Rice-field rats of Lower sind: abundance, reproduction and diet

Authors


*New England College of Optometry, 424, Beacon Street, Boston, Mass., U.S.A. 02115

Abstract

Data on the abundance, reproduction and diet of rice field rats were collected during three rice seasons. At rice harvest, Bandicota bengalensis nearly doubled its litter size and tripled its pregancy rate and greatly increased in abundance. Millardia meltada remained abundant and maintained a relatively high pregnacy rate over all stages of crop development. These differences corresponded to differences in diet. Before the onset of grain ripening, the diet of Millardia contained more high-energy food (weed seeds, insects and scattered grain) while the diet of Millardia contained more high-energy food (weed seeds, insects and scattered grain) while the diet of Bandicota contained primarily low-energy food (rice stems and unidentified plant fibres); although both species ate principally rice at harvest. During most months, Nesokia indica was seldom caught above ground and ate mostly unidentified plant fibres. However, when grain ripened, Nesokia was caught on the surface and stomachs contained principally rice grain. Nesokia showed a lower pregnancy rate and smaller litter size, but apparently greater adult survival. They bred more often in the cooler months, during and after harvest.

Some information on other topics is also presented, such as: sexual activity in males; substrate preference; relative adult longevity; the effect of excessive flooding of rice paddies; and the importance of underground rice caches, rice field weeds and swamp land to overwintering Bandicota. Estimates of the relative damage to the crop caused by each species at different stages of crop development were made by using data on rodent diet and abundanc

Ancillary