Snow at last!

After a very dreary, dismal January, February produced some nice snow. Not enough, of course, and it didn’t last. But for a few days, snow made the daylight hours brighter and provided splendid opportunities for reading critter tracks. Here are some samples, along with ancillary observations.

A morning snowshoe walk at SAGA meadows, with fresh snow and partial sunshine was very productive. A river otter left its distinctive five-toed prints and sliding track all along the base of the ridge on the eastern side of the valley; it came from the Amalga area, heading to the saddle where the old horse tram crossed over to the Eagle-Herbert drainage. It’s a lot shorter to go by land than by sea (out around the Boy Scout beach to the mouth of the river), but we wondered why this individual chose to go by land. Maybe it likes sliding better than swimming? Long overland journeys are not unheard-of: we once tracked an otter from the Hilda Creek canyons up and over to the Fish Creek drainage near the start of the upper cross-country ski loop.

Red squirrels had been very active, making highways between brush piles and trees, and often diving under the snow, popping up several feet farther on. Under the snow there were a few little caverns whose floors were littered with the remnants of alder cones, where a squirrel had a picnic.

Snowshoe hares left their tracks especially under the drooping conifer branches. It was clear that hares had been munching twigs of highbush cranberry—small twigs of many bushes had been recently clipped and hare tracks nearby left no doubt about the clippers. Small well-trampled areas indicated a place, perhaps a latrine (?), where a hare had spent some time, but only a few of these had scattered pellets. We speculated that the hares might have re-ingested fresh pellets to extract more nutrients (a habit they share with many rodents).

A small bird—probably a junco—had hopped around under a low-hanging spruce branch and then flitted off, leaving short wing traces in the snow. A mouse or vole had travelled from one thicket to another, and some small rodent had nibbled the bark of tiny shore pines. A porcupine had wandered about before the last of the snow fell, leaving now-blurred but unmistakable traces of its passage. Near a small frozen slough, a mink or marten had walked over toward a tree; the prints were not clear enough for us to discern the subtle clues that might tell us which kind of beast it was and the trail was lost in a snowless patch under dense spruces.

A flock of red crossbills enlivened the morning, calling and flying from spruce-top to spruce-top, occasionally prying open a cone to extract the seeds. Did their messy feeding activities contribute to the fall of seeds we saw scattered on the snow or did the wind bring them all down?

We found good examples of the rough-bark fungus infection on alders, which featured in a recent essay. Some of the infected sites had been heavily used by sapsuckers, but these birds had been active in many places, leaving broad patches of their sap wells in the bark. Very young alders, still with their reddish bark, also showed signs of the fungus attack.

That was a good day, and so was the next one, when we snowshoed the upper loop at Eaglecrest. It was still snowing a bit up there, while the rain fell at lower elevations. Here, in addition to lots of squirrel tracks and those of a mouse, ptarmigan had been very busy, sometimes running across a wide open space, sometimes walking sedately from bush to bush. In one place we saw a pair of traces where ptarmigan had glided down onto the snow, wallowed forward for a few feet, and taken flight once more, leaving tell-tale depressions (from the jumping take-off) flanked by wing marks.

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Snowy tracks

Snowshoes crunched over deep snow. The sky was cerulean blue and the sun gradually crept around the mountain peaks. These were fine days to be out, seeing what we could see. We were especially interested in the tracks left by the wild critters as they went about their daily lives.

–A shrew left a long line of tiny marks by the side of a beaver pond. Short digressions led to tufts of grass or a buried stick, where spiders and bugs, slowed by the cold temperatures, might be found. Shrews only weigh a few grams and have a very high metabolic rate, so they have to eat almost continually. We often see their trails running over the snow and plunging into miniscule holes that lead under the snow blanket where prey might be found.

–Mouse trails are much less common. But one day we found a line of hopping prints that went out of the forest and across the upper intertidal zone to the most recent wrack line. The piles of tumbled rockweed might harbor small crustaceans, wayward seeds, or lost insects—all suitable for a snack. Another line of tracks went straight back into the shelter of the forest.

–Snowshoe hares had been busy in some areas. They too were looking for food, maybe willow or blueberry buds. But occasionally there were heavily trampled spots, very localized, as if there had been a dance or other social encounter. Popular routes became hare highways, packed flat along a small ridge or between two dense spruce stands.

–An otter had cruised for hundreds of yards along a frozen slough, making side excursions to visit (briefly) several beaver lodges. The deep trough left by its passage seldom came out in the open but usually stayed under the fringing conifers. Reaching the shore of a well-frozen lake, the otter abruptly turned around and went back the way it had come. The only open water on its route was a very small runnel below a beaver dam—a place not likely to hold good otter food.

–Across some thin pond ice, a great blue heron had gingerly minced its way from one patch of open water, at the inlet, to another, at the outlet. Taking very short strides on its long thin toes, it seemed to have been treading carefully. Little sticklebacks and juvenile coho, beware.

–In several places, we spotted narrow grooves on the snow surface, where a slim body had propelled itself on small feet. These wandering trails led to grassy tussocks, dove under logs, circled a pile of branches, disappeared under the snow and came out again. A mighty hunter was at work: a short-tailed weasel or ermine, whose coat turns white in winter, except for the tip of the tail. The short-legged, long body of a weasel is well-adapted for diving down vole tunnels and other tight places. However, that body form means that a weasel can’t afford to put on heavy layers of fat; the belly would drag when the weasel tried to run—not good for a hunter that has to keep moving for much of the day in search of prey. In addition to their small size, the body shape of weasels gives them a lot of surface area (where heat is lost) compared to the body volume (muscles and organs that generate heat), so they have a high metabolic rate to keep themselves warm. And that means they have to eat a lot. They eat mice and voles and small birds, and carrion when it’s available.

–Porcupines seem to wander widely, and we’ve found their trails in many places, often still distinguishable under a layer of new snow. One day we found a very fresh trail of footprints and even some quill-drag; we followed it along a little dirt bank until it disappeared over the edge. Looking down, we saw that a small log, sticking out parallel to the bank, had been wiped clean of new snow by the animal’s passage; the trail ended near the end of the log. Of course, we went around to an easier place to climb down the bank and investigated the trail’s end. There we found a deep burrow, with hairs and a few dried-up fecal pellets and a good barn-y smell, that ran into the bank for over two yards: a snug, dry den that had been used repeatedly for some time. Upon close inspection, that little access log had thousands of scratches, evidence of many balancing acts as the porcupine had ventured out and back.

Harbor birds and snowy tracks

Sometimes, perhaps especially during the holiday season, it’s hard to fit a long, exploratory walk in among all the other activities. Then a quick trip to the harbors may produce some interesting observations.

On a recent harbor visit, we enjoyed watching Pacific Loons. They dove frequently, but we never say a loon with a fish in its bill, so we guessed that they were foraging on very small fish or even invertebrates—small enough to be swallowed immediately. The loons sported a variety of plumages: one was in good adult plumage, one seemed to be an unusually young juvenile without the typical juvenile plumage, and most were in well-marked juvenile plumage (check a good bird book!).

3 juveniles, and 1 adult, Pacific loon. Photo by Bob Armstrong

Pacific Loons winter all along the northern Pacific coast but nest on deep lakes in the Interior and across the Arctic tundra. Like other loons, they are typically monogamous and both parents incubate and rear the chicks. Loon legs are placed far back on the body, which is good for swimming and diving (when the legs are almost like propellers) but very bad for walking. So loons place their nests right next to the water’s edge. This makes them vulnerable to motorboat wakes that swamp the nest and to droughts that lower the water levels and make the nest too far from water.

The harbor visit also produced a couple of seals, several Marbled Murrelets in winter plumage, some Long-tailed Ducks, Red-necked Grebes, Barrow’s Goldeneyes, Buffleheads, one or two Great Blue Herons, and a Song Sparrow. We wondered if Song Sparrows (in springtime) might sometimes nest under the decking of the floats or if they merely forage there and nest, as usual, in shoreline shrubbery.

There were some large ‘jellyfish’ slowly pulsating in the cold water. Perhaps a foot or so in diameter, one was translucent white and the other was a murky orange with thick wads of tentacles. In our land-based ignorance, we didn’t have names for them.

On another day, after a recent snowfall, a tracking expedition was profitable. Snowshoe hares had seemingly conducted small riots under the spruces; their feet had created a maze of interlocking pathways and localized spots of concentrated activity. We saw no scats, perhaps suggesting that the hares had re-ingested them. Hares and rabbits (as well as many rodents) produce two kinds of feces: the ordinary kind, which is not re-ingested, and a softer kinds, produced by a digestive organ called a caecum, which is consumed—recycled, so to speak, to extract more nutrients from their food.

No small mammal trails were evident. Shrews, voles, and mice were presumably active but stayed under the soft snow. A porcupine lefts its customary trough where it had waded, up to its ears, in fluffy snow.

We followed the trail of an otter that seemed to know just where it was going. Several long leaps were followed by a smooth slide, then more leaps and another slide mark. Nobody else makes a trail like that! The otter had crossed a sizable pond, cut over a hill to another pond where it checked out a beaver lodge (from the outside), and gone down a small frozen stream to a deep channel where fish could be found.

The best find was along a shallow slough in which there were still small stretches of open water. A narrow furrow led out of one little pool straight over to the next one. ?A water shrew? But no, there seemed to be alternating footprints lightly covered with new-fallen snow. So, some critter that walked on two feet, from one bit of open water to the next, and then the next one, and so on for fifty yards or so. Finally we found some clearer footprints and a spot where something had landed and started to walk. Definitely a bird! But not a shorebird, because the hind toe was well-developed. So—a songbird, not very big, but not tiny, either. Well, who would be foraging in shallow water, going from pool to pool? Most likely an American Dipper, looking for aquatic insect larvae or maybe sticklebacks. Dippers often wander far from their nesting streams in winter. The real mystery is why it walked through the snow instead of flying.

Wandering

Someone once asked me if I go out on hikes and walks looking for something in particular. Many times, I just go wandering with my eyes and ears open, and maybe nothing special is observed, or maybe I get lucky. Sometimes, however, I do have a particular objective, and chance to observe something that is not related to my initial objective at all.

On a recent November stroll near the glacier, I was engaged in a survey of active beaver lodges. Beavers often build caches of branches near their lodges in fall. They pile up branches in a heap that often sticks up above the surface of the water and winter ice. This is the winter food supply; they can just cut off a chunk and carry it to the lodge for lunch. Beavers seldom come out on top of the ice; they are very vulnerable to predators when they cannot dive into deep water. According to the books, adult beavers eat less of the winter cache than young beavers do. The young ones are still growing and need lots of food, but adults can live mostly on body fat that is stored mainly in the tail.

The presence of a cache is a good sign that a beaver family is in residence. However, some lakes with lots of beaver sign don’t have a cache in front of the lodge. I see fresh cuttings and a dam in good repair, but no cache. So the beavers are there, for sure. Then I have to wonder if there’s no cache because there are no young, growing beavers in that lodge; I would love to know!

As I was cruising around, I got a lucky break. As I plodded along, a great flurry of wings beat through the brush. Startled, I spun around, and there was a goshawk in immature, brown and white striped, plumage just rising up into a young cottonwood.

Then I looked at the spot it had come from, and there was the limp body of a young snowshoe hare, still intact. The hawk must have just nabbed it. I quickly went on down the trail, so the hawk could eat in peace. Foot traffic on the trail was scant, so I hoped the predator would remain undisturbed.

About an hour later, I was homeward bound on the same trail, and again the goshawk flushed up into a tree. At the site where I originally saw it, there was only a scattering of fur. The hawk had moved its prey about fifteen feet through the brush. Now all that remained were the guts and hind legs. No doubt the hawk would have eaten more if it hadn’t been disturbed a second time.

I looked around for the hare’s head, and found only the lower jaws, separated and picked clean, and a small assemblage of tiny bone fragments. So I couldn’t add the skull to my collection. But this made me think about the fact that heads provide good nutrition for predators, not only in the musculature but also in the fat around all the nerve cells in the brain and behind the eyes.

Just a couple of minutes later and down the trail a short distance, I saw the hawk flying rapidly off into some spruces. Below its line of flight was a raven in a tree, with a large gobbet of fresh red meat and bone in its bill. The raven had quite a time, organizing its scavenged goodies into a tractable package. Then it, too, flew away.

The deceased hare had acquired part of its winter coat of white fur, so it was a patchwork of brown and white. White fur against a background of dead, brown leaves is very conspicuous, which may have increased the risks for this young hare.

Molting into winter colors in hares (and weasels and ptarmigan) is not keyed to the presence of snow on the ground—although that is when it would be useful as camouflage. The fall molt into winter white is probably triggered by shortening daylength, which does not always accord with the presence of snow. So there are times when hares are just the wrong color for safety.

Auk Nu in the deep freeze

As we drove to the trailhead, a full moon still hung in the sky. The temperature was a balmy twenty-three degrees or so, just a day after I registered minus six during the night at my house.

Those crispy temperatures meant that the trail was in the best condition we’d ever seen!

The numerous mudholes were frozen solid, most of the tree roots were buried, and the snow on the board walks was firm. There had been quite a lot of foot traffic on the trail in the days before our walk, so the trail was well-packed with crunchy snow but not icy. We never had it so good!

Hordes of pine siskins pried into spruce cones, chattering all the while, and swarmed from tree to tree. A dark mystery bird sat for several minutes in the top of a spruce, poking carefully at something in the uppermost whorl of branches. If I had to guess, I’d say it could be a pine grosbeak, but it flew off before I could make out any color or pattern.

Lunch in the John Muir cabin was a relaxed but quick affair. It was one of the shortest days of the year, so there was little time for dawdling. The view from the cabin windows was familiar but still spectacular—over the snowy meadows to the channels, where dark islands set in a bronzy sea.

The previous day I had prowled around some of the ponds in the Dredge Lake area. The recent cold temperatures had kept the soft snow in prime condition for checking animal tracks. Snowshoe hares must have been having a party—their tracks were everywhere, sometimes creating a hare highway from one thicket to the next. The tips of small willows showed signs of nibbling.

Mice had been more active than they were on the day just after the snowfall. Their delicate traceries ran from log to stump, or branch pile to grass tuft. I find these trails very beautiful. A shrew trail, even smaller than that of a mouse, ran from one tiny hole in the snow to another. These holes are only about the size of a dime. And in soft snow, the stubby-legged shrews often plow a wee furrow in the surface, as they make their way to a hole. There were tracks of squirrel, a porcupine, maybe a marten, and several weasels that zigzagged among prospective mouse or squirrel holes. Dog tracks were numerous, of course, but I found one set of canine tracks that could have been a coyote.

In the open areas, hoar frost had accumulated on the snow-laden shrubs. Some twigs were encased in a load of white that must have been five inches in diameter. Frost flowers had grown in dense gardens wherever snow did not cover the ice on the ponds; many of the crystals were at least two inches tall and almost as broad. Hoar frost clung to old footprints and ski marks, almost filling the depressions. All the frost and snow on everything certainly makes the short days brighter!

Trailside scrapbook

A common sight in our forests is a ‘nurse log’ that supports a row of small hemlocks and maybe a currant or blueberry bush or two. If the log decays, it will leave behind a neat row of trees in an otherwise rather disorganized forest. If the log persists, retaining its form and even spanning small gaps, the row of supported treelets may eventually stretch roots down to the soil.Then they can grow into tall, stalwart trees, still all in a row, with their roots arching over the nurse log. Although nurse logs with tiny trees are common, it seems to be uncommon for the whole row of supported trees to mature while the nurse log persists, but we found a fine example along Montana Creek.

If you walk long the bluff from False Outer Point to the Rainforest Trail, look down to what passes for a beach in this country. Much of the so-called beach below this trail is composed of boulders. But look closely, and you will see that some of the boulders are piled up in good-sized oval mounds, and several such mounds are lined up parallel to the bluff. According to Dr. Cathy Connor, well-known local geologist, these orderly piles of boulders were rafted here by the big ice that filled Lynn Canal thousands of years ago and got left behind when the ice retreated, about fifteen thousand years ago.

When there was lovely, fresh snow on the ground, the snowshoe hares near Steep Creek had been very busy. Their highways led hither and thither, especially among the young spruces. Out on the silt and sand flats where the willow thickets thrive and would offer a decent banquet for hares, there was little trace of hare activity. I’m guessing that the thick, low-growing branches of the spruces offered thermal cover as well as better places for hares to hide from dogs and perhaps aerial predators, and that took precedent over willow lunches.

Along the Old River Channel near the glacier, the eagles had been dancing, even prancing back in among the bushes. I couldn’t tell what they were cavorting about, except in one place right next to the stream, where pink snow gave evidence of an eagle lunch.

In one pond in the Mendenhall Glacier Recreation Area there are two beaver lodges, right across that pond from each other, with a single cache of branches in between them. This is an unusual situation, because beaver families are typically quite territorial and seldom share ponds. I’ll probably never know why this exception exists, but it is food for thought.

And thinking about beavers in another setting: the Switzer Creek area has two old, abandoned beaver ponds up on the hillside, on tiny streams. The dams are still sound, which is why the ponds are still there. When they are not frozen, they provide foraging areas for dippers, which roam widely in winter, and for snipe, which we sometimes find even in thickly wooded, damp areas near such ponds. I don’t know why these beavers disappeared—whether they were trapped or simply moved on. But this situation reminded me that we have found beaver works in other non-ideal locations, including Eaglecrest!—showing that beavers really get around, travelling quite long distances over land, upon occasion.

Coming down through the lower cross-country ski loops at Eaglecrest, the trail crosses Fish Creek on a fairly new wooden bridge (check out the remnants of an old log dam just upstream) and follows the Treadwell Ditch. Not very far after the wooden bridge there is a very new bridge over a small rivulet that flows down to the main creek. Surprisingly, this bridge is an arch made of reinforced concrete, faced with stone. It is expected to last much longer (possibly hundreds of years!) than traditional wooden bridges. This was a personal project of Dave Haas, secretary of Trail Mix, built with the advice of an engineer and the blessing of Trail Mix and CBJ, and the help of numerous volunteers. It will be interesting to see if this style of bridge might be useful in other sites on our trail system. Go out there and see if you like it, and let Dave at Trail Mix know your reactions!

Winter white, summer brown

This winter I’m seeing snowshoe hare tracks very commonly, in a variety of locations. Sometimes, repeated travels created well-packed hare highways through the brush. But I certainly don’t see the track makers very often, perhaps partly because I’m not out there at the times that they are most active. Another reason is that they are usually quite well camouflaged, with white fur in winter and brown fur in summer. Sometimes, however, the timing of the molt is not in synchrony with the background colors of the environment, and there’s a serious mismatch between hare and background: the hares become quite conspicuous as white patches on brown background or brown patches on white background.

There are at least ten mammal species in North America that show this kind of seasonal coat-color change, as well as some in Eurasia. In Alaska, we have the snowshoe hare, the Alaska hare, the short-tailed weasel or ermine, the least weasel, a species of collared lemming, and the Arctic fox. The ermine and snowshoe hare are the only ones in Southeast. Some of these species have large geographic ranges extending southward, where snow is less common, and the change to white doesn’t happen there; in contrast, hares in the Canadian High Arctic may not change to brown. In some cases, there is variation among individuals within a single population, some showing the seasonal change and others not. The general consensus seems to be that the observed coat-color changes are adaptive principally in providing seasonally appropriate camouflage and protection from visually hunting predators. Winter coats are often thicker and better insulated as well, but apparently the color itself does not greatly affect heat gain or loss.

As far as I can determine, in all species in which this has been studied, the physiological control of the coat-color change is driven mainly by photoperiod, or the relative lengths of day and night during a twenty-four-hour period, mediated of course by hormones. So if climate change brings less snow, but the physiological control of color change is still regulated by day length, there can be some serious mismatches between coat color and background. Seasonal timing may differ slightly for males and females, and for breeding animals vs nonbreeders. In some cases, temperature is thought to have a modifying effect: warm temperatures in fall, for example, may delay the molt somewhat, or hasten it in spring, but this effect is generally less than that of photoperiod.

In the bird world, ptarmigan engage in seasonal shifts from brown plumage in summer to white plumage in winter, and back again. Here too, the principal driver of change is photoperiod, and there can be timing differences between male and female. For example, willow ptarmigan females get their brown summer plumage earlier than males.

The most intriguing species is the rock ptarmigan. Males sport a showy white plumage in spring, for weeks after the snow has melted and their females have molted to a cryptic brown (which makes them very inconspicuous while incubating eggs in the nest). Males keep their conspicuous white coat until well after their female consorts have laid eggs and are no longer fertile. However, when egg-laying is underway, the males do something very unusual: they start to make their white plumage dirty, and by the time egg-laying is complete, they are very dirty—and much less conspicuous– indeed. But if the clutch of eggs is destroyed by a predator, or if the female is killed, suddenly the bereft males clean their plumage to a brilliant white again, and go a-courting once more. Most rock ptarmigan mate monogamously, but a few males are polygynous (with more than one female) and some may not obtain mates in any given year. The bachelors and polygynous males stay clean white longer than monogamous males, in keeping with their protracted potential for mating. Eventually, all the males turn brown, until it is time to turn white for the next winter.

Male and female rock ptarmigan in spring. Photo by Bob Armstrong

The rock ptarmigan use the seasonal pattern of plumage change for camouflage, like all the other animals that do the white/brown shift. But in addition, the males apparently use their white winter plumage as a sexual advertisement in spring and early summer, and female rock ptarmigan choose their males in part on the basis of this studly self-advertisement. There is no doubt a cost to showing off this way; rock ptarmigan suffer heavy predation, and those studly, conspicuous males are taking risks and paying a price.

Out and about

I try to get out for a walk every day, whatever the weather, although the weather may determine the length and location of the outing. How much I see of natural history interest varies greatly, depending on many factors, including a perceived need to watch the footing in sloppy mud or on slippery ice or wet rocks, sometimes a wish to be a bit sociable, or even do some serious (or not-so-serious) thinking. But most of the time, I like to keep my eyes and ears open to what is around me. So here are some bits and pieces from December.

As a cold snap settled in, Mendenhall Lake grumbled and growled and muttered in a long-winded soliloquy—the ice, talking to itself as the water froze and expanded. Smaller ponds were less loquacious but still murmured and popped at a lower decibel level. Meanwhile, overhead, large flocks of pine siskins flitted from spruce to spruce, sometimes swooping high over the canopy before disappearing in the crown of another cone-laden spruce.

In between short periods of deep cold, however, we had spells of surprisingly warm temperatures, turning our little bit of snow to slush and sending meltwater down over the existing ice on streams and ponds. Open water formed at inlets and outlets of ponds and along the fringes of Mendenhall Lake. A reliable observer reported seeing a beaver swimming in Mendenhall River in late December, when local beavers are normally snug in their lodges, sleeping or nibbling from their winter cache of twigs. That beaver was not the only one escaping cabin fever: in several locations, I saw very recent tree-cutting and branch-gnawing that had not been there a few days earlier.

On the ground near Moose Lake I found several small wind-broken cottonwood branches, with the upper sides nicely de-barked. Some lucky gnawer had capitalized on this bonanza. But who was it? Not a beaver, although beavers had debarked a cottonwood tree trunk near the lake, leaving the marks of wide incisor teeth. Not a porcupine—the tooth marks were too small. But the marks were too big for a mouse. My best guess was probably a snowshoe hare; hares are generally fairly numerous in the area and the incisor marks were similar in size to the teeth in a hare skull in my collection.

Photo by Pam Bergeson

Along the Treadwell Ditch are many trees, usually hemlocks, that show the marks of porcupine gnawing—tooth-marked, barkless patches, low on the trunk. This is a common sight around here, of course. I was particularly interested to find at least two trees that seemed to have been completely girdled sometime in the past. The bark had been removed all the way around the tree, which would interrupt the flow of water and nutrients between roots and crown, starving the roots of food and the crown of water. Yet these trees sported full crowns of needles and looked healthy. How could that be? The porcupines had removed all the outer bark and eaten most of the nutritious inner bark, but a meager, sketchy, brown network of inner bark was still visible. Could it be that enough strands of inner bark remained to connect the roots and the crowns? Hard to believe that would be enough to support a good-sized tree!

There are other little mysteries about porcupines and hemlocks. Some trees have obviously been visited repeatedly, in different years. Old chewings have partially healed, but new ones are there too. Are these trees particularly tasty? Also, I get an impression (untested, so far) that porcupine gnawing is more common on the uphill side of a hemlock trunk. Is that really so, and if so, why?

A special pleasure was seeing two humpback whales spouting as they cruised near Lena Point. They may have been late-departers for winter in Hawaii or they may have been among the few that overwinter here, feeding on herring (and any other luckless little forage fishes). Not on this day, but sometimes one can see a few sea lions swimming near the corners of a foraging whale’s mouth, trying to catch the fish that slipped away from the whale. The herring equivalent of ‘out of the frying pan, into the fire’!