Human activity in general has a profoundly negative effect on wildlife! That's an unfortunate point we can never get away from. It is never choosing between absolute positive and absolute negative, but rather between more bad and less bad... But just because something is only "less bad" doesn't mean we should go with the worse option.
Throwing up your hands and saying "well, renewables kill some birds every year, so there's no reason to switch from oil and gas which kill many, many more birds every year" is quite silly. Or at least, that's what my fecal detector tells me.