Abstract
Some reproductive and demographic parameters of a cropland population of the Indian gerbille (Tatera indica) were studied from 1977 to 1980 in central Punjab.. The females ceased to reproduce daring December-February. The smallest visibly pregnant female weighed 56.7 g and had a body length of 12,1 cm. The annual rate of pregnancy loaded from 22.7% to 47.2%; the average for the three years being 33.16%. Two pregnancy peaks one in April-May and one in October Novemb:1 were noted. The emb-ryonic litter size was 6,76* ..1:14 (5.E.) (range=2-10; N-=--39). The maternal body weight and size of litter were positively correlated (r = .56321; d,f.,3I: p<.001). The litter tended to be larger in April-May and October-November than those of other bimonthly periods. The average annual rate of reproduction was 47.32 young/ female/year. The proportion of sub-adults and juveniles in the yearly sarn. pies ranged from 16.7% to 26.5% and from 6.1% to 6.3% respec-tively and the respective averages for the entire period of study were 22.9% and 12.6%. The ratio of the two sexes approximated the hypothetical 1 1, The relative density of the gerbilles fluctu-ated widely in different crops. These fluctuations were largerly due to movemnt of tai: gerbil/es batween the crops and between tiro croppd and non-cropped areas,
IN TRODUC.TION
Formerly, the Indian gerbille (Tatera indica) in Punjab was largely confined to the banks of rivers above the flood level. When the tropical thorn plain of the doabs was converted to agricultural land and linked to the riparian habitat by the canal system, the gerbille penetrated the doabs along irrigation canals (Taber et al, 1967) and Infested the croplands. Pr3sently„ it is considered to be one of the most important rodent pests of agriculture in the Punjab.
