On The Trails: Basin Road, jumping mice, calypso orchids

A bumblebee looks at a Calypso flower, but won't find any food there. (Photo by Bob Armstrong)

By Mary F. Willson

On a recent chilly, drizzly day, I ventured up Basin Road with a friend. The flume trail was not available, due to some work project. Our time was limited, so we stuck to the road, up and back.

Despite the uncomfortable weather, several good things were there to be enjoyed. Yellow violets, always the first violas to appear, were flourishing in several places. Robins sang lustily and Wilson’s warblers chattered in the thickets. Ruby-crowned kinglets sounded off, so cheerily. One alder thicket, just leafing out, was explored carefully by a female Wilson’s warbler and a chickadee looking for bugs. Behind the thicket, a spruce tree hosted many foliose lichens on its lower branches, and we glimpsed a (downy?) woodpecker that was very busily poking among them.

Jumping mice?? Seldom seen (they are nocturnal) or talked about, they are here. There are two species of them in Southeast: the western jumping mouse occurs in southern Southeast and points south. The meadow jumping mouse (Zapus hudsonius) is widespread in northern North America, from southern Alaska to the Atlantic. They are not very big, usually weighing less than about 25 grams in summer (about the same as a deer mouse), but adding lots of fat before going into hibernation, then weighing as much as 35 grams.

A meadow jumping mouse. (U.S. Fish and Wildlife Service photo)

They earned their name from the lively jumps they make, easily leaping two or three feet, using their long hind legs and using the long tail for balance. They like to live in open, grassy meadows, preferably near water. Seeds are a big part of their diet, but they also eat insects and fruit. They hibernate for many months in winter (up to eight months). Winter nests are closely woven spheres of grasses, usually placed two or three feet underground, in dry ground. 

These jumping mice make globular (or sometimes flat) day nests of woven grasses, for temporary use. They are placed on or near the ground, hidden in tall grass or under roots and fallen timber, usually near streams. Females make maternal nests in denser vegetation in somewhat drier areas. They breed as soon as they emerge from hibernation; pregnancy takes less than three weeks. The pups stay with the mother for about four weeks or a bit more; they then become independent and she is likely to start another litter, sometimes producing three litters in a summer. The size of the litter varies a lot, sometimes as many as seven or even nine pups. The young ones mature in a couple of months, and some may even breed in their first summer. However, they don’t live very long — only two or three years.

Yellow violets, a very special early flower. (Photo by Mary F. Willson)

Calypso orchids are distributed in boreal forests around the world. The name Calypso comes from an old Greek word meaning "hidden" or "concealed," reflecting this plant’s small size and tendency to grow in protected spots. Lured by reports that one had been planted at the Arboretum, I went out to see if I could find it. I finally did…it is tucked in a little pocket between several other larger plants. Like other orchids, it forms special fungal (mycorrhizal) connections that are essential for seed germination and growth.

Calypsos bloom early, ahead of other orchids. There are several varieties, all belonging to one species (C. bulbosa) and they occur in various shades of pink and white. Calypsos offer no food reward for insects and are visited by naïve bees that soon learn to seek food elsewhere.

Calypso is also the name of a very seductive nymph in Homer’s Odyssey. She holds Odysseus captive for several years, entertaining him even as he longs for wife and home. She is enchanting for a time but offers him no long-term satisfaction. I imagine that the taxonomists who named the orchid had this parallel in mind.

• Mary F. Willson is a retired professor of ecology. "On The Trails" appears periodically in the Juneau Independent. For a complete archive of Mary Willson’s “On the Trails” essays, go to https://onthetrailsjuneau.wordpress.com.