I'll give it a whirl.
I'll start out with my boxes. I have been using rat traps but long springs can also be used but the box must be a bit wider to accomodate for the width of the trap. With the rat traps it lets you go 3 days between checks. With a long spring you are required by law to check them everyday.
I build them out of 1 x 4's and 3/8th plywood for the sides. You can use scrap lumber to save some money. The minimun size for inside dimentions would be 10" long x 3 1/2" wide x 5" high. You can make them bigger if you want but they must be at least that big to allow the trap to function properly and allow for easy baiting.
The front has a 2" hole with the bottom being 3" high. You can use a hole down to 1 1/2" but may have difficulty getting a frozen weasel out.
If you don't have a hole saw you could use a jig saw to cut a hole like this.
I may build some more boxes like this as a frozen weasel is easily removed. I would go with a hole that is only 1 3/4 wide and 3 inches up to the bottom.
The back I notched out the corners to allow air to flow through carying the scent of bait/lure further. Some prefer to bore another hole and cover with hardware cloth instead. They feel that it also lets the weasel feel like it's a tunnel rather than a box.
The lid is hinged just in front of the back piece as you can see from the third pic. From the fourth pic you can see I put the trap right up tight to the front and centered below the hole with the bait in the back.
For bait I have been useing liver mixed with anise oil. I have been salting it also for times when it gets really cold. Other good baits to use would be beaver, chicken and rabbit. The bait should be fresh and not tainted. I have also been useing lure but they can be caught without it. I just feel it helps me catch more especially in the colder weather.
Now for the most important aspect of trapping, no matter what your trapping is location. Also the hardest to explain so will use some pics to help. Keep in mind the number one prey for weasels are mice. Find places with lots of mice and you will find weasels.Once you find good habitat such as these places then you need to find the exact place to set up.
This location has some nice grassy cover. The culvert has open water which would make a poor place for a box, so I set up by the bush in front and have taken 3 in the last ten days here.
This spot I choose that uprooted tree for my location. There is no culvert here but the uprooted tree is a gate way for the weasel to get at an easy mouse. It also gives protection to my box from heavy amounts of snow. I have not got one here yet as my trap always has got a mouse or shrew. Most of them have been ate by a weasel after they have been caught.
This spot I shoveled down to the culvert an placed my box inside the culvert. That is what I like to do but not all habitat has a culvert. The reason I like culverts is
1. They protect my box from heavy amounts of snow.
2. They act as a funnel for weasel to get to the other side of the road rather than cross the road.
3. You are under the snow. Alot of a weasels time is spent under the snow chasing mice. In a culvert you are at the bottom. Can't run on snow above your box or beneath it.
4. It also enables me to locate tracks that would have otherwise been covered up by blowing snow
5. The only downfall to culverts is sometimes they blow shut and you need to shovel them out(extra work) But the trap still works as the weasel know the culvert is their and tunnel through snow to use them. I have made numeruos catches when I had to shovel out the culvert only to find a weasel in my trap. Sometimes up to 4 feet of snow over them. I believe they were under the snow and were going to use the culvert to get to the other side.
I only got one here but think I may have gotton more had I left it in place more than a few days.
This spot is another culvert I chose for a location. This one I usually need to shovel about a foot of snow to check. Have taken 4 at this location.
Here is another culvert location. This one requires little shoveling as the pic shows the wing on the plow goes right on top of and beyond the end of culvert. I have taken 7 here and my box is still there as the swamp is so big new weasel keep filling the vacant territory and over trapping is unlikely.
One important factor in trapping weasels is setting on sign. Locate some tracks and set as close to them as you can. You can't catch ghost weasels and the tracks are proof they are there. I have set up what I think are likely looking locations and caught weasels but not as many.
There are other sets such as a rat trap on a lath or nailed to a sapling with a baited trigger about 1 foot off the ground or a piece of 1 1/2 pvc pipe about 16" long wired to a tree with bait in the bottom that produce well I've heard in areas. I havn't yet tried them so am just speaking on what I have done. They would have the advantage of being able to handle heavier snows but also would require finding location where they would be on top of the snow. For my area there are plenty of culverts and feel a box in them is best. I am planning on trying the other methods out in certain situations in the near future.
With the cold we had last week it seemed moving to new locations has helped but seem to only catch one. Maybe that will change with warmer weather.
Hope this helps, If you have any ?'s just ask.