What I found
There were seasonal and spatial differences observed in habitat use patterns among the four ungulate study species. I found interesting correlations between the amount of crude protein and silica present in forage and the various grassland types. During winter, I observed that all ungulates selected the short grasslands for feeding as compared to the other grassland types, namely the Vetiveria dominated grasslands and the tall grasslands. Interestingly, during summer I observed that rhinos and hog deer showed a positive selection for the freshly sprouting forage within the burnt tall grasslands for feeding following the post-fire period, while wild buffaloes and swamp deer did not show variations in habitat use. When I correlated habitat use patterns with the nutritive value of the forage, I found that each species of ungulates tracked high crude protein levels in available forage based on their individual body requirements and ecological needs.
Conclusions
I found that crude protein and silica levels in grasses play an important role in determining habitat use by the four ungulate species studied. Rhinos and hog deer exploited areas having the highest crude protein and lowest silica content during both winter and summer. Wild buffaloes and swamp deer were observed to feed in short grasslands that had sufficiently high amount of available crude protein to satisfy their nutritional requirements during both the seasons. I also found that forage volume, an indicator of available food, played a significant role in determining habitat use patterns for the large-bodied ungulates, namely the rhino and the wild buffalo, which was in keeping with their physiology. Habitat use patterns of the Indian rhino were related to the availability of high crude protein and very little silica content in its forage.
My study indicates that fire as a management tool in the tall wet grasslands has important relevance to animal habitat use. Annual burning provides fresh forage with high levels of crude protein and low silica content of forage. In the short term, the management practice of annual burning seems to be beneficial for rhinos and even the hog deer because it provides highly nutritious forage and removes coarse, unpalatable grass. Of course, the long-term aspects of using fire to manage the tall grasslands need further investigation.
This project illustrates that grassland quality influences habitat use by Indian rhinos, and in turn, the nutritional landscape might largely govern how rhinos move across landscape mosaics, consisting of protected and non-protected areas. Ultimately, understanding how rhinos choose to move across such landscapes, will enable us to devise better solutions for human-rhino conflict.
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