Drift Fence Designs w/ OR w/o Traps & Trap Designs

[Noah M]

So I have been given an opportunity to set up some drift fencing on some interesting upland habitat. Near as I can tell, I can design it anyway that I want. I can make it as big as my labor and money allow. I can have two small ones if I want.

But here are the issues. Most drift fence designs I've read about or seen use pitall traps and funnel traps. The property is about 45 minutes away, so daily checking is not an option for me. I would at most probably be able to visit the location for a couple of hours on a weekend. Secondly, venomous species have been observed here. I'm not even sure I would feel comfortable trying to mess with a rattlesnake in a funnel trap. I would however be fine with using a snake hook to lift it up and over the side of a fence, or re-direct it away from the fence.

I've been reading literature about drift fences, and as far as cost, it seems as though silt fencing is the best option. The question I have is design.

Would simply putting a 100ft of fence in a straight line do anything?
Would using a Y or X pattern be effective w/o traps? How about compared to the straight line?
Is it even worth putting in a drift fence if you can't use traps; that is should I just hike the same area for 2 hours every Saturday morning?
Comments and suggestions welcomed!

I have thought about creating a giant funnel trap, perhaps even with a cover board in the middle, where in this diagram the black is fencing, and green are animals. I'll be turning a lot away, but hopefully a good number of things get lost inside the circle. It is not to scale, as the opening at the Vs would only be a few inches wide, big enough to let in large snakes.

[Noah M]

Okay, what about WITH traps?

Trap designs, purchased from a manufacturer, made at home, etc. What worked, what didn't work, what cost the least, etc.

If you fear that trapping designs will fall into the wrong hands, feel free to PM me.

[Soopaman]

I really don't know what the point would be without a trap.

If you design a large enough funnel trap with water bowls (think the kind that refill themselves from a reservoir as water is used), and a covering that prevents direct sunlight, you can leave animals in it for a week or two without issue.

[Tim Borski]

Put them in a "X" pattern with an opening of about 50 yards square in the middle. Fill the middle with AC (plywood. tin. carpet, etc... and check it when conditions are favorable. Walk the fence with a light after dark when you care to or conditions are favorable for movement...make sure to shine around the debris also.

Tim

[NACairns]

In my opinion traps are the way to go but just limiting the time they are open. If you could go out twice on the weekend you could open and close them and have a "fishing" time of 24-36 hours that would probably get you a good representation of the local diversity ( Is that your goal/target?). With regard to venomous species ground flush funnels on a "coop style" enclosure with a large top entry panel and movable "furniture" would let you safely check with your trap with a hook.
With some of these methods is you may create a predator sink by increasing densities in a restricted space with prolong times between checks. Traps can also lead to losses due to predation, but I think sporadic usage may actually help with this. We had to shut down a line after we lost a western hognose to a trap happy short-tailed shrew and I wondered what would have happened if we only trapped 2 days a week.
I understand the draw of having passive traps active 24/7 but in my opinion reduced captures are a small price to pay for animal safety.
Good luck and have fun,
Nick

[Noah M]

Well I think traps are the way to go. I will probably be making two trips over the weekends, once Friday after work to set the traps, and then once again on Saturday to check and close the traps. If I continue this every weekend, or even every other weekend, for the next 6 months, I should get an idea of what is in the area. Many observations by locals have been made, but as far as I know, nothing systematic has been done.

I will probably make my own traps using hardware cloth. However many traps I can make will determine the shape of the fencing array. 4 traps and I'll do a straight line with two traps on either side. 5-6 traps and I'll do a Y pattern (2 per leg). 7-8 traps and I'll do an X pattern (2 per leg).

Thanks guys!

[Tim Borski]

Put them in an "X" pattern with an opening in the middle. Fill the opening with ac....you'll never have to close traps and worry about that kind of stuff while you are absent and everything is happy. (Get permission in writing first...I always make a point of that.)

Tim

[Kyle from Carolina]

If using traps, here are a few things I've noticed:

I've used aluminum Gee-style minnow traps along terrestrial drift fences in long-leaf/loblolly pine forests. We would take care to make sure the traps were flush against the fence and then block the gap between the edge of the trap and the ground where it met the fence. However, a lot of times that didn't seem too important. There were times when a volunteer would careless replace traps and not secure them firmly against the fence and we would still get critters in the funnel traps even when it was sitting several inches from the drift fence. We got everything from eastern hognose, full-sized adult racers and copperheads, corsnakes, and pygmies. If using minnow traps, I think those with a shallow ramp/cone are better than those with a steep entrance. We also covered our traps with small sections of carpet as shade. We would also encounter un-trapped critters along the fence, particularly hognose and racers. Removing the clips on the minnow traps to release copperheads was never a problem, there was always a few inches between fingers and the wire, which is pretty fine grade. they can then be tipped open to let the snake spill out. You could also wrap the minnow traps in cheap hardware cloth or to reduce the mesh-size, which would increase retention of small litter snakes and lizards.

Aside from traps, pitfall buckets were good for small litter snakes, skinks, and fence lizards. However, you will need to put drainage holes in any buckets you use. Many small snakes like Tantilla will easily fit through these drainage holes so put leaf litter in the buckets too and they will feel less inclined to find a way out. It's also fun sifting through the leaf litter in a bucket to see what's there, usually a few Scincella. Buckets can easily be closed too. A friend once noticed a fleck of red through the drainage holes and lifted the bucket to find two scarlet snakes.

I recently saw a few cover boards with buckets underneath. This seemed like an interesting idea because you could bury a bucket, put the lid on, then replace the board overtop and forget about it. If the board looks like it's being used, I suppose one could then open the bucket for a day or two and see what falls in.

If not using traps:

One option would be put 90 degree corners in your drift fences, then fill this with cover. I think snakes would collect more readily under cover at a corner in the drift fence rather than if they could just keep moving past all the cover along the fence. For example, putting them in the 'X' pattern but making it a closed-off 'X'. A labmate of mine in grad school could passively corral frogs along drift fences by creating little 'cubbies' with the fence by making a three-sided box. I guess sometimes they would rather settle than backtrack. Don't know if it's worthwhile but it's a thought.

[Noah M]

I wanted to do what Tim suggested. I had suggested a big X with cover boards and AC in the corners, but, the land owner feels cover boards make the property look messy. I am wondering if he would be more open to them if they were not visible from the road where he gives tours of the property.

Buckets may be a good option. No need to worry about building traps. Putting a couple of small holes in the bottom for drainage should help, and removing a venomous snake should be really easy if the bucket has a handle. I can use a hook or stick to pull the bucket up and tip it over, freeing the snake. Slap on the lids to close the trap.

Buckets are cheap enough too ~$5 a bucket w/lid x 6-8 buckets. This may actually be cheaper than hardware cloth, zip ties, and some kind of latch.

[Noah M]

FYI, today should be the day the final stuff is put in. There was a bucket shortage; a friend who works at a deli offered to let me have many of their old buckets, so I had to wait for that. In the meantime, I found a much cheaper alternative to building funnel traps. Window screen! A 25' roll was only a few bucks, and I read elsewhere that instead of zip ties, you can just staple the screen and use binder clips or paper clips to attach the funnels. So I have 6 wonderful funnel traps that I'm taking out today.

Let the digging of holes for pit fall traps commence!

[Noah M]

Well, its done. 50ft by 50ft X with 6 double sided funnel traps and 6 pitfall traps.



Here is the design, not to scale. Circles are buckets, rectangle(ish) things are funnel traps.

[chris_mcmartin]

Animals cross using the palmetto fronds and continue on their merry way, without falling into the trap?

[Noah M]

Animals cross using the palmetto fronds and continue on their merry way, without falling into the trap?

Well not on the funnel traps. I checked the pitfalls today and found two toads, so evidently not. I think most animals would go under te palmetto fronds, like they do cover boards. They're supposed to be propped up against the fence to provide some shade for anything in the bucket, even though this is not what is shown in the picture.

The folks who work out there checked the traps within a few hours of us putting them up and got a corn snake in a funnel trap. Glad to know they work!

[Kyle from Carolina]

Looking forward to see what shows up. Do you have a species list of what you've found so far?

[steeve11]

I would also like to hear how this project worked out. Although I am on the west coast, which could be a different situation; (Rocky and dry), and most snakes here could easily climb out of a 5 gal bucket; the wind also lows like crazy sometimes and could blow the fence down or blow under the bottom, leaving a gap. What is your fence made of? I might try this if the catch rate is reasonable, like at least one snake a week, checking daily. What have you found?