Turns out weasels, minks, and as per wikipedia, raccoons are all part of the same family:
https://en.wikipedia.org/wiki/Mustelidae
I think they got it wrong on the raccoons. They are part of a different family tree.
Another in this bunch are otters. In our area, the Dept. of Conservation re-introduced river otters some years back with the idea they would confine themselves to rivers. Not so. Talked to a guy who ran a commercial fish hatchery and he said river otters would come in an wipe out an entire pond. Catch and kill all the fish in the pond and just toss them up on the bank or a float into a bloody pile and seemingly, just for the fun of it. He shot otters on sight as do a lot of farmers. Most folks who would like to raise fish now see river otters as nothing more than a 40 pound weasel and wish they had never heard of them.
So anytime you see a multiple kill situation like this one, with lots of dead birds, and even more so if they are in a pile, this is the group to suspect.
So the question would be what to do about it? About all one can do is tighten up. All openings covered with 1/2" x 1/2" hardware cloth. That is ALL openings. And if these were killed in the daylight hours, that pretty much eliminates free range or any open yard option.
Provided you were going to monitor them daily, a person living in an infested area might be able to setup a perimeter of weasel traps (rat traps in boxes) to thin the herd. Leave them going year round?