TY - JOUR
T1 - Experimental evidence that feral cats cause local extirpation of small mammals in Australia's tropical savannas
AU - Frank, Anke S K
AU - Johnson, Chris N.
AU - Potts, Joanne M.
AU - Fisher, Alaric
AU - Lawes, Michael J.
AU - Woinarski, John C Z
AU - Tuft, Katherine
AU - Radford, Ian J.
AU - Gordon, Iain J.
AU - Collis, Mary-Anne
AU - Legge, Sarah
PY - 2014/12/1
Y1 - 2014/12/1
N2 - 1. Small mammal species are
declining acrossnorthern Australia. Predation by feral cats Felis
sylvestris catus isone hypothesised cause. Most evidence of cat impacts on
native prey comes fromislands, where cat densities are often high, but cats
typically occur at lowdensities on mainland Australia. 2. We conducted a field experiment
to measurethe effect of predation by low-density cat populations on the
demography of anative small mammal. We established two 12·5-ha enclosures in
tropical savannain the Northern Territory. Each enclosure was divided in half,
with catsallowed access to one half but not the other. We introduced about
20individuals of a native rodent, Rattus villosissimus, into each
ofthe four compartments (two enclosures × two
predator-accesstreatments). We monitored rat demography by mark-recapture analysis
andradiotracking, and predator incursions by camera surveillance and track
andscat searches. 3. Rat populations persisted over
the durationof the study (18 months) in the predator-proof treatment,
where wedetected no predator incursions, but declined to extinction in
bothpredator-accessible compartments. In one case, cat incursions were
frequentlydetected and the rat population was rapidly extirpated
(<3 months); inthe other, cat incursions were infrequent, and the
population declined moregradually (c. 16 months) due to low recruitment.
We detected no incursionsby dingoes Canis dingo, the other mammalian
predator in the area. 4. Synthesisand applications. This is
the first study to provide direct evidence that catsare capable of extirpating
small mammals in a continental setting, in spite oftheir low population
densities. This finding supports the hypothesis thatpredation by feral cats is
contributing to declines of small mammals innorthern Australia. The
conservation management of native small mammals innorthern Australia may
require intensive control of cat populations, includinglarge cat-free
enclosures.
AB - 1. Small mammal species are
declining acrossnorthern Australia. Predation by feral cats Felis
sylvestris catus isone hypothesised cause. Most evidence of cat impacts on
native prey comes fromislands, where cat densities are often high, but cats
typically occur at lowdensities on mainland Australia. 2. We conducted a field experiment
to measurethe effect of predation by low-density cat populations on the
demography of anative small mammal. We established two 12·5-ha enclosures in
tropical savannain the Northern Territory. Each enclosure was divided in half,
with catsallowed access to one half but not the other. We introduced about
20individuals of a native rodent, Rattus villosissimus, into each
ofthe four compartments (two enclosures × two
predator-accesstreatments). We monitored rat demography by mark-recapture analysis
andradiotracking, and predator incursions by camera surveillance and track
andscat searches. 3. Rat populations persisted over
the durationof the study (18 months) in the predator-proof treatment,
where wedetected no predator incursions, but declined to extinction in
bothpredator-accessible compartments. In one case, cat incursions were
frequentlydetected and the rat population was rapidly extirpated
(<3 months); inthe other, cat incursions were infrequent, and the
population declined moregradually (c. 16 months) due to low recruitment.
We detected no incursionsby dingoes Canis dingo, the other mammalian
predator in the area. 4. Synthesisand applications. This is
the first study to provide direct evidence that catsare capable of extirpating
small mammals in a continental setting, in spite oftheir low population
densities. This finding supports the hypothesis thatpredation by feral cats is
contributing to declines of small mammals innorthern Australia. The
conservation management of native small mammals innorthern Australia may
require intensive control of cat populations, includinglarge cat-free
enclosures.
KW - Manipulative experiment
KW - Mark-recapture
KW - Predator-prey interactions
KW - Predator-proof fences
KW - Reintroduction
KW - Small-mammal extinction
KW - Survival
UR - http://www.scopus.com/inward/record.url?scp=84909970041&partnerID=8YFLogxK
U2 - 10.1111/1365-2664.12323
DO - 10.1111/1365-2664.12323
M3 - Article
SN - 0021-8901
VL - 51
SP - 1486
EP - 1493
JO - Journal of Applied Ecology
JF - Journal of Applied Ecology
IS - 6
ER -