This article is a discussion on the ‘vacuum effect’ and feral cats. I invite those of you active (or retired) with real TNR (trap, neuter, return) experience to comment on whether your colony cats keep other cats run off, or, in the case of removed colonies, did new cats take their place.

Studies show removing feral cats from these areas creates a “vacuum effect”: Cats from neighboring areas move into the newly available space to take advantage of food and shelter. These cats soon begin to breed to capacity. Before long, just as many cats can be found in the area as were there before.

In a scientific study at Marion Island in the sub-Antartic over 19 years, scientists noticed that when cats were cleared from a preferred area of the island, cats from another area took their place.

There are plenty of articles and charts on the vacuum effect and feral cats online. I’d prefer to gather information from actual TNR trappers who understand the importance of not disturbing a settled feral colony if at all possible.

Do your neutered males keep new cats from joining? Have you dealt with the heartbreak of having to move a colony and watching new cats take their place?

Please sound off in the comments. Note: Cat-hating trolls will not pass comment moderation so don’t bother commenting.