One February morning in northern Yellowstone, I watched a wolf pack moving along the tree line to the north. The wolves disappeared, but occasionally I would hear howling. Then nothing happened for a couple of hours, until around one o’clock, when I spotted a red fox traveling along Soda Butte Creek. The fox worked its way through the sagebrush, slowly coming closer. It began sniffing around, and after a few minutes, it started digging in a snowbank.

After a couple of minutes, the fox pulled out a hunk of frozen meat from the hole. It had apparently discovered a carcass or large cache, likely buried by a wolf or coyote. Foxes will sometimes follow wolves when they are carrying food, and they are particularly adept at finding wolf caches.

After hastily eating several bites, the fox trotted away with a small chunk, heading to the north. It soon returned without the piece of meat. It repeated this process five more times, taking different lines of bearings to re-cache chunks of meat at several new hiding places. I deduced two things: as expected, the original cache was not the fox’s, and it probably had a den nearby.

It was a stroke of luck that I happened to be there, in the right place at the right time, and that the fox paid me little regard. I’ve noticed that many mammals can be quite determined when it comes to food, sometimes overriding their fear of humans.

To state the obvious: to study animal behavior in the wild, one must first find an animal! The key is being in the right place at the right time, but how? –– easier said than done. Sometimes I get lucky, as I did with the fox at the wolf cache, but I can’t afford to rely on serendipity alone. I must make my luck by spending as much time in the field as possible, and by knowing my subject.

This starts with researching the behavior of the target species from an ecological context. How do these animals meet their primal needs for food and water, shelter and protection, rest and energy conservation, and procreation? Particularly important is identifying an animal’s preferred habitats, what it eats, and where and when it forages. Animals often move between multiple locations, crossing various habitats, such as when traveling from a den to a hunting area or from a water source to a daybed. For territorial animals like foxes, males especially will spend a significant amount of time patrolling and scent-marking their territory. By understanding how various factors affect an animal’s daily and seasonal activities and patterns of movement, I am more successful in finding wild animals and predicting their movements.

Once in the field, I spend my time scouting. I scan the landscape and consider how the animal will traverse the terrain, envisioning the invisible lines that an animal would follow. Animals don’t move with the geometric precision of straight lines; rather, they tend to move across the landscape with a natural, organic efficiency that conserves energy. Their lines of movement are characterized by curves that follow the contours of the terrain as they maneuver around trees, rocks, and various landforms.

An animal’s movements may manifest as a visible line of tracks, particularly evident in snow, dust, or mud. Following such a trail forward or backward can sometimes lead to a carcass, cache, or den. As creatures of habit, many mammals will follow established game trails, well-worn paths through the grasses and undergrowth, although such paths are often so faint as to be barely detectable. This tendency is especially pronounced in wild cats and canids, such as foxes, coyotes, and wolves, as they patrol their territories.

I also look for possible places where animal traffic converges. I’ve identified three basic cases. First, many mammals find that reusing paths already established by other mammals is more efficient than constantly breaking trail. Second, sometimes the terrain forms a natural gateway or constriction point through which mammals must pass to get from one point to another. Examples include an opening among rocks that creates a constricted passageway or a low saddle through which animals can move across a rocky ridge. Third, certain places attract animals, such as watering holes, foraging patches, carcasses, food caches, dens, and rendezvous sites. Recall how the fox’s lines of travel converged as it repeatedly returned to the wolf cache. Such convergence points concentrate animal activity and movement, making them reliable locations for observing and photographing animals. I am certain that predators also know the convergence points of their prey.

I carefully examine many other details, such as an animal’s stride and gait, and the subtle characteristics of tracks. The freshness of signs, such as digging, claw or rub marks, blood droplets, scat, and urine, indicates how recently an animal passed. These details help predict where to find an animal. By deciphering such clues, I also gain insight into an animal’s behavior, allowing me to interpret their story and build an integrated picture of how and why an animal moves across the landscape.

If animals are pursued, they may feel chased, become stressed, and spook. Then all I’d get are a few butt shots as the subject flees. Instead, I prefer to anticipate an animal’s route of travel. I position myself at a likely intercept point, considering the best observation angle. While this isn’t easy or guaranteed to work, I want the subjects to approach my position comfortably, in their own time, and pass by without me blocking their path. This way, they remain undisturbed. And, I’ll get nice frontal or side images showing normal behavior.

A couple of days later, snow was gently falling near Floating Island Lake. I was examining some tracks when I spotted a different red fox moving eastward about 200 feet away. Then the fox turned uphill, crossed a high ridge, and dropped out of sight. I moved east, anticipating the fox’s route of travel until I stood on a slope overlooking Elk Creek. I scanned the terrain. My eyes traced along the hill rising before me and down the slope as it fanned out. The gradient in the center was notably less than the steeper side slopes. While the steeper flanks had no tracks, three distinct lines of fox tracks crossed the more moderate slope, descended downhill, and converged to the right before crossing the road. It’s a logical place to cross the road as most of the far side of the road is a steep drop-off. These converging track lines caught my attention. The terrain formed a subtle constriction to movement. This seemed like a good spot to wait for the fox to appear or possibly to set up a remote camera trap.

I figured there was roughly a twenty percent chance the fox would come this way in the next hour. While a fox doesn’t follow the same path every time, it often moves in a circuit around its home territory that follows a general pattern determined by the terrain and known patches of vole habitat. I liked the odds here. I took a position partially concealed by the sagebrush across the road. Setting my camera on its tripod, I waited. My aim was to observe and photograph a red fox hunting and hopefully pouncing in a high-angled leap designed to penetrate eighteen or more inches of snow and pin a vole with its paws and jaws.

Patience paid off. Twenty minutes later, I spotted the fox working its way down the slope. I could tell it was a male based on its size, build, and head shape. It traversed the snow, coming directly towards me, and then veered to the right and crossed the road as I expected. The fox moved quickly, rather than hunting stealthily. It didn’t pounce. For that, I had to wait three more days.

I returned several times to search for the fox. I occasionally spotted him on the far side of the lake. On the third day, I searched all morning, and once I briefly spotted him in the distance just as he pounced. He quickly disappeared. I spotted him next at the bottom of a slope where signs indicated there were voles. Voles live in the subnivean zone, the interface between the ground and snow, but they also have tunnels that extend to the surface.

I watched and waited from a position downhill. The fox was clearly hunting as he worked his way up the slope, getting further away, eventually reaching the ridgeline. I was worried he would disappear again over the ridge. The fox stopped, head cocked, he listened. (A fox’s hearing is so keen it can detect a vole or mouse scratching under two feet of snow.) Then he moved again, slowly, stealthily, carefully moving one foot at a time, listening with each step. Suddenly, the fox leaped into the air in a high arc and plunged downward, thrusting head-first deep into the snow. Its body stiffened as it kicked its back legs up and pressed its forepaws down to pin its prey. Its jaws snapped shut. Success! The fox got a vole, and I got the shots.

This story was originally published in The Ranchlands Review, Edition 03: Lines.