The Executive Summary of Dickman (1996) states (in part):
"2) On the Australian mainland cats can impact on native mammals weighing up
to about 2000 g, but
impact falls most heavily on smaller species, especially those weighing <220
g. Vulnerability to predation
is enhanced for species occupying open or otherwise unprotected habitats,
and by behavioural
traits such as saltatory locomotion. Cats can impact on birds up to about
1000 g, but impact again
falls most heavily on smaller species weighing <200 g. Ground foragers and
ground nesters are most
vulnerable, especially in open habitats, although impact on hollow-nesting
species is also possible.
3) On islands, cats have had major impacts on terrestrial mammals up to 3000
g and birds up to 3500 g,
although smaller species are preferred. As in mainland situations,
vulnerability to impact is
increased if protective habitat is not available, if foraging, burrowing or
nesting activities take place
on the ground surface or other exposed sites and, for birds, if the island
is occupied year-round.
4) In mainland areas and on some islands where introduced mammals (rabbits,
Mus domesticus,
some Rattus spp.) or native mammals (usually Rattus spp.) reach high
densities, impacts of feral
cats on susceptible native fauna may be increased by a `subsidy' effect.
Impacts may be intensified if
other species of predators, such as foxes, are present.
5) Although long periods of apparently stable coexistence (i.e. several
years) are possible between
feral cats and potential prey, impact may still occur if `rogue' individuals
develop hunting skills for
particular prey species at any time. The impact may be major if the prey
population is small when
predation begins.
6) In Australia, in contrast to other parts of the world, feral cats are not
recorded to have impacted on any
species of reptiles, amphibians, fish or invertebrates. "
Reference:
Dickman, C. (1996). Overview of the Impacts of Feral Cats on Australian
Native Fauna (Report Prepared for the Australian Nature Conservation Agency,
Canberra).
Dr Stephen Ambrose
Ryde, NSW
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