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  • Writer's pictureKasia Majewski

Weaseling Out: The Art of Trapping Tanuki

Updated: Feb 4, 2023

The three of us huddle over the phone screen as the familiar black and white videos flick on and off, 25 seconds at a time, taken directly from the camera trap next to us. One features a rodent scurrying by. Another shows a bird flitting down from a tree and onto the ground before taking off out of frame. Others have the bright orbs of eye shine hovering far enough off the ground that we can tell they belong to a sika dear before the antlers even come into focus. We're standing in the heart of Seiburindo forest with a wire cage trap behind us, shut, emptied of bait, but devoid of mammalian life.

A rodent forages on the forest floor next to one of our baited tanuki traps.

After all our efforts to attain the funding, the permits, the bait, and the trap locations, the empty trap feels decidedly criminal. We'd been robbed. The videos hold the key to who dunnit. Rodent. Flick. Bird. Flick. Rodent. Flick. Macaque. Flick. But nobody approaches the alien metal cage that suddenly found itself in the forest, no matter how delicious the fish and peanut butter bait smells to them. Some woodland passerby's stop to sniff the air. Some stick their head through the door. But no one ventures in. The trap remains open.

Each of our traps was deployed next to a camera trap so that we could monitor any activity around the trap area. The resulting videos gave us a fascinating look at daily Seiburindo life, although we often feel like the wildlife is watching us just as much as we are observing them!

We notice the quick moving elogated body only for a second at first, but as it enters the trap, smoothly and without hesitation we recognize the culprit immediately. Surely only one type of animal could be so brazen. The trap snaps shut as it find the bait within. Instinctively, we all look towards the same trap sitting on the forest floor still, as if expecting the figure on the film to suddenly reappear, held within all along. But it remains empty as we knew it would. And only a couple 25 second clips later reveal the tricksters escape mechanism - despite being decidedly larger than a rodent, it moves through the spaces in the traps wire frame as easily as if they weren't there at all.

Two congruent videos spliced together show a Yakushima weasel foraging on the bait in our trap before entering it further and setting off the locking door mechanism, before exiting the trap between the wire in the rear of the trap and returning to the forest. One of many weasel videos we recorded during our trapping session.

We were bamboozeled by a weasel. You may remember from this post that the Yakushima weasels are an endemic subspecies found only on this island, and one of our research objectives is to identify if invasive tanuki (aka raccoon dogs) compete with this native carnivore. While they remain an integral part of our investigation, our permits are for trapping tanuki specifically, so the fact that this non-target species can exit our traps so easily is actually a good thing, save for the fact that now this trap was baitless and shut for the remainder of the evening. Over our trapping period weasels would become a fairly frequent feature on our camera traps, causing equal frustration and amusement. Macaques also continued their more careful examinations of our trap sites, thankfully leaving our bait intact.

Macaques visited our trap sites frequently, but thankfully did not interact directly with our traps, preferring to observe us as we went about our work.

Two young macaques show interest in the wire trap. Some excellent audio in this video!

Trapping and sampling animals safely and humanely is an artform which takes months of planning and a highly skilled and experienced team of researchers. Yet even with careful planning, the best equipment, and years of experience working with wildlife between us, there is still no guarantee things will go to plan. After 10 trap nights with no capture tanuki, we were starting to sweat. Two weeks to trap wildlife is a relatively short time, but our trapping period is constrained, and we were starting to feel the pressure of the task before us. Not least because we were now being teased. Clearly, word had gotten around the forest about the delicious smelling metal structures. Tanuki were now visiting the trap sites regularly, contemplating the risk they were willing to take to access the delicious smelling bait within, but so far none had chanced to enter. By the 5th day we had decided to sweeten the deal by following in the footsteps of Abe et al. 2006, and included doughnuts as one of the bait items in our traps. Despite having traps baited well enough to attract the likes of Homer Simpsons, we continued to leave the trap checks each morning empty handed (or rather, empty sample vial'd).

A tanuki investigates one of our traps seemingly tempted by the bait within, before reacting to the trap and leaving.

A pair of tanuki investigates our trap. I wrote briefly about the monogamous breeding habits of tanuki in a previous post titled Love at First Shite.

The morning of the 11th trap night, we undertook the trap checks as we had done for the days prior. All looked much as before - curious tanuki on film, weasels robbing some of our bait, but ultimately nothing in the traps. But in our final trap...

Our first captured individual peaks out from the trap.

We found ourselves facing our first captured individual. It is at this point that I feel obligated to mention that this was exactly the predication that our supervisor, Dr. Andrew MacIntosh, had made. "11th trap night!" he'd guessed. And here we were. Luck follows that man around like a weasel does peanut butter in a tanuki trap.

Kenneth prepares the sedative for the tanuki. Between my background in wildlife trapping and his experience as a veterinarian we have the ultimate team to undertake wildlife sampling.

We were so excited to be able to work with a live individual to collect hair, blood, saliva, and fecal samples, as well as microchip the individual as part of a capture/recapture population study. These samples will be invaluable in helping us understand more about the parasitology, diet, and population of tanuki on the island.

With this first capture it didn't take long for our luck to turn. Two days later we found a second individual in our trap! This was a small male. With the arrival of our new GPS collars courtesy of the wonderful folks at TechnoSmart, we are hoping to capture some larger individuals to track virtually as well, informing us about the home ranges and preferred habitats of the tanuki in Seiburindo forest.

A young male was capture in our traps on the 13th day of our study. We were happy to see the animals healthy and calm in our traps. According to other sources of literature, tanuki have a reputation for remaining relatively calm in traps, which adds to their credentials as an excellent study species.

The longest portion of our trapping methodology is actually the recovery period, where we ensure the animal has safely recovered from the effects of aneasthesia and sedation. The photo captures the moment this male awakens fully after having some vital samples taken, before he returned to the forest.

A year ago we had only just started our work in Seiburindo with a pilot study. This summer and autumn we returned for an intensive sampling trip, and I made some progress in investigating turtle predation by tanuki. I even had the opportunity to hike across interior Yakushima in hopes of finding some high elevation sampling sites (this adventure was featured in an AJET Connect article). Now it feels surreal to be able to proceed already with this next important step in furthering our understanding of this island invasive. It looks as though 2023 is already shaping up to be an exciting year for the YakuTan Project!

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