Islands of the North Cascades: Cascade Red Fox

This is part 20 in the series: Graduate Natural History Projects

You may be familiar with the Common Red Fox (Vulpes vulpes), the villain in many children’s tales, the sneaky trickster that always eludes capture. This cunning animal has gotten the short end of the stick when it comes to fairy tale character assignment, however in reality it is truly a spectacular creature. The Cascade Red Fox (Vulpes vulpes cascadensis) is a rare subspecies of the red fox that scientists know very little about.

This fox is a genetically unique species and only occurs in Washington State and in order to understand why this is, we have to take a step back into time and into the Ice Age. During the Illinoian glacial period (300,000 – 130,000 years ago), there was an initial migration of many species, including the red fox, into North America across a land bridge over the Bering Strait. When the ice receded, these animals became isolated and spread across the continent. During our most recent Ice Age, a massive glacier covered a large portion of North America, called the Wisconsin glacier (100,000 – 10,000 years ago).  Throughout this period, there was another migration of species across the land bridge and a second population of red fox occupied this part of the world.

Cascade Red Fox displaying its cold weather adaptations and preference for
high altitude regions. Photo by Geoff Schmid

These animals however, were genetically distinct from the first wave of foxes, which we can find evidence of in habitat preferences and morphological variances, such as skull size. As the Wisconsin glacier began to recede and our climate began to warm, the cold climate adapted fox in the western portion of North America, retreated into high alpine meadows and forests. Current day, there are montane habitat subspecies of the red fox in the mountains all up and down the west. These mountainous alpine regions however are relatively isolated from one another with large distances between them and they are effectively stuck on their “islands” of habitat.

The Cascade Red Fox that is exclusively found in Washington is considered the most genetically distinct out of all the mountain dwelling fox subspecies. The regions that these animals have been documented are scattered across the state and the population data within the North Cascades is still fairly unknown.

Lets first look at why these animals prefer to live in such a formidable and isolated habitat in the first place. The diet of a Cascade Red Fox is primarily small mammals that inhabit alpine meadows. This includes pocket gophers, snowshoe hares, ground-nesting birds, voles, as well as consuming high elevation plants. Additionally, historically there has been minimal competition or pressure from other carnivores in this habitat. This fox has adapted to the cold climate so well that it will remain at high altitude all winter long, unlike many other predators. Both of these factors allow for this animal to thrive in its specific niche, that is if the landscape remains unchanged as we move into the future.

Cascade Red Fox can have many different coat colors as displayed here with a
mom and her kit. Photo by Anthony Corado (Cascade Carnivore Project).

The Cascade Red Fox population is dwindling and as we consider the reasons why, we can consider the island biogeography model and how it may provide some answers. The goal for any population is to reach that equilibrium of extinction and immigration. In this case however, there is very limited immigration into these insular regions due to the vast distances between mountainous regions, the obstacles that are within those travel corridors (forest loss and human development), and their inability to breed with lowland fox species.

Although fairly similar in appearance, the Cascade Red Fox is genetically distinct enough from the introduced Eastern Red Fox species that they cannot breed. As for extinction, the species is holding on yet, however threats from forces such as climate change and human encroachment are reducing their habitat in consequential ways. As the Earth’s temperature rises, midlevel forest lines begin to creep up into the subalpine and alpine zones, reducing the alpine meadows that the fox requires for hunting. Additionally, many of the plants that their prey relies on cannot survive in warmer temperature, therefore having a cascade affect down the food chain.

Additionally, as humans satisfy their desire to explore and recreate in the backcountry, they are putting pressure on these shy animals and pushing them out of their home ranges. A particular issue that occurs in the winter is that areas that are usually undisturbed, with deep snow that prevents many predators from traveling, become packed down with snowmobiling and skiing. These packed down routes are actually allowing for competitors such as coyotes to make their way higher in elevation than usual and putting pressure on the Cascade Red Fox.

A young red fox starting to develop its adult coloration on a warm spring day on Mount Rainier.

As we learn how to share these spaces with the wildlife, conservation efforts are focusing on how to support these threatened animals and how best to support them moving forward. Determining the Cascade Red Fox’s population and their travel patterns will help understand if there is adequate genetic diversity to maintain a healthy population, otherwise the equilibrium will sway in favor of extinction, which could result in a loss of a beautiful animal from this
ecosystem.

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