Early winter walks

confluence tracks, a caddisfly on ice, and an orphaned bear

A visit to the lower reaches of the Herbert and Eagle rivers usually turns up something of interest. A recent warm spell meant that looking for critter tracks in snow would be a vain endeavor. However, the sands were well-decorated by several animals.

Deer tracks old and new went every-which-way. One trackway went right to the last bit of sand and disappeared, so that deer probably swam the river. Maybe it took advantage of the current to arrive at some point well downstream. There were mink track and a good print of a small otter. Beavers had trekked back and forth over the sand bar, one of them recently toting a twiggy branch that left a well-defined pattern. Local beavers had a big cache of small branches for feeding little, growing beaver-lets through the winter.

Perching on a convenient log and pulling a snack from a backpack had the often-predictable result of attracting a black-feathered opportunist. This raven was obviously an experienced moocher and stood expectantly less than fifteen feet away. So the snack was shared. As experienced as that bird was, it approached tidbits tossed only three feet away with the characteristic sideways hops, ready for a quick dash to safety if needed. Just as the supply of snacks ran out, another raven came in and missed the fun.

The west side of Mendenhall Lake caught the brunt of some very strong winds in early December, piling up big plates of broken ice. I went back out there a week later, when a light snowfall had brightened everything. The ice plates were still there, but this time one of them featured the only wildlife seen on that walk: a caddisfly. One of the big chunks of ice was tilted up, and the critter was walking down the steep edge. As it did, a small bit of ice broke off below its feet—I like to think that the insect kicked it off. Someone said it looks like the critter is climbing down its own Denali.

A winter caddisfly, sometimes called a snow sedge, walks down an icy ridge on the shore of Mendenhall Lake. Photo by Kerry Howard

This caddisfly has a name (probably Psychoglypha subborealis) and a nickname (snow sedge). It is winter-active: both males and females have been found at times of very cold temperatures—as low as minus twenty or thirty degrees Centigrade, having emerged from their freshwater larval stage in the fall. When they emerge, they are adult in form but sexually immature. They mature gradually during winter, using up stored body fat in the process and females developing their eggs. They mate and lay eggs (in open fresh water) in early spring, and then apparently die, after a life span of roughly six months.

This caddisfly is not unique among insects in having a life history involving winter activity, but there are not many spend an entire phase of their life history in winter. I wonder about the ecological pressures that led to the evolution of such an unusual habit. Certain kinds of stoneflies customarily emerge, as adults, from fresh water streams in late winter, as soon as the streams aren’t completely covered with ice. Temperatures are often below freezing, but these winter stoneflies have ways to cope with the cold. They are interested in mating at that time, maybe getting a head start for their larvae in the streams?

On a group hike to Crow Point and Boy Scout beach in mid-December, when there was nice, fresh snow on the ground, I found some mouse tracks, a vole highway between grass clumps and some wanderings, and a set of squirrel tracks. Weasel tracks were all over the place—maybe hunting was not-so-good and lots of searching was needed? Or are there lots of weasels out there? We watched a small black bear cub in the tall grass, where it was digging persistently for some time, apparently finding edible roots. There have been reports of an orphaned cub in this area (and elsewhere), and this one was all alone. However, it seemed to be fending for itself reasonably well, and although it was not very chubby, we hoped it could eventually hibernate successfully.

An orphaned bear cub forages in the meadow near the boyscout camp. Photo by Denise Carroll
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A quick visit to Gustavus

…a change of place

When the ferries are running, it’s an easy ride to Gustavus: about four and a half hours, usually, with chance of seeing Dall’s porpoises and other marine critters. The ferry often has a Monday-Wednesday schedule, which makes a quick two-night visit quite possible. The great, wide sandy beaches over there are a big draw; they offer a very different habitat from anything here in Juneau and therefore the possibility of seeing different animals, and it’s easy walking, too.

I made a visit there in mid-January. My naturalist friend had set a trail camera at a place where moose habitually cross a wet ditch, carving deep, narrow trails in the banks. The camera captured plenty of moose images, including mamas with calves. One image showed a very odd thing down in one corner, and for a long time we couldn’t figure it out. Then my clever friend got it: ‘twas the rear end of a duck, dabbling in the ditch in the dark of the night. All we could see was an end-on view of the tail with crossed wingtips above. Very odd-looking, indeed.

Out on the grassy flats where spruces have begun to colonize, we found owl pellets, probably of a short-eared owl, containing tiny mammal bones and a shiny beetle. We noticed that clumps of young spruces often seemed to grow on low mounds, where drainage might be better than in the swales. But do they need to grow on these slightly elevated places? Apparently not, because we found a number of very small spruces getting started in the low spots. So maybe a clump of little trees makes its own mound when needles and twigs are shed, or the branches intercept wind-driven dust and silt??

On the sandy beach, we enjoyed following the tracks of a raven fossicking in the tidal wrack and digging up some treasure from the wet sand. There weren’t many mollusk shells left below the high tide line, but I did find one nice piddock shell; just one, though, a contrast with last summer when there were many. Piddocks are burrowing clams, with a jagged edge on the shell for scraping a way into wood or packed sand or even soft rock. Other shells were scarce too: a few whelks in good condition, and some cockles and ordinary clams.

We made a brief foray into one of those long meadows that eventually drain out onto the beaches. Moose tracks going every which way, of course; moose are really common over there. Wolves had gone single-file as they entered the meadow and then fanned out, leaving their big paw prints on the way to the beach.

A rivulet that meandered through the meadow had some open water, despite the recent low temperatures. Peering down into the openings of the ice, we could see amphipods, caddisfly larvae, a diving beetle, and a couple of very small juvenile salmonids that quickly dashed for cover. The water temperature couldn’t have been much above freezing, yet all these critters were active.

We returned to the car on a game trail through the woods. Many critters used this trail, at least in places: moose, wolf, coyote, and best of all, a wolverine that had gone from the trail to the meadow, leaving nice clear footprints. Later, we went back to set the trail camera in this area and hope for some good videos. Along the road, we chanced upon a flock of pine grosbeaks, busily foraging on seeds (more on this next week).

swans-and-cygnets-hocker
Photo by Cheryl Cook

Back at the house, looking out on a bend of the Salmon River, we were treated to a small parade of trumpeter swans: a pair of adults, then another pair with a handsome gray cygnet. They pulled out on a gravel bar a little way downstream and so gave us a good look at them. An uncommon sight here in winter, although much of the Alaska-nesting population winters along the coast in various places. The swans have the interesting habit of incubating their eggs on their enormous feet, rather than in a featherless incubation patch on the adult’s belly, and both male and female can incubate. Cygnets keep some of their gray juvenile plumage into their second year, becoming fully white-feathered by the next year. Although occasionally they may pair up and start nesting when they are two or three years old, this does not unusually happen until they are about four years old.