CLIMATIC LIMITATION OF THE SOUTHERN DISTRIBUTION OF THE COMMON BLOSSOM BAT SYCONYCTERIS-AUSTRALIS IN NEW-SOUTH-WALES

This study investigates the importance of climate as a factor influencing the southern distributional limit of the common blossom bat (Syconycteris australis). Using the climatic predictive model BIOCLIM and 73 locality records, S, australis was predicted to have a coastal distribution in eastern Australia, where winter temperatures are relatively warm and moist conditions prevail throughout the year. The actual southern limit of S, australis, determined by mist-netting suitable habitats, was found to be at Booti-Booti(32 degrees 19'S 152 degrees 31'E) on the mid-north coast of New South Wales. BIOCLIM predicted the southerly limit of S, australis to be 150-200 km further south of their actual limit. Booti-Booti was occupied at relatively low levels of abundance year round, while the abundance of S, australis at a site 50 km to the north was much greater, fluctuating with changes in Banksia flower numbers. Seasonal range extensions beyond Booti-Booti were not detected, despite the availability of apparently suitable habitat at Myall Lakes only 20-35 km further south. Metabolic costs of S. australis at Booti-Booti were estimated to exceed basal metabolic rate (BMR) by 4.5 times, well above the physiologically predicted limit of 2.5 times BMR. These results, together with the lack of range extensions and the close correspondence of BIOCLIM'S predicted southern limit of S. australis with their actual limit, suggest that the bat's southern distribution is limited by cold, wet winters and dry summers.