A definition: A colony cat is a feral cat (usually) who is part of a group of three or more sexually mature cats living and feeding in close proximity. There are alternative definitions.
A managed colony is a colony that is controlled by a trap, neuter and return approach (TNR).
There are many managed feral cat colonies in the USA and in many countries. Volunteers feed them and carry out TNR programs. Managing feral cat colonies is becoming more popular and accepted by citizens and local authorities because it is the best and most humane way of relating to feral and semi-feral cats. Margaret Slater DVM PhD writes that she knows of three instances where feral cat colonies have disappeared because of the effectiveness of ten years of TNR combined with coordinated efforts to address the sources of feral cats.
A feral cat is “one that cannot be handled and is not suitable for placement into a typical pet home, that is a cat that is unsocialized”. Many colony cats became familiar with their human caregivers and therefore can no longer be described as feral. Around 50%-90% of cats in colonies are feral.
Mr No Ears was a famous colony cat who lived in a seaside resort in Portugal. Although he had some health problems, he was happy, loved, cared for and admired. You can read my review on a book about him by clicking on the following link:
That is it. I have a provided a definition (and a quote) from MR Slater in a chapter on the welfare of feral cats in the book The Welfare of Cats.