A Rubbish Diet

By Heather Crawford, Mike Calver and Trish Fleming.  Domestic cats (Felis catus) are one of the most widely distributed and successful carnivores globally. In cities, unowned cats (‘stray’) live in close association with human habitations and can roam across neighbourhoods, commercial areas, parks and bush reserves, hunting wildlife and scavenging food where they can find it (Figure 1).

Stray cats present a management challenge due to concerns about wildlife predation, pathogen transmission, and public nuisance. Stray cats also face many welfare threats, being especially vulnerable to motor vehicle collisions.

In Australia, there are few studies of stray cat biology. We therefore examined the remains of 188 euthanised strays collected from Perth, Western Australia to determine their general health, age, reproductive status, diet and parasite biomass.

Figure 1: Stray cat caught on camera at an urban bush reserve in Perth, Western Australia.

Overall, we found that stray cats appeared physically healthy with few life-threatening injuries or macroscopic evidence of disease. Parasites were extremely common in Perth strays, 100% of cats hosting fleas and 95% of cats positive for roundworms or tapeworms, all of which are transmissible to pet cats. As these cats roam through suburban areas, it highlights the importance of cat owners regularly medicating their pets against parasites.

Alarmingly, 57.5% of strays had scavenged vast amounts of human refuse. This included life-threatening items such as indigestible paper and plastic in volumes that had blocked their gastrointestinal tracts. One stray cat had eaten a half-spread of newspaper and another had consumed a fish-hook. Another had an entire pair of full-length ladies’ nylon stockings running from oesophagus to bowel. On average, 44% of the stomach contents of these cats was made up of refuse (Figure 2). We believe that many of the cats processed would have eventually died from bowel blockages caused by refuse.

Cat diet of human refuse
Figure 2: Examples of refuse in stray cat stomachs collected from Perth, Western Australia. a) An adult male consumed: 1. black plastic bag, Work-boot shoelaces, 2. Paper, 3. Aluminium foil, 4. a green plastic net, and 5. single shoelace from a work-boot. b) A juvenile consumed: woven plastic bag (for domestic animal-feed pellets), as well as a mouse (seen as grey furballs in picture) and sheep carrion (not shown). c) A juvenile female consumed: glass shards and (not shown) a wound bandage, plastic, paper and bark.

We also found proof that these stray cats were a predation threat for urban wildlife. Nearly 40% of the stray cats examined had consumed wildlife, including two species of endemic marsupial, the brushtail possum and quenda (Figure 3).

These findings reinforce the need to remove stray cats from the streets for their own health and welfare. Targeted control programmes, prioritising areas such as rubbish tips and urban bush reserves where native wildlife persists, needs to be an animal welfare and environmental priority.

Read more about this study: 2020 Crawford et al. diet of stray cats

bandicoot - Narelle Dybing
Figure 3: Quenda are found in the stomachs of Perth stray cats. Photo Narelle Dybing.

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