A bit more on weasels........formidable killers they are. Along with owls, hawks and snakes, one of natures most effective rodent controllers and all around bad ***.
https://en.wikipedia.org/wiki/Weasel
Google your state's DNR and weasel and most will likely have a page for them. This one was from Illinois. Most will have something similar.
https://www.dnr.illinois.gov/conservation/wildlife/Pages/LongTailedWeasel.aspx
So the nature of how they kill is to rush and attack the prey, and bite it on the back of the neck, killing it instantly. The reason for missing heads and no blood is they lick or lap at the blood. Ripping the head off a chicken would make it bleed more, and especially so if it still has a heart beat. They also go into a killing frenzy, so don't just stop at one. They may kill everything in sight, even if they are not hungry. So they just kill one after the other and move on. They say that given a choice, they feed almost exclusively on rats, mice and other small furry rodents. Take out "almost" and they would be welcome almost everywhere.
It is possible they are not really after the birds.....or at least not initially. It may be they initially were attracted to the coop for any mice or rats lurking about, but then find the birds and being the opportunistic killers they are, go for the birds instead. Since birds are easy prey, and since weasels do not have a large hunting area, they tend to come back to the scene of the crime for another easy meal. They also eat eggs, so that may be another reason for them to keep coming back to a chicken house.
They live in tunnels and burrows, so they can dig and it does not take much digging for them to get under a fence or coop. They can get through holes no larger than an inch or so. So the solution is to employ the apron trick around the perimeter........probably no larger than 1/2" x 1" welded wire, and 1/2" hardware cloth over all vent openings. No cracks or other openings anywhere.
If they stick around and won't go away, best way to get rid of them is a weasel box trap........a box with a hole in one end, and a rat trap waiting for them inside.
https://en.wikipedia.org/wiki/Weasel
Google your state's DNR and weasel and most will likely have a page for them. This one was from Illinois. Most will have something similar.
https://www.dnr.illinois.gov/conservation/wildlife/Pages/LongTailedWeasel.aspx
So the nature of how they kill is to rush and attack the prey, and bite it on the back of the neck, killing it instantly. The reason for missing heads and no blood is they lick or lap at the blood. Ripping the head off a chicken would make it bleed more, and especially so if it still has a heart beat. They also go into a killing frenzy, so don't just stop at one. They may kill everything in sight, even if they are not hungry. So they just kill one after the other and move on. They say that given a choice, they feed almost exclusively on rats, mice and other small furry rodents. Take out "almost" and they would be welcome almost everywhere.
It is possible they are not really after the birds.....or at least not initially. It may be they initially were attracted to the coop for any mice or rats lurking about, but then find the birds and being the opportunistic killers they are, go for the birds instead. Since birds are easy prey, and since weasels do not have a large hunting area, they tend to come back to the scene of the crime for another easy meal. They also eat eggs, so that may be another reason for them to keep coming back to a chicken house.
They live in tunnels and burrows, so they can dig and it does not take much digging for them to get under a fence or coop. They can get through holes no larger than an inch or so. So the solution is to employ the apron trick around the perimeter........probably no larger than 1/2" x 1" welded wire, and 1/2" hardware cloth over all vent openings. No cracks or other openings anywhere.
If they stick around and won't go away, best way to get rid of them is a weasel box trap........a box with a hole in one end, and a rat trap waiting for them inside.