Introduction

The almost ubiquitous presence of domestic cats in human society is evidence that people value this species highly, both as companions and as biological control of pests. In some countries, including the UK, USA and China, they have out-competed other species in becoming the most common household pet (Bernstein, 2005). However, the presence of cats can also give rise to a range of problems to humans and other species and they may experience welfare problems themselves. As cats can survive and reproduce successfully outside of human care, or indeed with human care but without human intent, their populations and the problems these present may increase to a level deemed unacceptable to society and hence the motivation for ‘cat population management’. The global number of domestic cats is a notoriously difficult figure to estimate; Jarvis (1990) suggested 400 million cats globally; however, an unpublished report to the World Society for the Protection of Animals (WSPA) in 2007 used published data on pet statistics and questionnaires of non-governmental organisations and veterinary surgeons to gather information from 194 countries, leading to an estimate of 272 million cats worldwide of which 58% were thought to be ‘stray’ or ‘feral’ (see the discussion that follows regarding these terms).