Trish Fleming

Debating impacts of owned cats Felis catus on wildlife diverts attention from improving cat health and welfare, which may also protect wildlife. We present a narrative review of the health and welfare consequences of indoor or outdoor cat husbandry. Roaming cats, especially young males, face substantial risks of traumatic injury and infectious disease, plus lesser risks of poisoning and abuse. A cat may die 10 or more years prematurely, while the cohort of outdoor cats has approximately 70–80% of the lifespan of the cohort of indoor cats. Owners also incur veterinary expenses for injuries to roaming pets, which sometimes cause lifelong, chronic conditions. There are also data-based claims for greater quality of life for contained cats, plus more satisfying bonds between cats and owners. Containment, however, may cause obesity, diabetes or behavioural problems, while solutions including environmental enrichment, exercise, and correct feeding, plus containment logistics, may strain owners’ time and finances. Contained cats are also unlikely to express all cat behaviour. We conclude that, based on health and welfare, the advantages of containment are considerable and the disadvantages often remediable. This conclusion supports existing arguments that including health and welfare in husbandry decisions benefits cats and wildlife conservation.

Utility-scale solar facilities (‘solar farms’/‘solar parks’) represent vast altered landscapes – currently covering ∼0.025% of the earth’s land surface. The rapid transformation of landscapes necessitates urgent research into biodiversity impacts of solar facilities worldwide. Evidence for fauna impacts at both concentrating solar power (CSP) and photovoltaic (PV) solar facilities was analysed. Solar facilities impact fauna through habitat loss and fragmentation, altered microclimate, and creation of novel habitat. Evidence suggests increases in insect, bird and bat species richness and abundance around solar facilitates built over degraded landscapes, likely due to introduction of novel habitat and presence of generalist species, but a decrease when comparison is made with intact reference landscapes. CSP facilities attract large numbers of flying insects and therefore insectivorous birds, while both heliostats (CSP) and PV solar panels are attractive to waterbirds, with the timing and direction of bird movements indicating they are responding to linear polarised light reflections from panels. While generalist bat species make use of solar facilities, data to date indicates a decrease in bat species richness and activity around solar facilities. Extrapolating from USA studies, an estimated 17.3 million birds die at solar facilities every year. Direct impacts of solar facilities include injuries and deaths due to collisions and burns, while entrapment, starvation and increased predation risk are also recorded causes of mortalities. Solar facilities significantly impact local fauna, particularly attracting and affecting insectivores and waterbirds. Further research is needed to fully understand these effects and develop mitigation strategies for sustainable solar energy expansion.

Although the domestic cat Felis catus is implicated in multiple faunal extinctions and threatens many extant species, there is widespread, well‐funded advocacy for desexing unowned cats near human habitation and returning them to site to be fed by volunteers, arguing that this prevents euthanasia, is unlikely to be hazardous to wildlife or a public health risk, and controls non‐native rodents. To the contrary, we present unequivocal evidence that this approach harms cat welfare, does threaten wildlife and public health, and exacerbates rather than controls rodent problems. We argue instead that unowned cats near human habitation can be controlled effectively by intensive adoption and responsible euthanasia when necessary, supported by licensing and containment of adopted/owned cats.

Introduction of the domestic cat and red fox has devastated Australian native fauna. We synthesized Australian diet analyses to identify traits of prey species in cat, fox and dingo diets, which prey were more frequent or distinctive to the diet of each predator, and quantified dietary overlap. Nearly half (45%) of all Australian terrestrial mammal, bird and reptile species occurred in the diets of one or more predators. Cat and dingo diets overlapped least (0.64 ± 0.27, n = 24 location/time points) and cat diet changed little over 55 years of study. Cats were more likely to have eaten birds, reptiles and small mammals than foxes or dingoes. Dingo diet remained constant over 53 years and constituted the largest mammal, bird and reptile prey species, including more macropods/potoroids, wombats, monotremes and bandicoots/bilbies than cats or foxes. Fox diet had greater overlap with both cats (0.79 ± 0.20, n = 37) and dingoes (0.73 ± 0.21, n = 42), fewer distinctive items (plant material, possums/gliders) and significant spatial and temporal heterogeneity over 69 years, suggesting the opportunity for prey switching (especially of mammal prey) to mitigate competition. Our study reinforced concerns about mesopredator impacts upon scarce/threatened species and the need to control foxes and cats for fauna conservation. However, extensive dietary overlap and opportunism, as well as low incidence of mesopredators in dingo diets, precluded resolution of the debate about possible dingo suppression of foxes and cats.

Aim
Introduced predators negatively impact biodiversity globally, with insular fauna often most severely affected. Here, we assess spatial variation in the number of terrestrial vertebrates (excluding amphibians) killed by two mammalian mesopredators introduced to Australia, the red fox (Vulpes vulpes) and feral cat (Felis catus). We aim to identify prey groups that suffer especially high rates of predation, and regions where losses to foxes and/or cats are most substantial.

Location
Australia.

Methods
We draw information on the spatial variation in tallies of reptiles, birds and mammals killed by cats in Australia from published studies. We derive tallies for fox predation by (i) modelling continental-scale spatial variation in fox density, (ii) modelling spatial variation in the frequency of occurrence of prey groups in fox diet, (iii) analysing the number of prey individuals within dietary samples and (iv) discounting animals taken as carrion. We derive point estimates of the numbers of individuals killed annually by foxes and by cats and map spatial variation in these tallies.

Results
Foxes kill more reptiles, birds and mammals (peaking at 1071 km−2 year−1) than cats (55 km−2 year−1) across most of the unmodified temperate and forested areas of mainland Australia, reflecting the generally higher density of foxes than cats in these environments. However, across most of the continent – mainly the arid central and tropical northern regions (and on most Australian islands) – cats kill more animals than foxes. We estimate that foxes and cats together kill 697 million reptiles annually in Australia, 510 million birds and 1435 million mammals.

Main conclusions
This continental-scale analysis demonstrates that predation by two introduced species takes a substantial and ongoing toll on Australian reptiles, birds and mammals. Continuing population declines and potential extinctions of some of these species threatens to further compound Australia's poor contemporary conservation record.

The red fox Vulpes vulpes is one of the world’s most widespread carnivores. A key to its success has been its broad, opportunistic diet. The fox was introduced to Australia about 150 years ago, and within 30 years of its introduction was already recognised as a threat to livestock and native wildlife.

We reviewed 85 fox diet studies (totalling 31693 samples) from throughout the species’ geographic range within Australia. Mammals were a major component of fox diet, being present in 70 ± 19% of samples across n = 160 locations. Invertebrates (38 ± 26% n = 130) and plant material (26 ± 25% n = 123) were also both staple foods and often the dominant food category recorded. Birds (13 ± 11% n = 137) and reptiles (10 ± 15% n = 132) were also commonly reported, while frogs were scarcely represented (1.6 ± 3.6% n = 111) in fox diet studies.

Biogeographical differences reveal factors that likely determine prey availability. Diet composition varied with ecosystem, level of vegetation clearing and condition, and climate zone.

Sample type (i.e. stomach versus scat samples) also significantly influenced reporting of diet composition. Livestock and frogs were underrepresented in records based on analysis of scats, whereas small mammals (native rodents, dasyurid marsupials, and bats) were more likely to be recorded in studies of scats than in studies of stomach contents.

Diet varied seasonally, reflecting activity patterns of prey species and food availability. This synthesis also captures temporal shifts in fox diet over 70 years (1951–2020), as foxes have switched to consuming more native species in the wake of successful broadscale biological control of the invasive European rabbit Oryctolagus cuniculus.

Diet analyses, such as those summarised in this review, capture the evidence required to motivate for greater control of foxes in Australia. This synthesis also highlights the importance of integrated pest species management to meet biodiversity conservation outcomes.