Over the last 15 years, my adopted feral cat has brought down and, occasionally, brought in everything from birds to rabbits - but no squirrels, even though we have dozens of grey and even a few black ones. She was born wild and has steadfastly refused to be a strictly an indoor cat, although in her old age she's grown more wary and divides her time 50/50, mostly remaining on our small property.
My point is this: our neighbors quickly accepted her hunting once they saw the number of mice and even rats, by far her main prey, that she brought in from around our suburban neighborhood and nearby landfill. Mankind has negatively impacted and altered the ecological landscape far, far more than any cat. Now cats, both pets and feral ones, are just filling the needed predator role instead of the native prowlers we have for the most part eliminated. Our county actually supports the spaying or neutering of feral cats, then releases them back into the wild to provide rodent control.
I know my roaming cat Speedbump may very well someday provide some wandering coyote or fox or big bird a snack - but that's the rules by which she's insisted on living and I for one can't fault her decision. It's her nature (Read Tribe of Tiger, a great book on our cats and their behavior)
One last soapbox: Please be responsible and SPAY or NEUTER those roaming pets!