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  • Writer's pictureShäman Cröwe

How To Build, Bait And Place A Successful Weasel Box Trap

Updated: Jan 30, 2022

Nothing worse than a weasel in a poultry operation. A single weasel can eliminate an entire flock overnight and often kill everything they can, even if they don't intend on eating them all. Once all preventions have been seen to fail there is only one solution... You'll need to build a trap.

Weasels (and other members of the family mustelid) tend to kill and then collect birds into small piles. Bites on the back of the neck are often prevalent and only the head or neck will be eaten or bitten off. There will likely be a lingering skunk-like odor as well.

If there are bites around the vent area with intestines visible or removed, or the bodies are hidden or missing altogether, you may be dealing with a martin, a fisher or a mink and not a weasel.

A weasel can squeeze through any opening the size of a quarter or better so it is necessary to first cover any and all potential entry points with half inch hardware cloth or another type of heavy screen to avoid them gaining entry to begin with.

Clean up any leftover food and discourage rodents as they in turn attract mustelids. Store feed in rodent safe containers or bins or secure lids with bungee cords or rope.

Bury any fencing to avoid predators from digging underneath and avoid allowing any free-range chickens to remain unsecured after nightfall. Mustelids are more likely to attack after the sun goes down and they are protected by the cover of darkness.

If all your preventions still fail to dissuade a would-be marauding mustelid, it will be necessary to set a trap. Unfortunately, mustelids are not typically capable of a symbiotic relationship with poultry.

A weasel investigates every hole it meets, especially if it smells appetizing. This can be used to its disadvantage.

A weasel box trap is the ticket. If you are unfamiliar, it is basically just a wooden box with a small access hole and a baited rat trap inside.

This is not a humane trap and it is important to understand that there is no way to rid yourself of a weasel once it has moved into the area other than by dispatching it. Fortunately, when used correctly, a weasel box is a relatively quick means of accomplishing this task.

A large rat trap can be purchased from most any store that carries standard mouse traps and is the only real cost involved, as most of the parts can be gleaned from your scrap wood pile, aside from a bit of screen.

Using 1-inch-thick (2.5cm) wood, build a box at least 7 inches (17.75 cm) long and no more than 4 inches (10cm) in height and width. It's important to build it sturdy to withstand the application and allow for extended use. With any luck you won't see many weasels but if you build it well the first time, you'll have it whenever you find that you might need it.

Always check using your rat trap to make sure that there is adequate clearance. You want the interior of the box to be twice the length of the trap and have plenty of clearance for the spring to clear once the trap is engaged. You may find that you need to make the box longer than 7 inches (17.75 cm) or higher than 4 inches (10 cm) but it is recommended that the width remains no more than 4 inches (10 cm) wide. This keeps the quarters tight and adds to the efficacy of the trap by making it more difficult for the weasel to turn around once it is inside.

Once your dimensions have been chosen, measure two end pieces to match the width and height of the box to attach the side, top and bottom to. Before you cut them, take a drill with a 1-inch hole saw attached and drill a hole through the center of each of the pieces. Some people only install a hole in one of the end pieces but at Silver Prairie Stock & Poultry Farm we go the extra step of installing a second hole, which we will explain in a moment.

After drilling the holes, cut the pieces to measure and then obtain a piece of 1/4 inch hardware cloth or other tough screen material that can be fit and placed over the hole in one of the ends. This allows for one access point while still allowing any available light to shine through the box, giving the weasel the false sense of security of there being an exit should it enter. It also lends to a sense of airflow, which allows the weasel to feel as though it will be less confined should it venture inside.

Nail or screw the sides and bottom to the endcaps, leaving the top off initially. If using screws, it is a good idea to predrill holes prior to avoid splitting the wood.

You should have a open box at this point, without a lid. A hole on either end, one of which is covered by a screen.

Place the rat trap inside and use a couple of screws to secure it to the bottom of the box to one end. The bar system should be faced toward the screened hole as close to the end as possible but while still allowing for the free movement of the mechanism. The bait area of the trap should be faced toward the open end while the trap mechanism butts up against the covered end. Always be careful when operating the rat trap. It is not a pleasant experience to get your finger caught in a mousetrap. Just imagine how bad it feels to get one caught in a large rat trap.

Take the top board and place it on the open box. Using a drill, make two holes through the top board. On the end with the open hole drill directly through the top board and the top of the end piece no more than 1/2 an inch (1.5 cm) roughly. On the screened end avoid drilling much past the top board.

Once completed, take a nail of screw smaller than the drilled hole and fix it through the top board into the screened end piece beneath. This should make a pin hinge and the top should swing side to side without too much resistance. Place a similar nail or screw in the opposing end. It should fit inside the predrilled hole as a pin to hold the top in place but should be easily removed to allow for access to the inside of the box. You may also choose to simply seal the box and remove the top with a drill every time as well.

It doesn't need to be pretty, unless you want it to be. As long as there is no other gaps or entry points aside from the single unscreened hole.

Now that the trap is finished it is time to find a good spot to bait and place it.

At Silver Prairie Stock & Poultry Farm we've had reasonably good results with raw fish, cat food with high fish content and what we refer to as bloodfat. The fish seems to smell the most and thereby seems to attract them to the trap a bit better. Bloodfat is by far the best option however, but it is much more time consumptive in its preparation. If you want to give it a shot, here's how:

  • Gently warm 4 tablespoons of lard, stirring in the same measurement of fresh blood and mix thoroughly using the fresh thawed blood drippings of any beef, pork or poultry.

  • Pour the resulting mixture into a container, and allow it to cool.

  • Smear the V-shaped bait holder on the rat trap with a good large gob. Wild predators crave fats, and the added scent of blood makes bloodfat irresistible. A few poultry feathers under the trap add attraction as well.

  • You may want to place a few feathers and a miniscule portion of bloodfat outside the box to whet their appetite as well. However, don't overdo it, you don't want to give your prey a free meal that results in them going home without exploring further. If you notice that the portion is missing, avoid leaving more. Unless the portion inside the trap is missing, in which case, replace as required. If you are placing the trap inside where your birds have access do not place any portions of bloodfat outside of the trap.

Once you have baited the trap, affix the lid and find a good spot to put it. You can either place the baited trap inside your poultry enclosure or out. It really depends where your issue has proven to be. By this time, you have likely already fixed any entry points you may have discovered, so it is likely that the best place would be outside the enclosure. If you are having trouble figuring out how the weasel is getting in in the first place, you might choose to put it in with your birds instead. Either way, the trap should be placed alongside the wall lengthwise. If you have found the entry point you should place the trap near there, after closing off it off, of course. In the case of an entry point having been discovered and fixed, the trap should be placed outside of the building and not inside. The weasel is unlikely to be hiding inside the enclosure but it will definitely be returning at some point. Have patience, when it does the smell of the bait should prove to be a good lure.

In addition to trapping, a couple of good barn cats can help. Cats tend to remove a lot of the rodent population that attracts mustelids in the first place, so if you have mustelids you likely have an abundance of mice as well. That is the benefit of having mustelids on your property, if any. They devour a huge number of rodents. Unfortunately, as mentioned above they also really like poultry too. When the rodent population begins to come under control from mustelid predation, mustelids begins to look for other food sources.

A good livestock guardian dog is priceless as well. At Silver Prairie Stock & Poultry Farm we are extremely fortunate that we have a great farm dog that is an excellent weasel hunter. We use a combination of traps, cats and dogs to maintain the safety of our poultry flock. We've found in our experience that the more defenses you have the better your chances.

Hopefully armed with the information contained herein you will also find success in keeping your property mustelid free and your flock healthy and safe. It's heartbreaking to find that a weasel has visited in the night, leaving devastation in it's wake. With a bit of luck, a few best practices in place, and a good offensive strategy that uses a multifaceted approach, you will at least be prepared in the event that a mustelid should decide to move into your area.


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