Cavity-nesting birds

Nesting in a cavity—a hole in a tree, a burrow in a bank, or another enclosed space—gives a bird significant advantages. Cavity nests are generally safer than open-cup nests. The nest contents are concealed from predators (to some degree), although some predators can sniff out the nests anyway (think of snakes, monkeys, squirrels, marten and weasels, and so on). The cavity opening may be easier to defend than a wide-open cup. The eggs and chicks, and an incubating or brooding adult, get some protection from inclement weather, be it cold or hot or wet or whatever. For birds raising chicks in a nest (not applicable to ducks), nest-tending and food-delivery activities of the adults makes the nest a focus for observant predators; reducing the length of time needed for such activities reduces the risk of being observed and attacked. So open-cup nesters are in a hurry to get their chicks out of the nest, while cavity-nesting birds generally have longer incubation and nestling periods. 

If you put a dot for every cavity-nesting bird species on the evolutionary tree, the dots would be scattered all over the many branches of the tree. Clearly, cavity-nesting has evolved many times, appearing in such disparate groups as ducks, falcons, woodpeckers, owls, puffins, petrels, chickadees, nuthatches, bluebirds, flycatchers, and others.

In many cases, these birds depend on finding an existing cavity, perhaps in a rotting or storm-damaged tree, perhaps in a rock crevice, or perhaps in a hole made by another animal such as a rabbit or a woodpecker. Interestingly, sometimes closely related species differ in their use of nesting cavities: for example, common mergansers nest in existing cavities but red-breasted mergansers (in the same genus) make open nests on the ground. Birds that are dependent on existing cavities often face intense competition for suitable, available spaces, which can be limited in supply. For example, there are many observations of European starlings displacing bluebirds or tree swallows from cavities. Likewise, tree swallows and chickadees sometimes contest ownership of a nice cavity.

There are two ways around that problem. One is for each bird to excavate its own cavity. The most familiar excavators (to most of us) would be woodpeckers. All of the birds we call woodpeckers excavate holes in trees or tall cacti, but some of their relatives in the southern hemisphere or the Old World do not.

Hairy woodpecker. Photo by Bob Armstrong

Another excavator familiar to us is the belted kingfisher, which digs tunnels in earthen banks. There are many kinds of kingfishers; not all eat fish, but all are reported to excavate their nesting tunnels in earthen banks or termite mounds. A related group of many species, called bee-eaters, are also burrowers, often nesting colonially in earthen banks.

Other examples of excavators are found among the penguins, shearwaters, and petrels. The three species of puffin are usually dig burrows, the Atlantic and tufted puffins in soil and the horned puffin commonly in rocky places. All parrots make cavities for nesting, usually in trees, but one species stands out: the burrowing parakeet of Chile and Argentina regularly digs nesting burrows in limestone or sandstone cliffs. Three of the four species of North American nuthatches can excavate their tree nests from scratch, although all four more commonly use existing holes, modifying the cavity as needed. Our chickadees can excavate holes in soft rotten wood but often use existing holes.

The swallows, some of which are cavity nesters, provide an example of marked variation of nest type within one taxonomic group: Bank swallows (called sand martins in Europe) excavate tunnels in earthen banks, but rough-winged swallows generally depend on finding old holes in the banks. Tree swallows are not known to excavate but need cavities; cave swallows and barn swallows make open-cup nests. Cliff swallows, however, make covered nests of mud, stuck onto a vertical surface—which leads me to the second way of avoiding competition for nesting cavities:

Some birds aren’t cavity nesters (strictly speaking), but achieve some of the advantages of cavities by constructing a covered nest. The cover may be made in different ways, but it serves to conceal the nest-contents to some degree. Here are some examples: In Latin America, a large set of species typically constructs covered nests, often of clay; the resemblance to old-fashioned adobe bake-ovens earned them the sobriquet of ovenbirds. They are not, however, related to the North American ovenbird (a warbler), which builds a ground nest woven of plant material, with an entrance on the side. Marsh wrens and sedge wrens weave semi-globular nests of grasses and reeds; dippers, too, make bulky, more-or-less spherical nests of moss and plant parts, with a side entrance. Then there are the oropendulas and caciques of Latin America, the penduline tit of Europe, the orioles of North America, some weaver birds of Africa, among others, who weave bag-shaped nests, suspended from branches.

American dipper. Photo by Bob Armstrong

It would be wonderful if it were possible to unravel the genetic and ecological events that led to each evolutionary twig or branchlet with one or more cavity-nesting species, diverging from their open-cup relatives.

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Winter may be here

The days grow shorter and darker, until we turn a corner at the winter solstice and the sun slowly starts to come back. At this time of year, my little excursions tend to be short too. Even so, some things of interest always appear.

Around Thanksgiving time, the West Glacier Trail offered a spectacular collection of hair-frost displays. A cold snap froze many rain-soaked sticks, forcing out thin strands of ice. Some displays featured long stretches of two-inch long curved strands; other displays had multiple sets of shorter strands, each one curling in a different direction, like an enviably wavy hairdo.

Dippers were sometimes foraging and singing in Steep Creek. Two otters, possibly a female with a juvenile, were fossicking about in a nearby pond, observable from the viewing platform. Eventually they went over a small ridge toward the pavilion—and as I went up the ramp in the same direction, I could look down into another pond, where I saw the otters again. The bigger one caught a nice coho and both otters went up the bank to feast. Later, I learned that this was a fish that had been radio-tagged by the Forest Service in the Holding Pond—a fish that apparently backed out and went farther up-river to try Steep Creek instead. The remains of this fish were found by a Forest Service fish biologist.

At the lower end of Steep Creek, a beaver dam slows the main stream just before it reaches the lake and creates a good pond for the beavers’ lodge. Unfortunately, in late November and early December, some very unhelpful person(s) were destroying part of this dam, which thus drastically lowered the water level in the pond. This vandalism served no useful purpose whatsoever. The pond protects the entrances of the beaver lodge; this is the lodge featured in the educational ‘beaver cam’ in the visitor center, allowing visitors to see beavers at home. The pond is also habitat for over-wintering juvenile salmon, as well as feeding sites for dippers and ducks. There were no more coho coming in, and in any case, they commonly enter this pond over a small dam off to the side. Fortunately, a spell of warm weather melted the ice and allowed the beavers to repair the breach in the dam to some degree—there were several new beaver trails going up the banks, for collecting more repair material.

I like to walk along the lake shores when the water level comes down. It’s often a good place to look for animal tracks and sometimes an unusual bird. In late November, I found a nice group of swans in the Old River Channel—three adults and a juvenile—in a spot that seems to be popular with swans on migration.

Then, at the very end of November, there was some snow at Eaglecrest, so it was fun to see what animals had been out and about. Two little explorations with friends noted the usual perpetrators– hare, porcupine, weasel, red squirrel, shrew, a possible coyote, and numerous tracks of deer of all sizes. By the end of the first week of December, there was a lovely thick blanket of snow, traveled by the same array of critters and, by us, on snowshoes. In addition, a small bird, probably a junco, had hopped over a still-open rivulet and spent a lot of time jumping up to reach some seed heads that poked up out of the snow.

In early December, the snow in one of the lower meadows on Douglas was too crusty for the tracks of small things. But again there were lot of deer tracks. A tiny shore pine, no more than three feet tall but possibly quite old, did not seem to be doing very well. It had only eleven tufts of needles on the few living branches. But it bore dozens of old cones—perhaps this was its last attempt to reproduce.

Over on the Outer Point Trail on north Douglas, a friend and I remarked with great pleasure that the recently revised and improved trail passes just below the long beaver dam, leaving the dam undisturbed. Major kudos to CBJ and Trail Mix for using ecological sense!

In the first muskeg after that beaver dam, I noticed something that I should have seen on one of the many times I’ve passed that way: Most of the small pines (less than about three feet tall) were thriving, but virtually all of the mid-size ones (six to ten feet tall or so) were dead. This pattern is not repeated in other muskegs that I have visited recently. So the question is What kind of event(s) might have wiped out a whole size-class of shore pines in this place?

On our way down to the beach, we spotted a few varied thrushes and a red-breasted sapsucker that should have been on its way south by now. We startled a small porcupine, who scuttled off a few feet and waited for us to pass. At the uppermost edge of the beach, a sprawling little herbaceous plant had green leaves and out-of-season buds. Two alders had crossed their branches very closely, rubbing hard against each other until each one had flattened scars where the rubbing occurred. We joked that now they are just ‘rubbing along together’ more or less comfortably.

A stroll with another friend in the Dredge Lake area was not very eventful until we were almost finished. On the trail ahead of us, we spotted two birds. It was so dark that almost no color could be discerned, so it took us a minute to decide what they were. Juncos? No, too big and they were walking not hopping. Blackbirds? No, tail is too short and bill is too stout. Then one of them hopped up into a nearby shrub and a white wing bar could be imagined. But what really gave them away was their characteristic behavior: they were snatching the fruits of high-bush cranberry, stripping and dropping bits of pulp, and gulping down the seed. Bingo! Pine grosbeaks doing their namesake behavior: their scientific name is Pinicola enucleator, meaning pine dweller that extracts ‘nuts’ or seeds.

Tracks in December

A warm, very wet spell in early December made the lichens and mosses all perky and colorful. Beavers left their distinctive foot marks in a thin dusting of snow and swam out around their winter caches of twigs, tail-slapping when we passed by. In a ‘real’ winter, they would be tucked up into their lodges, snoozing a lot, talking quietly with their offspring, and occasionally nibbling a twig from the cache. The kits of the year, however, would be chewing twigs all winter long, as they continue to grow. Bears were out and about too, mom and cub leaving their tracks near Dredge Lake, instead of entering into serious hibernation. That entails a profound reduction of metabolic rate, shutting down digestive processes, and very little activity inside the den, quite a contrast with beavers.

Then, in mid-December came a lovely and welcome snowfall, just a few inches at sea level. It wouldn’t last, of course, in this time of warming climate, so I dug up my snowshoes and headed to Eaglecrest. There the snow was maybe a foot or so deep and just right for poking around on a day when the lifts weren’t running. Snow was falling thick and fast, quickly covering any little tracks of mouse or shrew. But under the trees were prints of snowshoe hares. A small-footed canine creature had run across a wide open area, leaving a long, straight line of well-spaced prints. There was no evidence of any human anywhere nearby, so I guessed that a coyote had raced along. But very few critters made themselves visible—a porcupine that seemed to think that if it could not see me, then I could not see it; and one flying insect, probably a stonefly. Nary a bird to be heard or seen not even a hopeful, attendant raven.

A couple of days later, a nice little cold snap meant that even at sea level, there remained a few inches of snow cover. I went out the road to some meadows, where I plonked along on snowshoes—a convenient way to deal with snowy humps of frozen grass. Oddly, there were no shrew tunnels to be seen, nor any squirrel tracks, and again not a bird could be found.

But otters had been quite busy. They had fossicked along a tiny rivulet, trampling some spots quite flat; there were more than one of them, apparently, so perhaps a family of mom and well-grown pups. I lost their trail when it went under the trees where there was no snow. However, a few minutes later, I encountered their characteristic slide marks where they had crossed a snowy, open area, pushing off strongly with the hind legs and gliding smoothly even over flat ground. This is probably more fun than stomping around on snowshoes! A bit farther on, otters had come up out of a tiny stream and snuffled all around the nearly buried ends of several low, trailing spruce branches. What was going on there, I wonder.

Some days later, I looked for tracks in another meadow out the road, but there had been little recent activity. A couple of squirrels had explored the meadow edges, out of the trees and back again, diving under humps of bent-over grasses. Before the last little snowfall, porcupines had trundled over the meadow in several places, on their usual meanderings. They seem to travel quite extensively, perhaps in search of just the right twig to nibble (?). Along a small creek, some critter had burrowed into the bank in several spots—possibly an otter.

Surprisingly, there were no little shrew-size grooves on the surface of the snow, no tiny holes where a shrew dove under the white blanket. Yet this was a meadow that, in previous years, had been laced with trackways of shrews. One shrew had even taken a dive off a vertical mudbank and gone skittering over a gravel bar in a creek. But where are all those shrews now?

A fluttering on the creek-bank caught my eye and eventually turned into a dipper. This bird was foraging along the water’s edge but apparently found little of interest, because it soon took off, upstream. That was the only living animal to be seen, except for one red squirrel crossing the creek on a broken-branch bridge.

Later that day, on another stream, I checked a long-occupied beaver lodge. There were no signs of recent beaver activity here, although the lodge may be currently occupied. However, other woodland folks were interested in the place: porcupines and mink had visited on more than one occasion in recent days. Was this perhaps a multi-species condo? It wouldn’t be the first time that happened.

The slanting light of midwinter that stabs one blindingly in the eye at certain times of day on Egan Drive, did some beautiful things out by the meadows. Some conifer-clad hilltops were brilliantly lit, contrasting with darker slopes below. Light mists collected in the valleys caught the light rays and turned golden. Overhead, some dark clouds gathered amid some white fluffy ones, but bright rays came through the many unclouded areas, where blue sky was a cheery sight.

Trailside observations

Here’s an assortment of winter observations that gave pleasure to some trail-walkers.

–Late November, Eaglecrest. Parks and Rec hikers on snowshoes went up the road, but the majority decided to go home for lunch. Two of us went on, over toward Hilda meadows, and perched on a log for a snack. Too busy feeding our faces for a few minutes, we eventually began to notice what was around us. Right behind our comfortable log was a big spruce tree with two lumps at the very top. The upper lump was pretending to be a moss wad, while the lower one was eating spruce needles. Both young porcupines were very wet, but the lower one suddenly roused up and rapidly shook itself dry—moving faster than I’d ever seen a porcupine move. The upper one slept on.

–Late November, Mendenhall Lake beach. A small stream flowed over the beach, creating a little opening in the ice. Three eagles were bickering over the remnants of a salmon carcass, which was probably fairly fresh (judging from the bright red blood stains on the ice). We often see late-spawning coho in the streams that feed the upper Mendenhall (years ago, in December, I counted over a hundred eagles on the stretch of Dredge Creek below Thunder Mountain; they were there because the creek was full of coho). One of the eagles snatched up the tail piece and flew off, hotly pursued by a pirate that eventually won the tasty morsel.

–Mid December, Eaglecrest. Lovely soft snow covered the ground, so animal-tracking was really good. Shrews had been very busy, running over the snow from one bush to another. Lots of other mammals had been active, too: deer, weasel, hare, porcupine, red squirrel, and mouse. Sadly, we found no ptarmigan tracks at all.

–Mid December, Dredge Lakes area. After a deep freeze, a warm spell had melted ice cover and opened up some of the ponds, and beavers had become active. There were new cuttings in the woods, new twigs in the winter caches, and some of the perpetrators were repairing their dams. The Beaver Patrol was called out of its own winter torpor to make notches in a few dams, lowering water levels in certain ponds so that nearby trails were dry , permitting passage of any late-spawning coho, and allowing juvenile salmon to move up and down stream if they chose to do so.

Photo by Kerry Howard

–Late December, Mendenhall wetlands. ‘Twas a very uneventful walk in a blustery wind. But suddenly two small birds blew (not flew!) in and tumbled into the grass. Righting themselves, they revealed themselves as a pair of gray-crowned rosyfinches, a species I’ve seen in upper Glacier Bay and on Mt Roberts, but not out here. That turned the day into a ‘plus’.

–Late December, Dredge Lakes area. Very low temperatures had refrozen almost all the ponds and streams. However, the ditch from Moraine Lake to Crystal Lake had a couple of very small ice-free patches. And there we saw a dipper, bobbing in and out of those dark pools, no doubt very hungry.

Any sensible dipper would go downstream, perhaps to an estuary, where bugs and fish would be more available!

–Early January, Herbert River trail. A mink had coursed along the elevated riverbank, in and out of the brush, occasionally down to the water’s edge. A set of extremely large moose tracks crossed the trail. That long-striding giant was really moving—the foot prints were often five feet apart. The trackway led through brush and over the arching branches of a fallen tree—almost four feet above the ground. Those long legs! I would have loved to watch that beast (from a respectful distance)!

–Early January, Perseverance trail. Recent heavy rains had brought down some small landslides, not unexpectedly. Unlike the trails near the glacier, this one was nearly clear of ice, and walking was easy. There was fresh snow on the ground, up past Ebner Falls, showing up a few porcupine tracks and some very recent red squirrel trackways. A mouse had crossed the trail with big jumps, several times its body length, leaving clear footprints as it hustled into cover across the open trail. I like seeing mouse tracks, in part because I don’t see them very often.

–Mid January, Switzer Creek area. Before the predicted rains and rising temperatures wrecked the lovely fresh snow, we found tracks of deer, porcupine, possible coyote, and a few mysteries. A shrew had scuttled across the soft snow, making a narrow groove marked by its tiny feet. A good find was a trackway of a grouse, striding through the snow and under low-hanging bushes in the woods. This took a few minutes of searching to determine the track-maker, because the new snow was so soft that it often fell down into the tracks, obscuring the prints. But finally we found good marks of three avian toes.

Rambling

There’s little I like better than rambling around the woods, meadows, and beaches, just seeing what’s to be seen. Sharing these little explorations with a like-minded friend is the best, but solo jaunts are good too. There is always something of some interest. Although November is one of the hardest times of year for curiosity-driven rambling, here are a few observations.

We walked the west-side beach of Mendenhall Lake toward the glacier, planning to return on the West Glacier Trail. The water level is low in the lake in winter, so the beach is broad and offers easy strolling. A few bits of interstadial wood poke up out of the silt and sand, probably washed down from the area next to the glacier terminus where the stumps of this old forest still stand. Windrows of dead alder leaves lie a remarkable ten to fifteen feet into the brush above the upper limit of the beach, suggesting that there must have been a tumultuous day on the water not very long ago.

Four ravens were focused intently on something in one of the shallow streams that course over the beach to the lake. As we approached, the ravens backed away, revealing a female coho lying on her side in about an inch of water. She appeared to be a relatively recent arrival, with no fungal patches at all. But she was missing the eye on the upper side and her gills on that side had been torn up—we thought she was dead. But not quite—she could still move a bit, although her eggs were beginning leak out. Her minutes were clearly numbered, but we gently moved her into deeper water so those last minutes might be slightly more comfortable. Of course, the ravens came back as soon as we moved on and finished their meals. The big question for us was how she got into this sorry situation. There were no wounds indicating that a bear or eagle had tried to grab her but abandoned her there. Was she just a late arrival, trying to get up this little creek to spawn and finding the water too shallow?

There were a few bear tracks on the beach, not very recent ones. However, the bruins (probably) were still around, because a few days later I found two fresh-looking lower jaws of coho lying in the middle of the trail (and they had not been there on our earlier walk). Of course in the water there was no sign of the poor, mauled female we’d seen earlier.

An informal trail cuts up from the end of the beach to the West Glacier Trail and crosses a tiny stream. There we spotted a pair of very shy coho consorting, and we quickly departed, leaving them in peace.

On the way back on the main trail, we accidently spooked three ravens on a very small creek on the hillside. They were squabbling over something, which on closer inspection turned out to be the picked-over remains of another coho.

Other members of the feathered tribe included a flock of juncos in the beach-fringe alders (and they were still there a few days later), maybe collecting alder seeds, and a kingfisher who was annoyed by our passing near its hunting perch. At the little pond partway up the side of the rock peninsula, a dipper foraged along the edge, diving and swimming, for several minutes before departing downstream.

On another day, well up the Perseverance Trail, a dipper was foraging in fast water, dodging in and out among boulders. It then spent several minutes on a single large, flat rock with shallow water sheeting over it. The bird worked over the surface of that rock assiduously, picking up numerous miniscule prey items—so tiny that they could apparently be swallowed immediately, without mandibulation. Possibly blackfly larvae??

On yet another day, after enjoying some swans floating about on the far side of Windfall Lake, we had some fun with a make-believe critter on the trail. We couldn’t put a name to it, so we just called it Mossy. A Rip Van Winkle sort of critter, sleeping for a long time? An escapee from the Ark? An antediluvian creature revisiting the earth? As I said, November can be a rather slow time for little explorations, so imaginations went a tad wild.

The real excitement was in Auke Bay (and I wasn’t there): a friend recorded a gang of orcas attacking a couple of sea lions—circling, circling, head butting, body slamming from above and side, flipping out of the water, tail bashing. Then quiet, cruising back and forth, presumably grabbing the pieces, and the gulls came to get the scraps. Maybe I should be spending more time near the big water!

Today, my verbal rambling may match the real rambling!

Recent finds along the trail

A stroll across Bridget Cove tide flats in early July brought us to a stand of eelgrass. To our surprise, the eelgrass was dotted with many thousands of fish eggs. We thought this was too late in the season for herring, but a forage-fish expert told me that herring have been known to spawn there in early July. The eggs would need to incubate for about two weeks (at a temperature of eight degrees centigrade) and the embryos of these eggs appeared to be in early stages of development. If we went back a week or so later, they probably would have hatched.

After the recent jökulhlaup, I went to inspect the ‘gooseneck’ area on the lower Mendenhall River, where a sweeping loop in the river has created a narrow peninsula just upstream from Vintage Park. I imagined that the big water coming down would have breached the really narrow part of the peninsula, flowing over the top and eroding at least an overflow channel. But no! There is indeed some new erosion of the bank on the upstream side. On top, trees now lean downstream, their roots tipping up and making large cracks in the soil; they will probably fall rather soon, reducing the top of the peninsula to just a couple of feet in width. Something to keep our eyes on!

Just on the other side of Cropley Lake, in a wet area, is a stand of pale yellow flowers. This is a species of fireweed called yellow fireweed or sometimes called yellow willowherb (Epilobium luteum). The familiar pink flowers of the usual fireweed (formerly a species of Epilobium but now reclassified in a separate genus, Chamaenerion) are evident all over town, but the yellow one is much rarer. We’ve seen small numbers of this in only a few places around here. It can propagate vegetatively, so once a plant gets established from seed, it can spread locally if the habitat is suitable. And by the way, why is the pollen of the pink fireweed sometimes blue-green?

Another familiar local plant is known as goatsbeard (Aruncus dioicus). This species is dioecious, bearing male and female flowers on different individuals. On a recent stroll up Perseverance Trail, we looked more closely at the narrow flowering tassels. Indeed, just as expected, males and females were distinguishable. However, we were interested to see that in a very few male plants, a small number of seed pods were developing on some of the tassels. I recall that some other reportedly dioecious plant species have similar transgender issues at least upon occasion. Because the female plants were well past flowering and had well-developed seed pods, we could not tell if any of them had once sported male parts.

On Gold Creek, a female harlequin duck was foraging, dipping and diving among the rocks. We enjoyed watching her skillful maneuvers, swimming upstream underwater, skittering rapidly on the surface of a broad, flat rapid, doing balanced skids on wet rocks, and ferrying across the fast chutes just like a kayaker or a canoeist would do. Humans may have learned this technique, long ago, from the ducks.

A friend reported a dipper nest in the spillway on Gold Creek, so I went to look. Sure enough, in a big crack in the concrete was a pile of moss with an opening through which I could see movement. Mama dipper was either incubating eggs or brooding chicks, while Papa was on guard on a boulder nearby. Later, I looked again, and now the adults were both outside, feeding three or four small, piping nestlings. Big loads of caddisfly larvae and other goodies went down the begging mouths. Very satisfying to observers, as well!

One day we walked on the sand flats of Eagle River along the Boy Scout Trail. There were small footprints in the sand, looking a bit like a baby’s foot but with five claw marks well ahead of the pad. Hmmmm, probably a porcupine. And presently we saw the perpetrator, busily nipping of the ends of beach greens (a.k.a. seabeach sandwort; Honkenya peploides) shoots. After some minutes, the critter bustled off toward the woods, and we went to look at the nibbled shoots. It had ignored the shoots with seed pods and seemed to have concentrated on the shoots with flowers.

This area of sand flats has many clumps of beach greens, whose shoots sprawl out in all directions. In one portion of this plant colony, most of the clumps had been rolled up from one side…the long shoots on that side were flopped over the ones on the other side, consistently in the same direction. We know from reports of other observers that porcupines sometimes roll up outdoor carpets and lick what is underneath. Could these plants reflect similar behavior? If so, what are the animals getting?

Thanks to Darcie Neff for information and references.

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.

Winter explorations

Wonderful snow! Brightening our short December days; under that full moon, it was spectular.

All that glorious snow drew me out, day after day, looking for little stories writ there. There were all the usual perpetrators: deep, winding furrows made by wide-bodied, peripatetic porcupines, lots of snowshoe hares (especially near the visitor center), a mink bounding over a frozen rivulet, red squirrels tramping back and forth between trees, a deer or two—or lots in some places, an ermine, some good otter slides, a few voles and shrews (and a couple of mysteries that I shall gloss over).

There were also a few real highlights. Out near Peterson Creek, after watching a hungry dipper searching for some open water, my friend glanced up and spotted something odd-looking about ten feet up a spruce, right next to the trunk. This looked like a mushroom, stuck in a tuft of twigs. Really? So my friend climbed up, to look more closely. Indeed, not just one but five or six mushrooms were wedged in a tight stack, in among the twigs. Ha!—a squirrel cache. Red squirrels are known to store mushrooms in dry places, such as the tops of well-drained stumps or logs (but cones are usually stored in damp places, so they don’t open and drop the seeds). This squirrel clearly thought that the twiggy tuft was good enough to warrant stashing several valuable food items there.

The sloping base of a huge spruce in Amalga Meadows had been an active site. Small prints of a critter that could bound six or eight inches decorated the trunk up about three feet, as well as all the surrounding snowy ground. Hmm, not a vole, which usually scuttles along, nor a jumping mouse, which hibernates, but probably a deer mouse.

We looked out over the wind-swept open area of the meadow, where the snow had been draped over tussocks and small conifers. We saw immediately that these looked like sea lions lunging up from the water. There was a big, thick-necked bull, and a whole squadron of juveniles, not far behind. No great imagination needed to provide some sound effects as well!

Some friends like to explore old mines in the Juneau area and recently explored one near the base of Thunder Mountain. The adit was barricaded by stout icicles, but a few were persuaded to break, allowing human entrance. Not too far back in the tunnel, observers spotted a number of harvestmen (a.k.a. daddy longlegs) on the wall. Near the end of the eighty-foot adit, many of these were clustered into a close group, with their long legs sticking out in all directions.

Harvestmen are related to spiders, but not very closely. In contrast to spiders, they are not predatory; they feed chiefly on bits of plant and animal debris. They are also not venomous and cannot bite you with their weak jaws. They are often gregarious, gathering in bunches, but why? One suggestion is that they are behaving like what is known as a ‘selfish herd’. Each animal tries to put as many others as possible between itself and the edge of the group, where the risk of predation is highest. For these harvestmen, the most likely predators are spiders, or possibly mice.

Early April jaunts

Decent weather in early April encouraged several low-elevation jaunts. Parks and Rec hikers went to the rock peninsula on the west side of Mendenhall Lake, stopping for lunch amid a fine display of purple mountain saxifrage. Some clumps were in full bloom, and others were just starting, so the little purple flowers will be there to entertain visiting bumble bees and wasps for a while. Saxifrage flowers on the east side of the lake don’t get as much sun, so they lag behind by a week or more, but they should appear soon. After lunch, some hikers went on to the face of the ice, checking out the interstadial forest on the way, while others settled for a pleasant walk back to the cars.

A stroll with a friend on the Outer Point and Rainforest trails on north Douglas was enlivened by the songs of ruby-crowned kinglets and Pacific wrens—such big voices from such little birds! Several bumblebees circled our heads, even though we don’t look much like blueberry flowers, which were blooming in profusion, just waiting for a bee.

We detoured briefly out to Shaman Island, where the crows were starting to nest; lots of dilapidated old nests were easily visible in the conifers. Going along the tombola (or berm) we gently turned over a few rocks, cautiously replacing them after we looked at the critters hiding underneath. One rock sheltered six small tidepool sculpins, as well as several tiny urchins and sea stars. We found a mossy chiton, a ribbon worm, some pricklebacks that quickly slithered under the next available rock, a scale worm, and a very small, bright green polychaete worm. One tiny sea star, less than half an inch across, was huddled over a pile of yellow eggs, as if brooding (?or eating?) them. All of this was such fun that we barely made it back to the mainland with dry feet—the tide really came up fast!

Out at the mouth of Eagle River, the usual golden-eye ducks and Canada geese cruised around, moving up stream as the tide came in. A pair of swans sailed in stately splendor among the clutter of lesser fowls. At Windfall Lake, there were at least eight swans, conversing with each other and foraging on the far side of the partly ice-free lake, as hikers basked in the sun by the cabin.

Photo by Mary Willson

The bright yellow hoods of skunk cabbage gleam in the understory in many places, but are sometimes nibbled off by deer or seriously frostbitten and black. But those are not the only complications. The inflorescence sheltered by the yellow hood is composed of many tightly packed flowers, each of which is first female, with receptive stigmas, later becoming male, with mature pollen. In early April, every inflorescence we inspected bore only female-phase flowers. No males! This poses a conundrum: These early-appearing, beetle-pollinated flowers may not set seed, because there is no source of pollen (and no beetles yet). It is possible, however, that the first pollen maturing at the bottom of the inflorescence might pollinate some lingering female-phase flowers at the top, if pollen from the same individual is effective. Indeed, one study has reported that this is possible, because the plant is self-compatible. But there might be another, wilder, possibility: Maybe these plants that first emerge from the ground have sacrificed at least some of their female function and, eventually becoming male, will pass on their genes chiefly by fathering many seeds on other, later emerging, plants that are still acting as females.

At Steep Creek, the American dippers have been trying to set up a territory, as usual. Unfortunately, they may not be using their traditional nesting site near the waterfall. This site has been used for many years (at least fifteen in my experience), and there are no other satisfactory nest sites on this stream. But this year the disturbance of the nest site area by humans has been serious. The little waterfall attracts too many people to the gravel bar that is very near the nest site, preventing the birds from courtship and nest-building there. This spring, we have seen groups of people spending twenty or thirty minutes or more on that gravel bar, photographing, throwing rocks, piling up rocks, and playing, oblivious of the needs of the birds even when informed of the disturbing effects of human activity, and even when they then see a dipper fly in, touching down briefly, and fleeing upstream. That kind of behavior is disrespectful of the birds and of the many other people who enjoy watching them. One can hope that humans can eventually learn to avoid disturbing birds at their nest sites.

Streamsides in winter

I take a walk on one of Juneau’s many trails almost every day, alone or with friends. Sometimes it’s a bit hard to get myself out the door, because there’s a deluge or big wind, or I’m just feeling lazy. So I remind myself that sitting inside my house practically guarantees that I won’t see much of interest—so get out there and look around, something may turn up. And something always does.

Here’s a sampling of small pleasures that turned up along Juneau streams in January:

–Fish Creek: Huge, thick plates of ice had washed far over low banks on the small, upstream floodplain and into the forest, and also into the meadows around the combat-fishing pond. It was fun to speculate what it would have been like to actually see the ice cakes pushed out of the creek and into the forest (from a safe distance, of course).

–Eagle River: A dipper was foraging along the edge of the river, occasionally disappearing under the ledges of ice that lined the shores. It searched diligently in the riffles and sometimes brought up something that required some work before swallowing—maybe extracting a caddisfly larva from its case.

–Mendenhall River: I checked out the ‘gooseneck’ peninsula where a breakthrough seems imminent. The narrow neck of land is thinner every time I look, and it seems as if one more good jökulhlaup might be enough to make an island of the peninsula tip. I have to guess that hydrologists have determined the large buildings just downstream to be safe from such events.

–Fish Creek: Winter-active beavers had dragged brush from recent cuttings over to their home pond, leaving trails in the old snow. These beavers, and others in Juneau, have obviously not read the books that report beavers holing up in their lodges for the winter.

–Mendenhall River: A pair of hooded mergansers, the snazzy, gorgeous male with a more-demurely -plumaged female, sailed sedately downstream. Hooded mergansers are the smallest of the mergansers; they eat a more varied diet that includes not only fish but also lots of invertebrates. Males and females commonly pair up in late fall and hang out together through the winter until nesting time in spring. Then the female choses a nesting cavity in a tree or nest box, usually not too far from water, lays her fertilized eggs, and incubates the clutch of eggs, while the male, having done his studly task, goes off and leaves her to do the work. When the eggs hatch, the tiny ducklings almost immediately jump out of the nest cavity, fluttering down to land with a little bounce, and follow mama to feeding areas. This species nests in some places in Southeast, but not commonly. In winter, it favors coastal waters such as shallow bays, estuaries, and tidal rivers, so we see it occasionally.

Photo by Bob Armstrong

–Eagle River: Small insects were flying, possibly midges, looking rather like miniature mosquitoes. Some other insects, such as certain stoneflies, regularly fly in winter, but I’d like to know more about midges (if that’s what they were).

–Cowee Creek: A kingfisher winged upstream and perched over a pool. I hoped to see it catch a fish, but apparently it saw nothing worth pursuing. Kingfishers and many other birds have two small areas, called fovea, on the retina of the eye (humans have just one); foveas have a high density of visual cells and provide good acuity. One fovea, near the bill, is used for monocular, sideways vision; this fovea has especially numerous visual cells and is used for finding prey (as well as keeping track of other birds and predators). When a kingfisher dives and enters the water, its vision switches from that fovea to the other one, located away from the bill; using these lateral fovea in both eyes gives the kingfisher binocular vision and better depth perception as it gets close to an elusive small fish that may try to dart away. When the bird dives, its eyes are protected by a nictitating membrane. As some of us have found out when we try to grab something underwater, refraction often causes us to misjudge the depth of that object; kingfishers can avoid much of that problem by diving vertically after prey that is deeper than a couple of inches.

Kingfishers nest in burrows alongside or at least near streams. I have found nest burrows by several Juneau streams. The lower Mendenhall River and Cowee Creek, where it flows through the meadows, have cut steep mud banks that are perfect places for kingfisher nests. But there’s a problem: in both areas the streams are rapidly eroding those banks; what remains is still potentially suitable for nest burrows, but the stability of the banks is obviously uncertain, and high water in spring and summer could wipe out a kingfisher nest.

–Peterson Creek: A little light snow had fallen on top of old, crusty snow. Shrews had traveled far and wide over the top of the snow. One shrew had plunged, presumably deliberately, over a small mud cliff at the edge of the stream. A few feet downstream, its tracks continued on a flat shelf of shore-bound ice. It sure looked like the critter swam from the base of the cliff to the ice. There is a shrew that is adapted for swimming, but it is not as common here as ordinary shrews, which apparently can swim if necessary.

What did I get out of those little walks? Some really fresh air (Juneau is good for that!), mild exercise (followed by a comfy cup of tea), sometimes companionship, sometimes a solitary meditation, and some observations to think about. Not bad for a small investment.