Likely as not, that damage was done by coons. Even adult coons can get through some small spaces and half grown coons that are learning to hunt this time of year, even smaller. Coon predation is so bad this time of year, good rule of thumb is to assume it is coons until you find out otherwise.
Not likely OP has Minks (1 1/2" opening) or weasels (1").....but either of those would kill a lot of birds by severing back of neck at the base of the skull......and might even rip the heads off in doing so.......but seldom chow down on the necks and crops like that.