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Bemidji Wildlife Survey

posted Mar 10, 2020, 11:07 AM by Jonathan Poppele   [ updated Mar 11, 2020, 12:53 PM ]
On Leap Day 2020, a group of students and faculty from Bemidji State University joined with trackers from the Minnesota Wildlife Tracking Project for the second Hobson Forest Wildlife Survey this winter. With sunny skies and warm temperatures, the teams explored the digs and runs of mice and squirrels, followed in the footsteps of fisher and porcupine, and examined the scattered remains of a barred owl. Here is the story of our day.

We arrived at Hobson Forest as the temperature was climbing into the 20s with morning clouds beginning to break up. For winter tracking, conditions were difficult. It had been a couple of weeks since there had been a fresh snowfall. The ski trails we were following through the woods had been packed hard by groomers, skiers, hikers and repeated thawing and freezing. The trails were covered with boot prints and domestic dog tracks—but our own boots were barely leaving any mark at all. Unlike last December, when our teams found the tracks of red fox, gray fox, coyote and wolf along the ski trials, we were not able to pick out the tracks of any wild canines this day. We believe that the temperature fluctuations played a role in what tracks were being left behind. Night time temperatures had consistently been below freezing, so the trails would be frozen hard when nocturnal animals were on the move. But on warm, sunny days, the trail would soften in the afternoon and the tracks of daytime users—skiers, hikers and domestic dogs—would register clearly.

A sign that was evident along the trails was the digs of squirrels. Across the trials, we found fist-sized holes dug into the hard-packed snow. In and around these holes were fragments of acorn and hazelnut shells. In a few of these holes, trackers found the fine, ticked hairs of gray squirrels.

Fisher Tracks
Unlike the hard packed trials, the snow in the woods was knee deep, loose and granular. Few tracks showed any detail, and even track patterns were difficult to distinguish. What we were able to find in the forest was fisher trails. Lots and lots of fisher trails walking through the deep snow.

It took us some time to identify these trails. With a stride length around 18” and a trail width of about 4”, the track patterns were a good fit for bobcat and plausible for red fox. The tracks themselves appeared quite large, but with loose snow and repeated freezing and thawing the size was clearly distorted. You can see a typical example here. Following these trails out, however, revealed them all to be fisher. One trail passed smoothly through a fence with openings that looked to be a tight squeeze for a bobcat or fox. Others showed occasional lopes and bounds characteristic of fisher. A few trails had individual prints clear enough to identify, including one trail out on the wind-packed snow over a small lake. Bounded on both sides by pockmarks where the animal broke through the crust, our team found a short string of the most perfect fisher tracks many of us have ever seen.

Once we developed an eye for these trails, we saw them everywhere. They seemed to be the most common trails in the forest. And yet fisher populations are generally low density, rarely exceeding one individual per square mile. Hobson forest is 240 acres—just 3/8 of a square mile. So, on average, we expect this patch of forest to house only one fisher who spends less than half its time there. All the tracks and trails we identified were similar in size, and could reasonably have been from the same animal—an animal that was investigating every bit of that forest. Perhaps in search of porcupines.

We spent some time in search of porcupines ourselves, and were rewarded for our efforts. There is abundant porcupine sign throughout Hobson forest, and our teams found trails, scat and feeding sign. We also had some live sightings of these large arboreal rodents. One of these sightings, in the northwest corner of the property, was of a porcupine actively feeding in an oak tree. Porcupine are often difficult to see clearly when they are in the canopy, but this one was out in the open and offered us a great view. With binoculars, we were able to see details such as the pebbly texture of its feet and the dark orange color of its incisors (which have an iron oxide compound in the enamel). We were able to watch how the porcupine moved about on the tree limbs, and used its tail as an extra support while climbing. We also watched it poop, and got a look at fresh-as-can-be porcupine scat.

Barred owl feathers
Our most dramatic, and puzzling find of the day were the scattered remains of a barred owl. Our team found several clumps of barred owl feathers, widely scattered near a trail junction on the western side of the forest. Though there was a porcupine in a tree above one of the clumps, it wasn't talking, and we found no clues to the owl's demise—only evidence of scavenging. Some of the feathers showed signs of being chewed by a carnivore, while other clumps were surrounded by corvid tracks and scat. We also found a clump of feather remains and small bone fragments in the trail that may have been a raven pellet. But we never found the carcass or anything that looked like a kill site.

By the time we wrapped up, the sky was sunny, the temperature was well above freezing and the trails were softening—clearly registering our own tracks as we walked back to the trailhead. We left the forest and headed to the Bemidji State University campus where we shared our stories and our photographs from the day. You can see more of what we found on the Hobson Forest Wildlife Tracking Survey iNaturalist project page.