Unlicensed pest control vans
At lunch today, Ching mentioned that one thing to look out for is pest control vans. She had an experience where they came to trap the cats in the area where she lives and the van had no markings on it. She called around and found out that the company was not licensed - so that's one thing to look out for. If it is an unlicensed company, they have no right to trap the cats. Unmarked vans - so X-Files.
Remember try and get as many details as possible - do not obstruct a pest control company by trying to touch them. There is of course no need to be rude as well but there is nothing wrong with taking photographs so that you'll know which cats were caught for example. Write down the name and number of the pest control company - as I mentioned, photos are good too. Some pest control companies may get upset if you are there, so be prepared for that, but you're just there to take down as much information as possible so that the cats can hopefully be saved after. They are doing a job - and so are we.