REPRODUCTIVE SEASONALITY OF THE BUSH RAT (RATTUS FUSCIPES GREYI) IN SOUTH AUSTRALIA

The reproductive seasonality of the bush rat (Rattus fuscipes greyi) w as investigated in Scott Creek Conservation Park near Adelaide, South Australia, by catch and release trapping conducted at irregular interv als over a 4-year period in a population of higher density than previo usly reported for this species. A seasonal pattern in breeding activit y was observed with the production of young in spring and summer (Octo ber-February) with a peak in December. There was seasonal variation in the testicular index of males with minimal values from April to June. Some animals may have retained the ability to mate throughout the yea r but there was no evidence of offspring surviving from any winter mat ings. Differences were seen in the timing and intensity of the non-bre eding season between years. Possible causes of reproductive seasonalit y were seasonal changes in vegetative growth and the abundance of fung i and insects and predictive cues provided by seasonal changes in ambi ent temperature and photoperiod.