REPRODUCTIVE-BIOLOGY OF THE WHITE-THROATED SAVANNA MONITOR, VARANUS-ALBIGULARIS

The reproductive biology of the white-throated savanna monitor lizard, Varanus albigularis, was examined in the arid savanna of Etosha Natio nal Park, Namibia. Both sexes were solitary during the the hot/wet sea son when prey were abundant, and during the hot/dry season when prey p opulations were declining. Male-male and male-female behavioral intera ctions were confined to a 2-3 week period at the transition from the c ool/dry to the hot/dry seasons when prey populations were depleted. In teractions occurred at locations occupied by estrus females. Male-male interactions were restricted to resident males chasing intruding male s after visual contact Males appeared to initially locate the general area occupied by females through scent cues. Once in visual contact wi th females, males exhibited a spasmodic body shudder, after which fema les responded by flattening their bodies. Mating generally occurred in trees. No aggression was noted between pairs during courtship or mati ng. At peak estrus, females had elevated (100 to 500-fold increase ove r non-reproductive period) plasma testosterone and total estrogen tite rs. Males showed similar dramatic increases in plasma testosterone lev els during the mating period. Aspects of the reproductive biology of t his species are discussed in the context of general patterns for the f amily Varanidae. As a group monitor lizards appear to be very conserva tive in the length of gestation, but highly variable in length of incu bation. Length of incubation appears to be variably timed in order to place hatching during the period of greatest abundance of invertebrate prey.