M. Lampo et Ga. Deleo, THE INVASION ECOLOGY OF THE TOAD BUFO-MARINUS - FROM SOUTH-AMERICA TOAUSTRALIA, Ecological applications, 8(2), 1998, pp. 388-396
Mark-recapture studies indicate that Bufo marinus populations introduc
ed into Australia tend to attain densities much higher than those repo
rted in native habitats in South America. Moreover, its high rate of s
pread into northern Australia is raising concerns about the local faun
a. The major ecological factors contributing to the observed differenc
es in density are unknown. A population model based on empirical data
from both continents was derived to explore the relationship between t
he life history parameters and population densities of this species, a
nd to identify those parameters most likely to explain the differences
in densities observed between continents. Model predictions seem cons
istent with the empirical data. The model predicted equilibrium densit
ies in Australia one order of magnitude higher than those reported in
South America. Moreover, a sensitivity analysis showed that adult equi
librium densities were much more sensitive to variations in adult surv
ival than to variations in any of the other parameters at high densiti
es. Coincidentally, it is adult survival for which the biggest differe
nces between continents have been detected, suggesting that the higher
toad densities reported in Australia are likely to be the result of h
igher adult survival in that continent. On the other hand, the high se
nsitivity of adult equilibrium densities to adult survival also has im
portant implications for control of this species in Australia.