They are invasive species(not always a bad thing), driving out the native songbirds through competition(they are supremely adapted to living with humans[:@]. They cause a lot of problems as they build thier nests everywhere (not to mention s**t on everything)
when i was growing up my brother and myself had a contest all summer long with our pellet guns

....the count always stretched into the thousands

but it didnt make much of a difference.....