Trowbridge’s shrew

Over the holiday I visited the western Cascades with old friends from Ashland. We stayed in a forest service cabin at the Fish Lake Remount Station – an historic waypoint on the Santiam Wagon Road. The wagon road was once a thoroughfare for pioneers crossing from the high desert to the lush Willamette Valley. Climbing between high volcanoes, Mount Washington and Three-fingered Jack, the road crossed many lava flows. These must have been tough on wooden wagon wheels. Now the road is a pleasant walking trail. Near the head of the McKenzie River it passes through evergreen forest dominated by Douglas fir.

At the intersection of the Santiam Wagon Road and the McKenzie Trail we saw a tiny gray shrew scurrying haphazardly over the path. Last week was clear and cold with temperatures below freezing, and much of the ground was frozen. Shrews are burrowers, and this one may have found itself above ground and unable to retreat. Based on the location where we found the animal, the lack of contrast between the belly and back, and the strongly bicolored tail, I think that our shrew was a Trowbridge’s shrew (Sorex trowbridgii).

Shrews appear in the fossil record 160 million years ago. At that time, the high Cascades were being pressure-cooked hundreds of miles beneath western North America, and dinosaurs like Allosaurus haunted the continent’s riverways. Shrews were, and still are, primarily eaters of invertebrates, though Trowbridge’s shrew also partakes of Douglas fir seeds. This diet does the shrews little good when they are caught in live traps baited with peanut butter and oats; they frequently die.

I can only guess about the name “Trowbridge”. Sorex trowbridgii was named in 1857 by Spencer Baird (1823-1887). In 1854, William Trowbridge (1828-1892) donated a large collection of fishes to the Smithsonian, which Baird curated. Did Baird honor the ichthyologist William Trowbridge by naming an obscure western shrew after him? Or was it a joke? Maybe Trowbridge wore something resembling a shrew pelt while receiving an award. I would love to know.

 

Sources:

Alt, DD and DW Hyndman. 1978. Roadside geology of Oregon.

A shrew in the high Cascades. Sorex trowbridgii?

A shrew in the high Cascades with a bicolored tail and little contrast between back and belly. Sorex trowbridgii?

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Frozen basalt. Bad for burrowing.

Frozen basalt. Bad for burrowing.

 

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About Leighton Reid

Restoration Ecologist
This entry was posted in Ecology, Evolution and tagged , , , . Bookmark the permalink.

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