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 influenc ing the southern distributional limit of the common blossom bat (Sycon ycteris australis). Using the climatic predictive model BIOCLIM and 73 locality records, S, australis was predicted to have a coastal distri bution in eastern Australia, where winter temperatures are relatively warm and moist conditions prevail throughout the year. The actual sout hern limit of S, australis, determined by mist-netting suitable habita ts, was found to be at Booti-Booti(32 degrees 19'S 152 degrees 31'E) o n the mid-north coast of New South Wales. BIOCLIM predicted the southe rly limit of S, australis to be 150-200 km further south of their actu al limit. Booti-Booti was occupied at relatively low levels of abundan ce 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 detect ed, despite the availability of apparently suitable habitat at Myall L akes only 20-35 km further south. Metabolic costs of S. australis at B ooti-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 cl ose correspondence of BIOCLIM'S predicted southern limit of S. austral is with their actual limit, suggest that the bat's southern distributi on is limited by cold, wet winters and dry summers.