PATTERNS OF BODY-TEMPERATURE, ACTIVITY, AND REPRODUCTIVE-BEHAVIOR IN A TROPICAL MURID RODENT, ARVICANTHIS-NILOTICUS

Nile grass rats (Arvicanthis niloticus), are murid rodents from tropic al Africa that exhibit diurnal patterns of wheel-running. In the prese nt paper we describe the temporal organization of several other behavi ors in these animals, as well as daily rhythms in their body temperatu re. In the first experiment, we characterized rhythms of gross motor a ctivity and core body temperature in four adult females implanted with telemetry transmitters and kept on a 12:12 light:dark (LD) cycle. In all animals body temperature and gross motor activity were clearly diu rnal, with peaks often occurring around dawn and dusk. In the second e xperiment we recorded the times of mating and parturition in eight mat ing couples housed in a 12:12 LD cycle. We monitored animals 24 h a da y using a time-lapse video recording system, beginning when males and females were paired, and ending after the birth of the second Litter a nd the associated post-partum copulation. Mating almost always began j ust before the lights came on, and parturition generally occurred in a n ''anticrepuscular'' pattern, outside of the periods around dawn and dusk. Thus, these animals exhibit an interesting mosaic of temporal ad aptations, with some crepuscular tendencies expressed within a predomi nantly diurnal pattern. (C) 1997 Elsevier Science Inc.