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

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

On The Trails: Early winter walks

By Mary F. Willson

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 tracks 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 kits through the winter.

A likely orphaned black bear cub forages for roots near a popular recreation area in Juneau. (Courtesy Photo / Denise Carroll)

A likely orphaned black bear cub forages for roots near a popular recreation area in Juneau. (Courtesy Photo / Denise Carroll)

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.

[Ice and quiet on the trails]

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.

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?

[Twice-told tales —Juneau style]

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.

Thanks to John Hudson for caddisfly info.

• Mary F. Willson is a retired professor of ecology.“On The Trails” is a weekly column that appears in the Juneau Empire every Wednesday.

More in News

The Aurora Borealis glows over the Mendenhall Glacier in 2014. (Michael Penn / Juneau Empire File)
Aurora forecast

Forecasts from the University of Alaska Fairbanks’ Geophysical Institute for the week of Nov. 27

Mountain reflections are seen from the Mendenhall Wetlands. (Courtesy Photo / Denise Carroll)
Wild Shots: Photos of Mother Nature in Alaska

Superb reader-submitted photos of wildlife, scenery and/or plant life.

Clarise Larson / Juneau Empire 
At Wednesday evening’s special Assembly meeting, the Assembly appropriated nearly $4 million toward funding a 5.5% wage increase for all CBJ employees along with a 5% increase to the employer health contribution. According to City Manager Rorie Watt, it doesn’t necessarily fix a nearly two decade-long issue of employee retention concerns for the city.
City funds wage increase amid worker shortage

City Manager says raise doesn’t fix nearly two decade-long issue of employee retainment

(Michael Penn / Juneau Empire File)
Police calls for Saturday, Dec. 3

This report contains information from law enforcement and public safety agencies.

Molly Yazwinski holds a 3,000-year-old moose skull with antlers still attached, found in a river on Alaska’s North Slope. Her aunt, Pam Groves, steadies an inflatable canoe. (Courtesy Photo /Dan Mann)

 

2. A 14,000-year-old fragment of a moose antler, top left, rests on a sand bar of a northern river next to the bones of ice-age horses, caribou and muskoxen, as well as the horns of a steppe bison. Photo by Pam Groves.

 

3. Moose such as this one, photographed this year near Whitehorse in the Yukon, may have been present in Alaska as long as people have. Photo by Ned Rozell.
Alaska Science Forum: Ancient moose antlers hint of early arrival

When a great deal of Earth’s water was locked up within mountains… Continue reading

FILE - Freight train cars sit in a Norfolk Southern rail yard on Sept. 14, 2022, in Atlanta. The Biden administration is saying the U.S. economy would face a severe economic shock if senators don't pass legislation this week to avert a rail worker strike. The administration is delivering that message personally to Democratic senators in a closed-door session Thursday, Dec. 1.  (AP Photo / Danny Karnik)
Congress votes to avert rail strike amid dire warnings

President vows to quickly sign the bill.

Mark Sabbatini / Juneau Empire
Juneau state Sen. Jesse Kiehl, left, gives a legislative proclamation to former longtime Juneau Assembly member Loren Jones, following Kiehl’s speech at the Juneau Chamber of Commerce’s weekly luncheon Thursday at the Juneau Moose Family Center.
Cloudy economy, but sunnier political outlook lie ahead for lawmakers, Kiehl says

Juneau’s state senator tells Chamber of Commerce bipartisan majority a key to meaningful action

(Michael Penn / Juneau Empire File)
Police calls for Friday, Dec. 2

This report contains information from law enforcement and public safety agencies.

Alaska State Troopers logo.
Hunter credits community members for Thanksgiving rescue

KENAI — On Thanksgiving, Alaska Wildlife Troopers released a dispatch about a… Continue reading

Most Read