Feral Cat Control in Britain; Developing a Rabies Contingency Strategy

Feral cat (Felis catus) control is required for reasons of public health, the welfare of cats themselves, and rabies control should an outbreak occur in Britain. A prerequisite to the control of feral cat colonies would be establishing their location. A method for locating colonies was developed and tested in four urban areas with a mean area of 157 sq km. Each area was surveyed on foot and by car to obtain the number and distribution of feral cat colonies. The method involved making inquiries at premises most likely to be frequented by cats ("high risk areas"). Most (94%) of the 116 feral cat colonies found (comprising approximately 874 cats) were found at the nine high risk categories. Few feral cat colonies occurred elsewhere, confirming that high risk categories were useful in locating finding feral cats. Information concerning the efficacy of cage trapping as a method of feral cat control was also investigated. A wide variety of baits were used in the traps including proprietary dry pelleted cat food, which was considered to be the most effective and was used in all the subsequent trap trials. In a series of 12 field trials, using live capture cage traps, between 82% to 100% of feral cats in the colonies were captured. Altogether 202 cats were captured at a rate of 21 cats per 100 trap nights. Proc. 16th Vertebr. Pest Conf. (W.S. Halverson & A.C. Crabb, eds.) Published at Univ. of Calif., Davis. 1994. INTRODUCTION Cats in Britain may, according to circumstances, be referred to as pets, strays or feral and it is apparent that a range of cats exist with varying degrees of dependency on humans for food and sociality (Figure 1). One extreme may be seen on Monarch Islands (Randall 1972) where people no longer live but feral cat populations are sustained by feeding on rabbits and nesting birds. In contrast, a domestic cat confined almost totally to an upstairs flat in a city would be wholly dependent on humans for food, harborage, sociality and if neutered would be incapable of reproduction. A stray cat may be considered to be around 50% dependent on humans for food, harborage and sociality. Stray cats are usually solitary but are likely to eventually join a feral cat colony though some were observed associating with pet cats (Page et al. 1992). If a rabies outbreak were to occur in Britain, colonies of feral cats would be among the potential vectors of rabies that would be controlled in order to eliminate the disease. For rabies emergency plans, a feral cat colony has been defined as a group of three or more cats which the owner of the property where they occur would be unable to confine, if required to do so under the 1974 Rabies Act (Page et al. 1992). Because cats living in such colonies are unowned, for the purposes of rabies control, they are regarded as wild animals and will be controlled by the Ministry of Agriculture Fisheries and Food. The control of feral cats is necessary for several reasons including public health, the welfare of cats and rabies control. Cats are hosts to parasites which affect humans including Campylobacter, Cryptosporidia (Bennett et al. 1985), Toxocara cati and Toxoplasma gondii (Langham and Charleston 1990). Toxocariasis may cause blindness in humans and Campylobacter and Cryptosporidia are a cause of diarrhea in humans. Cow pox virus which affects man (Baxby 1977, 1982) was isolated from feral cats which may be the natural host for the virus (Gaskell et al. 1983, Bennett 1989). Feral cats are particularly susceptible to feline panleucopaenia (Gillespie and Scott 1973). Southam (1981), and Passanisi and Macdonald (1990) reviewed the health hazards posed by feral cats. Figure 1. Diagram showing gradation of cats from entirely feral to wholly domestic. Colonies of feral cats are not uncommon in Britain, particularly in urban areas and, although cats will not support a rabies epizootic alone (Wandeler 1991), their control would also be required in the event of a rabies outbreak. The control of feral cat colonies is labor intensive but necessary, as the use of vaccine bait,