Spring has sprung

After a slow start, the season has sprung into full swing. The early avian harbingers have been joined by lots of other speciesin the first part of May. Out on the wetlands, flocks of small shorebirds and little brown songbirds swooped around and settled invisibly in distant sloughs or the brown grasses. Some of those little brown songbirds eventually turned into Lapland longspurs, savanna sparrows, and (near the forest edges) white-crowned sparrows.

On one lucky day, I saw four mountain bluebirds perched on the fence posts at the edge of the golf course; later I saw three of them perched on the tall, dried seed-heads of dock plants. That same day, three species of swallow (barn, tree, violet-green) coursed up and down one short section of a tidal slough. A big group of northern shovelers hung out on the river, more than I’ve seen together in one place previously. A few American pipits ran along the grassy edge of a slough.

Two days later, there were no bluebirds to be seen; maybe they took advantage of the good weather to make the trip over the mountains to the Interior. From the dike trail, I saw twenty-two white-fronted geese huddled on the river with a single snow goose. Out over the dry grasses, a northern harrier (in brown plumage, therefore female or juvenile) flew low, back and forth, and then dropped straight down to the ground and began pecking repeatedly at some invisible prey. Three ravens chased a hawk with agitated calls, disappearing into the distance. I had to wonder what that hawk had done—or was suspected of doing…

In other places: Kingfisher Pond hosted red-winged blackbirds, tree swallows, and a coot, with yellow-rumped warblers flitting in the shrubbery. Another observer there recorded Wilson’s warbler, green-winged and blue-winged teal. Hermit thrushes began to be heard in the forest. North Tee Harbor reported female bears with cubs, prowling about. A big bear wandered through my yard in the middle of the month. Little white butterflies flitted over the dandelions and emergent greenery. And fern-leaf goldthread flowers appeared along some wooded trails.

Rufous hummingbirds always appear at my feeder a couple of weeks or more after they are reported from Fritz Cove Road. But they finally showed up, perhaps a pair, but they visit the feederseparately, usually in the afternoon.

A male hairy woodpecker landed on my deck railing and was chased off by a squirrel. He came back a couple of times and visited the peanut butter offerings. I was reminded that in a previous year a fatherly hairy woodpecker brought his fledgling to the deck for daily lunches. Could that happen again? The local red-breasted nuthatches are making lots of trips to the seed feeder for sunflower seeds, quickly zipping back into the spruces, sometimes returning so soon that I begin to think they are just stashing the seeds somewhere, for later eating. I hope they will nest here again. A varied thrush comes to collect seeds from the deck railing, but it spends most of its effort on a suet feeder—lunging up to jab the suet with its bill while madly flapping its wings (not a graceful hoverer).

The big excitement on my home pond was the unexpected appearance of two pairs of wood ducks. I’ve never seen them here before, although they’ve been rumored to nest occasionally in the lower Valley. As of this writing, the wood ducks have been here for over a week, and I saw one pair copulating. They nest in boxes and tree cavities, but I have no idea if suitable cavities are available near here. They got along peaceably with the mallards that remained on the pond.

Wood duck male. Photo by Bob Armstrong

Sometime early in the month, all the females and most of the male mallards departed from my pond. A lone male floated on the pond for a few days and eventually was joined by a solo female who stayed for several days; they often rested side by side on the bank. I’m guessing that she had laid some eggs but lost them to a predator, and she was here to start another clutch. Mallards are ground nesters, relying on camouflage and concealment (and luck) to survive the long incubation process, but the eggs are vulnerable to wandering dogs, bears, ravens, and other predators.

One of my favorite things in spring is watching the skunk cabbage plants. First, the little green spears emerge from the shallow waters, but I impatiently await the cheery, brilliant yellow spathes that announce the flowers of ‘swamp lanterns’. The hood-like yellow spathe (if not nipped off by frost or deer) surrounds the spike (or spadix) of densely packed flowers. Each of those flowers is female first—with pointy little stigmas sticking out for potential pollen reception. But the earliest plants to bloom, being all female, have no source of pollen, unless they can somehow pollinate themselves, as the flowers mature into the male phase. Eventually, all the flowers become male, producing yellow pollen. Now we begin to see insects hiding down deep in the spathe, sometimes tiny flies and dozens of black beetles. The beetles are thought to be pollinators, crawling over the male flowers, eating pollen and getting it all over their bodies, then carrying the pollen to later-blooming individuals, still in female phase. We never see as many beetles hiding in spathes around female-phase flowers as in spathes with male-phase flowers. And female-phase individuals often have no beetles at all, so it seems that beetle visits to females are intermittent, and I suspect that females send out air-borne messages that attract the beetles just when the time is right for pollination.

Early male-phase skunk cabbage flower, with pollen just starting to appear. Most of the flowers are in female phase, with pointy stigmas. Photo by Mary Willson

The red alder trees along the highway are popping out little leaves, catching up with some of the shrubs that leafed out earlier. Now every day may bring some new development for the season—such fun!

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Rough-skinned newts

Juneau has four resident amphibians that breed in fresh water: wood frogs and western (boreal) toads, which have geographic ranges extending way up north, Columbia spotted frogs, which range to about the northern border of Southeast, and rough-skinned newts, which are at their northern limit in the Juneau area.

Adult rough-skinned newts are small, less than about eight inches long and have a pebbly texture on the back that gives them their name.
Photo by Bob Armstrong

These newts (Taricha granulosa) are a west-coast species, from California northward. As the glaciers of the great ice ages retreated, newts apparently expanded their range into coastal BC and then the island archipelago of southern Southeast; not too long ago, in geological time, they reached Admiralty and Shelter Islands. The move to Juneau, probably a few decades ago, is thought to have happened with human assistance.

How did they move north from one coastal island to another? There are several non-exclusive suggestions, but apparently nobody really knows. Perhaps not all of the present-day islands were separated by seawater when the big glaciers prevailed and more dry-land connections might have existed; then terrestrial dispersal may have been feasible in some areas, although land in front of the retreating glaciers would be perhaps too cold and barren. As the glaciers melted and sea levels rose, however, this potential pathway would disappear (unless the land, gradually released from the weight of ice, rose enough). But freshwater drainage from melting glacial ice would make a lens of fresh water on top of the sea water. Could that have helped dispersal? Or did they come down the big river drainages from the interior? But there is no known population source in British Columbia. Or did they get carried around by Native kids as pets, and eventually released on various islands? Or can adult newts tolerate seawater, at least for short periods? Exposure to salty water is known to have deleterious effects on newt embryos (and those of other amphibians), the degree of damage depending on the salt concentration and temperature, and very salty runoff from ice-melting roadway salts is bad for adults too. However,apparently the newts in some populations can tolerate brackish water. It might be surprising for an amphibian to tolerate salt water, although toads can, to some degree. But I have, so far, not found a study of salt tolerance in adult newts. The questions remain unanswered!

Rough-skinned newts (and a variety of other critters) are well-known for a powerful neurotoxin (TTX for short) in the skin, which causes paralysis and is usually lethal to a consumer. However, toxicity varies among populations; for example, newts that live above 500m elevation are much less toxic and can be eaten by mammals and other predators. Toxicity also varies among individuals within many populations. 

Various species of garter snakes are known to be resistant to this neurotoxin even in large doses (and egg-eating caddisflies areresistant to the toxin in newt eggs too). Most other predators are reported to be killed when the toxin is ingested (although they survive when eating newts from nontoxic populations). Garter snakes in areas with the most toxic newts tend to be the most resistant. The snakes are reported to be able to judge the toxicity of a newt by grabbing and partially swallowing it, rejecting the newt if it is too toxic. In turn, a newt can smell if a snake has recently eaten another newt and try to avoid it. 

The initial, and appealing, story was of a co-evolutionary arms race between predator and prey. The arms race means that the more toxic prey escape more often, so more resistant predators then become more successful; they eat more newts and there then is natural selection for more toxic prey, which in turn favorsmore resistant predators, and so on. But the initial story was tested by exceptions: populations with no correspondence between newt toxicity and snake resistance, and now researchers suggest that various other factors are probably involved too. (Note: specimens from a particular lake on Wrangell Island and from Juneau were very toxic…but there are no garter snakes there; garter snakes are extremely rare in Southeast). Research continues.

Adult newts have dark backs and orange ventral surfaces. Toxic and venomous organisms often advertise their dangerousness to would-be predators, commonly with bright color contrasts. The combination of blackish and orange or yellow is one of these warning colorations, as in bumblebees and wasps. When an adult newt is threatened, it typically adopts a distinctive posture: arching the back, bending the head back over the shoulders and arching the tail over the body, thus displaying the warning colors. This color display deters at least some predators (and the presentation of a peculiar posture might look difficult to grab). 

Newts are carnivores, eating a variety of worms, snails, crustacea, insects, spiders and such, as well as the eggs and tadpoles of other amphibians (and sometimes those of their own species), and occasionally small frogs. Adults are semi-terrestrial, often occurring under logs and other damp places on land.

They mate in fresh water in spring (at low elevations; later at high altitudes), sometimes migrating overland to suitable pools. A courting male becomes smoother-skinned and slimy. Heclimbs onto a female’s back, hugging her behind her forelimbsand wrapping his hind legs around her abdomen. He rubs his chin on her nose, releasing chemical signals from his chin gland. If she is receptive, she lifts her head, and the pair stays clasped together for an hour or more. They change their positions, and he releases a spermatophore, which she picks up with her cloacal vent. Then the male usually mounts the female again for a while (sometimes many hours), which prevents other males from interfering while the sperm are entering her reproductive tract. Competition among males is said to be intense, and the mate-guarding behavior protects a male’s investment.

A pair of rough-skinned newts beginning the process of mating in a local pond this spring. Photo by. Bob Armstrong

Two or three weeks after fertilization of the eggs, a female lays them, singly, attached to vegetation. The eggs are toxic, like their mothers, and hatch in three or four weeks. Tadpoles have frilly, external gills and forage on protozoans and other tiny organisms on the vegetation, sometimes eating smaller tadpoles. Tadpoles metamorphose into adult form the following summer or the next summer, depending on the weather. Newts don’t mature until they are four or five years old, and mature females do not mate every year.

A frustrated avian predator

The second week of April began quietly, with a few snow flurries and early-morning new ice on my home pond. The ice was gone by midmorning and on the ninth, the first mallards arrived. Males and females, they swam in the narrow open channel between the ice and the bank or loafed on the ice platform in the center of the pond. And they came every day thereafter.

Seeds on the deck railing attracted the usual juncos, chickadees, and nuthatches. But one day a raven came. It marched the full length of the railing, snapping up seeds of all sizes, one at a time. Reaching the end of the line of seeds, it turned around and did the same in the other direction, until its crop began to bulge. Raven visitations have been extremely rare this winter, and I wonder what prompted this one to come.

One evening, I glanced out my front window and saw a hawk sitting on a dark lump on the pond ice. A juvenile northern goshawk had killed a male mallard, and a few fluffy feathers were strewn about. The hawk had one foot clamped on the duck’s bill, with the other one on the body. As the hawk pecked at the duck’s head, getting small tidbits (the mallard was past caring), it frequently looked all around, as if to check for possible thieves. Then the hawk tore off some body feathers and took a couple of bites, grabbed the duck’s head with one foot and flapped laboriously over to a nearby snowy bank, the prey dangling limply and precariously just above the water surface.The duck probably weighed about as much as the predator, so this was quite a load (although goshawks are known to take prey more than twice their own body mass).

A very damp juvenile goshawk tries to drip-dry on its perch. Photo by Mark Schwann

Once on the bank, the hawk changed its foothold from head to wing, but the prey slid down the steep little bank into the pond and floated immediately under a ledge of snow that stuck out from the bank. Now the hawk had a problem: from the bank above the duck, all it could grab was a wing, while the body was lodged under the ledge. The hawk tried several times to haul the body up over the ledge and onto the bank, taking intermittent rests in nearby trees. By now, it was starting to get dark, and the frustrated, slightly bedraggled hawk took off for a nighttime perch somewhere else. Apparently, the hawk never figured out that if it pulled the wing toward the ice, the body would come out from under the snow ledge and be available. Alas, no photo of all this action was possible without disturbing the process.

Meanwhile, although a squirrel scolded continuously, avian activity on the deck railing continued as usual, with the addition of a face-off between a nuthatch and a junco, which was won by the nuthatch. Ten minutes after the hawk left, other mallards came back to the pond where they’d spent most of the day.

By six-thirty the next morning, there was no sign of the dead mallard in the pond and no new scuffle marks in the snow on the bank. There were muddy footprints, probably of a dog, crossing the ice platform, but at some distance from the place where the duck was last seen. Hmmm, did the hawk come back and figure out what to do or did somebody else appropriate the prey? That all left a frustrated observer too!

Ah, but late that afternoon, I looked out my window again. And there was a river otter, munching away at the carcass on the ice platform, not far from where the hawk had struggled with it. The otter tore big gouts of muscle from the keeled sternum and stripped the long bones bare, mauling the carcass in all directions to expose more edible tissues. By the time the otter went for a cleansing swim, there was just a messy pile of feathers, guts, and bloody bones. None of that disturbed the mallards loafing at the other end of the ice platform!

After the otter swam around the pond (which did scare the loafing ducks) and departed, an eagle arrived. It found a few bitsleft by the otter, gobbled up the intestine, tore the tough gizzard into chunks, and flew off with the bones of the pectoral girdle and parts of two wings in its talons. A raven arrived in the evening, but too late! Only loose feathers and bloody ice were left. And so the duck’s death profited three other critters. A fitting end to the story!

This nesting female goshawk in juvenile plumage attacked the photographer, giving him a good clout on the head with her fists. Photo by Bob Armstrong

Note: The bird I watched was probably a year old (possibly two): its plumage was very dark brown with no sign of transition to adult plumage. Goshawks sometimes start breeding when they are only a year old and still in juvenile plumage, perhaps chiefly in low-density populations where competition for territories is not intense, but tend to have low reproductive success. Some reports indicate that individuals that don’t initiate breeding until age three or four tend to have better nesting success. Foraging experience probably contributes to success at nesting (and having an experienced mate to share chick-feeding duties might help compensate for inexperience in one member of a pair), but many factors, including prey density, prey species, and habitat quality, influence nesting success. Detailed studies are few.

Bits and pieces in early April

The first week of April brought us a little snowfall on several days. My home pond is still ice-covered, firm enough to support several transits by a big, galloping dog. The new berms are shrinking at last, and the one under my deck shows the old tunnels made by a neighboring squirrel in search of spilled seeds. One of my (indoor) cats is a regular window-shopper for squirrels, but one day his ears were unusually perked and he was very intently focused on something not far away. So of course I looked out that window—and saw a shrew exploring the old squirrel tunnels. The cat may not have seen one of those before, so his curiosity was roused.

Out on my deck, I’ve spread some bird seed on the railing, a temporary offering until I can restore the feeder than hangs over the pond. The winter gang of juncos is reduced to just a few (mostly males) and flocks are still seen in some places, although some can be heard singing and getting ready to mate; it seems like the juncos collectively aren’t quite ready for spring. The chickadees are fewer too, presumably setting territories somewhere. A pair of nuthatches seems to be resident and I hope they will raise another brood this year. Sometime in March, I began to see a pine siskin—just one. (How often does one ever see just one of them??). For two or three weeks, there was just one, and then suddenly there were two; an occasional third one was quickly chased off. Could they be nesting nearby?

A walk on the dike trail at low tide revealed a sizable flock of juncos; these were not yet setting up territories and advertising for mates. A loose flock of robins moved about in the grass, not settling long in any spot. On the river, eight or ten buffleheads, both males and females, kept together, occasionally diving but never straying far from the others. Dozens of mallards loafed on a sandbar, a few swimming desultorily just offshore. Not far from them was a very different duck, diving regularly. The bright russet head and upper neck suggested perhaps a Redhead; I did not see a pale crown stripe that would name it a European widgeon. Several trail-walkers notice a large, white bird, floating all alone, in a lagoon way across the river. We couldn’t tell which species of swan it was. Although tundra swans go to the far north for nesting, trumpeters don’t go so far and sometimes nest near the north end of Lynn Canal.

Photo by Kerry Howard

Along the Outer Point/Rainforest trails, wrens and varied thrushes were singing. A red-breasted sapsucker energetically tapped on a dead tree, sending out notices of his presence and readiness for the season. Not far away, I noticed a fallen hemlock trunk with old sapsucker wells all in a tidy vertical row. I’ve previously seen arrays of sapsucker wells that occupied patches of ten or twenty square inches on some trees. But those trees were willows and alders, which have smoother bark than hemlocks. So maybe the vertical row of wells was opportunistically exploiting a channel between thick bark ridges where the bark was thinner.

Sapsucker wells. Photo by Mary Willson

On the way down to the beach, a loud rattle was soon accompanied by a second one, not far away. It soon became apparent that two kingfishers were having a serious discourse, just above the tree canopy. They did not visit the rocks at the waters’ edge but went somewhere else, out of sight. Out on the beach, no mermaid’s purses (embryo cases of skates) had yet appeared in the washed-up piles of seaweed, although in other years they sometimes have shown up about this time. Just off-shore, a seal floated by on its back, sculling slowly along with just its nose and chin above water. Oddly, that seal was the only visible vertebrate critter in the bay; usually that place is more active.

Mendenhall Lake is still frozen and a few risk-taking skiers have been seen out there. The gulls are already circling and calling above the lake, contemplating a return to their nesting places on the west-side rocks, and then flying back out to sea–for now.

On a rainy day, the Boy Scout trail was a very quiet place. In grassy meadows, red berries of an herb sometimes called (very inappropriately) false lily of the valley or mayflower lay on the ground, awaiting the arrival of migrant thrushes that would gobble them down and disperse the seeds. Beach rye showed greenish shoots a few inches tall. Geese arrived in pairs, but there was one loner; eventually they all grazed together peaceably. I suspect these geese are our resident ones, already paired up. Gulls loafed on sand bars or frolicked in the water nearby. A scattering of big, empty horse clam shells dotted the lower beach. A flock of fairly small, apparently black birds with white wing patches whizzed by and may have been pigeon guillemots, although this seems a bit early for them. Two immature eagles were wading in the shallows while adults perched high in the trees. Not a single raven invited itself to a picnic lunch on the beach.

To end the week on a cheering note: the temperatures at my house crept up over fifty degrees for the first time this year.

Spring comes slowly

Winter came late this year—the good snows and cold temperatures didn’t arrive until after the new year began. One last observation from the winter: the creeks in the Dredge Lake area were frozen, and their icy surfaces held mini-forests of feathery ice crystals. A shrew had ventured out among those feathery tufts, mowing down a channel through them, leaving a trail rather like a big caterpillar. 

The vernal equinox has just passed and the now-dirty and rotten snow still lies over much of the ground. I looked out my front window at all that snow and my ice-covered pond a few days ago and was swept by a wave of nostalgia for the deciduous forests of the Midwest, with their wonderful array of flowering woodland ephemerals that bloom in early spring before the trees leaf out. When I was little, an elderly neighbor lady took me for walks, just to look at them. Years later, I learned to appreciate them in a different way, when my grad students and I studied the pollination biology of seven species of white-flowered ephemerals in Illinois woodlots. Other species soon flowered too, all taking advantage of the sunlight reaching the forest floor before the canopy closed. Never-mind that March is a tad early, even for those early-flowerers—I must be very ready for spring events here.

Trail-walkers comment on their impatience for the arrival of spring, and I’m just as eager as they are for the exuberant burst of spring that’s still in the offing. Meanwhile, signs of spring are appearing slowly, almost one by one. A couple of deer along the highway still had their thick, dark winter fur coats. But we hear juncos singing in many places, varied thrushes and wrens are tuning up, and robins forage in beach grasses. A dipper is singing at Steep Creek. The serious declines in bird populations here and elsewhere make each sighting or hearing more valuable than ever. Mountain goats are seen quite regularly near Nugget Falls, as they rest in the infrequent sunshine and look for edible lichens. Squirrels have done their mating chases. Elderberry buds are fat and almost ready to open; new shoots of devil’s club are becoming visible at the tips of the prickly stems.

As I await more and bigger signs of spring, there have been good things to see along the trails. One day at Fish Creek, a rotund otter rested at the edge of the ice that still covered most of the pond. After a few minutes, it dove and came back up in a crack a little farther offshore. There it dove repeatedly, but if it caught anything at all, the prey was very small.

Photo by Jos Bakker

Lots of elderberry bushes grow at the edge of the woods on the ‘island’ at the end of the berm. A friend and I were curious about bud development, so we inspected the branches. Yes, the buds were growing but, more interestingly, almost all the twigs at the branch ends were missing, chewed or torn off, although a few of the tallest branches had escaped mutilation. I have seen porcupines demolishing elderberry twigs and deer are known to browse woody vegetation in winter, especially when snow is deep, so there are two likely perpetrators—if they ever wander out to that ‘island’.

Out on the wetlands, an anomalous spindle-shaped form caught my eye, and binoculars revealed it to be the back view of a heron, standing sleek and still. It turned a little bit, and I had a beautiful view of its light-colored chest feathers, all fluffed out and fluttering in the breeze. I’d never seen such a huge ‘chest beard’ on a heron. No other herons were visible; maybe it was merely drying out its plumage (?).

Near Shaman Island, a harbor seal floated placidly, sometimes making short dives but mostly just looking round. A flotilla of red-breasted mergansers cruised by, two males and four females. The males had their long, green crests erected and occasionally thrashed the water with their wings; there may have been tension between them, but most of their cruise looked peaceable. One of the females drifted away and went foraging, but the others kept on sailing. Red-breasted mergansers often over-winter in salt water bays and estuaries and move inland to nest near big lakes and rivers. This merganser regularly nests on the ground, unlike our two other species of merganser. Their name derives from Latin words meaning ‘diving goose’, but they bear almost noresemblance to geese. The diet is mainly small fish, with some additions from invertebrates, snapped up by that narrow bill. 

My eagerness for full-blown spring will not hurry it along, so I’d best settle down and patiently(?) enjoy whatever I can observe as the days go by.

Winter in Juneau

Winter is an odd time of year here. Sometimes it rains, seemingly forever; sometimes a low, gray cloud parks itself over us for days; sometimes it’s absurdly warm but at other times it’s quite cold and the little bit of wet snow on the ground turnsrock-hard. Even expert forecasters don’t always get it right. When we’re lucky, there’s a good fall of deep, soft snow that makes skiers smile.

One such good snowfall at the end of February sent me and a couple of friends out on snowshoes, plonking around the big meadow near the Eagle Valley Center. That meadow often offers a fine winter record of animal activity on the snow, but on this day we didn’t even see the usual squirrel and porcupine tracks. However, we did see three long shrew trails, way out in the open. The deep snow had a very light crust on top, just enough to support a shrew without much body drag. This was long-distance travel, over many meters—looking for what? Near the far end of the meadow, we spotted the tracks of a medium-size canid that had poked around under some conifer branches and gone off in another direction. Nowhere on our tour had we seen any doggy tracks associated with the quite fresh human boot tracks, so we cheerfully decided that a coyote had been there(maybe).

Photo by Kerry Howard

Bird observation in winter is just as variable as the weather. Sometimes we see quite a few loons, of two different species, but no luck (for me, anyway) this year. Snow buntings and Lapland longspurs show up on the wide, grassy meadows sometimes. Magpies arrive from the Interior, but this year I haven’t seen as many as usual. Pine grosbeaks come too, but I’ve seen none at all, so far. Nor have I seen the occasional slate-colored form of the junco, which comes from the Interior. And where are the siskins and the crossbills??

Favorite occasional winter arrivals are small flocks of the elegant Bohemian waxwings, which sometimes can be seen foraging on mountain ash fruits. They get part of their name from little red blobs of ‘wax’ on the tips of their secondary wing feathers; the red blobs are bigger on older birds and (along with other features) may influence mating success. They are obviously not strictly Bohemian at all, being distributed over both North America and Eurasia, nesting in boreal forest regions and moving somewhat south (including to Bohemia) for the winter. They feed largely on sugary fruits, with additions from insects especially in the breeding season, and sometimes buds, flowers, snails, or other oddments. There has been little intensive research into their ecology.

Photo by Kerry Howard

Unlike the ever-changing winter weather and the often-unpredictable winter bird populations, trees stand there all year round. But they do their own kinds of changing.

The leaves of deciduous trees avoid winter problems by dropping off the trees. But conifer needles face cold temperatures, sometimes wind, and lethal water shortages if the ground freezes.  When the ground is thoroughly frozen, the needles receive no water and cannot conduct photosynthesis; then too much sunlight can be deadly, leading to the accumulation of free-radicals and other damaging particles. Needles have some built-in features that provide some protection, such as a waxy cuticle and a small surface area that conserve water and resin content that is resistant to cold. In addition, they may increase photo-protective carotenoids, and they have a lower metabolism at low temperatures and an ability to continue photosynthesis at a reduced level.

If, despite that first line of defense, ice crystals form in the cells, they can damage critical organelles inside the cell: the nucleus with genetic instructions, the mitochondria that control metabolism, the chloroplasts that house chlorophyll that captures light to initiate photosynthesis, and other miniscule particles that carry out normal procedures. The crystals also can ruin the cell membrane, exposing those organelles to damage and destroying the cells. 

Activated by short day-length and cold temperatures, there’s a second line of defense at the cellular level: cells make some changes to reduce that potential damage. Cell membranes become more pliable, as saturated fatty acids are replaced by un-saturated fatty acids, which freeze at lower temperatures. Some cellular water is moved out of the cell to the interstitial space between cells where, if it freezes, the crystals cause less damage. Furthermore, as interstitial water freezes, it releases a tiny amount of heat, which may help keep the cellular fluids from freezing. Inside the cells, starches are converted to sugars, lowering the freezing point. Lipid concentrations may increase too, and there can be some particular proteins that resist freezing.

Come spring, with warming temperatures and longer days, if the cells remained undamaged, those cellular changes are reversed, restoring the cells to normal conditions. Metabolic rates rise to normal and photosynthesis is again conducted at the usual rates. That’s an impressive array of seasonal adjustment in a seemingly simple thing like a conifer needle.

February trails

January whined its way toward its end, with seemingly interminable days of warm rain—what a miserable excuse for a winter. And then—surprise!!—a starlit night, a nice day, lower temperatures, and then some lovely snow. A great way to end one month and begin the next one. Yes, of course, I had to shovel my deck and the berm left by the city plow, but a neighbor helped with the heavy part of the berm, and altogether the wonderful white stuff was well worth the labor.

So it was ‘Find the snowshoes and let’s go see what we can see.’Partway up the Eaglecrest road, no parking was readily available near the lower meadows, so we ended up plonking around the ungroomed lower loop. We found several deer trails, partly obscured by recent snow. Snowshoe hares had been out in the night. And there were several fresh tracks of squirrel and weasel (no doubt in its white winter coat). There were no little birds in the trees and no signs of porcupine or grouse, which was unusual up there. But it felt like winter was happening!

Early in February, after a good snowfall, I wandered down the east side of Mendenhall Lake on snowshoes, relearning an old route. The snow had covered all the animal tracks, if there had been any, and draped the small trees with heavy white shawls. Strangely, the fog created an eerie illusion that the big rock peninsula on the west side of the lake had somehow advanced, so that it now approached the beach on the east side. Reassuringly, when the fog lifted for a while, the peninsula was back in its usual place. The highlight of the walk was seeing dippers foraging in the lower reaches of Steep Creek, one working along the edge of the creek and a second one soon joining.

In mid February, more snow…replacing what the rains had wrecked. A friend and I went to the meadows by Peterson Creek on snowshoes; that’s a place where we’ve had good animal tracking sometimes. Off we went, but our stroll was curtailed by high water in the numerous sloughs; it hadn’t been cold enough to freeze them. So the walk was short, but we found squirrel tracks, bounding from creek-side to the trees, deer tracks out in the open, and a long trail of porcupine tracks wandering hither and thither. The creek was running high and no dippers in sight.

A few days later, during a little snowfall, we wandered over the Outer Point Rainforest Trail. Along the forest trail, a wren did not care to be watched and zipped speedily under some logs. Out on the water, a little group of goldeneye ducks cruised lazily along. The glaucous-winged gulls loafed on rocky points and a few of them floated quietly, heads tucked next to the body, looking totally relaxed. Just one bird was actively foraging– a small grebe made repeated dives. 

On a rugged bedrock outcrop not far above the high tide line, a number of little potentilla plants flower in the summertime. On this February day, we expected to see only flattened brown leaves and decrepit seed stalks. But behold! There were ever-so-tiny green leaves peeping out from behind the protection of the old brown leaves! 

In the Dredge Lakes area, another friend showed me a lovely colony of a spectacularly orange fungus, growing on an old cottonwood snag. This is Flammulina populicola or velvet shank, a gilled saprophyte that grows only on dead poplars and aspens. It has the unusual habit of fruiting and producing spores in the winter (hence an alternative common name of winter fungus). It has special ice-binding proteins that keep ice crystals from ripping its cell walls (the proteins are similar to those found in diatoms and bacteria that inhabit icy waters). The brilliant orange color is best developed in light environments; if it is growing in the dark, the fungus is whitish.

Photo by Jos Bakker

A little walk on the dike trail began in a light snowfall but—in true Juneau style—it soon changed to rain. There were throngs of geese grazing out on the flats near the open water, a scattering of goldeneyes and buffleheads in a lagoon near the trail, but no mallards. An odd lump moseying along the edge of a not-too-distant slough attracted my attention and, with binoculars, it turned into a killdeer. I’ve been told that it is not very unusual to see killdeer here and in the Fish Creek estuary across the channel in the winter, when other shorebirds have gone south.

Photo by Bob Armstrong

Thanks to Jenifer Shapland for putting a name to the orange fungus.

Nitrogen

Nitrogen is essential for growth and development of living things. It’s involved with almost all aspects of life: in amino acids that constitute protein, in DNA and RNA that control genetic inheritance, in ATP molecules that provide energy for cellular metabolism involved in muscle contraction and nerve impulse propagation, in lots of enzymes that control physiological processes, and in some vitamins (e.g., B complex), and so on. It’s abundant in earth’s atmosphere, comprising almost eighty percent of all atmospheric gases. But it’s not in a form usable by many organisms, including all the ones we can actually see without a microscope.

This essential element is provided in small quantities by lightning bolts, which separate nitrogen atoms from each other and lets them bond with oxygen in the air, to be picked up by water droplets and dropped as nitrates to the earth in rain. However, most of the nitrogen used by living things is retrieved from the atmosphere by bacteria, many species of them. They have the machinery to ‘fix’ nitrogen into forms usable by other organisms by oxidizing it to nitrates (nitrogen with three oxygen atoms).) These so-useful bacteria live in all kinds of places: in the soil and decomposing litter, in root nodules of legumes (e.g., lupine, beans) and alders, inside conifer needles, certain ferns, fungi, and lichens, in water, on leaf surfaces in the crowns of trees and shrubs, on tree bark, and many other places.

Nitrates are water-soluble, so they can leach out of bacterial cells, fall with rain from leaves to the ground, ooze in and out of root nodules and roots, get picked up by fungal networks and so transferred to plants. Plants are the basis of most food chains, providing food for herbivores that are food for carnivores. Soils differ in nitrogen content and nitrogen is often a limiting factor for plant growth (witness the use of commercial fertilizers).

Vertebrae muscle tissues usually have about fifteen to thirty percent protein, by wet (raw) weight. Insects seem to have more protein, on average (but it’s highly variable), although some of that protein is in chitin (e.g., in the exoskeleton of insects), and apparently only some birds and mammals can digest chitin well. So, with some exceptions, animals that eat other animals seldom have problems with nitrogen supplies; the nitrogen in animal tissues is generally in a form usable by consumers.

However, in general, plant tissues have lower levels of protein (usually less than twenty percent by dry weight, often much less). Plant-eating animals (herbivores) consume fresh green plant material and the wet weight varies with the water content, which is highly variable, depending on growing conditions, among other things. For comparison purposes, try fifty percent water, giving less than ten percent protein in plants. Plants and plant parts differ a lot in nitrogen content, availability, and digestibility; for instance, young needles of spruces have more than twice as much protein as old needles—but still a relatively low value. Pollen and seeds tend to have more protein than the green parts.

Ptarmigan. Photo by Bob Armstrong

Herbivores feed on green vegetation that often has relatively little nitrogen, so how do they obtain enough nitrogen? Some forage selectively; for example, the giant panda eats mostly bamboo but it favors young bamboo shoots, which have more nitrogen than older shoots. Another way is to eat large volumes of vegetation, which is most possible for large animals with large guts (elephants, horses, cows). Or an herbivore may pass small volumes of vegetation through the guts rapidly (panda); aphids and other sap-sucking insects ingest lots of fluid in order to get enough nitrogen, excreting the excess water and sugar as honeydew.

Herbivores have a variety of specializations of the digestive tract. But fundamentally, all vertebrates (and invertebrates too) depend on vast populations of microbes to process food. Some plant-eaters do a lot of food-breakdown in the stomach, which is generally divided into compartments; examples are camels, kangaroos, hippos, sloths, and the ‘ruminants’ (deer, cows, sheep),which can burp up a meal from the stomach to be reprocessed by the mouth. The first stomach compartment (the rumen) holds populations of microbes that do the work of digestion. Other herbivorous mammals (horse, elephant, manatees, gorillas) have enlarged colons for microbial digestion. There are billions of these microbes, which have many digestive uses, but they have very short individual lives. When they die, their multitudinous bodies can be digested by still other microbes, which produce amino acids usable by the herbivore.

Deer eating alder. Photo by Bob Armstrong

Many herbivores have special physiological adaptations that allow them to recycle urea (a metabolic product of nitrogen digestion, which humans excrete in urine) back into the digestive tract where it is used by gut microbes. Herbivorous birds such as grouse and ptarmigan can reflux urine and digestive material back ‘upstream’ from the cloaca where it is collected into the large intestine to be reprocessed. Or those things can be refluxed into ceca (sacs attached to the intestine in which further microbial digestion occurs). Lots of small mammals and some birds have ceca, which can retain fluids and small particles that can be digested more easily than large particles in a second round of processing.

Still another means of recycling is ingestion of feces (coprophagy). Many small mammals (lemmings, rabbits) with ceca produce two kinds of feces: ordinary ones that have only passed through the intestine and cecal ones that have been reprocessed by the ceca before being excreted. Cecal feces, reprocessed, have higher nitrogen content than ordinary feces, and are consumed by these herbivores. Much of that nitrogen results from microbial activity.

Hoary marmot. Photo by Jos Bakker

Vertebrate herbivores have solved the problem of nitrogen acquisition in many ways! I’ve emphasized vertebrates here, in hopes of keeping this subject tractable and within my usual space limitations.

Bricolage for October

A walk down the Boy Scout Camp trail was notable for the near-absence of birds—no geese out in the big meadow, no gulls on or over the sandbars in the broad estuary, no eagles perched on stumps or trees, no ducks fiddling about in the shallow or resting on the sands. Very odd! On the way back to the car, we saw two or three gulls flying around and one eagle on a snag. Where is everybody??

The most interesting observations were the tracks in the sandy slough of a mama bear and a cub, who had wandered along there before heading over to the forest. Around the edges of the meadow, in several places, we found groups of dug-up lovage plants, leaving reddish stems behind–Bear-digs, for sure, maybe done by the track-makers. Strangely, we found no scat piles in any of these places.

We paused for a snack on the beach and, of course, the opportunistic ravens were there almost immediately. One was clearly dominant over the other, racing in to grab proffered bits and leaving the other one to complain in the background. Only rarely could the one in the background scoot around to grab a morsel.

Back at my home pond, a pair of female-plumaged mallards had been consorting all through September, occasionally joined by a third. (I assumed they were the same ones—they got very used to my daily disturbances at the bird feeders nearby). I was becoming convinced that they really were females, because I’d seen many males elsewhere in good breeding dress. But in early October, I began to notice subtle differences between the two regulars. Oooops! One of those girls is a guy! He’s just now starting to show a touch of green on the head and a shading of rusty color on his chest. This fellow is far behind many other males; maybe he is much younger? And will the other one eventually turn into a male also? A hint maybe came a few days later, when there were four males on the pond, all just beginning to show breeding plumage.

A break in the clouds and in the tourist traffic encouraged me to check out Steep Creek. The coho were in, and from the footbridge I watched a tattered female hover persistently over a stretch of gravel, probably guarding a nest. Off to one side, in a quiet pool, there were ten or so big fish, all lined up very close together and facing downstream. A couple of Dolly Vardens huddled with the coho for well over an hour. My companions suggested that they might be having a committee meeting, deciding what to do. That huddle was a puzzle—the eagle perched on the bridge railing was long gone, and so was a dog that splashed into the water on the other side of the creek. What was that huddle about?

Dippers were foraging on the lower creek and near the footbridge, swimming where necessary and wading in the shallows, poking occasionally at some potential prey. I was hoping to see them pick up some drifting salmon eggs, but no luck. They often snatch up loose eggs, such tasty bite-sized morsels. They aren’t the only ones to feast on them…Dollies hang out by spawning females and gobble up the eggs, and eagles eat them in gobs from captured female salmon.

Photo by Matt Knutson

A friend reported seeing varied thrushes and robins foraging on mountain ash berries, observing that the birds had stuffed themselves but then became uncommonly still. If the berries are now fermented, perhaps the birds were a bit drunk and not steady enough to fly. That often happens late in a warm season. Some decades ago, in late summer back in Illinois, people would bring robins and waxwings to my lab, thinking they were sick. So I’d put the invalids in big cages, give them ordinary food and water, and leave them in peace. By the next day, they had recovered from their alcoholic binge and were ready to head out the window for more. Bird-doctoring was easy in such cases.

That foraging observation triggered other thoughts too. The mountain ash berry crops are huge this year; the trees just droop with the weight of the ripe fruits. But several folks have commented to me that they don’t see the usual gangs of fruit-eating birds taking advantage of the bounty this year. And others have remarked that they just don’t see many small birds at all, in contrast to previous autumns. The fall weather has been unseasonably warm; perhaps there will be an influx of fruit-eaters later? There is a huge, worrisome decline in avian abundance in North America and elsewhere that’s been taking place over the years, and more and more species are at risk of extinction. Is the paucity of local autumn observations part of that general decline or some more idiosyncratic, regional trend?

Photo by Kerry Howard

Cottonwood trees near the lower part of the Perseverance Trail were nearly leafless, their branches beautifully emphasized by fog. Farther up the valley, smaller cottonwoods graced the hillsides with shining golden leaves. As the fog lifted, it left drops of water on leaves and twigs, and the coming sunshine picked them out as points of silver.

Water drops on plants

Gardeners sometimes see leaves fringed with droplets of liquid. The droplets are not dew or rain, and plants don’t sweat. So what are they? Those drops are a way for the plants to excrete excess water, perhaps taken up from very wet soil or resulting from metabolic activity. They are produced mostly at night. During the day, water is drawn up through the plant and evaporates from openings (stomata) on the leaf surfaces. Stomata often close at night, but root pressure still forces some water up to the leaves and out pores at the leaf edge. Production of those droplets is called guttation (from the Latin word ‘gutta’ for a drop).

Guttation drops contain not only water but also sugars, proteins, and probably minerals. The additional substances are associated with a variety of interesting interactions, nutritional, protective, or otherwise.

A recent study examined the guttation drops of a blueberry species native in eastern North America. In this case, the drops were produced both day and night, especially during shoot and early fruit development. Researchers tested the survival and egg production of three insects (an herbivorous fly, a parasitic wasp, and a predator) on a diet of guttation drops compared to diets of water plus sugar or protein (or both). Sugars and proteins contributed to longevity and fecundity: Survival was better on guttation drops or sugar water for all three insects and for the predator on sugar and protein also. In general, females produced more eggs on guttation drops and on sugars plus protein. In short, guttation drops were indeed nutritious, providing useful nutrients.

Furthermore, there were effects on the arthropod community. Lots of arthropods visited the drops on plants in the field. The most common visitors were ants, fruit flies, lacewings, crab spiders, and parasitic wasps. Researchers set traps near plants with guttation drops and those without drops. More predators and parasites were captured in traps near plants with guttation drops, although herbivores were not affected. Given that the production of drops in this blueberry is unusually reliable for a period of time, it seems possible that the drops contribute to biocontrol of pests.

In other cases, the guttation fluid might contain certain proteins that would protect the plant from motile microbes on the leaf surface that could invade the plant through the leaf-edge pores. Another study noted that grasses are often associated with symbiotic endophytic fungi that grow in the inter- cellular spaces and produce alkaloids that help protect the grasses from grazers; in some cases, the alkaloids get into the guttation fluids, where they might provide additional protection. On the negative side, there’s a certain kind of bacteria that causes disease in tomato plants and gets into guttation drops; any contact with a contaminated drop can then transfer the disease to another tomato plant. Corn plants germinated from insecticide-coated seeds produced guttation drops laden with that insecticide, which is lethal to honeybees (and presumably other insects) that might come to sip on the fluid.

Fungi also produce guttation drops, although the process by which they do so is apparently not known. There’s a certain fungus that attacks sugar cane, producing necrotic lesions by secreting toxins in guttation drops (just when the fungus is making spores). A fascinating interaction may occur between two facultatively parasitic fungi that can attack the same fungal host. The guttation drops of one of the parasites contains hydrogen peroxide (plus enzymes), which is generally toxic to the second parasite–and species #1 produces guttation drops chiefly when in competition with species #2 for the same feeding space on a host.

Guttating fungus. Photo by Bob Armstrong

Clearly, guttation drops can have ramifying effects on a variety of interacting species, although the possibility of such effects has not been explored extensively. There are probably lots more of these interactions still to be discovered—yet another way that plants (and fungi) can affect ecosystems!