The trails more traveled

TIP: Animal trails provide a sneaky peek into animal habits

Posted: Friday, December 24, 2010

It’s early morning on Admiralty Island, and I’m skulking along a trail, looking for Sitka black-tailed deer. I spot a narrow dirt track off the side of the human-made trail, so I divert onto it. It meanders through the thorny sticks of dormant devil’s club, winding around a tree stump, ducking under a fallen tree that I choose to climb over. Soon it dead-ends into another trail that snakes away uphill. That trail seems purposeful for a while, then the ground becomes a little harder and it dwindles away.

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Abby Lowell
Abby Lowell

Why would deer, or any other animal, create a trail? Why not simply wander wherever looks good? This trail I’m following isn’t just a single set of hoof prints, it’s a track about six or seven inches wide where the deer have worn away the top layer of vegetation and moss. It’s clear my suspects have passed this way more than once. But why?

Deer — and other animals such as meadow voles (a mouse-like rodent), beaver and even brown bears — are creatures of habit to some extent. Just as you have your favorite routes to the grocery store or to work, they find a route they prefer and use it repeatedly. Maybe they only use it during a certain season, or when a specific food is available; maybe one animal uses it repeatedly, or maybe a number of animals share the route. Whatever the case, these critter highways show visible evidence of animals’ habits.

There are clues in the shape and placement of a trail indicating what animal created it. Deer have sharp, narrow hooves that create a trail with a v-shaped cross section. Voles create small tunnels in snow usually less than an inch in diameter. Beaver trails start or end in water. Bear trails have a u-shaped or flattened cross-section.

If you’ve ever tried bushwhacking off-trail in Southeast, you realize why animals would choose a trail. They often follow routes of least resistance in the terrain, circumnavigating obstacles if possible, taking advantage of a slightly less steep incline here, an easier stream crossing there. Instead of searching for a safe place to cross every time it comes to the same stream, for example, a deer saves energy and reaches dinner faster if it goes where it knows the bank is accessible and the water shallow.

What does a deer do that keeps it constantly on the move? For safety, deer are active mainly at dawn, dusk and night. They lie low — literally — by bedding down in thick cover during most of the day. Staying out of sight is their strategy to avoid predators. At dusk they meander to nighttime feeding areas, often in more open places than where they spend the day. After eating, they find a place to bed down. In the early morning, they return to daytime bedding areas. These daily movements, although not always exactly the same, form trails the deer use frequently.

While staying at an older cabin with friends, we woke up one night to a scratching on the floor. From the glimpse we caught in the flashlight beam as it escaped, we guessed the identity of the infiltrator: a meadow vole, a type of mouse with a short tail. The next night I noticed a high amount of activity along the path to the outhouse. I heard slight rustling in the grass, and occasionally a mousey shadow darted across the path. Later, we found all the toilet paper left in the outhouse in shreds. The voles were the prime suspects.

On a smaller scale compared to deer, voles form their own elaborate trail networks. They are nocturnal, and prefer real estate with dense grass or plant cover. They create intertwining trails through tall grass, connecting feeding areas with nesting and food storage burrows. Multiple routes to reach each destination allow for quick escapes from predators. Since nearly every predator in Southeast, including weasels, coyotes, foxes, owls, gulls, and sometimes even great blue herons like to snack on voles, a little paranoia is justified!

In the winter, voles remain covertly active. They tunnel through the snow, munching on flattened grasses. Sometimes they tunnel vertically to reach seedheads on grass and other plants. As the snow melts in the spring, you can see the evidence of their tunnels in the flattened grass. Owls and other predators that hunt by hearing, will sometimes zero in on the scampering of the voles in their tunnels. They dive-bomb or pounce suddenly, smashing through the tunnels in an attempt to grab their prey.

Beaver create and use trails for slightly different reasons than their vole cousins. Water is where beavers feel safest from predators, so they build dams to create ponds in which to reside. Their trails lead to places where they cut trees or find a good salad bar. Often you can see a groove worn into the bank where they habitually enter or exit their aquatic home. They tend to use trails intensively for a short time until they exhaust the wood or food supply, then find a new destination.

Beavers also create water trails, called channels, for moving logs to use in construction projects. Although they use the same lodge from year to year, they can’t resist making additions and improvements constantly. A beaver is always in need of building material. But, they can’t lift or drag large logs. Instead, they dig channels just deep and wide enough to float heavy logs to their home pond, especially as they use up nearby trees. These wide waterways remain, sometimes filling in if not maintained, even after the beaver abandons them.

Brown bears are one more culprit in creating trails. They are the semi trucks of the animal world: their trails are very wide, and if heavily used are deeply worn into soil. One research project on Admiralty identified bear trails through the criteria of being able to fit both feet next to each other, with a hand placed on either side, within the trail edges. When salmon are running, bears create highways along streams to the most heavily used fishing spots. Other trails connect salmon streams, parallel the forest edge along the beach fringe, or link feeding areas and favorite spots to bed down. Bears also use human trails. Why not? They are wide enough for bears, and conveniently kept clear of debris.

One mysterious sort of bear trail looks like a staggered set of circles worn into the ground. Bears create them by stepping carefully in the same footprints over and over, sometimes for generations. Some research footage shows bears adopting a stiff-legged gait, twisting their feet into the ground on these trails. In one Admiralty Island study, researchers found these trails most often near trail junctions or trees bears had marked by rubbing repeatedly against them or with claw or bite marks. One conjecture about these distinctive trails is that bears are rubbing scent from glands in their feet into the trail, leaving a clear signpost of their presence to all other bears that pass along the route. Why they do this in addition to other signs is unclear, however, and the bears aren’t talking.

• Beth Peluso is a freelance
writer and illustrator and avid birder. She enjoys spying
on wildlife across Alaska.

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