We've got to be really careful with those numbers. There's a massive difference in the ecosystem between continents. While we've become used to flora and fauna from continental Europe being brought to the rest of the world, that doesn't make them native there.
The issue in the report you linked isn’t cats living outside, the issue here is european flora and fauna existing at all in the US, where it doesn’t belong. This issue isn’t limited to cats, it even includes things like different species of lawn grass being invasive in regions it doesn’t belong.
The issue in the report you linked isn’t cats living outside, the issue here is european flora and fauna existing at all in the US, where it doesn’t belong. This issue isn’t limited to cats, it even includes things like different species of lawn grass being invasive in regions it doesn’t belong.