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

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

Forecasts from the University of Alaska Fairbanks’ Geophysical Institute for the week of March. 19

The FBI Anchorage Field Office is seeking information about this man in relation to a Wednesday bank robbery in Anchorage, the agency announced Thursday afternoon. Anyone with information regarding the bank robbery can contact the FBI Anchorage Field Office at 907-276-4441 or tips.fbi.gov. Tips can be submitted anonymously.  (FBI)
FBI seeks info in Anchorage bank robbery

The robbery took place at 1:24 p.m. on Wednesday.

Kevin Maier
Sustainable Alaska: Climate stories, climate futures

The UAS Sustainability Committee is hosting a series of public events in April…

Reps. Tom McKay, R-Anchorage, and Andi Story, D-Juneau, offering competing amendments to a bill increasing the per-student funding formula for public schools by $1,250 during a House Education Committee meeting Wednesday morning. McKay’s proposal to lower the increase to $150 was defeated. Story’s proposal to implement an increase during the next two years was approved, after her proposed amounts totalling about $1,500 were reduced to $800.
Battle lines for education funding boost get clearer

$800 increase over two years OKd by House committee, Senate proposing $1,348 two-year increase

A call for a joint session of the Alaska State Legislature to cast a vote that would reject recently-approved salary increases for legislators and top executive branch officials is made by State House Speaker Cathy Tilton, R-Wasilla, during a press conference Tuesday. Senate President Gary Stevens, R-Kodiak, rejected the joint session in a letter to Tilton on Wednesday. (Mark Sabbatini / Juneau Empire)
House efforts to nix legislative pay raises hit Senate roadblock

Call for a joint session rejected by upper chamber, bills to overturn pay hikes may lack support

A simulated photo shows the tailings stack and other features of Hecla Greens Creek Mine under the most aggressive of four alternatives for expanding the mine in an environmental impact assessment published Thursday by the U.S Forest Service. The tailings stack is modestly to drastically smaller in the other alternatives. The public comment period for the study is from March 24 to May 8. (U.S. Forest Service)
New study digs into alternatives for Greens Creek Mine expansion

Public comment starts Friday on four options that could extend mine’s life up to 40 years

This image shows the Juneau Lions Club Gold Medal Basketball Tournament's logo. The club is looking for submissions of logos for the historic tournament's 75th anniversary. The winning artist will receive a $250 prize. (Screenshot)
Take your shot at a Gold Medal logo

Upcoming milestone prompts call for art.

(Michael Penn / Juneau Empire File)
Police calls for Thursday, March 23, 2023

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

The Juneau School Board recently announced the three finalists for the district’s superintendent position: Frank Hauser, Carlee Simon and Thom Peck. The district is hosting a public forum from 6 to 7:30 p.m. on Monday, March 27 at Thunder Mountain High School for students, parents and staff to meet the three candidates. Additionally, the trio will be interviewed by the school board on Tuesday, March 28. (Clarise Larson / Juneau Empire File)
School district announces finalists for superintendent post

Public forum and interviews scheduled for next week.

Most Read