A Wintery Walk

a wonderful weasel encounter

Days are rapidly getting shorter, and the peanut butter junkies at my feeders are voracious. The familiar Oregon juncos that thronged the feeders all summer are now scarce. But I’ve begun to see slate-colored juncos, here from the Interior for the winter. Closely related to the Oregon types (both are usually classed as subspecies of dark-eyed junco), but the new arrivals took at least a week to figure out how to exploit the peanut butter feeder. Maybe they watched the chickadees and got the idea.

On a lovely, sunny but cool and windy, day in mid-October, a little group of friends strolled up the road at Eaglecrest to go off onto the upper ski loop. Darting in and out of the angular rocks that line the road toward the Black Bear lift was a small white critter that disappeared almost as soon as it showed its head. So it took us a little time to ascertain who it was: of course, a short-tailed weasel or ermine (called a stoat in Europe). It then gave us many chances to see it as it explored both sides of the road, around the turn and past the Kimball memorial bench, popping up its head every so often to look around (and perhaps to check on us). The weasel was presumably hunting for something edible, such as a vole or shrew, but we saw no evidence of success.

Photo by David Bergeson

The white winter fur was certainly conspicuous against a background of gray rocks and brown fern fronds. When there’s snow on the ground, of course it’s a different matter—the white fur is great camouflage then, only the black tail tip and a beady black eye marking the beast on a white background. “Our’ weasel apparently had turned its coat from summer brown to winter white well before snow would cover the ground (although a little dusting fell a few days later). Molt is said to be initiated by changes in photoperiod (day length), and modified by temperature, but southern ermine don’t change to white at all. In northern populations, the physiology of molting to winter color is not closely timed to reliable seasonal snow cover; in fact, on snow-free Haida Gwai’i, ermine still acquire a white winter coat. This leaves open a question about why molt is not better synchronized with background color everywhere.

Weasels are built long and slender, which enables them to slip into narrow tunnels, even into vole hideouts in pursuit of prey. However, that elongated body has a lot of surface area (where heat is lost) relative to body volume (where heat is generated), so weasels have a high metabolic rate that generates heat– but necessitates lots of food. An active hunting style presumably provides more encounters with prey (than a sit-and-wait style, for instance), but has its own energetic costs. They need to eat several times a day (taking in about thirty percent of their body weight!) and have a well-insulated nest (often stolen from a victim) in which to rest between hunts. If the usual prey of small rodents is scarce, weasels may hunt hares, squirrels, birds, and even eat worms and bugs and carrion if necessary. They cache dead prey for future meals.

Mating season is in spring, but fertilized eggs are not implanted in a female’s uterus until nine or ten months later. Then the embryos develop into babies in about a month, the newborns staying in the nest for a couple of months or so. Litter size is variable, usually four to eight kits, but well-fed females can produce much larger litters (up to eighteen kits!). Juvenile females become sexually mature while still in the natal nest and may (if a mature male was nearby) already carry fertilized eggs when they disperse to establish their own home ranges. Males can’t inseminate their female litter-mates because they don’t mature until about a year old.

Here are a few more interesting tidbits about weasels: They have excellent color vision, unlike most mammals. They climb well, with reversible ankle joints (like squirrels) so they can descend a tree head-first. If threatened by a superior predator, such as a cat, they may pretend to be dead; if not eaten, they quickly revive and run away.

At this time in October, there was a thin sheet of ice on my home pond in the morning and the ponds at Eaglecrest were ice-covered. Nevertheless, we saw caddisfly larvae in their cases, hanging out on the bottom of a few ponds or moving extremely slowly. They probably spend the winter as larvae, feeding on detritus when possible, but otherwise quiescent; pupation and metamorphosis into flying adults would occur the following year.

A few blueberries clung on their bushes, and I was informed that they were exceptionally tasty. The bright green fronds of deer fern and fern-leaf goldthread stood out on a background of brown, dead and dying vegetation. On the surface of some old skunk cabbage leaves, tiny pools of water had coalesced and frozen solid, forming jewel-like, nearly spherical beads that gleamed in the sunlight.

We ate our lunches in warm sunshine, all spread out in the lee of a grassy bank. The first wintery walk of the year turned out to be a good one.

Fun at Home

looking out the windows

I love to walk our trails, just to see what I can see. But sometimes there’s a lot to see in my front yard and pond. Then I wear a path from window to window (with side trips to the fridge and tea kettle). This spring has provided some home-based fun.

The shenanigans of the mallards are an annual happening. The ducks start to visit the pond soon after ice-out. Pairs sort themselves out and by late May mama ducks start to bring their tiny ducklings for an occasional visit. This year there were several brood of eight or nine and one brood of just one duckling.

The littlest ones have a hard time jumping up to join mama on the bank for a rest. They zip back and forth in front of her and make lots of futile little leaps. The female often tries several spots before finding one they can all master. Sometimes only part of a brood makes the jump and the rest have to find access at some distance and make a small overland trek. When ducklings are small, the mother broods them, making herself as broad as possible to cover them all, although even then a few heads and tails poke out from under her.

The unpaired males that have already fathered these broods are hanging about, all revved up and looking for more action. They harass any late-forming pairs and even mothers with babies, causing lots of fuss and flapping. The female with one offspring was persistently pursued, driving her to protest continually and even leave the pond several times. If I opened the windows, I could hear the little one peeping in apparent distress.

A flotilla of visiting ducklings is probably what brought an eagle down to march along the bank, eyeing one brood with malevolent intent. (Yes, I know, eagles have to eat too.) A swoop or two over the water failed, as the brood scooted for cover, and the eagle left, still hungry.

Juvenile juncos had been chip-chipping in the woods along various trails since mid-May. Here at home, there were well-fledged juveniles, of two separate families, by the first week of June, quite able to pick up seeds for themselves but often waiting for dad to deliver. It was the male juncos that stuffed the juveniles with peanut butter and seeds, leading me to suspect that the females were back on eggs again, for second broods. (They can do three or four a year.) The juveniles tried the peanut butter feeder occasionally but looked like they needed some practice, and they preferred to wait for dad.

A male hairy woodpecker made occasional visits to peanut butter and suet, but by mid-June his visits were quite frequent. He hacked out big chunks of suet and carried them off, leaving crumbs for the little birds to pick up. He would swallow several bits of peanut butter but carry away one last load in his bill. So I knew he had a family. And finally, a big, well-feathered fledgling joined his father on the deck railing and begged for peanut butter. I wondered if the mother was tending another young one somewhere.

The chickadees were feeding big kids too. And a great treat was seeing the whole family of nuthatches crowding together on a small block of suet. Two sleek fledglings chipped off bits of suet for themselves, but were also happy to have chunks delivered by the parents.

A bear came to eat horsetail in my front yard. They do this every year. Often they lie down flat and just scoop in the green stuff. This guy got up and wandered up toward the house, sniffing and sniffing, then stood under the edge of the deck to sniff some more. No doubt the aroma of peanut butter was in the air. Before I could say oh-oh, the bear shot up a nearby tree like lightning, just a black blur. It went up above the roof level, out of sight. Now, I’m not too enthusiastic about a bear on my roof (or deck). I raced outside to check the roof, but by then it was already down and gone. The tree was just a bit too far away from roof and deck. But just in case, I have moved the alluring feeder to the other end of the deck; the birds are getting used to the new arrangement.

One more bear story: A medium-size cinnamon bear came and foraged on horsetail. That gave me time to see that she looked like she’d worn a collar for a long time because her fur was very worn in a circle around the neck, but she had no visible ear tags. Eventually, she started to wander out of sight. Immediately, an alder tree across the pond gave a violent shudder, and a massive glossy-black bear suddenly appeared in the yard. He chomped a couple of horsetails but was much more interested in her, and he followed her off into the neighbors’ yard. It’s that time of year for bears!

Winter wanderings

In early January, the ice on the ponds in the Dredge Lake area was good and solid, although there were isolated spots of open water where upwellings slowed the formation of ice. I traipsed around some of the trails and ponds, finding tracks of shrews, hares, and a mouse. Otters had slid over a beaver dam and then up a frozen slough, no doubt hoping to find a fish or two.

One day in mid-January, a friend and I explored a frozen pond, walking on snowshoes to spread out our weight, in case of a spot of weak ice. A little snow was falling, so it was a beautiful walk.

Beavers had made a small food cache near their lodge, including some hemlock branches. There were lots of spider webs and long, trailing silk threads used by airborne spiders. We wondered if any critters, in addition to some spiders, eat that silk to recycle the protein.

Around the bases of several trees at the edge of the pond, we noted the tracks of a small bird, probably a junco. It had apparently inspected each tree base quite closely, possibly picking insects from the spider webs that curtaining the gaps between the upper roots or searching for stray seeds.

A vole had crept out of one bank of a frozen rivulet, crossed he ice, and scuttled back to where it came from. My companion had observed such behavior in other places when the animal was seen to be a red-backed vole, so we assigned that perpetrator to those tracks. Deer tracks crisscrossed the pond ice, and deer had been feeding on the witches’ hair lichens that grew on small trees at the pond edge. My sharp-eared companion heard a brown creeper, which we soon saw as it hitched its way up a spruce trunk.

Many of the alders in this area had neither cones from last summer nor any male catkins for next spring. This was unlike other alder stands we’d seen, so we wondered why this stand was evidently reproducing very poorly. Perhaps the high level of water in the pond was too much for them.

We also noticed that here and in some other places the alders had retained many of their dried and shriveled leaves, instead of letting them drop to the ground. Blueberry shrubs sometimes do this too. In other regions, oaks, beeches, and other trees also retain many of their dead leaves throughout the winter. The term for retention of withered old flowers or leaves is ‘marcescence’. Marcescent leaves have attracted a good deal of speculation about why these plants do this, such as deterring deer and moose browsing, trapping snow for release of moisture in spring, or delaying decomposition until spring, when nutrients are most needed for growth. However, apparently very little investigation has explored those ideas. In some cases, particularly when marcescence is occasional and not regular, the retention of dead leaves may just happen incidentally because the weather suddenly changed in a way that prevented the usual mechanism of leaf-drop (formation of the cut-off or abscission layer at the base of the leaf).

A few days later, along the Auke Lake trail, (and later in other places) we noticed that many of the blueberry bushes had small galls on the twigs, often at the bases of marcescent leaves. The galls are really quite small, and I have to wonder how many times I have walked past them without noticing. They do seem to be more conspicuous against a snowy background…Some blueberry galls are made by midges or wasps, but these did not fit the descriptions of such galls, so the makers of these galls remain to be determined.

Toward the end of January, I went with a friend on the Pt. Bridget trail. Near the trailhead, we found a place where a weasel (I think) had fossicked about in the mud at the bottom of a hole in the snow, and come up to leave a string of its small, muddy footprints on the snow, before diving back down under the deep snow in a new spot. Somewhat to my surprise, the lower branch of the trail, along the edge of the big beaver meadow, was quite passable, provided one didn’t mind a couple of inches of water here and there. A moose had used the trail too, taking advantage of a deeply trenched part of the path—and a small wooden bridge—to avoid some of the post-holing that was required in the rest of the meadow. The bible-camp horses had left ample evidence of time spent on this side of Cowee Creek, on the beach fringe as well as in sheltered places under the conifers. Pawing away the snow and stirring the long, dead grasses, they also had clearly been looking for precocious green shoots under the snow…and had found a few.

As we left the area near the cabin, my companion spotted an owl, probably a short-eared owl, as it swooped down to some bare ground next to a tidal slough (the tide was out). It was probably trying to catch an unwary rodent, but we could not be sure it was successful. It soon flew up into the nearby trees, changed perches, and eventually took off across the wide meadows, screened from clear view by tall spruces.

A day or two later, when Plan A for a beach-walk was foiled by ferocious north winds on Lynn Canal, another friend and I eventually found a sheltered beach near Amalga Harbor. Moving slowly and quietly, we managed to share the beach with a trio of common mergansers that paddled slowly along the tide line. Then they all hauled out and snuggled up in a close-packed row to sun themselves.

I have learned a new word for verbal bric a brac like that found in this essay: bricolage. ‘Tis a very useful word for assortments of diverse things brought together in some more or less unifying way. There may be more bricolages here in the future.

Vocalization and predation

begging chicks, whispering whales, and clicking moths

Four baby juncos, in a nest tucked under a dropping clump of grass, lie low and are very quiet. Only when their parents come with food do they raise their heads and beg. When the parents leave, the chicks again are still. There’s a good reason for this: a nestful of lively, loud chicks would probably attract predators, who are always on the watch for succulent little morsels. Even the repeated back-and-forth trips of attentive parents are often enough to alert watchful predators to the location of a nest.

The nestlings of many other songbirds (robins, sparrows, warblers, etc.) behave in the same way, for the same reasons. They nest in open-cup nests, which are vulnerable to all comers. Cavity-nesters, such as woodpeckers, can be a little more brash in their protective holes. Predators may come, but only some of them can enter or reach into a deep cavity, and if they do, they may face a barrage of sharp beaks. Predations rates on cavity-nesters are much lower than on open-cup nesters. As the chicks get bigger, they sometimes perch right next to their front door, poking their heads out and yelling for food (that’s how I easily found the nest of a black-backed woodpecker, some years ago).

Ducks and shorebirds do it differently. Wherever they nest, the chicks leave the nest soon after hatching, typically following a parent around but feeding themselves. When incubation is done, there are no back-and-forth parental feeding trips to lure a predator to a particular place. The family is now a moving target, not a stationary one.

Among mammals that are subject to predation, we find a similar dichotomy. The young of some species follow their mothers, but in other species the babies cuddle in a nest. Humpback whale calves stay close to their mothers, and recent research shows that they talk to them in ‘whispers’—soft vocalizations that cannot be heard at any distance. This may reduce the risk of killer whale attacks. The young of deer, moose, zebras, elephants and other large herbivores are also able to accompany their mothers soon after birth; I wonder if they whisper too!

Young marmots stay near the den, which offers a quick retreat when danger threatens, and young beavers gain some protection from the pond outside the lodge, a haven, when the alarm sounds. Smaller mammals have a variety of arrangements, mostly depending on being cryptic and hard to find.

But some small rodents add another feature that improves safety: They can produce ultrasound: too high-pitched for human ears (hence, “ultra”), these sounds have a very short wavelength along with the very high frequency. Such sounds attenuate rapidly with distance, so they do not carry very far; they are more directional than low-frequency sounds, but they get scattered by reflecting off twigs and leaves. Young lemmings, mice, and rats emit ultrasounds to call their mothers, if they have become separated too long; the calls prompt the mother to retrieve the wandering pups. Although many predators of small rodents cannot hear ultrasound, some can (e.g., dogs and cats and their relatives), and a short-range call of distress might reduce the risk of predation from such carnivores.

Adult small rodents also use ultrasound as a form of social communication within a group, quiet talk among companions. Certain ground squirrels emit ultrasounds that alert others to the presence of a distant threat, the rapid attenuation ensuring that the sound does not carry as far as the potential threat.

On the other hand, some predators have evolved the ability to use ultrasound in hunting—as an aid to predation (rather than a way to avoid it). The toothed whales use echolocation (sonar), much of it in the ultrasonic range, to navigate in turbid waters and to detect their prey. Our resident killer whales, for instance, use ultrasound to locate and capture their fish; the transient killer whales, however, seldom use it while hunting their prey of marine mammals. Not only are the prey mammals much larger and easier to see than the prey fish, typically, they are also more likely to be able to hear the sonar calls of the hunting killer whales. So the transients usually hunt silently.

Bats are perhaps the best-studied predators that hunt using ultrasound. The short wavelengths permit the sounds to bounce off small prey, such as insects, and bats emit very high intensity (‘loud’) ultrasounds as they close in on a hapless bug. Not all insects are hapless, however! Some toxic tiger moths make ultrasonic clicks to warn off approaching bats, which then often abort their attack. Other, nontoxic, tiger moths use their ultrasound to jam the sonar of an attacking bat, making the attack less likely to be successful.

Echolocating calls sometimes also allow the bats to communicate with each other, as they are looking for roosts or food. Because the calls can be individually recognizable, young bats can communicate with their mothers, and friends can talk to each other (although others may eavesdrop). There remains much to be learned about the social uses of sound in bats.

Four bird-baby stories

ducklings, crow-lings, and warbler-lings

Spring is the season of babies, in the woods, on the beaches, in the ponds and meadows. Baby birds can be great fun to watch. Here are four little stories about them.

–After watching the shenanigans between male and female mallards on my home pond, followed by lazy males loafing around with each other, I finally got to see what I was waiting for: seven tiny ducklings scooting around the pond. They seemed to be totally unsupervised; no mama was in evidence. So the little fellows skittered all over, jumping up to catch a bug on an overhanging alder leaf, streaking across the water for no obvious purpose, nibbling small things along the shore. After some minutes, a female appeared from downstream. But she ignored the ducklings and hobnobbed with another female; they foraged together on the shoreline vegetation in apparent amity. Two males sleepily lurked in the brush at the upper end of the pond, ignoring everybody else. Eventually, one of the females rounded up the fuzzy little ones, and they all disappeared.

–A few days before the little duckies appeared, I watched a female junco feeding on some spilled seed, while her fledgling danced all around her, begging—beak open, wings aflutter. She turned her back, it scuttled around in front again; she turned away, it sidled around to face her. This litte dance repeated itself several times. The kid was perfectly capable of feeding itself, and did so occasionally, but it wanted mama to provide. Mama did her best to ignore the importunate youngster, but occasionally gave in and poked a seed into the little beggar.

–A friend found a crow nest, tucked under a good-sized log. A nest on the ground isn’t the usual thing for crows around here; mostly they seem to nest in densely branched spruce trees. Sometimes several nests are fairly close together, in adjacent trees, forming a loose colony.

Some days after the discovery, we went back to look for the nest. Meanwhile the vegetation had grown exuberantly, so the sheltering log was invisible. So we hunkered down behind some bushes and kept watch for the parental crows. Eventually they came in, bringing food for the chicks, and after several feeding trips, we had the nest location pretty well pin-pointed.

baby-crow-blue-eyes
Photo by Bob Armstrong

After the adult crows had left the area to find more food, we walked up the to spot, parted the surrounding vegetation, and peered under the log. There were two big, well-feathered chicks with bright blue eyes, staring warily up as us. I bent down low, and discovered that there was a third chick, less well developed than its siblings, cowering in the ‘back room’ farther under the log. The third chick may have hatched a bit later than the other two and, because it was therefore smaller, it was likely to be last in line when the parents brought food. If food is scarce, it may the first to die. Because the usual clutch size is four or five eggs, it is possible that other runts may have already died. (Or maybe I just can’t count higher than three!).

–Near the Visitor Center, I accidentally discovered a yellow-rumped warbler nest, wedged into the fork of a tall willow tree. I think they had very young chicks at that time, and during the following days, they grew rapidly. Soon four tiny beaks could be seen, reaching up above the rim of the nest when the parents came to feed them. A day or two later, fuzzy, downy heads were visible. A few days more, and the nest was starting to collapse on one side. Two hefty, feathered chicks held tight to the tipped bowl, while two more huddled just outside and behind the upper rim. A couple of days more, and they were gone.

Yellow-rumped warblers are widespread, but their plumage and songs vary geographically. At present, this variation is represented in about four subspecies, which are known to interbreed at times. The adult birds at this nest were interesting: The female seemed to be a typical ‘myrtle’ type, with a white throat. At first glance, the male appeared to be another subspecies, called ‘Audubon’s’, with a yellow throat. But one of Juneau’s top birders suggested, after seeing photographs of the head markings, that the male was probably an intermediate form, perhaps a result of previous hybridization between myrtle and Audubon’s. Apparently this pair was busy rearing more intermediate forms of this species.