Do introduced apex predators suppress introduced mesopredators? A multiscale spatiotemporal study of dingoes and feral cats in Australia suggests not

1. The role of apex predators in structuring ecosystems through the
suppression of mesopredator activity and abundance is receiving increasing
attention, largely due to the potential benefits for biodiversity
conservation. In Australia, invasive mesopredators such as feral cats
(Felis catus) have been identified as major contributors to Australia’s
mass mammal extinctions since European arrival. The introduced dingo
(Canis familiaris) has been proposed as a novel way to suppress the
impacts of feral cats, however scientific evidence of the dingo’s
suppressive role is equivocal. 2. We used camera traps to investigate
whether a large introduced predator (dingo) suppresses the activity of an
established introduced mesopredator (feral cat) across a national park
site conserving endangered species, and an agricultural site supporting
cattle grazing enterprises. 3. Feral cats and dingoes exhibited marked
overlap in both temporal and spatial activity, indicating coexistence.
Some temporal separation was evident at the agricultural site, however
this reflected higher diurnal activity by dingoes, not a responsive shift
in cat activity. Cat activity times were unrelated to dingo presence and
did not differ between areas occupied by dingoes and dingo-free areas.
There was no evidence of dingoes excluding cats from patches at either
site, nor was there evidence of within-night fine-scale spatiotemporal
avoidance of dingoes by cats. 4. Species co-occurrence models revealed
dingoes had no negative effect on the probability of cat presence. The
probability of detecting a cat on the national park was significantly
higher in areas with dingoes than in dingo-free areas, while on
agricultural land, cat detectability did not differ between areas with and
without dingoes. Cats remained active, abundant and widespread across both
sites, with evidence of cats hunting and breeding successfully in areas
occupied by dingoes. 5. Synthesis and applications. Our findings indicate
that feral cats can coexist with dingoes, without apparent suppression of
cat activity, abundance, or fitness. Proposals to reintroduce or restore
dingoes and other large predators to suppress invasive mesopredators and
conserve biodiversity should be carefully evaluated on a site-by-site
basis, as their ability to suppress cats and protect species of
conservation significance will likely be context dependent.