Lynx Exclusion Devices on the Maine Marten and Fisher Trapline

Sometimes politics get in the way of trapping and wildlife management.  It’s just a reality that trappers in some states have to deal with, and such was the case with marten and fisher trapping in northern Maine.  After a long battle in the courts over incidental trapping of ‘Endangered’ Canada lynx, Maine trappers were required to use newly approved – and specifically designed – ‘lynx exclusion devices’ to use any bodygripping traps on land.

In simple terms, these devices are boxes made of wood or wire, with specific-sized openings and setbacks that restrict larger animals from accessing the bait and being caught in the trap. The two approved device designs are distinct from each other – one for 120 sized traps, and another for 160 or 220 sized traps. The smaller 120 sized devices allow the animal a direct line of sight – and access – from the front of the box to the bait and trap in the back. They restrict lynx access by requiring the trap be set at least 18” back from a maximum 4”x4” diameter hole.  The larger devices – 160 and 220 sized – allow a larger opening at the entrance, but do not allow a direct line of sight between the front of the box and the trap and bait.  There are two design options for the larger boxes to keep a lynx from reaching the bait despite the larger hole: 1)the entrance contains a baffle that requires an animal to make two small turns to get through the entrance and to the bait, or 2)the entrance requires an immediate 90 degree turn before entering the box and accessing the bait.

If you’re confused or overwhelmed by these regulations, you’re not alone.  Many trappers hung up their traps when these rules were put in place. It was a huge change from what they’d been used to their entire trapping careers, and a very costly one as well. There was no guarantee the rules would remain in place over the long term, and rumor suggested the box designs were not that effective at catching marten, and even less so with the larger fisher.

I wanted to trap.  I’ll always want to trap, and instead of sitting on the bench, I was determined to get out marten trapping despite the new regulations. So in 2016 I put together a few dozen wire cage designs for 120 bodygrippers and set out a line.  The same year, Bob Noonan tested similar devices made of wood and reported his results in an article in “Trapper’s Post”.  I had limited success on the line – struggled, really, and despite the limited snow to see tracks, I noticed a number of refusals. I caught half a dozen marten and no fisher, but did have one set that was batted around by a large fisher, trying to find the entrance to the cage and get at the bait, with no luck.

Lessons learned from 2016 led me to believe that the small cages were ineffective for a few reasons. The cage design didn’t allow animals to distinguish its entrance easily, and some tried to get the bait at the rear of the cage without going the long way around through the entrance. Marten seemed hesitant to walk on the floor of the cage, likely due to the multitude of gaps to step over and unstable footing (ever see a cattle guard?).  Finally, the cages were too light and easily moved around for a fisher to squeeze into them without being anchored to a leaning pole.

My 2017 marten and fisher season started in the spring, with a determination to build a better exclusion device.  I milled 1” pine and spent weeks building boxes that would be heavy duty, meet the specs, and hopefully eliminate my problems. In addition to the 120 size boxes, I built some for 160 and 220 sized traps as well, hoping the larger opening would allow for more fisher catches.  In the end, I had 60 boxes to set, along with some spares.  I decided to set 30 small and 30 large boxes, and keep track of the catches in each.

It took two trips deep in the woods with a loaded pickup truck bed to get all those boxes out, and I was excited about the season.  In the past, 60 sets would get you a 25 marten limit pretty easily in northern Maine.  Trouble was, this wasn’t most years.  Marten catches in Maine fluctuate widely on an every-other-year basis.  This is directly related to food availability.  Even years tend to bring low food availability and hungry animals, from bears to marten and fisher.  Odd years are high mast years, where beech nuts and other wild foods are very abundant, and the critters don’t need to work very hard to find plenty of food. As old timer trappers have told me, the odd years certainly are odd.  You’ll find marten up on the hardwood ridges, and you’ll struggle to bring them to your sets.  I’m not sure how 2017 stacks up in the history of mast years, but it must have been near the top.  Food was absolutely everywhere, and many trappers reported the worst year marten and fisher trapping they’ve ever had.  So I had a lot stacked against me.

I tended traps for weeks with poor results, but was determined to stick it out.  I figured I’d put in all the effort to get a line set up, I might as well keep it going.  I’d catch a marten per tend, and maybe a marten and a fisher occasionally, with a few weasels mixed in, but never had a big catch.  The snow cover was light early on, making it impossible to tell what was going on at my sets, but tracks on the road made it evident there were plenty of fisher around, and some marten as well.

Later in the season, despite things being so slow, I began noticing a trend.  I’d caught six marten and three fisher, and every single one of them had come from the 120 boxes. What was going on?  I had just as many 160/220 boxes on the ground, and they had produced nothing but the occasional weasel.  It was around that time when a few small storms put good tracking snow on the ground, and things got interesting.

As I approached each set I investigated for tracks, and a pattern started to emerge.  Fisher, and marten were visiting the boxes and refusing to go in them.  I found numerous cases where they’d walk up to the box, circle around the entrance, and simply leave.  There were even tracks on top of some of the boxes.

I thought back to one of the first lessons I learned from an old timer when he taught me to trap.  We found a marten location one day and made three marten sets, all within ten feet of each other, in the good old days when such things were legal. One was a leaning pole set, the second was a wooden box cubby on a downed log, and the third was a natural hollow at the base of a cedar tree, bait thrown in and a 120 in front of it.  The very next day, we found a marten at the base of the cedar, and it forever ingrained in my mind the importance comfort and efficiency play in a marten’s feeding habits. The leaning pole required more energy, the cubby was something odd the marten may have been less comfortable with, and the hollow was natural.  Given the choice, the marten chose the most familiar and convenient option.

In a year when food was abundant and entering lynx exclusion devices was both unnatural and inconvenient, marten and fisher just weren’t having it.  After seeing a few of these refusals, I parked at a set location with fisher tracks crossing the road toward my set.  With some hope, I followed them right down my trail to the box, a 160 style design with the 90 degree entrance.  But it turned out to be more of the same.  This fisher had circled the box three times, stepped to the very edge of the entrance and peeked his head in, and hadn’t entered!  Apparently it was hungry, or at least curious, and I couldn’t help but think how I’d have him and most of the other refusers in past years.  I decided to try an experiment, and went back to truck to grab a 120 box, with the 4”x4” opening with a direct line of sight to the bait.  I set it a few feet away from the 160 box, and five days later, it had caught a marten.

I pulled my traps just before a big storm, and probably about the time the trapping would get good.  The box-wrecking black bears (another story) were in hibernation, and the furbearers may have finally started to get hungry.  It took fifteen hours and two vehicles (yet another story!), but I got the 60 traps pulled and picked up another marten and a fisher.  Just to prove the rule, these were the first two I’d caught in 160 boxes.  I also noticed about half a dozen additional refusals at other sets I pulled.

My 2017 marten line was physically and emotionally challenging, and it was a huge learning experience.  Unfortunately, I’m finding that one season isn’t nearly enough to answer all of the questions I have, and more questions keep popping up.  Two pretty obvious patterns emerged from this season.  First, it’s clear that the lynx exclusion devices are not as effective at catching marten and fisher as were the previous methods available to Maine trappers, and their deficiency is probably much more apparent in high mast years when marten don’t need to work hard for their food.  Second, there’s something about the larger 160/220 devices that’s really discouraging marten and fisher from entering.  You’d think the larger entrance would be more inviting, but apparently not.  In fact, I caught fisher weighing up to eleven pounds in the smaller 120 boxes, while numerous fisher refused the larger ones.

It may just be speculation, but I have a couple of thoughts on why marten and fisher refused the larger boxes.  First and foremost, I think visual attraction is a critical component of a predator’s feeding habits, and with the smaller boxes, they could see the bait.  Not only could they see it, they could also see the rest of the box’s interior, and quickly determine that nothing else potentially dangerous was in there.  Thus if they were hungry, it wasn’t much of a risk to squeeze through that small hole (for those small enough to get through it) and go for the bait.  The second possibility concerns the physical aspect of making the 90-degree turn at the box’s entrance to get to the bait.  It’s a bit of a job to get around there, especially if you’re not completely sure what lies ahead.

I have a lot to learn in the marten and fisher trapping game, and fellow Maine trappers and I will be experimenting with these devices to be more effective trappers as long as they’re required.  Sometimes it’s a pain to deal with all of these changes, but I like to think on the bright side.  We’re gaining experience and learning as we go. It’s not the best situation, but it’s way better than sitting the season out!