I once found a huge trail of lemmings outside leading up to my cat. Quite difficult feeling for somebody who loves cats and also all other creatures. Luckily the cat has fully adjusted now for an indoor live.
I believe the author mentioned that the cat was adjusting to life indoors.
Is there anything a cat owner can do, when having an indoor cat isn't an option? Some kind of collar that produces noise maybe?
Yes, a collar with a bell reduced predation by cats, and is recommended by the Royal Society for Protection of Birds, among others.
Now, to be fair, it is not without its cost. It happens that cats get it tangled in fences or other obstacles and die by strangulation or predation.
You can put a wide-ruffled, brightly-colored collar (with a bell) on the cat. My wife found one on Etsy for our little fluffy hunter, and the combo of noise/color allows the birds to hear/see him coming and skedaddle.
I will never look at cats the same way again.
It was quite malnourished so I'm guessing it didn't catch much.
Probably none? Sounds like they brought her in to live indoors…