by Whit Gibbons

December 5, 2010

Where would you find a fisher, a pika or an aplodontia? TV nature shows bombard us with the lifestyles of fascinating animals from exotic lands--kangaroos and koalas from Australia; gorillas and giraffes from Africa. But we need not go so far afield to find engaging creatures. The trio mentioned above is found in the United States. I have been asked the following questions about them.

Q: Does any animal eat porcupines?

A: Yes. The fisher, a tree-climbing mammal in the same family as skunks and weasels, is a primary predator of porcupines. Most other carnivores, including wolves, coyotes, foxes and nearly all the large cats, spend little time trying to make a meal of a porcupine. For most predators the cost of a face full of quills outweighs the benefit of a meal. But the fisher, with the agility of its close relatives the minks and otters, can circle rapidly around the porcupine and attack the face area, which has no quills. This dining plan still has risks. But it apparently works often enough for the porcupine to have become a common prey of fishers, although they also eat smaller rodents and snowshoe hares.

Fishers, which reach the size of a house cat, weigh up to 10 pounds or more. They have thick, glossy fur, and unregulated fur trapping drove them to the brink of extinction in the 19th and early 20th century. With the aid of cooperative programs initiated by U.S. and Canadian biologists, fishers have been successfully reintroduced into some areas from which they were extirpated decades ago. Though still rare in most places, fishers are once again found in most northern states from New England to Washington and far north into Canada.

Q: What are pikas? Are they rodents?

A: Pikas are lagomorphs, the same as rabbits. Neither of them are rodents. Pikas, little balls of brown or gray fur, are restricted to high mountain regions where they live among rocks. They have big rounded ears and no tail, and they make squeaking sounds like a squeeze toy. Pikas eat mountain vegetation and store grasses beneath boulders for a food supply during cold periods. The most likely place to see a pika in the wild is in the mountains at one of the western national parks.

Q: Some strange beaverlike mammal that lives in the Northwest carries a weird type of parasite. What is the mammal, and is the parasite something to be concerned about?

A: The mammal you are referring to is known as the mountain beaver, or aplodontia. Mountain beavers are rodents that live around water, but they do not fell trees or build dams. They belong to a completely different family from true beavers. In fact, the family consists of only the single species, which some scientists consider to be the most primitive rodent in the world, having changed little over millions of years compared to other rodent species.

Mountain beavers are restricted to coniferous forest portions of the three West Coast states and British Columbia. These cute little vegetarians, little more than a foot in length, look somewhat like dark brown guinea pigs. They have tiny ears and eyes and no obvious tail.. Little is known of their biology except that they live along the edges of waterways where they make underground burrows and trails.

Mountain beavers carry an unusual parasite, a type of flea that is found on no other mammal. It would not bite a dog or human. Just as mountain beavers are distinctive among rodents, their special flea is also atypical. Mountain beaver fleas are the largest fleas in the world, reaching a length of almost a third of an inch. Pretty big for a flea. The flea is noted among parasitologists as being one of the most primitive fleas in the world.

Without question, animals from other continents can be fascinating. But we have intriguing biological specimens here at home. Fishers, pikas and aplodontias are three such creatures.

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