I have some 1" square wire cloth and some j-clips to make colony traps. What size should the end opening be? 6X6 and 5"X5" so the two sizes nest, one inside the other? or 7X7 and 6X6?

Most of mine are 6 x 6 x 24 collapsible

If you want nesting, id go with 6x6 and 7x7(or 8x8). Around here most times the bigger colonies fill the runs better.

4x4, 5x5, 6x6, 7x7 & 8x8 as well. They fit lots of different locations.





A guy who bought a set of them from me sent me these impressive pictures! 8 rats in a 7x7x24" colony trap!

bending and twisting over the years; so go with 2 inch differences for inserts

I have some I made that are 6X6 and 3 feet long. Most rats I ever got in one was 5.
Most interesting catch was a rat, female mink, and a male mink. They were in the trap in that order. I figure the mink were chasing the rat in the run.

It all depends on your laws. In WI we are hampered by a 6X6 opening. It also depends a lot on your water depths. I like to have some 5x5s and some 6x6s and when I trapped In ND I used 7x7s and 8x8s. In my opinion 36" long traps are way to long. All my traps are 30" long. And the best I ever did was 12 rats In one 7x7x30" trap.
For the most part If your not trapping runs and just trapping dens you can get away with even a 5x5x 24" trap. Your pretty much just going to catch rats coming out of the den. Unless there is a well used run going into the den.

If you can trap culverts (we can't) it's game over for any rat swimming through that culvert, The best I ever did with 4 7x7x30" traps In a culvert was 23 rats. And like I said before one of those traps had 12 rats In It. The more productive culverts are those that are completely full.

1"x1" square funnel trap. Pretty big not sure of dimensions. 1/4" screen funnel construction. These big traps are bulky. But you get them in the right place early season ice before winter die-off and they will hold a lot of rats. Get 3 or 4 working good and that's about all the skinning I care to do, maybe 10-12 /trap/check. You can make them round too.
Scratching up a few spring rats ( low population post winter kill) they are good for wide open areas and culverts.
Edit: Counting squares this one looks to be about 36x12x12

x2 on the large funnel traps.
I have used the round ones.
Great in feeder creeks,channels below beaver dams,thru cattails,culverts and the shallow entrance of beaver houses.

You definitely want some 5x5