An Isolated and Expanding Population of the Introduced Toad Bufo marinus in New South Wales

Abstract

The distribution of Bufo mannus in north-eastern New South Wales (Australia) was surveyed in 1975 and 1978. Hitherto it had been assumed that the toads in New South Wales were derived from a southward migration from Queensland, but the populations proved to be disjunct, being separated by 25 km of coastal seaboard. Estimated times of first sightings suggest that the toads have been dispersing for at least 12 y from an initial introduction near Byron Bay. The mean rate of spread from Byron Bay is 1.07 km y-1. The maximum rate, 3 km y-1 is attained across flat or gently undulating rural areas. As there are no major climatological or geographic disjunctions at the present boundaries, the Queensland and New South Wales populations are likely to meet within 4-12y, and further dispersal southwards appears certain.