Wildlife Tracking at Snoqualmie Pass

On Friday, February 2nd, I had the opportunity to go snowshoeing with a some fellow animal biology and anthropology students. We left Edmonds Community College around 8:30 a.m., and arrived back to the college around 6:00 p.m. We snowshoed at the lower basin of Gold Creek near the I-90 bridges at Snoqualmie Pass. Throughout the entire day and during the drives, it was mostly overcast and raining. However, at one point, the sun broke through the clouds when we were snowshoeing in six feet of snow. I decided to go on this field trip because I have never had the opportunity to go snowshoeing before and I’ve never been in more than six inches of snow. Additionally, I have been wanting to take an anthropology class, however, I did not have time to fit one in my schedule. Because this field trip was for both biology and anthropology students, I figured that it would be interesting to receive both an anthropological and biological perspective on wildlife tracking. On this field trip, we learned some fundamentals for identifying animal tracks, and inferred other details about the tracks based upon other evidence from the tracks and our knowledge on the animal that likely left the track. Using this knowledge, when we came across and animal track, we were able to observe the details and come to a conclusion about what animal left the track, when they left the track, and how they left the track.

Tracking Animals in the Snow and Animal Biology

While we were snowshoeing, we stumbled upon several animal tracks. At the entrance of the trail, shortly after we had began snowshoeing, we encountered our first track. This track was made by a quadrupedal, meaning it moves on four feet. We were able to identify this characteristic because there were distinct tracks made by both front and back feet. By observing the shapes of the tracks, we determined that this animal had paws, since claws were also visible in the prints. These tracks led into the woods, off the trail, and back onto the trail again. Based on these observations, we came to the conclusion that these tracks were only made by an off-leash medium or large-sized domestic dog that someone brought along with them.

Shortly after identifying the domestic dog track, we stumbled upon another track. This track was relatively small, and left simple, oval-shaped prints. These tracks likely had been on the trail for a while, and probably had a more distinct shape when they were first left by the animal. The prints left by the front feet were aligned, as were those left by the hind feet. We were challenged to think about how this animal moved. The prints appeared as if the animals bounds were hops. The stride length was pretty small, and the prints of the hind feet landed within the prints of the front feet from the previous bound. This explains why the prints of the front and back feet are not staggered. From this, we were able to determine the direction that the animal was moving. This track led across the trail and toward a nearby tree. Using this information, we concluded that the animal that left the track was a Douglas squirrel. Based on the location of the track, I was able to infer a couple of the adaptations that the Douglas squirrel. They are light and quick on their feet, allowing them to move through deep snow without sinking into it. The Douglas squirrel track in the snow was shallow, so we could conclude that this squirrel did not have a problem traveling through the deep snow. Because the tracks led toward the trees, the Douglas squirrel likely spends a lot of time in the trees during the winter, since squirrels have long, sharp claws that allow them to climb trees and travel from one to the next.

Later in the snowshoeing trip, we came across another Douglas squirrel track, however, this one was slightly different. It looked like there was more than one track because there were several overlaps, suggesting that there was more than one animal in the same location. However, we could determine the direction this squirrel was traveling, based on the depth of the track either in the front or the back. When you walk, most pressure goes to the front of your foot so you can push off  for the next step. This causes a slant visible in the tracks. As a result, the way the animal is traveling is the direction in which the print is deeper at the front. Using this technique, we concluded that two of the tracks were going the same direction, and the third track was going the opposite direction. Though it was possible that these tracks could have been made by more than one Douglass squirrel, we concluded that it was likely only one squirrel running back and forth between two Noble Fir trees. Assuming that this squirrel made multiple trips to the same tree, it could have been collecting some kind of resource to bring back to one area. The adaptation that allows the Douglass squirrels to have high mobility in deep snow allows squirrels to still collect resources in these harsh conditions.    

Figure 1: This is one bound of a track left by the Douglas squirrel.

Eventually, we came across a river. Right next to the river, there was one tree that was completely tipped over, and another tree bedside it that was almost tipped over, and it was gnawed around the base of the trunk. Teeth marks on the trunk revealed an golden-auburn colored bark underneath the outer layer of bark. Around the base of each tree were several footprints. Only a couple hundred feet upstream, there was a beaver dam visible. We concluded that these tracks were left by a North American Beaver, which are much larger than mountain beavers. The size of the teeth marks on the wood corresponded to the size that a North American Beaver would make. After concluding which animal made the mark, we begun to use evidence to determine when the beaver gnawed the trees and which way the beaver’s head was oriented while doing so. The beaver likely gnawed the tree that morning because there were piles of bark shavings right on top of the snow, and the color of the wood suggested that the wood was fresh and the marks were recently made. Even though there were footprints around the trees, they did not lead all the way back to the dam. Instead, they appeared at the edge of the river, suggesting that the beaver swam from the dam, up the river, and climbed onto the land once it arrived at the tree. This would explain why there were footprints leading to the tree from the edge of the river. Additionally, the teeth marks on the tree trunks were horizontal and slanted, so the beaver’s head was likely oriented sideways when it was gnawing the tree. The strength and thickness of the North American Beaver’s teeth allow it to gnaw on wood, which the beaver uses as both food and resources for building a dam.  I learned that beavers eat the cambium layer of wood in trees, which is underneath the outer layer of bark. The beaver then uses sticks and branches from the tree to build dams in a river or stream. Because of this, the beavers teeth are a very important adaptation, as they are strong and durable for continuous usage throughout the beaver’s lifetime.

Figure 2: This is the tree that the beaver began to gnaw. The pile of bark is on top of the snow, suggesting that the beaver recently chewed on the tree.

Figure 3: This is the tree that the North American Beaver gnawed at until it tipped over.

Near the end, we stumbled upon another track. This one looked similar to that of a Douglas squirrel, however, the bounds were longer and the prints were larger. Additionally, the prints left by the front feet were staggered, while those left by the hind feet were aligned. The prints of the hind feet landed really close to the prints of the front feet from the previous bound, suggesting that this animal hops. As shown in Figure 5, the back feet of this animal were larger and longer than the front feet. Because we were able to determine that the larger prints were made by the back feet and the smaller prints were made by the front feet, we figured out that this animal was traveling from right to left. Because these tracks were larger than those left by the Douglas squirrel tracks that we encountered and because of the shape of the hind feet, we concluded that these tracks were left by a snowshoe hare. The snowshoe hare’s long hind feet increase the surface area of the animals feet as it bounds across the snow. This adaptation prevents the snowshoe hare from sinking down into the snow. In a way, the snowshoe hare’s hind feet have a similar function to that of the snowshoes that we used on this trip. Additionally, the snowshoe hare has a white coat of fur in the winter, allowing it to blend into the color of the snow. This adaptation helps the hare blend into its environment, so it can hide from any predators. As the seasons change, the snowshoe hare’s coat undergoes a gradual transformation from white to brown. As a result, once the snow melts, the hare is still able to blend in with the environment to make this animal harder for predators to find year-round.

Figure 4: This is a track left by a snowshoe hare. Based on the orientation of the tracks, the snowshoe hare is traveling from right to left.

    There was a lot that I learned on this field trip that directly related to material that we have been discussing in animal bio. I think one of the most significant things we discussed was that when roads and highways are built, populations of animal species are divided. As we learned in class genetic drift is a geographical division of a population by a physical barrier. Genetic drift is one of the mechanisms of evolution, because after the division, the allele frequencies in the resulting populations are not the same. On the field trip, we discussed that inbreeding of species is not uncommon in this situation, because the selection of mates is limited. As a result, after several generations, the animals in the species of each resulting population are related to each other in some way, and the genetic diversity of the population decreases as a whole. An overall decrease in genetic diversity can have major consequences on a population because when environmental conditions change, the population will not be able to evolve in response to these changes. This is because natural selection cannot act upon individuals when there is no genetic variation within a population. This idea pertains to Darwin's four postulates for the theory of evolution that we discussed in class. The construction of the overpasses and underpasses of the I-90 Wildlife Corridor is so important because one of the reasons they are being put in place to reconnect habitats, which will prevent a continuous decrease in genetic diversity.

Human Ecology

              Wildlife tracking is commonly used to understand how animals interact with their natural environments and other organisms within their environments. Tracking provides valuable data because it provides insight into how species move, interact, and behave when they are in the wild, rather than in captivity. Tracking can help biologists gain a better understanding of the impact that environmental factors have on animal species and how they change the behavior of these animals. With sufficient data, biologists can use the observations to compare and contrast how animals of the same species behave and interact with their surroundings when their circumstances are different. In other words, wildlife tracking provides valuable information about the adaptations of animals in the environment that ultimately increase the fitness of each individual.

    Wildlife tracking is specifically useful for the I-90 Wildlife Corridor because it provides insight into which animals utilize the corridor, when they use it, and why they use it. Some species may use the corridor to migrate to a different location when the environmental conditions change with the seasons, while others utilize it to gain access to a larger variety or resources. Additionally, the corridor allows animals to migrate to find a mate to prevent continual inbreeding in their species. Several organizations work with the I-90 Wildlife Corridor to help preserve animal species. The mission of the organization Conservation Northwest is protecting wild lands, connecting habitats, and restoring wildlife. Protecting the environment is vital in order to allow the wildlife to live in an area where resources are plentiful so they can thrive in their environment. Conservation Northwest worked with the Washington Department of Transportation to promote the I-90 Wildlife Corridor Campaign. Since then, Conservation Northwest has partnered with several organizations to build four undercrossings beneath the freeway to allow the wildlife to live on either side of the freeway, and allowing them safe access to either side of the freeway so they can utilize a wider variety of resources. Currently, Conservation Northwest is building two overcrossings, or bridges, that will allow the wildlife alternate passages that run over the freeway. Additionally, Conservation Northwest partners with other organizations to restore and reintroduce endangered species. Conservation Northwest offers a large variety of volunteer programs to provide people with the opportunity to contribute to the wildlife restoration and conservation initiative.

Reflection

This field trip changed my perspective on the connection between science and society, especially in regards to relationships between animals and humans. After learning about several of the organizations that have taken initiative to help promote the restoration and conservation of wildlife, I realized that people can have a huge impact on the animals and their environments. I never took too much time to think about what I could be doing to improve conditions for the wildlife here in the Pacific Northwest. Because of this, my perspective on science in society has transformed the way I view societies ability to contribute to improving wild lands and wildlife, and I feel inspired to take part in this initiative.

Overall, this experience also changed how I think about biology and anthropology. It increased my appreciation for these subjects because I realized how intuitive the thinking must be to reach a conclusion based on the evidence was left. I thought that the most interesting aspect of this field trip was the thought process that is used to identify the animal that made the track, and the follow up questions that provided further information about the animal. Before this trip, I never would have thought to ask anything beyond what animal made the track. I learned that the details are just as important and provide a lot of valuable information to biologists, like what time of day the track was made, what direction the animal was traveling, how the animal made the track, and why the animal made the track. Additionally, looking at all of the tracks in an environment can be very informative, rather than looking at each of the tracks individually. The location of the tracks in the environment can provide information about how animals of the same species and animals of different species interact with each other within the same environment by paying close attention to the relative locations of the tracks within the environment.