SEASONAL-VARIATION IN THE DIET AND FORAGING BEHAVIOR OF BRANTS WHISTLING RAT, PAROTOMYS BRANTSII, IN NORTHERN NAMAQUALAND

The diet and feeding behaviour of a population of Brants' whistling ra ts, Parotomys brantsii, was studied in northern Namaqualand. The diet of P. brantsii in this winter rainfall area confirms that it is a gene ralist herbivore, feeding on most plant species in proportion to their abundance, with winter annuals as well as succulent perennials being of particular importance. Summer was the only season in which foraging time (searching for food) exceeded feeding time. Additionally, feedin g rates were depressed in summer, indicating that whistling rats may h ave been nutritionally stressed at this time. The findings of this stu dy support the view that P. brantsii, whose physiology is not particul arly well suited to the semi-arid regions in which it occurs, has part ly overcome this constraint through diet selection. Furthermore, in th e winter rainfall area where this study was conducted, individuals wer e least able to feed and forage effectively during summer when food av ailability is presumably lowest.