I have a drainage tile under a road that beaver,otter and muskrat all seem to swim through. Ive been making colony traps for the rats and thought about making a half barrel size colony trap. The tube is 15 inches across. If i make one to fit inside the tube, has this been done? Im prototyping tomorrow but wanted to hear your thoughts. So i think 48" long x 15" wide with a matching curved bottom to sit directly against the pipe. . I have 1x1 wire mesh.

I would guess a beaver and otter will tear it to shreds.

What size colony traps are you using?

Is there a legal size limit on colony traps In your state?

use the search in my signature, several old threads on beaver colony traps

give me a second I got all that in my scrapbook thread,I'll transfer some of it

Magnum21 on Beaver Colony Traps :

The guy Is asking about trapping rats In that tube. How did we get to trapping beaver?

He said that beaver, otter and rats are using the culvert. Why not catch them all?

I guess I missed that.

So Is the tube full to the top or is It only partial filled?
The thing I have found Is that about 90% of the time a otter will pull out and travel over land when It comes to most tubes.

The other thing Is If you build a trap that will fit the tube you better tie It off so It Isn't pushed back Into the tube where you won't be able to get It out.

Before the counties in my area replaced all older 18" culverts with new 24" ones I zip tied 18-12" extension funnels(look like those pet cones for licking) to my standard 12" round funnel colonies where I could put them fully submerged. Worked great in culvert not partly filled with silt. Have not yet made more than one set of extensions to go to 24". Used a few of the 18" in 24" culverts. Caught m'rats but don't know how many if any slipped by the about 6" top gap. I don't believe it is many as they but at least two got by the cone deep in the culvert and didn't find their way out(stuck outside and above colony death gripped to it. Grass was wadded in the top gap at the culvert opening end of colony.

Your plan should work fine you just have colonies that probably wouldn't be usable in most other situations, larger and bulkier. 12x36 colonies hold a dz or m'rats which is not often more than the capture in our 3 day check. If you do go with a larger round colony design it will work in your favor for holder stronger otter as the culvert won't let them deform colony walls but make sure you make STRONG funnel ends with at least 6" opening(w, swinging divider door flap to help contain mink and m'rats).

Beav is correct about securing colonies in culvert otherwise beaver and otter push them in.

When trapping In ND I used 9X9 X30" colony traps. I would fill the culvert with them I even stacked them on top of each other. But that took a lot of colony traps. So I just added 9X9 wings on each side of the colony trap. Now I could cover a 27" area with one trap. A few zip ties and your good to go.

Beav, have you found any predominance between hi/low cluster setting? The few places I have been able to try it have not show me a pattern. I have one location where I can place three sq ones side by side and have only ever caught one in the middle one. That culvert is half full of silt so the two outside colonies are basically BE placement. All my sq colonies have folding 12" flaps attached to one end(held folded back to sides with 1/2" binders clips). I carry extra flaps for other end if needed(zip tie like Beav). Bank dens with undefined runs(entered from front and angles) is my most common colony location so the flaps on the opposite bank end really help funnel approaching m'rats in if they are not already in den when trap is placed. Some heavier trap wire is handy to wire flaps open on double ended flaps when slipping into culverts not fully submerged enough for round colony or partially filled with silt.

I use to do a lot of stacking when the tubes were full to the top with water. And yes I caught rats In the top ones. But I stopped doing It since It was a lot of extra traps being used for the few rats that were being caught. I figured those top traps would do better sitting In some other place.

It's a crap shoot as to which trap or traps In a culvert are going to take rats. Best I did was 22 rats out of 4 9X9X30 placed In the same culvert 2 In each end. One trap had 12 rats In It.

That Is a great Idea where your using the flaps on those rat runs leading to the den site. We can't do that here In WI but what a great concept I can see where that would dramatically up your catch In certain situations. Thanks for sharing.

If I could find 100 good culverts In good rat country I wouldn't even set a foot hold.

Same here Beav, but I am lucky to have couple dozen out at anyone time. Just can't find ways to place them that can keep more than that productive(especially the past couple of seasons with our m'rat pop down so low. It really unfortunate your state has such restrictive regs on colonies. They are so NOT based on good management science.

Locklear did some videos on his very big colony traps for beaver. Got beaver and otter. Your pictures show it can be done

Ztrap manufacturer Neil Ziegman has a cage trap for beavers. I’m told it works well.