Three out of four cats will wear a collar (for the six months of the duration of the research project).
And not just indoor/outdoor cats should wear collars.
And indoor-only cats can get lost. Lord’s recommendations from this study are informed in part by her previous research, which has found, for example, that 40 percent of lost cats in one community were indoor-only cats, or that free-roaming cats without collars are very likely to either be fed by strangers – reducing the likelihood that they will return home – or to be ignored as strays.
“The return-to-owner rate is abysmal for cats. Fewer than 2 percent of lost cats are returned to their owners,” she said. “If we could get cat owners to try using a collar with identification, it would be a big deal.”
As far as the dangers of collars go (getting the collar caught in the mouth, getting a leg through the collar, the collar snagging on branches, and the cost of replacement collars for Houdini cats), I stopped buying commercial collars long ago.
Instead I buy the soft blue aquarium hose and straight connectors, and Jiffy Tags (although currently Bear has a real tag). Cut a piece of hose, trim to the appropriate length, slide the tag ring on, and fasten around the cat's neck with the connector. The cat can chew through it if they get it caught in the mouth, and the hose will pull off the connector if the cat gets hung up or puts a leg through. And these collars are cheap cheap cheap. They also don't rub a collar mark on the cat's neck.