Abundance, Habitat Relationships and Behavior of the Semi-Fossorial Indian Desert Jird, Meriones hurriancae, in Kachchh, Gujarat

Abstract

Population sizes, habitat relationships and behaviour are among basic ecological aspects pivotal to demystifying a species and its place in the ecosystem. Numerous in species and number, desert rodents offer immense scope for such investigations. The Indian desert jird, Meriones hurrianae, though common, is remarkably little known. This study, conducted in Kachchh, Gujarat, estimates population sizes, examines factors in the habitat likely to influence their occurrence, and elucidates the activity pattern and time budget across 2 land use types, agricultural and natural areas, during winter (December February) and summer (March-May). Animals were caught in 9 colonies using Sherman traps and population estimated under closed population Capture-Mark-Recapture framework in Program MARK, using individual covariates (age class, gender, body weight, site). Colony parameters (length, width, number of holes) were regressed against known Mark-Recapture (MR) population estimates to develop predictive models for estimating population size from indices. Population sizes varied from 2 to 10 individuals. Number of holes in a colony provided robust estimates of the number of individuals in that colony (N=16, R2=0.96, t=18.19, p<O.OOI). Jacknife estimation was performed and population sizes based on this were strongly correlated with MR estimates (R=0.958, p<O.OOI). Habitat variables were recorded in 84 and 75 sample plots in a 4sqkm area each, in agriculture and natural areas respectively. These were tested for multicollinearity using correlation, univariate logistic regression and residual regression. Logistic regression models were run with a final set of predictors, where proportion of clay in the soil (B=0.116, SE=0.036, p=O.~OI) and presence of agricultural areas (B=4.216, SE= 1.515, p=O.OO 1) significantly explained occurrence of jirds. Behaviour was observed using scan and focal animal sampling methods in 3 and 4 colonies in agriculture and natural areas respectively, during winter and summer. Activity periods were different for the 2 seasons. Irrespective of season and site, major proportion of active time was spent foraging. Vigilance was another key behaviour along with foraging, indicating a trade-off for optimization which requires further testing. The study delivers baseline information for a trophic level that can impact predators and prey (including vegetation) alike