A bit of a background into TNR
All around the world there are populations of essentially unowned cats. Some are truly feral, meaning they avoid human contact and interaction and are self sufficient in providing food for themselves by hunting.
Other groups, termed ‘street’ or ‘community’ cats, living either singularly or in colonies, are often rather dependent on provision of food, and sometimes shelter, by humans. Among these there may also be some previously owned cats which have been abandoned, and end up becoming a street/community cat.
Cats are prolific at breeding, an unneutered female cat can have 3 litters of kittens a year averaging 5-6 kittens per litter, so potentially 18 offspring per year. From all those offspring also breeding, in total one female cat can be responsible for 20,000 descendents in five years. There are a number of problems associated with having a lot of unowned cats in areas.
For the cats themselves, large numbers means infectious diseases can become rife and spread quickly. The larger the number the more strain on food resources as well, whether this is by hunting or supplied by humans – the latter can become a serious financial drain on the carer.
Neutered cats are in general healthier than un-neutered cats; males fight less, and females are not having to devote a lot of their energy into pregnancy and lactation, so can sustain their own health better.
From a public perspective, street or comunity cats can become a nuisance; raiding bins, making a lot of noise with fighting and mating, causing injury to owned cats, and in holiday destinations, ‘hassling’ restaurant goers for food.
Sometimes unfortunately this results in people taking it upon themselves to eliminate those cats by poisoning. This is deemed to be unacceptable from a welfare point of view, and is generally not a successful long term solution – the void left will quickly be filled by new cats & kittens colonising the same area.
Trap-neuter-return (TNR) is a well recognised system to help control the number of these cats, subsequently improving the welfare of those individual cats and the general population through disease control. Care4Cats is one of many charitable organisations which run TNR programs.