Bricolage for October

bear tracks, fish eggs, and mountain ash

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.

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Water drops on plants

the process and functions of guttation

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!

Late September notes

quiet trails, fall colors, and dragonfly migration

It’s been rather quiet along the trails in late September: here a pair of hermit thrushes, there a trio of varied thrushes, and a stray robin or two. Coho were milling about in Mendenhall Lake, rumpling the water surface. From the beach on the west side, I watched a seal or two making bigger rumples as they tried to grab a fish. I saw no coho going up the west-side streams, as they usually do, but they were going up Dredge Creek on the other side of the lake.

I met a dog-walking fellow who remarked on his enjoyment of the fall colors, as we looked at the golden cottonwoods, yellow willow leaves, and the red/pink/yellow leaves of highbush cranberry. Dwarf dogwood has been spectacularly red along some trails, with small spots of color from trailing raspberry and nagoons. Along the lakeshore trail, new willow-roses were developing, showing brilliant red on a background of still-mostly-green willow leaves. The midge larvae inside will emerge next spring, having fed on the inside of the gall, and face the world as adults.

Willow “rose” midge gall

Meanwhile, I was sent a link to an article in a Wisconsin newspaper about huge swarms of dragonflies headed south on their fall migration. Tens and maybe hundreds of thousands of dragonflies were on their way, attracting so much public attention that they even made it into the newspaper (and there are other migrating swarms, on the east coast, near the west coast, and in between). Several species had joined the swarm, but the great majority of them were green darners (Anax junius)—possibly my favorite dragon, very snazzy. The Latin name means June king—“king” perhaps because of its large size, with a wingspan of almost twelve centimeters, bigger than most other North American dragons. They typically breed in quiet waters of vernal pools and marshes, where the females lay their eggs on aquatic plants. These mighty predators are able to capture and eat other adult dragonflies, as well as many other insects. They range over most of North America, coast to coast, from southern Canada to Mexico, Hawaii, and beyond. They don’t get to Alaska except by accident of vagrant winds. But their regular migrations take them from the northern part of the range to the southern part in fall, and back again in spring.

Green darners are well-known for making long-distance migrations and we now know a little more about their fall travels. The advent of miniature radio transmitters, small enough to be glued onto a dragon’s back, allowed researchers to follow their progress for several days. The dragons made an average of about twelve kilometers per day, with stopover days for foraging in between the flight days. They took advantage of northerly winds, after a cool night or two, and typically flew with the wind, although they seldom flew on very windy days.

The swarms are apparently more common in fall than in spring. Swarms are composed of individuals from widespread areas, gathered together in fall to follow shorelines, ridgelines, and other landmarks. Individual dragons bore natural markers in the form of isotopes that could be identified to their approximate sources; natural isotopes of hydrogen, for instance, can have one, two, or three neutrons, changing their atomic mass (‘weight’). The proportion of hydrogen isotopes (in water, for example) varies geographically (e.g., latitudinally), and this is reflected in the body composition of the critters that grew up in different areas.

A simple version of green darner migration divides things into three generations. Generation #1 emerges in the south in February to May, flies north, where it breeds and dies. Generation #2 emerges from that breeding activity in the north, flies south to breed and die. Generation #3 are the offspring of fall migrants and do not migrate; these residents breed and die in the south and their offspring migrate north in spring.

But it’s not really quite that simple! Individuals in the green darner population of some places (data from two studies in the north) seem to be comprised of individuals with two different migratory patterns. A given population may have some adults emerging and breeding in summer, whose slowly growing larvae overwinter in the breeding pond, emerging the next summer to breed there as adults. Other individuals in the same pond are small larvae in early summer (whose parents were spring migrants); these grow quickly, with adults emerging and breeding in late summer and fall, and then disappearing on fall migration. This makes it seem that these northern populations contain both residents and migrants.

Studies of the population genetics have shown that green darners have not differentiated into distinguishable populations but rather exhibit widespread similarities, which indicates genetic mixing throughout the whole population. Spring migrants probably do not go back to where the previous generation of their parental lineage came from; they may settle to breed somewhere along the way. Their offspring therefore cannot be closely adapted to particular rearing conditions in various geographic areas. So researchers now consider the possibility that the life-history differences (resident vs migrant) may be flexible. Perhaps the early larvae decide which life history to take on the basis of some environmental trigger.

There is much to be learned about migratory strategies in green darners. What cues do the migrants use for orientation on the long flights? How do they decide where to settle and breed? Do the offspring of a given female actually embark on differing life histories, depending on circumstances? If life histories are flexible, what are the triggers that determine which alternative prevails? Will the relative frequencies of the two pathways change as the climate changes?

Late-summer bricolage

a colorful songbird, a dragonfly encounter, and other observations

Good news from Kingfisher Pond: the male Common Yellowthroat that has been singing and hanging out in the low vegetation apparently got a mate! Because this species is uncommon here (although not in some other regions, hence its English name), I had wondered if a female would show up, and there was evidence that one did so. In mid-July, he was seen carrying loads of captured bugs, presumably to juveniles lurking somewhere nearby.

Photo by Helen Unruh

Revisiting Kingfisher Pond in early August, I found well-grown broods of ducks and a male red-winged blackbird who was still singing and frequently giving his warning whistles. So I guessed that he had some fledglings somewhere in the sedges.

On the West Glacier Trail I saw some agitated fluttering down on the packed dirt. I stooped to look more closely and saw a cluster of small, brown moths(?) having a serious tussle. Aha—one of them was a female, just a bit bigger and paler than the others. Two males were fighting to have-at her, wrestling and twisting and flapping so vigorously that that whole group skittered across the ground. Two other males were flitting about, hoping to join the fracas. The action went on for several minutes, and finally one guy won. She then wandered off with him, backward and upside down, still attached to her by the tip of his abdomen.

As I was bent over, hands on knees, watching that little show, other trail walkers passed by, giving me a wide berth. One kind soul inquired if I was OK and, being told that I was watching something, quickly departed. Not one passer-by asked what I found to be so interesting. Hmmm.

Above the tram on lower Gold Ridge on a foggy day, we found the frog orchids blooming. When we started back down the trail, a huge porcupine shuffled aside to let us pass and then moved a foot or two more into denser vegetation. Clearly it was not much worried by our presence and just wanted to have its lunch undisturbed.

On the Horse Tram Trail, toadlets from the big Amalga diaspora were still crossing the lower part of the trail in early August. I even found an extremely small one (less than 1 cm long) at the top of the hill, far from where most of the dispersers were observed.  It was accompanied by a grown-up toad about two inches long, an unusual association and presumably temporary.

Along that trail, some of the bunchberries had been chewed—something had left deep divots in the fruit, exposing what remained of the white interior. Slugs are the suspected perpetrators. But one day I found a little green caterpillar chewing on the red outer skin of the fruit, so there could be more than one nibbler involved.

Photo by Mary Willson

That observation made me think about larger consumers of bunchberries: What about vertebrates? The fruits are edible (if not especially tasty), and many kinds of vertebrates in other places are known to eat the berries. The list of vertebrate consumers is long, including grouse, thrushes, vireos, and sparrows, as well as black bears, marten, rabbits and hares, and rodents. Most of these critters would digest the fruit pulp and disperse the two small seeds inside each fruit. But what happens here? Some of the consumers on that list live here, but somehow, so far, I haven’t seen evidence of much vertebrate activity on bunchberry.

In early August, near Crystal Lake in the Valley, I was checking out the status of high-bush cranberry crops, which were just starting to ripen. Along came a German couple, exploring some Juneau trails on the multi-year adventure of sailing all over the world. They asked what I was doing, which led to a long chat on various topics. As we talked, a big dragonfly known as a blue darner came in, appearing to be very interested in us. It stayed with us for a long time, perched on our caps, our shoulders, our hands, and seemed quite happy to have its photo taken at close range. We all had fun with him, but I still wonder what he thought he was doing!

Photo by Mary Willson

Meanwhile, back at the ranch, I’ve been enjoying the numerous chickadees that throng the seed feeder over the pond—when the big blue bullies aren’t hogging it. A few juncos are here too, including some portly juveniles from midsummer broods.

Autumn arrives…

…gradually!

Fall is unofficially here, whatever the calendar says: fireweed has gone to seed, sending parachuted offspring into the breezes. Geese are numerous on the wetlands, with more arriving from time to time; more flocks are landing in the big meadow near the Boy Scout camp. Some male mallards are showing signs of developing their breeding plumage. Robins are flocking up and shorebirds have gone south. Cottonwood trees have a few golden leaves, which are released one by one to float gracefully to earth.

Most of the wildflowers (at sea level) have finished blooming. The tall stalks of cow parsnip stand sere and brown. Here and there I can find the very last flowers of lupine and beach pea, but yellow rattle and yarrow still have some fresh flowers, and yellow paintbrush looks good. Among the late bloomers are hemlock parsley and purple asters (not to be confused with the purple daisy, which usually blooms earlier at sea level). Marsh felwort is always late to appear.

The woods are showy with red berries: bunchberry, elderberry, baneberry, the native species of mountain ash, and devil’s club. It has been a good year for high-bush cranberry too; some of the flexible branches droop with the weight of fruit.

Here are a few observations from the last half of August:

–We spotted two small Columbia spotted frogs near lower Dredge Creek; they are known to breed in this area and at the community gardens.

–As I drove Out The Road one day, I noticed severe alder defoliation over long stretches of roadside. The woolly alder sawflies, assisted by the green alder sawflies, have been busy skeletonizing the leaves.

–I recently learned a new plant—a non-native perennial that appears in spots around here. I noticed it in a big clump at the beginning of the Horse Tram trail near the Eagle Valley Center. I was pretty sure it wasn’t a native, so I took a specimen to the Arboretum for the expert horticulturalist to identify. It’s comfrey (Symphytum officinale), known to gardeners as an exotic,noxious weed that spreads itself by thick underground stems(and presumably by seeds, but I found no information about seed dispersal). The pink flowers are pollinated by nectar-gathering bees, which are said to shake loose the pollen by vibrating their bodies when they are inside the flowers, but some bees can be nectar robbers and not pollinators. It is reported to be poisonous, but it also has medicinal uses.

–Along the dike trail, on the lower section before the gazebo, we noticed large stands of another invasive, exotic plant: hemp nettle, native to Eurasia. There are several species in the genus (Galeopsis). The small pink flowers are said to be bee-pollinated, but the species in our area may self-pollinate. This annual plant earns its nettlesome name by the fact that it is spiky all over (almost). The stem bears small sharp spines, the leaves are a bit bristly, and the narrow calyx that cups the base of the flower has major spines, several millimeters long. Woe betideany critter that bites or grabs this plant.

Hemp nettle

The seeds have no special device for dispersal and probably just fall to the ground, but they don’t remain viable for more than three years. A flower can make severaI seeds, which lie in the base of the cup formed by the calyx. Each plump seed is almostthree millimeters long. I was fascinated to learn that, in Europe, the seeds of an unnamed species of Galeopsis are harvested and cached by Willow Tits and used for winter food. I wonder how they do that (assuming that the birds harvest the seeds directly from the plant and not from the ground). For the species we have here (G. tetrahit), the narrow calyx cup is six or seven millimeters deep, rimmed with five sharp spines about four millimeters long. If the hemp nettle species harvested by willow tits is similar, wouldn’t the birds get stabbed in the face? And I also wonder if our chickadees will learn to do this!

–Another local naturalist observed some juvenile ravens at Eagle Beach. One of them carried a spruce cone, laid it down, and deftly extracted the seeds, one after another. Where did it get the idea—maybe from watching some other critter? Had it done this before? In any case, this seems like unusual and interesting behavior.

Photo by Bob Armstrong

Thanks to Elizabeth Graham, FSL-USFS, for info on alder sawflies, Ginger Hudson at the Arboretum for identifying comfrey and showing me the hefty rhizomes, and Bob Armstrong for the raven observation.

Bricolage

this and that from various explorations

There were good minus tides in May and June, and I went out with some friends to take a look at the intertidal zone in two places that we’ve checked in previous years. We found lots of small white cucumbers, numerous green sea urchins, and theusual sea stars, but fewer of them—and only one baby king crab, no whelks, few hermit crabs or lined chitons, and so on. In general, the diversity and abundances of intertidal critters seemed low to all of us who had looked there in other years.

Strange things have been and are happening in the regional and local environment. Sometimes devastation of intertidal communities is widespread; for instance, in 2021, high temperatures wiped out invertebrate populations, exposed at low tide, for many miles of coast in southern B. C and northern Washington. But locals surely would have noticed if such a major event had occurred here (although a recent Pacific marine heat wave may have left residual effects in our area). 

Other effects are more localized. Outbreaks of the wasting disease have damaged sea star populations. Heavy rains can overwhelm the local wastewater treatment system, so that ‘dirty’ water enters the marine system. The past winter brought very cold temperatures, big storms, and the risk of wind-chill toexposed intertidal invertebrates. Massive winter snowfall followed by heavy rains and unusually warm temperatures in spring increased freshwater input to coastal waters, and the present summer brought extremely high air temperatures for days at a time. These kinds of extreme conditions probably affected many intertidal animals (and plants). Such effects would probably vary among local areas, depending on exposure to sun and wind and freshwater input, slope of the rocky beaches, among other factors. As a marine biologist commented: things seem to be somewhat out of balance and the consequences are likely to be patchily distributed.

One day in July, I went out (on another good minus tide) to one of the places we visited in May and June, not wanting to believe the impression of a depauperate fauna. I didn’t change my mind on that, but I had one piece of good luck: lying on the mud under a small, flat rock, I found a little fish that was obviously not the usual gunnel or prickleback. It was a graveldiver! It had a long, thin body with a slightly knobby head—looking (as some have said) like a tiny snake; its tan color was distinctive (although some individuals may be darker). I found a good match for this creature in Aaron Baldwin’s on-line field guide(Sea Life of Southeastern Alaska, co-authored by Paul Norwood).

Graveldiver. Photo by Aaron Baldwin

That was exciting! But it seems that very little is known about the biology of these little fish—I reckon that they are hard to study in detail. Some researchers suggest that they may burrow very deeply and carry on their reproductive activities deep in the sediments and gravels. They have tiny, sharp teeth and are presumably predators. 

Bits and pieces from other places: Out at Pt. Louisa, I saw a shrub that looked strangely lacy from a distance. Close up, I could see that it was an alder almost all of whose leaves were severely skeletonized. The agents of defoliation had been chewing all summer, and I found the culprits working away on the few remaining leaves that had green tissue between the veins. They were woolly alder sawflies, a European species that occurs in various parts of North America, including British Columbia and Alaska. Female sawflies lay their eggs near the midrib of the leaf. The larvae are reported to feed first on the upper surface of the leaf and later move to the under-surface. The last larval instar of this species is covered with a white, woolly secretion, giving it its name. They overwinter in cocoons in the soil, emerging as adults next spring.

Woolly alder sawfly larvae

In mid-July, as I walked along the Boy Scout camp trail, I spotted an extremely small shrew, sitting in the middle of the trail, having lunch. I stopped and watched; it calmly nibbled away for a few more seconds and then scooted off the trail. I presume this was a young individual of one of our relatively common species here, which weigh roughly five or six grams as adults; the one I watched was that big. There are, in Alaska, two shrew species that are extremely small: the pygmy shrew, at about three grams (slightly smaller than most of our rufous hummingbirds), and the Alaska tiny shrew, at approximately two grams. But they live Up North and are not recorded from Southeast. (For the record, shrews are too small to store enough fat to overwinter, and they stay active all winter long, looking for food, burrowing through the snows.)

In Haines, there is time between ferry arrival and departure (after the loop up to Skagway and back) to take the convenient Haines Shuttle out to the Battery Point trailhead for a short walk; walking on conifer needles instead of roots and rocks was a treat. Baneberries were ripe; the common color is bright red, but there were two plants with white berries, an uncommonmutant form. Partway along that trail is Kelgaya Point, a lovely, rocky headland with a variety of micro habitats for plants. In late July, numerous small iris plants showed no evidence of having flowered, with one lone exception. A ground-covering mat of crowberry, which we more usually see at mid-elevations, had apparently produced no fruit at all. The flower show was provided by spectacular stands of yellow paintbrush and blue harebells.

Whelks

…and a growth form of hemlock

In the course of looking up some other information, I came across an interesting tidbit about whelks. Whelks are predatory snails; there are many species, belonging to several genera, some of which occur in our intertidal zones. Whelks generally feed by extending a proboscis that has a mouth, leading to the esophagus and stomach, and a file-like radula, bearing lots of small teeth, that shreds the flesh of the prey—conveniently near the mouth. The rasping teeth on the radula are replaced quickly when they wear out. Whelks often feed on bivalve molluscs such as clams and mussels, barnacles, and also various other invertebrates. Access to the body of the prey is commonly achieved by drilling a hole in the hard shell with the radula, assisted by secretions of a chemical that weakens the shell. In other cases, whelks insert the proboscis through a partially opened bivalve shell, sometimes wedging open the two parts of the shell with the edge of their own shell.

Dogwinkle (Nucella). Photo by Aaron Baldwin

Here’s the bit that sparked my interest: Whelks can learn! In lab experiments, European dog-whelks (genus Nucella, related to ones that occur here) were fed on mussels for three months and then were presented with barnacles as prey. Initially, they drilled through the outer shell of the barnacle, but after sampling just a few barnacles that way, they began to shift methods: They started to enter the barnacle through the opercular plates (valves that barnacles open and close when they feed on small prey).This mode of entry is easier and quicker than drilling thru the barnacle shell, so the profitability of whelk foraging effort increased.

Similarly, dog-whelks that were initially fed on barnacles and then encountered small mussels learned to focus on the thinnest parts of the mussel shells. When presented with large, thicker-shelled mussels, they learned to attack the shell at a point above he most nutritious part of the mussel (the stomach area). So, although the foraging effort was high, the food reward for that effort was high.

It turns out that they can also learn to avoid areas when members of their species have been injured or eaten by predators. And they can remember that for several weeks.

These whelks can learn by experience, although they don’t have a real brain. Instead, they have a set of paired nerve clusters (ganglia) in a ring around the esophagus. Those ganglia are well-connected to each other (and the rest of the body), but this arrangement is not called a brain. (Hmm, I know some critters with proper brains who do not learn so quickly!)

Western hemlocks sometimes have trunks that are deeply ridged and furrowed; this is called ‘fluting’. The ‘flutes’ are the furrows; the ridges are referred to as buttresses. Fluted hemlocks are most common along the coast, with western exposure, in situations where the trees are exposed to wind (e.g., near beaches and shoreline cliffs, in clearcuts or other openings). The so-called buttresses and adjacent roots develop most strongly on the side away from the strong winds. In Southeast Alaska, fluted trees are common in the dominant trees of even-aged stands.  Here, we see them commonly on west Douglas and near Auke Rec.

Fluted hemlock trunk

Flutes start to develop where branches emerge from the trunk, particularly when the branches in the lower crown of the tree become senescent and die. Researchers have suggested that branches interrupt the flow of nutrients to the cambium (the layer under the bark that lays down wood, among other things) in the trunk, and nutrients are not distributed equally around its girth. So the annual growth rings are not the same thickness all around the trunk—creating the ridges and furrows.

Cross section of fluted hemlock

Flutes often start to develop near the base of a young tree. They gradually get deeper and deeper, sometimes (after many decades of tree growth) closing right over the bark in the furrow. Then the flutes are not so readily visible from the outside.

It seems that most of the research about hemlock fluting was done some years ago. Many questions are still out there. Why are western hemlocks particularly susceptible to fluting? What about mountain hemlocks? Exactly how does a branch change nutrient flow to the cambium? How do fluted trunks compare to cylindrical trunks in resisting wind? Are there certain genetic strains that tend to develop flutes or that favor windy habitats? And so on…

Thanks to Robin Mulvey, USFS, for help in getting references on hemlock fluting.

Wild animals with injuries

Surviving against the odds

If a vertebrate animal has broken bones or lost the use of a leg, its chances of surviving for very long are usually small, and we seldom note their passage. Most die of starvation or predation. Sometimes a hardy or lucky individual manages to go on making a living for a considerable time, and there are a few scattered reports –a rabbit with a healed hind leg, or a shrew with a separated fracture in one leg, and an elk with a healing leg fracture. A couple of long-legged wading birds with misaligned leg fractures managed to survive. A few non-migratory curlews on a tropical island survived several years with broken wings and even a mallard (victim of hunting) is recorded with healed breaks in a wing. A rough-legged hawk was able to snag prey such as a rabbit even though it had only one functional leg; that leg later healed. 

Much of the evidence for such exceptional individuals comes from museum specimens that became specimens long after their wounds had healed. A nice example is a lynx in Spain: an old female had lost one foot, yet she had recently produced a litter of kits. Gray squirrels in Georgia showed healed fractures in thirty-seven specimens of a sample of over ninety specimens, including seventeen with healed long-bone fractures. A study of several species of small mammals in northeastern U.S. found that thirteen to twenty-five percent of adults had healed broken bones. 

These critters had survived despite serious impairments. They lived by the motto of a centenarian who (as various body systems faltered, one by one, and began to fail) said: “you just have to get on with it!” A coyote in Gustavus has been doing just that: this one has only three functional legs; one hind leg dangles uselessly. But for over a year, it had been hunting for itself, even making those wonderful leaps that pounce down on some rodent in the grass. 

Photo by Katherine Hocker

Many animals are able to self-amputate a leg or a tail—the list includes some spiders, crabs, centipedes, true bugs, salamanders, and lizards (notably NOT birds or mammals). This capacity is well-documented as a means of distracting or escaping predators or, in the case of arthropods, to free a molting individual from being stuck in its old exoskeleton. A self-amputated leg is even used by certain male invertebrates as copulatory plug after he’s mated with a female, to prevent other males from inseminating her.

There is, however, another possible function for self-amputation: reducing the damages associated with a serious injury. All the animals listed above are known to break off an injured appendage upon occasion, but the adaptive value of doing this has been little studied. A study of the leaf-footed cactus bug showed that there is, in that species, an advantage to cutting off a seriously injured leg: individuals that self-amputated survived better than those that did not. However, it was not clear exactly by what means survival was improved.

Self-amputation has costs, of course: the animal has to function without that limb at least until it regenerates or do without it. There may be some loss of body fluid and a risk of infections, although self-amputation takes place at particular places where healing may occur quickly. And there is the additional metabolic cost of regenerating the lost limb, if that is possible. To be adaptive, the benefits have to outweigh such costs.

Waiting for spring

Looking forward to the awakening season

As February became March, the longer days and a streak of relatively warm days meant that folks on the trails were greeting me with “It smells like spring!” and “Spring is in the air!” Of course, we weren’t really done with snow—one day in the second week of March, I slithered and slewed, creeping through deep slushy snow on the North Douglas highway, and my driveway was thick with the same.  More snow came a few days later.

Critters and plants are getting ready for spring, too. Ravens carry sticks to build a nest. Eagles are building too, bringing sticks to a growing platform that will, one day, hold some eggs in a soft cup. Mallards are seen in pairs on the wetlands; mergansers too. Juncos begin to sing, but not yet in full voice. There is a report of snow geese, the first of their kind this year.

Eagles nest-building. Photo by Jos Bakker

Plants also know what’s coming. Skunk cabbage pokes sharp green tips of folded leaves above the surface of ice-fringed ponds. Buds on elderberry and cottonwood are getting fat, preparing to send forth young leaves in a few weeks; buds on the rose bushes at the end of the dike trail are also showing promising signs. Woolly cinquefoil on a rocky outcrop above the beach shows green leaves tucked under old brown foliage.

Meanwhile, we’re still ski-ing the campground and the Montana Creek trail. The big lake and the ponds in the Valley are still covered with (softening) ice. The slate-colored form of dark-eyed juncos that visit us from the Interior are still here, coming to feeders along with the local Oregon form.

We all have signs of spring that we await eagerly and greet with glee. Here is a sampling of favorite signs from a few trail-walking friends (a few of these examples have happened already!):

–Pussy-willow catkins, males presenting pollen

–the squalling of varied thrushes

The first crocuses on a sunny bank. Photo by Pam Bergeson

— the first bumblebees, coming to crocus flowers and willow catkins

–mermaids’ purses (egg cases of long-nosed skates) washed upon a particular North Douglas beach

–the rollicking song of ruby-crowned kinglets

— early yellow violets

–wren songs from the thickets

–footprints of a bear, just emerged from hibernation

–arrival of sapsuckers, their drumming and tapping and calling

–the appearance of rufous hummingbirds (in addition to Anna’s, some of which stayed all winter)

–a flight of shorebirds on their way north for the nesting season

Spring swans. Photo by Jos Bakker
Blueberry flowers. Photo by Bob Armstrong

–alder catkins starting to get soft and limp, in preparation for releasing pollen

–the refreshing aroma of cottonwood buds (after some warm days and nights)

Looking for signs of spring as they develop is a big part of the pleasure in taking a walk at this time of year. Given Juneau’s assortment of microclimates, we can expect to see things happening at different times in different places. And the lookingwill only get better in the next few weeks!

Birds’ sense of smell

…they do have one!

A long-standing myth says that birds have no (or very little) sense of smell (olfaction). Myths usually have long lives, and this one became dogma despite many casual observations suggesting that birds can smell. Only gradually, over many decades, and facing lots of resistance, has the myth lost strength—and finally we can say with certainty that the myth is effectively dead. Birds do have a very functional sense of smell and they use it in many ways (just as mammals do).

Scientists have determined the genetic basis of the olfactory sense and birds have the requisite genes for appropriate receptors. Studies of birds’ brain activation during exposure to odors show definite responses, usually very specific to particular odors. The olfactory bulb of brains varies in size, but even the very small ones (representing a lower number of olfactory receptors) have exhibited clear functional responses. Anatomy, electrophysiology, and genetics back up interesting observations and experiments that clearly demonstrate the variety of uses for the avian sense of smell. Some examples follow:

The myth of no-sense-of-smell began to be perforated by the late 1900s; although at first, the few documented examples were just ‘exceptions’ to the dogma. The examples accumulated, and a number of birds were generally acknowledged to use olfactory cues for foraging. For instance, kiwis of New Zealand have a long bill with nostrils at the tip, and they use that long sniffer to grub for earthworms in the soil. Woodcocks in the northern hemisphere do that also. Carrion-eating turkey vultures can detect the aroma of freshly decaying meat (not rotten) far downwind of a carcass (sometimes misled by the same odor coming from leaking natural gas pipelines). Seabirds such as albatrosses and petrels can follow the odor plume of an aggregation of krill for miles, until they reach a concentration of that favorite planktonic crustacean. In Europe, storks can trace the smell of newly mown grass to find meadows for hunting bugs and rodents. European great tits and blue tits track down the volatile chemical aromas emitted by pine trees that are assaulted by insects, and there they find lots of prey. 

More myth-perforating information appeared from studies of navigation. For example: Homing pigeons exhibit an ability to locate their home lofts by smell, especially in conjunction with using visual, landmark cues. European starlings can return to their nest sites after being experimentally displaced for long distances, if their sense of smell has not been blocked. Shearwaters can navigate over the open ocean, back to their nesting colonies, using their noses.

Furthermore, several kinds of song birds, including European starling and blue tit, can detect the presence of predators such as weasels; parent birds spent less time visiting their chicks if the nest cavity was decorated with the scent of weasels. Hummingbirds often forage on flowers, but they are deterred by ants—not just the presence of ants but even the aroma of the ants’ formic acid (which they can spray to deter their own attackers). Several kinds of birds (e.g., starlings and blue tits in Europe, russet sparrows in China) add aromatic herbage, such as yarrow, milfoil, and wormwood, to their nests. The effects of the greenery seem to differ among the species, often leading to better chick growth–in some cases reducing parasites (ticks, bacteria), or reducing mosquito bites at night, or somehow improving the parents’ incubation patterns, and even affecting mate choice.  

Such observations and experiments completely shredded the myth and demolished the dogma. But there was still skepticism about the use of smell in social relationships among birds— Canbirds identify kin, sex, and the identity of individuals? Can theyuse olfaction in avoiding conflict or in courtship and mate choice? Oh yes! Many studies now have shown that the avian sense of smell is sufficiently finely tuned to be used in these ways too. Here are some examples:

Some birds can self-identify: kiwis can discriminate between the odor of their own feces and that of other individuals, and are said to show territorial aggression when another individual has been detected nearby. Some petrels and prions can identify their own nest burrows by scent alone, avoiding conflict that would occur if they mistakenly entered someone else’s nest burrow. Blue petrels can identify their own eggs and avoid those of other conspecifics.

House finch males can assess the quality and social rank of other males. Spotless starlings can tell the sex of other individuals by their odor, and male mallards get really revved up by the smell of females in the courtship season. Kin recognition by smell can be accomplished by some species (e.g., storm petrels, house sparrows, zebra finches), in some cases avoiding mating with kin, in other cases preferring to associate with kin. Antarctic prions can recognize their mates by smell. Young zebra finches can recognize the odor of their siblings and the natal nest.

How do the birds make such particular identifications? It’s likely that genes involved with the immune system are involved (as they are in mammals, including humans). These genes vary a lot among individuals and are known to affect odor (somehow).They may be dispersed over the birds’ bodies when oils in the preen gland at the base of the tail are spread over feathers as the birds preen to keep feathers in good condition. These genes have been associated with mate choice in house sparrows and petrels. House sparrows make mate choices in part on the immune system, avoiding individuals with too few immune-system genes, preferring those with a good diversity of those genes.Blue petrels prefer mates with immune systems differing from their own, although that was not the case for Magellanic penguins.

An intriguing example comes from crested auklets, a colonial nester on sea cliffs around the Bering Sea. In the courtship season, they engage in the endearing behavior of ‘ruff-sniffing’—nuzzling each other’s feathers at the nape of the neck. The feathers there are specialized, emitting a citrus-y aroma, which comes from certain volatile lipids called aldehydes. These compounds can deter ectoparasites such as lice, and one of them seems to indicate that the owner has good metabolic stress responses (perhaps indicating status and making it a good potential partner). Auklets are attracted to the scent, and sometimes the ruff-sniffing involves several individuals. Birds emitting lots of this aroma can transfer more parasite deterrent and they are more attractive; they are likely to be favored as mates. If the possible status-indicator is transferred, the recipient might then falsely advertise its (unearned) status. These parts of the story needs more study.

Crested auklets. Photo by Gary S. Drew

We can expect to see more and more research revealing that birds can use their olfactory sense in many different social ways.

For more on auklets’ ruff-sniffing, see this article.