干旱区生态环境知识资源中心

During July, 1990 - June, 1992 we collected stomach contents of necropsied rodents that totalled 494 Arvicanthis niloticus (Desmarest, 1822), 356 Mastomys natalensis (Smith, 1834) and 273 Tatera valida (Wroughton, 1906) from natural, savanna fields in Nigeria, and 528 Arvicanthis and 367 Mastomys from nearby irrigated fields, where Tatera was never trapped. The materials were processed and microscopically analyzed to determine patterns of diet selection. Sites were sampled for vegetative cover and rodent food resources. More than 90% of the stomach materials could be identified to one of four categories: dicots (vegetative), monocots (vegetative), seeds, and insects. Seeds constituted approximately 50% by mass of foods consumed by all species in both sites during the rains. Mastomys (in both sites) and Tatera maintained the same levels of seed intake year around. Unlike Mastomys, the amount of seeds consumed by Arvicanthis was enhanced by irrigation. In both sites during the rains, monocots and insects made up 12-46% and 14-26% of the rodents diet respectively, but their importance diminished in the natural site during the dry seasons. Tests of MANOVA indicated significant species differences and effects of site, season and their interactions on foods selected. A few plant species dominated the vegetative cover, and dramatic differences in the quality of seasonal herbage were observed.