What the cat dragged in : quantifying prey return rates of pet cats (Felis catus) with outdoor access in the UK

Non-native predators can cause great harm to natural ecosystems through competition for resources and by directly predating on native species. Domestic cats (Felis catus) predate on wild prey throughout the world and have been implicated in a number of species declines. However, in the UK, long-term, widespread research is lacking. Here, the study aimed (i) to quantify prey returned home across the country and (ii) to investigate factors which may influence these return rates. A predation survey was conducted on 553 cats across the UK for up to 43 months (2018–2021), recording all prey returned home and subsequently detected by the cats' owners. All owners of cats with outdoor access were encouraged to participate, the only exclusion criterion being indoor-only. Data were gathered upon registration regarding the age, sex, and body condition of participating cats, allowing for the analysis of the potential influence of such factors. It was estimated here that the current UK population of pet cats (10.8 million total) return a total of between 37.25 million and 140.4 million prey per year, the majority being mammals (83% of detected prey). Sex, age, and body condition of cats, along with the presence of a cat flap, whether a bell was worn, level of urbanisation, and the season of data collection all had a statistically important effect on prey return rates. While most cats returned 0–1 prey per month, a small minority (n = 3 cats) returned over 15 individuals monthly. It is important that true predation rates (in addition to the return rates found here) are further explored and quantified, along with the actual impact that this has or does not have on prey populations. Future efforts to limit the impact of cat predation should focus in particular on identifying super predators with a view to limiting their predation.