Community structure and demography of small-mammal populations in insular montane forests in southern India |
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Authors: | Kartik Shanker R Sukumar |
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Institution: | (1) Centre for Ecological Sciences, Indian Institute of Science, Bangalore 560012, India e-mail: rsuku@ces.iisc.ernet.in, Fax: +91-80-3311280, IN |
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Abstract: | bstract Small mammals were studied in insular montane forest patches in the Upper Nilgiris in southern India from February 1994 to
September 1996. Nine patches were selected at two sites, one with a single large 600-ha patch, the other with several small
patches ranging in size from 0.2 to 60 ha. The population characteristics and community structure of small mammals were studied
in relation to patch size and habitat structure within the patches. The two most abundant species were Rattus rattus (2–36 individuals/ha) and Suncus montanus (0–11 individuals/ha), while the abundance of seven other species recorded were very low. The population characteristics
of R. rattus examined were density, biomass, proportions of juveniles, sub-adults and adults, mean weight of all animals, mean weight
of adults, sex ratio and persistence. The proportion of adults, sub-adults, mean weight of animals, and mean weight of adult
males were correlated with patch size. Persistence of sub-adult females in the large patch was especially high. The density
and biomass of other small-mammal species were also studied. Two indices of diversity, species richness and proportion of
R.␣rattus were compared as measures of community structure. Seven habitat characteristics were measured; of these, canopy cover, canopy
height and tree density were correlated with the size of the patch. Density and biomass of species other than R. rattus and proportion of R. rattus were correlated with canopy height. Density and biomass of species other than R. rattus were highest in smaller patches. While the population characteristics of R. rattus may be affected by patch size, the density of rare species may be influenced by factors related to lower canopy height. Migration
between patches may be an important factor in maintaining populations in these patches.
Received: 5 January 1998 / Accepted: 23 March 1998 |
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Keywords: | Rattus rattus Small mammals Community structure Insular populations Patch size |
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