Analysis of nutrition quality and food digestibility in male Javan rhinoceros (Rhinoceros sondaicus) in Ujung Kulon National Park

Adhi Rachmat Sudrajat Hariyadi, Donjon Sajuthi, Dewi Apri Astuti, Hadi Sukadi Alikodra, Heri Maheshwari

Abstract


The Javan rhinoceros (Rhinoceros sondaicus) is the rarest species of rhino. The last remaining wild population is found only in Ujung Kulon National Park (UKNP), Banten, Indonesia, where the conservation of its habitat is a crucial management priority. The Javan rhino is typically arbivorous, feeding on leaves, shoots and saplings. Three healthy male rhinoceros were observed as samples to study their home ranges, the nutritional quality and digestibility of food plants, and nutrient intake. Following the trails of Javan rhinoceros allowed in-depth observation of their feeding habits in their natural habitat. Comparing the acid insoluble ash (AIA) content of faeces and in the dry weight of food provided reliable estimates of digestibility, and this method has potential for wider application in situations where total collection of faecal matter is not feasible. There was a strong positive correlation between the size of home range and diversity of food intake, and between the size of home range with the numbers of wallow holes used. The quantity and quality of food intake were variable among rhinoceroses and over time. Overall energy consumption was related to the size of the animal, while the digestibility of plants consumed appeared to be influenced by individual age and habitat conditions. Analysis of patterns of consumption showed that rhinos generally selected the food that was most readily available. ‘Preferred’ food plants (e.g. Leea sambucina, Zanthoxylum rhetsa, and Diospyros macrophylla) were not among those identified in the UKNP as being most highly nutritious (e.g. Moringa citrifolia, Callicarpa longifolia, Chisocheton microcarphus). This discrepancy could suggest that the studied rhinoceros live in a nutritionally suboptimal habitat. Moreover, even if overall nutrition is adequate, marked fluctuations in nutrient intake over the mean that rhinos may face shortages of specific nutrients, especially fat, at certain times of the year. This is turn may affect the size of home ranges and limit the population density that can be supported by the habitat. Thus measures to improve habitat quality by planting nutritious food plants could make a significant contribution towards safeguarding the future of the last remaining wild population of Javan rhinoceros.

Keywords


javan rhinoceros, nutrients, digestibility, model for population management

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