Wind turbines are such a blight on the landscape

[caraher]

35. Not really

The Humane Society says there are 86.4 million cats kept as pets in the US, and I've seen it estimated that there are another 60 million feral cats for a total of almost 150 million cats. For cats to kill 500 million birds a year that works out to an average of a bit more than 3 birds per year per cat.

So your cat is pretty average. (Maybe above average - she might kill some you never see.) I'd imagine the feral cats kill more of necessity, compensating for housecats that never get out to hunt birds.