Colony traps come in all sizes but for me they only come in one size - Big. I have for a long time said that every swamp has one killer set, the trapper just has to find it. Using a big enough trap, that can catch rats, mink, otter and beaver (up to 25 pounds or so) in that one spot allows for a quick check and a "down the road to the next location". Most swamps by me are 10 to 20 acres, not the monster swamps that are in other parts of the country. My traps are 10 inches wide, 6 inches tall and anywhere from 3 to 4 feet long. 1x2 inch wire, 14 gauge. All have multiple doors inside to create "kill chambers". Flap type doors are strengthened by bending them in a "U" shape, no mink can slip out alongside these doors. They are designed to catch from either direction but more than 90% of the time I set them to catch from only one direction. That end has a large piece of wire to act as blocking, the only way thru is thru the trap. We have a limit on beaver and otter in NJ so if I do not have a tag for them then the door on the "back end" is not wired shut, they can simply then blow the door out and escape. Mink and rats cannot do that so they are caught. All pics are on a 24 hour check.
First pic is a nice male otter. It shows the wire guide on the front. This trap was slid into a culvert connecting two swamps under an old railroad bed.
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/04/full-11499-255712-op46.jpg)
Second picture is 3 mink and a rat, again from that same location under the railroad bed.
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/04/full-11499-255713-op86.jpg)
20 pound beaver and a rat same place as above
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/04/full-11499-255714-op87.jpg)
6 black rats
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/04/full-11499-255715-op88.jpg)
Otter and a rat
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/04/full-11499-255716-op89.jpg)
This picture shows how to set a colony trap in a muskrat hole. always leave the trap back 8 to 12 inches from the hole so rats can enter and get caught on the way out. Jam the trap up tight to the hole and all you will catch is rats already in the hole.
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/04/full-11499-255717-op155.jpg)
Next 2 pictures are the same culvert. Always set on the downstream side if there is a current or chance of a flood to keep the trap from being pushed up inside the culvert and plugging it.
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/04/full-11499-255718-op180.jpg)
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/04/full-11499-255719-op181.jpg)
The last 2 pics are in swamps with a ditch thru them. wire front blocks off the ditch. First trap has rats and mink, second pic is only rats. In this situation I cover the submerged trap with grass, reeds or whatever is handy to keep birds of prey or herons from damaging caught animals. This covering also aids in catching otter and mink in them.
![[Linked Image]](https://trapperman.com/forum/attachments/usergals/2025/04/full-11499-255720-op192.jpg)