Changes

''Felis silvestris'' is not a native species in the Americas or Australia, so that the impact it might have on wildlife in those regions may be considered much more serious and intrusive to local ecology. For example, it is estimated that i the USA free-ranging domestic cats kill 1.4-3.7 billion birds and 6.9-20.7 billion small mammals each year <ref name ="Loss">Loss, S.R., Will, T., Marra, P.P. (2013) The impact of free-ranging domestic cats on wildlife of the United States. ''Nature Communications''. 4 (1396).</ref>.  

''Felis silvestris'' is not a native species in the Americas or Australia, so that the impact it might have on wildlife in those regions may be considered much more serious and intrusive to local ecology. For example, it is estimated that i the USA free-ranging domestic cats kill 1.4-3.7 billion birds and 6.9-20.7 billion small mammals each year <ref name ="Loss">Loss, S.R., Will, T., Marra, P.P. (2013) The impact of free-ranging domestic cats on wildlife of the United States. ''Nature Communications''. 4 (1396).</ref>.  

This raises the issue of the impact of pet vs. feral populations. No accurate current estimate of the UK feral cat population is available, but the total population was estimated at 6 million in 1980, with 1.2 million being feral <ref>Harris, S., Morris, P., Wray, S., Yalden, D. (1995) ''A Review of British Mammals: population estimates and conservation status of British mammals other than cetaceans'', Peterbourgh, U.K.: Joint Nature Conservation Committee.</ref><ref>Tabor, R. (1981) General biology of feral cats. In: The Ecology and Control of Feral Cats. The Universities Federation for Animal Welfare, Potters Bar.</ref>. The current estimate of the UK pet cat population is 8 million, according to the Pet Food Manufacturers Association, and the population of feral cats is likely to be lower in 2014 than in 1980 due to active TNR programmes over the last 30 years. The situation in the UK is quite different from Australia and the USA:

This raises the issue of the impact of pet vs. feral populations. No accurate current estimate of the UK feral cat population is available, but the total population was estimated at 6 million in 1980, with 1.2 million being feral <ref>Harris, S., Morris, P., Wray, S., Yalden, D. (1995) ''A Review of British Mammals: population estimates and conservation status of British mammals other than cetaceans'', Peterbourgh, U.K.: Joint Nature Conservation Committee.</ref><ref>Tabor, R. (1981) General biology of feral cats. In: The Ecology and Control of Feral Cats. The Universities Federation for Animal Welfare, Potters Bar.</ref>. The current estimate of the UK pet cat population is 8 million, according to the Pet Food Manufacturers Association, and the population of feral cats is likely to be lower in 2014 than in 1980 due to active TNR and rehoming programmes over the last 30 years. The situation in the UK is quite different from Australia and the USA:

* Australia: 3 million pet cats, 10-20 million feral cats <ref>Jongman, E. C., Karlen, G.A. (1996) Trap, neuter and release programs for cats: a literature review on an alternative control method of feral cats in urban areas. Pp. 81-84, In: S. Hassett (ed.), ''Urban Animal Management Conference''. Australian Veterinary Association, Ltd.</ref><ref>Dickman, C.,Denny, E. 2010. Strategies to reduce conflict: managing feral and stray cats. Pp. 41-45 In: M. Tensen and B. Jones (eds.), ''Proceedings of the RSPCA Scientific Seminar'', Deakin West ACT, RSPCA Australia.</ref>

* Australia: 3 million pet cats, 10-20 million feral cats <ref>Jongman, E. C., Karlen, G.A. (1996) Trap, neuter and release programs for cats: a literature review on an alternative control method of feral cats in urban areas. Pp. 81-84, In: S. Hassett (ed.), ''Urban Animal Management Conference''. Australian Veterinary Association, Ltd.</ref><ref>Dickman, C.,Denny, E. 2010. Strategies to reduce conflict: managing feral and stray cats. Pp. 41-45 In: M. Tensen and B. Jones (eds.), ''Proceedings of the RSPCA Scientific Seminar'', Deakin West ACT, RSPCA Australia.</ref>

Based on the most recent estimate, the UK feral cat population is perhaps 15% the size of the pet cat population, whereas in the USA these populations are similarly sized and in Australia feral cats outnumber pet cats by a factor of 10-20 to one.

Based on the most recent estimate, the UK feral cat population is perhaps 15% the size of the pet cat population, whereas in the USA these populations are similarly sized and in Australia feral cats outnumber pet cats by a factor of 10-20 to one.

Trap-neuter-return (TNR) programmes have been shown to be effective in a number of studies. <ref>Levy, J.K., Gale, D.W., Gale, L.A., (2003) Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population. ''JAVMA''. 222, 42-46.</ref> showed a 66% reduction in population size over an eleven-year period in one free-roaming population. In the UK, nationwide trap and neuter programmes of this type have been in operation for more than a decade. In the UK and Germany, levels of neutering are generally high, which helps to limit population growth<ref>Heidenberger, E. (1997) Housing conditions and behavioural problems of indoor cats as assessed by their owners.'' Applied Animal Behaviour Science''. 52, 345-364.</ref>. Similar programmes are now also being run elsewhere by organisations such as International Cat Care in [http://www.icatcare.org/potugal/delegates/inside-the-centre Portugal] and [http://www.icatcare.org/in-action/sudan Sudan].  

TNR programmes have been shown to be effective in a number of studies <ref>Levy, J.K., Gale, D.W., Gale, L.A., (2003) Evaluation of the effect of a long-term trap-neuter-return and adoption program on a free-roaming cat population. ''JAVMA''. 222, 42-46.</ref> showed a 66% reduction in population size over an eleven-year period in one free-roaming population. In the UK, nationwide trap and neuter programmes of this type have been in operation for more than a decade. In the UK and Germany, levels of neutering are generally high, which helps to limit population growth<ref>Heidenberger, E. (1997) Housing conditions and behavioural problems of indoor cats as assessed by their owners.'' Applied Animal Behaviour Science''. 52, 345-364.</ref>. Similar programmes are now also being run elsewhere by organisations such as International Cat Care in [http://www.icatcare.org/potugal/delegates/inside-the-centre Portugal] and [http://www.icatcare.org/in-action/sudan Sudan].  

However, the most significant factors in the maintenance of a large feral population are climate and the availability of prey. The temperate climate of Northern Europe limits kitten survival, compared to the warmer climate of Australia. Australia also has a diverse population of prey species that have evolved in the absence of an equivalent predator to ''Felis silvestris''.

However, the most significant factors in the maintenance of a large feral population are climate and the availability of prey. The temperate climate of Northern Europe limits kitten survival, compared to the warmer climate of Australia. Australia also has a diverse population of prey species that have evolved in the absence of an equivalent predator to ''Felis silvestris''.