Adult body size, mass and condition predict reproductive success and survival, and hence fitness, in mammals and many other animals. Here, we assessed morphological variation and body condition in populations of the red fox (Vulpes vulpes) along an urban to natural land use gradient in the Sydney region, Australia. The red fox was introduced into Australia in the mid‐19th century and is a recent but successful urban adapter as well as a highly effective predator of naïve native species. As the red fox has successfully invaded urban environments in many parts of the world where it readily exploits anthropogenic sources of food, we hypothesized that individuals should be larger and in better condition in urban than in natural habitats. We found that individuals (N = 135) of both sexes had larger body mass and skeletal measurements in urban than in more natural habitats; body condition, by contrast, showed no consistent variation. Thus, the urban environment of Sydney provides conditions that favour an increase in size in red foxes so that individuals are now larger than, but in similar body condition as, their non‐urban counterparts. Increased body size and mass may enable red foxes to hunt a broader array of prey species, and as such would be of added concern for the management of native wildlife in Australia's urban environments, a possibility that warrants further investigation.

Carnivore conservation translocations are assumed to provide numerous ecological benefits, including conservation of the translocated carnivores, regulation of prey species and restoration of ecosystems. Reviews of mammalian carnivore conservation translocations and resultant ecosystem effects have focussed on large carnivores. We reviewed global terrestrial carnivore conservation translocations across all taxa, including taxonomic bias, problems influencing their population establishment and their ecosystem effects. We obtained data from 536 conservation translocations of 54 species of terrestrial mammalian carnivore (order Carnivora and family Dasyuridae, 30 g–196 kg), comprising mostly Mustelidae, Canidae, and Felidae species. A third of all projects translocated carnivores into South Africa and a third into fenced reserves. Significant bias occurred relative to threat status, with over‐representation of Mustelidae and Canidae conservation translocations relative to the number of threatened species in each family. Additionally, conservation translocations of small carnivores were generally under‐represented compared to those of large carnivores. Seventeen percent of small carnivore conservation translocations failed, compared with 25% of large carnivore conservation translocations; failure was primarily due to reported anthropogenic mortality. Effects on resident prey species or ecosystems of carnivore conservation translocations were rarely investigated. We found no significant relationship between the carnivore family or size and effects on prey or ecosystems; however, prey impacts were frequently attributed to Felidae, and ecosystem effects were frequently attributed to Canidae and Felidae. Challenges to translocations of mammalian carnivores include threats to resident threatened prey species and difficulties in monitoring the ecological effects of carnivore conservation translocations. Poor postrelease monitoring and a lack of empirical studies remain persistent problems, contributing to the poor understanding of ecosystem effects following carnivore conservation translocations.

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