How many times have you awakened at 3 a.m. to the sound of rustling leaves close to your tent? Have you ever misplaced a bag of trail mix only to find it later scattered around your camp? If these scenarios sound familiar to you, you have also probably wondered what critter(s) were involved in these shenanigans. Most likely, any number of common small mammals might be to blame.
One of the most common visitors in camp is the Virginia opossum, which is actually not a mammal, but North America’s only marsupial, carrying it’s young in a pouch similar to kangaroos. Opossums are common in western Washington lowlands and wooded habitats. They are opportunistic omnivores; eating carrion, road kill, fruits, vegetables, insects, frogs, worms, and possibly your breakfast if you’re not careful.
Shrews (Sorex spp.) and moles are very common camp visitors, especially in western Washington wooded habitats or meadows. These closely related groups feed mostly on insects and worms, and tend to be nocturnal. That scurrying in the leaves near your tent is very likely a shrew searching for it’s next meal. Shrews can echolocate using ultrasonic ‘squeaks’, similar to bats. Moles have the ability to tolerate very high levels of carbon dioxide because of their underground lifestyle. Water shrews and Townsends mole occur around marshes and streams where they hunt for aquatic insects and small fish.
Lagomorphs are a group of mammals that include pikas, rabbits, and hares. There are 30 known species of pikas; however Washington has only a single alpine species found at or above tree-line. Pikas are diurnal, so you’re likely to encounter them during daytime traverses of rocky slopes. Two non-native species of rabbits have been introduced to Washington state: the European rabbit on the San Juan Islands and the Eastern cottontail, introduced statewide. Snowshoe hares occur statewide, but other native rabbits and hares are limited to east of the Cascades, the Cascade Crest or the Columbia River basin. Almost all lagomorphs are herbivores.
Sciurids are very familiar camp visitors to most backpackers and include the chipmunks, squirrels, and marmots. Some of the more interesting species you might encounter include the Northern flying squirrel, the Olympic marmot found only in Olympic mountains, and the Washington ground squirrel whose populations along the Columbia River basin are declining. Many of these species are prime suspects when investigating a camp raid. My first experience with a marmot cost me a pair of boots. Sweat ran down my legs and dried at the top of my boots, leaving a salt deposit on the leather. I left my boots outside overnight and a salt-deprived marmot came along and chewed the top off my boots. Sciurids can be cute, but pesky.
Rodents are another cute but pesky group. Mice, rats, and voles are very common camp visitors, usually arriving at dawn or dusk (crepuscular) or at night (nocturnal). The deer mouse (Permoyscus spp.) can carry two diseases well-known to backpackers: Lyme disease and Hanta virus. However, not all rodents are as menacing. For example, if you’re observant, you might come across an interesting group of mice and rats—the jumping rodents. Ord’s Kangaroo Rat, and the Western and Pacific Jumping Mice can leap up to 10 feet. Impressive for animals that are on average only 1-3 inches long. Bushy-tailed wood rats and muskrats are found throughout Washington; muskrats are restricted to lowlands in or around water. The Northern bog lemming is found in bogs and moist meadows in the northern Cascades and Okanogan Highlands. Voles often like moist meadows near marshes and streams, and most species are found west of Cascades. Most rodents are largely herbivorous, feeding on plants and seeds, but many species will opportunistically feed on carrion.
When traveling in central Washington, you might encounter another familiar rodent: the porcupine. Porcupine quills are modified hairs covered with keratin, a protein similar to human fingernails. Quills are embedded in the muscles of porcupines allowing the animal to raise (when threatened) or lower the quills. Contrary to myth, porcupines cannot shoot their quills. Rather, the quills are released after embedding in the attacker. Porcupines re-grow lost quills.
Small mammals provide an excellent opportunity to develop or sharpen your skills as a naturalist while backpacking. Their behavior is fascinating and entertaining. To gain a deeper appreciation of the diversity of small mammals visit the American Society of Mammologists online list of mammal species. This lists each mammal species found in each state and provides specific information about the habitats and location of each species. Developing knowledge about the animals and plants you encounter on your hikes will deepen your experiences and appreciation for nature.
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