Gunther I, Finkler H, Terkel J: Demographic differences between urban feeding groups of neutered and sexually intact free-roaming cats following a trap-neuter-return procedure, J Am Vet Med Assoc 238:1134, 2011.
There have been few studies conducted to investigate the effects of neutering on free-roaming cat populations. This study observed over a one year period 184 free-roaming adult cats and 76 kittens living in 4 feeding groups in an urban area of Israel. Cats in two groups were subjected to the trap-neuter-return procedure (TNR) and the other two groups were left untreated. It was noted that the two neutered groups increased in size significantly because of higher immigration (cats moving into the groups) and lower emigration (cats moving away) rates than in the unneutered groups, in which the number decreased. It appears the neutered cats formed a stable feeding core, resulting from the decreased roaming and increased survival rates of cats after neutering. Sexually intact cats also immigrate into the neutered groups more readily. Kitten survival rates were significantly higher in the neutered groups. The study concluded in part that to maintain a high proportion of neutered cats in such cat groups, persistent TNR campaigns are considered necessary. [VT]