Small vertebrates in winter

On the last day of November, on the way to the end of the dike trail, I saw a warbler fossicking about on a mossy area near the spruce trees. It was probably finding small moribund insects and spiders. I got a good look at it: a male Wilson’s warbler. That was a surprise! I didn’t expect to see any warbler at that time of year, especially since we were having a series of cold night with temperatures in the teens. I could only hope that he would find enough food to fuel a flight to somewhat warmer places.

Photo by Gus Van Vliet

I began to wonder if this sighting was unusual. So I explored the information recorded in ebird.com a little and found that, over the years, this warbler has been spotted in northern Southeast Alaska uncommonly in November and December and even, but very rarely, in the depths of winter. Then I wanted to learn what other warblers (of those that commonly breed around here) are seen at this time of year. In particular, I thought of orange-crowned warblers and yellow-rumped warblers, which I often see in early spring (March-April), so they seemed like candidates for appearing in early winter too. Although yellow-rumps are recorded quite frequently in November-December and rarely in deep winter, orange-crowns are rare in northern Southeast in November-December. Then I found out that early arrival is not necessarily a good predictor of late fall sightings; Townsend’s warbler comes early but is seldom seen in late fall.

Do the warblers that sometimes stay into late fall have anything in common that might explain their presence? All our warblers feed chiefly on arthropods. Wilson’s, orange-crowns, and yellow-rumps are also known to eat berries and other small fruits at times, but so do some other warblers (but perhaps less often). And, in any case, our region does not offer many small fruits suitable for small birds. Maybe those three just strayed from a relatively nearby wintering ground? But that could not be the case for Wilson’s, which winters in Mexico and the Gulf coast. So neither what we know of diet nor proximity to wintering grounds goes very far to accounting for the three late-stayers. Perhaps they just misread a cue or get delayed by some unknown matter.

Other small birds characteristically spend the winter in Alaska: Pacific wrens, black-capped chickadees in the Interior and the closely related chestnut –backed species here, red-breasted nuthatches, and brown creepers. All of these species usually weigh about the same as the warblers discussed above: in the range of 8-12 g (YRWA at the top of the range). Being small means that they cannot store large quantities of fat to sustain themselves overnight or for several days— their metabolism is quite high and they are so small that there is no place to store a lot of fat on the body as large animals (such as bears and beavers) can do. And they don’t hibernate—they stay active all winter. Some of them (chickadees, nuthatches, occasionally creepers) include seeds in the diet, which are available in winter and which the warblers don’t eat. Chickadees, creepers, and nuthatches often cache their food—in effect, storing their energy outside the body, and black-capped chickadees (possibly also the others) have a temporary increase in brain size, with increased spatial memory during winter.

Red-breasted nuthatch. Photo by Bob Armstrong

In addition, chickadees (the black-capped species has been studied, but other species may do this also) can reduce their metabolism at night and let body temperature decrease; this saves energy, although in extremely cold conditions, it may be impractical, because body temperatures can’t drop too far (being ‘warm-blooded’). The over-wintering species have several tricks that are apparently not used by the warblers. Roosting in cavities, away from the winds, can increase the effective temperature by 25% or more, saving energy, and any sheltered site would be helpful to some degree. Moreover, roosting with companions would also help save energy. Both sheltering and companionship are used by these four species upon occasion. Wrens sometimes roost in cavities, sometimes communally. Chickadees sometimes roost in pairs, sometimes in cavities but more usually in dense foliage. Creepers sometimes roost in small groups, often in sheltered spots. Red-breasted nuthatches may sometimes use cavities, and if seed crops fail, they travel southward in search of better foraging. Apparently none of these methods (except for travelling south) is used by the late-staying warblers (as far as is known).

I can’t resist adding one more bird species: the common redpoll, which is slightly larger than those birds already mentioned, averaging about 13 to 14 g. They eat lots of seeds, especially in winter. And they have the intriguing habit of using snow blankets, dropping down to the snow and making a tunnel with a chamber at the end, 6-11 cm below the snow surface.

Shrews are very small, short-lived mammals that stay active during the winter. They can’t store sufficient body fat, so they have to keep eating every day—twice or three times their body weight in bugs, worms, and other inverts, to maintain their high metabolic rate. European common shrews (Sorex araneus) , weighing less than twelve grams, undergo a marked autumnal reduction in body size, including spine, internal organs, skull, and (!!) brain, as they enter their first winter. Home ranges are smaller and cognitive function related to spatial explorations seems to be diminished in winter. But they regain body mass and re-grow these parts in spring, almost to the original size, ready for the mating season. Researchers suggest that those winter reductions may be a way for saving energy. I have not found comparable information about Sorex species in Alaska, but similar seasonal changes might occur. I wonder what the Alaska tiny shrew does, living in the Interior and weighing less that two grams. Interestingly, the pygmy shrew (in a different genus) does not show these seasonal patterns, leaving open a number of intriguing questions.

European studies of least weasels and stoats (or ermine) have also revealed seasonal changes in depth of the braincase. (Both stoats and least weasels are considerably larger than shrews: stoats weigh up to about 330 g (esp. males), and the weasels weigh up to about 190g, esp. males. However, the long, narrow body shape means heat conservation is difficult, and the metabolic rates are high). Again, brain size reduction may be a way of saving energy. Juveniles decrease braincase depth during their first winter but regain it the next summer. Adults also lose braincase volume in winter and regain it the following summer, but males regain more than females (perhaps related to female’s energy expenditure on rearing offspring and less need to range widely).

Thanks to Gus van Vliet for helpful consultation.

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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.

Fun at Home

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!

Chickadees

A friend and I stood in a small muskeg on Douglas, checking out some deer tracks, when little twitterings announced the arrival of chickadees. Two of them scoured the twisted trunk of a dead pine right next to us, but we soon saw that there were two more—no, four more—no, maybe six or eight more—thronging the foliage of nearby hemlocks. They might be finding overwintering spiders or insect pupae and even adults.

I enjoy watching the flock that hang out around my house, too, as they diligently pick out little black sunflowers seeds from the feeders and flit into the adjacent spruces. They may eat some of those seeds immediately but sometimes the return trip to the feeder happens so quickly that there was only time to stash the seed in a hand crevice for a later snack.

Watching these chickadees stirred me to dig for more information. The species that lives in our area is the chestnut-backed chickadee, which lives principally in the Pacific coastal rainforest. Of the seven species of chickadee in North American, four (including ours) breed regularly in Alaska.

Chestnut-backed chickadee. Photo by Bob Armstrong

All the chickadees share the habit of nesting in tree cavities. The cavities may be natural ones left by a broken branch or a woodpecker, or they may be excavated in soft, decaying wood by the chickadees themselves. Clutch sizes tend to be large, averaging seven or eight eggs per nest. Both parents care for the chicks, but in some cases, not all the chicks in a nest have the same father because, as in many other birds, some hanky-panky goes on! Predation on nest contents of cavity-nesting birds is commonly lower than for open-cup nesters, but nest predation on chestnut-backed chickadee nests can be as high as fifty or sixty percent of nests; red squirrels are a principal predator on eggs and chicks.

When chickadees forage through the canopy, they often hang upside down to glean from the undersides of twigs and leaves. They can do this very agilely, reportedly thanks to well-developed special leg muscles. Chestnut-backs often forage in flocks in winter, sometimes joined by other species such as nuthatches and kinglets. In the southern part of their geographic range, as many as fifteen other species have been recorded in mixed-species flocks with chestnut-backs.

Where chestnut-backs overlap with black-capped chickadees in Washington, their foraging patterns differ slightly. Chestnut-backs have slightly smaller bills and are more closely associated with conifers. They forage especially on foliage and twigs, while the blackcap forages more often on the bark of tree trunks and branches. Although both of them hang upside down to reach the undersides of leaves, the blackcap reportedly does so more often.

Chestnut-backs apparently have been much less intensively studied than blackcaps, which is arguably the best-studied songbird in North America. Because detailed information about chestnut-backs is hard to find, I thought I’d summarize some of the details about blackcaps, which range all across North America and nest in the Interior of Alaska. It seems likely that much of what is known about blackcaps also applies to chestnut-backs, but that remains to be ascertained. In the meantime, here is some cool stuff on blackcaps, particularly their winter flocking and its consequences, food storage behavior, how they get through the cold season, and their calls.

The winter flocks of black-capped chickadees are strongly hierarchical, with males generally dominant to females and older birds dominant to younger ones. Winter ranks have carry-over effects to the subsequent breeding season. Dominant male breeders are in better body condition than subordinates and tend to have better nesting success, at least in some habitats. They also participate more than subordinates in hanky-panky outside of the socially monogamous pair. Higher winter ranks of females also lead to their better survival in the breeding season.

Black-capped chickadees store food in fall and winter, each one stashing hundreds and sometimes thousands of seeds and insects in bark crevices or among conifer needles or in cracks in trunks and branches. Unlike red squirrels, which create piles of cones, the chickadees generally store items singly. They are very good at remembering where these items are stashed, being able to retrieve them after several days or even weeks, if one of the many potential thieves (squirrels, mice, nuthatches…) has not stolen them.

The part of the brain associated with memory is called the hippocampus, which increases in size in the fall, when food storage is a common activity. Blackcaps in the north store more food and have larger hippocampi than those in the southern part of their range. Blackcaps also have larger hippocampi than chickadee species that do less food storage.

Dealing with cold winter temperatures requires metabolic energy, and the colder the weather, the higher the metabolic costs. Blackcaps in Alaska are reported to have a metabolic rate about fifteen percent higher than those farther south. Heat generated by the muscular activity of foraging, during the day, also contributes to staying warm on winter days. At night, however, blackcaps allow their body temperatures to drop ten or twelve degrees centigrade, saving substantial energy; however, the blackcaps in Alaska are a bit different (of course?), and only let their temperature drop about three degrees. At night, they roost in cavities or in thick vegetation, usually singly.

The calls of black-capped chickadees may sound to us like indistinguishable twitterings. But not so, among themselves. They can distinguish the subtle variations in each other’s calls and identify specific individuals (as can many other songbirds). Furthermore, the “chick-a-dee” alarm call varies according to the relative risk from a potential predator that is visible; a different call indicates a predator that has been heard. Other species, such as nuthatches, eavesdrop on blackcap alarm calls and respond to the signal. Recent research has shown the male black-capped chickadees sing at higher pitches when the level of anthropogenic noise is high (for example, near heavy traffic, construction, logging activity, and so on), which may have consequences for breeding (as it does in some other songbird species too).

Colors in confrontation

I once worked in an office in which a co-worker announced that the color red was aggressive, so red clothing should be disallowed in the workplace—or anywhere else!

Well! I’d always found red to be a rather cheerful hue, the color of ripe cherries and raspberries, of wild columbines and scarlet monkeyflowers, of holly berries and Santa Claus. There are some un-cheerful associations with that color, too, such as blood, but to ban a color entirely seemed excessive, to put it mildly. Perhaps you can guess what color my shirt was, the next day!

In the bird world, color is used as part of the process of attracting mates, as we have seen. Color (not just red) is also used to signal social status and levels of aggressiveness.

For example, black-capped chickadees, close relatives of our chestnut-backed chickadees, vary in the darkness of their black cap, and dark-capped individuals enjoy higher social status. Their greater dominance allows them better access to food in winter. House sparrows (those European introductions that can be seen in cities and farms all over the Lower Forty-eight) with high levels of testosterone develop large black patches on the chest. Big patches show other birds that these individuals would win a confrontation. And Harris’ sparrow males that have a high rank in the dominance hierarchy also have large black chest patches. The big black badges signal ‘don’t mess with me!’ There is an advantage both to the males with large patches and the subordinate males with small patches, because they can recognize each other’s status and avoid a direct fight.

White-throated sparrows breed across much of northern North America and occasionally wander into Southeast. Adults, both male and female, come in two color phases. One has black and white stripes on the crown of the head, and the other has brown and tan stripes there (as do juveniles). Detailed research has shown that the black-and-white-striped adults are more aggressive, spending much of their time chasing potential rivals. Although they often obtain and keep the best territories, they tend to neglect their parental duties. So if both members of a pair have black and white crowns, their nesting success tends to be low.

In contrast, a pair of brown-and-tan-crowned adults are less aggressive and markedly more attentive parents. They often lose battles with the black-and-whites and may be forced into suboptimal habitat, where even their better parenting cannot compensate entirely, so their nesting success also tends to be low. Thus, the most successful pairs of white-throated sparrows have one member of each kind: an aggressive black-and-white one and a parental brown-and-tan one.

Experiments with eastern bluebirds (whose appearance is much like the western one) have shown that males with brighter blue plumage out-compete the duller males in contests over nest boxes. So the brighter males get the best nest boxes, and get them earlier, which also gives them first choice of females. I’m tempted to speculate that, like bright mountain bluebirds, they also do well in obtaining extra-pair copulations.

Photo by Bob Armstrong

Red-winged blackbird males have red epaulets with a yellow border. In aggressive encounters with each other, they show off these bright red patches by flaring the wings and erecting the feathers. (You can sometimes see them in the marsh by the Pioneer’s Home or in the big marsh on Eagle River.) They can cover the epaulets with black feathers on the upper back when they want to sneak into a neighbor’s territory unaccosted by the owner. In this case, the optional display of color signals not social status but level of aggressiveness.

In an earlier essay, I noted that much of the variety of color and pattern that we see in the animal kingdom is the result of mate choices and competition to be attractive to the other gender. Another portion of the array of colors and patterns can now be seen to be a result of signaling social status and level of aggression.

I have not addressed the matter of color with respect to camouflage, or signaling age or gender or species, or mimicry, or warning colors, and so on. But all of these things contribute to the diversity we see. Perhaps in a future essay…?

Out and about in mid-June

I went, with a friend, into Sheep Creek Valley one morning, to listen to bird songs. I especially wanted to hear Swainson’s thrush, whose vigorous, upward-spiraling song is beautiful, and Sheep Creek Valley is usually a good place to hear them. We entered the valley around eight o’clock, and I heard fox sparrows, an orange-crowned warbler, a Lincoln’s sparrow, a ruby-crowned kinglet… and a few unenthusiastic, feeble-sounding Swainson’s thrushes. The valley was far quieter than I had expected, even though we missed the dawn chorus, which would have started about two-thirty—this being near the summer solstice. Then, about ten o’clock, the Swainson’s got warmed up and tuned up and sounded like their normal selves.

There’s a conifer grove in the midst of the cottonwoods, alders, and willows, and there we saw a chestnut-backed chickadee, perched just over our heads. It took a surprising interest in my cap, approaching it from front, side, and back and looking closely at it. I have no idea why it was seemingly so fascinated. The cap is red, but that doesn’t seem to signify. On the front is a picture of a crowned crane, which has a big white cheek patch (like a chickadee) framed by black (like a chickadee), and we wondered if that could have been the attraction. We’ll never know!

On another day, we wandered up to Cropley Lake, to check on the stands of yellow-flowered fireweed that grow in wet patches on the back side of the lake. We fund a big boulder to sit on while we had our morning tea and crumpets, but as we started to settle down, we flushed a female sooty grouse and a tiny chick from the dense ground cover. Mama grouse clucked and fussed, and they both took refuge at the edge of a willow thicket fringed with dense ferns. Mama kept peeking out to check on the ‘monsters’ that had entered her domain. We thought she might be waiting for a few more chicks to catch up with her, from farther up the hill, and we were perhaps keeping the family from re-uniting. So we gathered up the tea party and moved about a hundred yards away, where we may have bothered some jays. We found the yellow fireweed plants, just budding and not yet showy.

Other treats on this walk included a set of very tiny deer fawn tracks in the mud, and an olive-sided flycatcher singing from the tops of mountain hemlocks: “Quick, three beers !!!” again and again. The little insectivorous plant called butterwort or sometimes bog violet (it is not a violet, but the flower is superficially similar) was blooming, sometimes hidden in the other vegetation but often making a nice purple show in barer patches along the way.

The Dredge Lake area is once again a site for nesting American redstarts, not a common bird around here. Females do the nest-building and incubation, but both parents feed the chicks. Northern waterthrushes have been heard frequently and might possibly nest here, near some of the ponds. In addition to the usual mallards, ring-necked ducks (neck rings seldom visible) have been seen and may nest here, so we might yet see a brood or two of ducklings. The little ones don’t learn to dive well until they are about a week old, but eventually get most of their food by diving. I have reports of curious doings by tree swallows at a nest site, where more swallows than just the nest owners were interacting, and sightings of solitary sandpipers, which have the unusual habit of nesting—not on the ground, like other sandpipers, but in abandoned nests of birds such as robins.

Back home: on several days, I was entertained by the view out my front window. A juvenile bear came into the yard, which is a riot of fireweed, nagoons, horsetail, and buttercups. He (yes, definitely a male) foraged avidly on horsetail, avoiding the buttercups and spitting them out if he happened to grab one while gobbling horsetail. Very selective feeding, and probably a good thing, because buttercups are known to be poisonous to livestock and can cause contact dermatitis to humans who handle the plants a lot.

Autumn is here in earnest

We pass the autumn equinox, and the days get ever shorter. They’ve been getting shorter ever since late June, but now we really begin to feel it. The fall rains are here, and when we look out our windows, we see gray gray gray. It’s seldom as bad as it might look, however, so it pays to get out and about.

In fact, I think that getting outdoors is an important part of living with short days and gray skies. Some folks flee the fall and winter by going south, but I have found several ways to enjoy staying here during those seasons. I try to get outdoors every day, talking a walk on one of our trails; maybe not a long walk, but I’m out in the fresh air, seeing something besides four walls. I sometimes play a game with myself: the challenge is to find at least one thing (preferably three things!) of esthetic or natural-history interest. Sometimes these things are connected: I like to recall the visiting musician who took a walk in the forest and found that the rich variety of green tones in the mosses and ferns reminded him of a piece he had just played; now every time he plays that piece, he’ll see the rainforest. I greatly enjoy the rich cultural life in town, especially the music; the visual and thespian arts are also alive and well, and various lecture series can be both instructive and entertaining. Also, I do best when I have a project or two to work on; it doesn’t much matter if it is writing or building bird houses—a project that engages what’s left of my aging mind.

When I’m out, there are actually several autumn things to look forward to. Great rafts of scoters gather in the coves and channels. It is fun to watch them do what I call ‘chain diving’—a whole line of scoters dives, one after the other, in the same spot; then they all come up, one at a time, a little farther away. I have not yet found anyone who can tell me exactly what they are doing or what food they might be finding or why they do it in that way.

Out on sandy, gravelly bars, there might be small flocks of shorebirds that spend the winter with us. Rock sandpipers and dunlins often hang out together. Adults in breeding plumage of both species have black belly patches, and some show the black blotches as winter goes on, so look closely to distinguish them. These shorebirds breed on the Arctic tundra of western and northern Alaska. Sometimes there are surfbirds on rocky reefs and points; they nest in alpine tundra of Alaska and the Yukon. I occasionally flush a solitary snipe, not only in the marshes and swamps where they might have nested but even along streams in the forest.

I look forward to spotting the first slate-colored juncos that arrive at the bird feeders; they come from the Interior to spend the winter with us. Oregon juncos live here all year but mix with the slatey ones in winter. At present, both kinds of juncos are classified as the same species but different subspecies or races.

Thinking about Oregon juncos reminds me to ask a question: these birds are distinguished from slate-colored juncos in part by a chestnut-brown back. Likewise, our chickadees have chestnut-backs that are lacking in the other North American chickadees. Is there a particular reason why chestnut backs are popular here? Is there something about rain forests that favors that plumage pigmentation?

Of course, the black-billed magpies come to us in the fall too. They temporarily monopolize bird feeders, tease the eagles, and sample leftover salmon carcasses. On a rare sunny day, the iridescence of their black feathers makes them quite spectacular.

Flowering season is over in fall, but you might spot a few late purple asters alongside the trail. Behind the Visitor Center at the glacier, there has been a very late blooming Romanzoffia sitchensis (the common name is Sitka mist-maiden). In the muskegs, look for tiny yellowish cups that might be mistaken for flowers. These are the seed heads of the swamp gentian. Each two-parted cup holds a little cluster of seeds; when a rain drop hits the cup, the seeds get splashed out and so dispersed. This ‘splash-cup’ dispersal is not common, but it is shared by the bird’s nest fungus.

Gentian seed pods

One of my favorite things to do is watch the coho arrive in local creeks. When they do, the bears—which have been waiting for them, ever since the sockeye run ended—get busy again in the streams, and that makes for great bear-watching. I think that many of our local bears really depend on coho to ‘top-up’ their fat deposits in preparation for hibernation. The amount of fat laid down in fall is important in determining how many cubs a female bear can feed while they are in the winter den and it is probably important for winter survival of juvenile, subordinate bears that are not yet expert foragers.

I don’t know all the factors that regulate the size of coho runs, but there is evidence that juvenile rearing habitat is one important factor that helps determine the size of a local coho population. Incoming adult salmon are commonly able to slither over or jump over most beaver dams, so dams seldom limit the spawners. However, juvenile coho rear in pools in streams and in beaver ponds, and research has shown that they grow really well in beaver ponds. Down in the Pacific Northwest, biologists have even re-introduced beavers to certain stream systems, so that their ponds will increase the available rearing habitat for salmon and help restore the diminished populations. Because salmon typically return to their natal stream when it is time to spawn, juvenile rearing success helps determine the size of the spawning run. Thus, when beaver dams are removed from streams where coho spawn (so that their ponds are drained), or when beavers are trapped out of a system and their dams (and ponds) are no longer maintained, and rearing habitat is thus reduced, there is reason to expect that the coho population of that stream will decrease. And that leads to the expectation that the bears living in the area would lay down less fat, possibly survive less well, and produce smaller litters of cubs.