how many birds does a cooper's hawk eat?

i like seeing bird-eating hawks because that means there are enough birds living around to *feed* the hawks. i was thinking they eat one bird a day, so each coopers hawk i see means therea re enough for 365 *extra* birds in that area all year. and i see a LOT of coopers hawks these days. but do they really eat a bird every day? or one every other day? do they eat mice? i know red-tailed hawks eat mice, not birds, but do coopers hawks also eat mice and fish adn stuff? or just birds? i hardly ever see sharp-shinned hawks. i see coopers hawks often (could be the same ones).