Re: News story and more pictures
The collar I saw them attach to one of the cats they trapped behind our house was pretty big. Felt sorry for the feline having to wear that around the woods. Batteries, I guess, are still the biggest (literally) factor. That, and you know how difficult it is to keep a collar on a cat - of any size. I'd think a RFDI chip would work, with perimeter reading devices in stratigic locations. Still, you gotta catch 'em to tag 'em.
It all comes down to money to fund it. I think several goverment agencies are funding this study, started before the crash of aught 8, and the current wave of budget cuts.