Title

Resource heterogeneity and the foraging ecology of the Malabar giant squirrel Ratufa indica

Date of Award

1989

Availability

Article

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Biology

First Committee Member

Theodore H. Fleming, Committee Chair

Abstract

I investigated the influence of food resource heterogeneity on the foraging ecology of the Malabar Giant Squirrel Ratufa indica at two sites in western India. R. indica (Family Sciuridae, Subfamily Sciurinae) is a large, arboreal, facultatively frugivorous, obligate herbivore. It is a territorial, solitary squirrel. The sexes occupy separate territories that may overlap.I estimated the spatial and temporal heterogeneity of food resource availability at the level of individual squirrels. Individuals were found to vary significantly in the fruit resource base available to them due to territory locations and inter-individual interactions. This resulted in tremendous inter-individual variation in daily consumption of preferred fruit resources. I also examined the relationship between resource availabilty and the social structure and life-history parameters of this squirrel. Squirrels with neighboring territories utilised common resources by a system of time-sharing and encounter avoidance. Mechanisms facilitating this mode of resource utilisation are discussed.I examined heterogeneity in nutritional value of food resources. I analysed 93% of food items at Magod and 94% of food items at Bhimashankar for their contents of gross energy, ash, fat, nitrogen, total non-structural carbohydrates, minerals (Na, Ca, Mg, K, Fe, Zn), fiber, tannin and lignin. The presence of alkaloids was qualitatively recorded. I investigated the nutritional factors that influence food consumption. Squirrels consumed food items in proportion to their water content. They may use the water content of food items as a cue to their profitability with regard to nutrient content. They also consumed items in proportion to the intake rates of nutrients from those items. Tannins and other digestibility reducers influenced food item consumption only at one study site. Squirrels were capable of detoxifying only certain secondary compounds. They were selective in their utilization of tree species and specific portions of those species depending on their secondary chemistry.Each individual squirrel required a unique amount of insurance against shortages of preferred resources. I suggest that large body size in this squirrel may be an insurance against shortages of preferred, profitable, more easily digestible fruit resources, by providing dietary flexibility resulting in the ability to exploit fibrous, low-profit resources on a uniquely individual schedule.

Keywords

Biology, Ecology

Link to Full Text

http://access.library.miami.edu/login?url=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:8922706