Rambling in winter

owl wings, wolf tracks, otter sign, and ice formations

The short December days don’t allow for long explorations, but even short ones can be productive for a curious naturalist.

I took a little stroll on the wetlands on the north side of the Mendenhall River. At least four short-eared owls were coursing low over the grassy meadows, with their distinctive slow wingbeats. They were looking for voles, their favorite prey. Vole tunnels were evident under the thin and patchy snow, but I did not witness a capture, despite some serious watching. Short-eared owls often forage during the daylight hours, probably using visual clues to supplement acoustic ones. Like other owls, they have the ability of pinpoint a prey animal by using only their ears, but in daylight, their eyes are useful too.

short-eared-owl-by-Jack-Helle
Photo by Jack Helle

Plodding on snowshoes around some mid-elevation meadows, we noted lots of deer tracks, some not-recent porcupine trails, and several sets of hare and squirrel tracks. But the big excitement, in two widely separated sets of mid-elevation meadows on two different days, was finding clear, recent footprints of wolves; they wove in and out among the trees at the edges of the meadows. That was a high point of the rambles on those days!

A friend and I walked out toward Crow Point and the Boy Scout beach, but we soon forsook the trail for explorations right along the river. There was not a lot of bird activity—a little squad of Barrow’s goldeneyes and a few gulls, but on a little grassy rise above the sandy river-shore we did find something interesting. In the snow that covered some of the grass, we saw otter tracks leading up to the top of the rise. There we found three or four spots where the grass was torn up and heaped off to the side. What were the otters doing? Just playing? Scent marking (the grassy heaps smelled faintly sweet)?

Where the trail reaches the beach, recent heavy erosion had chopped off a good part of the dense stand of little spruces and carved a steep cliff in the sandy edge of the grassy bank. The most severe erosion was very localized. Just around the corner, where the beach extends southward, erosion was much less. We wondered if there had been a big northerly wind that coincided with a good high tide. Possibly the bank around the corner was somewhat protected from wind and wave by the broad, sandy flats that extend away from shore and are exposed at low tide.

We walked south on the beach, watching gulls at the water’s edge picking up and carrying black lumps that were probably little clumps of mussels. The gulls did not do much else with those lumps, at least while we were watching. Gulls tracks were everywhere. In the dry sand at the top of the beach were many tracks of another kind of bird—something small, smaller than a robin. But not a shorebird, because this bird had a well-developed hind toe, which shorebirds lack. The unusual thing about these small birds was the gait—lots of running, with intermittent hopping. Most of our small birds, such as sparrows, seldom run; they usually hop. So what bird could this be? I think the two most likely candidates are pipits and horned larks, but December is rather late for them to stay here.

Another stroll, just after a few days of freezing temperatures, yielded some of the most beautiful ice formations we’d ever seen. Dead twigs and fallen logs had absorbed water from fall rains; as the low temperatures froze the water, it expanded. The expanding ice was extruded from the wood in thin sheets of fine, almost silk-like strands. The most elegant sheets were up to five inches long, curving gracefully like a tousled head of wavy hair. Alas, no camera!

High tides

long-tailed voles and short-eared owls

In early October, the highest tides of the year (over 20 feet) brought sea water up close to the airport dike trail. Much of the extensive meadow of grasses and sedges was flooded. Although there had been 18-foot and 19-foot tides in previous months, this area is so flat that just another foot or two of water means that much more area is covered.

In intervals between big tides, long-tailed voles move out into the meadow, looking for food and perhaps even nest sites. Voles typically eat green vegetation and seeds. They have a very rapid reproductive cycle; the time from conception to sexual maturity is just a few weeks. But that short period is not sufficiently short to fit between monthly big tides of 18 or 19 feet. The mega-tides of 20 feet, however, occur at wider intervals, and voles could nest successfully in the meadows that are only covered by the biggest tides.

Whether nesting or exploring, the voles in the tidal meadows encounter major adventures with the coming of the mega-tides. As the water creeps up through the grasses and sedges, the voles flee. We can sometimes see them swimming for their lives toward higher ground, including the sides of the dike itself.

When that happens, predators have a good time. During the early October mega-tide, a friend watched an eagle snatch a vole from the water. Then a gull swept in and took another. (I was on the dike trail but apparently in the wrong place at the wrong time, since I missed the action).

In a different year, another friend saw a short-eared owl perched out in the meadow. The owl pounced on a swimming vole and sank partway down into the water. The owl pulled itself and its prey up and went to a nearby little snag, where it swallowed the vole whole. Twice! Down the gullet once, then coughed back up, and then down again, this time permanently. (What a trip!)

short-eared-owl-by-Jack-Helle
Photo by Jack Helle

Short-eared owls are widespread, but they are quite specialized. They inhabit grassy areas and open fields, where they flit low over the ground in search of prey. They sometimes take large insects and small birds, but voles are a favorite food. Naturalists have collected regurgitated pellets of short-eared owls from the wetlands, inspected the undigested bones and teeth in those pellets, and found that long-tailed voles comprised most of the diet. Here in Southeast, they are migratory, passing to or from their nesting areas in the Interior.

Sadly, they sometimes view the grassy edges of the airport runway as foraging habitat, where they are at risk of being shot and killed. I wonder if that grass could be replaced by some other material that wouldn’t attract voles and owls (and geese), and thus reduce the worries about bird strikes by airplanes.