Plants supplement their income

…with a dabble in heterotrophism


Green plants are called ‘autotrophs’, meaning that they feed themselves . (This is in contrast to all animals, which are ‘heterotrophs’ that gain nutrition by consuming other organisms.) These green plants feed themselves by photosynthesis, converting carbon dioxide and water into sugars (and oxygen). They also draw water and minerals from soils, and sometimes from water. So we are inclined to think of them as functionally independent entities, in terms of nutrition.

There are some salient exceptions to this simple plant-autotroph versus animal-heterotroph dichotomy. The carnivorous plants consume insects as a dietary supplement, so they are, in effect, both autotrophic and heterotrophic (see also A few plants are not green at all and live a totally parasitic existence, drawing nutrition from host plants; they could be called heterotrophic too. For example, dwarf mistletoe that infects hemlocks and other conifers in our forests is not capable of much photosynthesis, and depends on its host tree for nutrition. Heavy infestations can kill the host tree. (However, the witches’ brooms that they create are useful to squirrels and birds). Northern ground cone, which is common near the Visitor Center at the glacier, is parasitic on the roots of alders (and a favorite food of local bears).

However, most of the other, supposedly autotrophic, plants actually live in association with other organisms that supply nutrients. Many species, including orchids and blueberries, associate with fungi that supply important minerals to the plant; these associations are called mycorrhizal (fungus-root) (see also Some species, such as alders and lupines, form root nodules that are inhabited by nitrogen-fixing bacteria that turn atmospheric nitrogen into a form usable by plants. Many trees form natural root grafts with their neighbors, drawing water and nutrition from each other (and sometimes diseases too).

Then there are the so-called hemi-parasitic plants, which I mentioned a couple of weeks ago in this space. They are green and can photosynthesize carbohydrates and live independently, but which also commonly parasitize other plants. They often grow better and set more seeds when they tap a host’s resources, but a host is not absolutely necessary. Their effect on host plants is generally negative, reducing growth and seed production. As far as I can determine (so far), we have three kinds of hemi-parasitic flowering plants in our flora.

Indian paintbrush (genus Castilleja; about twelve species in Alaska): They grow from sea level to the alpine zone. The colorful bracts of the inflorescences range in color from red to pink to yellow. Some are pollinated by hummingbirds, some by butterflies (especially Down South) and some are pollinated by bumblebees. Paintbrushes can accumulate selenium from soils and become toxic to humans and other vertebrates. They parasitize the roots of grasses, herbs, and some trees.


Yellow rattle (genus Rhinanthus; one species here): It is also known as rattlebox or rattlepod. The yellow flowers are bee-pollinated. When the petals drops off, after pollination, the remaining green calyx contains the loose (rattling) seeds. A root parasite mostly of grasses and legumes, it is known to decrease the productivity and survival of grasses. Therefore it is used in some regions to restore meadows and prairies where cultivated grasses have been grown; by decreasing the cover of grasses, there is more room for wild flowers and thus a diverse community of plants. And the helpful yellow rattle plants eventually get shaded out.

Louseworts (genus Pedicularis; about twenty species in Alaska): Louseworts have their unfortunate name because of an old, very silly, belief that they caused grazing cows to have lice. There are hundreds of species of lousewort in the world, with flower colors of all hues. Most are pollinated by bumblebees or other relatively large bees, but at least one is also pollinated by hummingbirds. Only some have nectar in the flowers. Louseworts are root parasites, often of members of the heath family, such as blueberries.

The bottom line of all this is that green, flowering plants are not such independent entities as one might think. Many, if not most, of them interact with other plants, fungi, or bacteria to supplement their nutrition. Our forests and meadows would be impoverished without these interactions.

More August Observations

jumping mice, and the gift of salmon carcasses

Fall came early this year—the August rains seemed endless. I returned from a short hike almost as wet as I’ve even been (barring a swim or a nice hot shower). The creeks and rivers were ‘on a tear’, roaring along full of sediment, branches, and logs. Flattened grasses showed where the water had recently been even higher.

On the way home, I stopped at the grocery store. When I checked out with my purchases, a young gal offered to carry out my bags. I said “You don’t really want to go out in THAT!” She said, with a smile, “We live in Juneau,” as she picked up my bags. Good on ya, gal! (But I did carry my own bags out to the car, after all.)

An interesting, but sad, finding in the middle of the trail one day was a dead mouse. Not any old mouse, mind you. This one had a very long, bicolored tail, unusually large hind feet, huge ears, and magnificent whiskers. I thought it was a young jumping mouse, which I’ve never seen alive around here, although they are known to occur in Southeast. It was very thin and may have starved or drowned when its habitat got flooded. (However, the Museum experts said I was wrong—it was just a Keen’s deer mouse. Sigh. But I’ll tell you about jumping mice anyway!)

There are two species of jumping mouse in Southeast, but they are difficult to distinguish. Typically, they live in meadows, wet shrubby areas, and near marshes, and they eat bugs, fungi, and seeds. In summer, they build globular nests on the surface of the ground in tall grass or near small shrubs. They are said to be active only about three months of the year. They hibernate for about nine months, but reportedly many of them, especially the smaller individuals, die before the next summer if they don’t put on enough fat to last through the long winter months.

Near our backyard glacier, bears were actively foraging on sockeye, strewing partially eaten carcasses over the landscape. A yearling fled up a cottonwood when a big bruiser of a bruin approached; the youngster hissed and huffed from its refuge, but soon settled down for a nap.

On the ground near the viewing platform were many carcasses in various states of decay. One had been host to a teeming mass of fly maggots two days earlier, but now it lay limp and mostly decomposed. The maggots were dispersing into the surrounding mats of grass and moss (packed down by bear feet), presumably in search of pupation sites, where they could transform themselves into flies.

Many of the maggots never made it. A juvenile robin appeared and nabbed them one by one, working over several square yards of matted vegetation. The robin foraged repeatedly over the same area, getting more maggots with each pass. She captured several dozen juicy little bits of fat and protein in just a few minutes. A sibling joined her and foraged in the same area, but the first bird had the best pickings.

Photo by Bob Armstrong

Two juvenile Lincoln’s sparrows were maggot-hunting near another rotting sockeye, with much less success than the robins. Other small creatures come to capitalize on the fishy bonanza—juvenile hermit thrushes, a young varied thrush, a pine siskin, mallards, voles, and shrews. Nothing gets wasted, even in the absence of eagles, gulls, ravens, and crows, which scavenge carcasses on lower stream reaches. The surviving maggots make more flies, which nourish next year’s barn swallows (which nest nearby), warblers, and occasional flycatchers. Anything left gets leached into the soil, to fertilize the vegetation and, eventually, the stream. Research, both here in Juneau and in British Columbia, has shown that more birds nest near salmon streams than near streams that lack salmon runs, suggesting that the vegetation is more lush or that insect prey is more abundant around salmon streams. It could be said that salmon fuel the natural economy of Southeast.

Mountain Goats

extraordinary Oreamnos

One day in late March, I wandered toward the Mendenhall Glacier in search of mountain goats. March is often a good time to see them near Nugget Falls or across the lake on the big rock peninsula at the foot of Mt. McGinnis. Or even on the lake itself! In winter, mountain goats leave their summer range in the alpine and venture down into the forested zones, where they can find some food, albeit sometimes of poor quality, under the trees.

I had previously tried several times to find them near the glacier but I had been ‘skunked.’ And I was beginning to think that perhaps the rangers at the Visitor Center had locked up the goats somewhere (along with the beavers that are never visible in the beaver cam when I look for them).

Finally, on this day, I got lucky. There, just beyond Nugget Falls, was the elusive white beast. But wait—this one had eight legs! It was a nanny, with a nearly year-old kid walking right next to its mom, but on the far side of her, so I could only detect its presence by those supernumerary legs. I was too far away to tell if the nanny was pregnant with this year’s kid, which would be born later in the spring.

Female mountain goats in Southeast don’t reproduce until they are four or five years old, according to ADFG research. Then, if conditions are good, they may produce a kid every year for several years; if conditions are poor, they may skip a year. However, the probability of survival in Southeast decreases steadily after age four or five, and drops rather quickly after age eight or so.

Photo by Jos Bakker

Snow can create big problems for mountain goats, especially as they get older. Deep snow makes much of their plant food inaccessible and also makes travel energetically expensive, unless the snow is well compacted and can support their weight. Fresh snow on unconsolidated snow pack can lead to avalanches, a significant source of death for goats. I once found an entire skeleton of a fairly young goat (its teeth were not very worn) at the base of a long avalanche chute. In general, mountain goat survival in Southeast decreases as snowfall increases. Late winter and early spring are seasons of lowest survival, when the cumulative effects of winter difficulties take effect. Old animals and males are the hardest hit.

You might think that summer is totally benign, in terms of weather. But mountain goats can’t handle really warm weather. When temperatures rise, they tend to seek north-facing slopes, or shady spots behind rocks, or higher elevations, or at least a nice cool snow pack for resting. Average temperatures greater than about 48 degrees F in July and August are ‘hot’ even for young goats. The average temperature is correlated with the number of days that reached over 60 degrees F. Older goats may suffer heat stress at even lower temperatures. Recent ADFG research in Southeast suggests that warm summers are often followed by increased winter mortality, especially for older goats.

Why should warm summers create difficulties? One possibility is that high summer temperatures melt the snow rapidly, so that the ground vegetation all matures in a relatively short time. In contrast, a cool summer would melt back the snow pack more gradually, so that the emerging vegetation is exposed over a longer period of time. Some evidence suggests that young, emerging plants have higher nutritional value than mature ones. Then cool summers would offer high quality forage over a longer period of time than warm summers. Furthermore, higher temperatures may more directly cause lowered forage quality because the plants grow faster and contain more indigestible fiber. Cool summers also reduce heat stress and may allow goats to forage more efficiently and perhaps more often (if they don’t have to seek shade as frequently). Thus, cool summers might allow goats to go into winter in better condition than after warm summers.

Mountain goats, like some other alpine specialists, tend to develop localized populations that are genetically different from each other. For example, ADFG research has documented distinct goat populations east and west of Berners Bay, and north and south of the Katzehin River, with little movement of animals between populations. Relative isolation of populations often allows the development of local adaptations specific to each population, if environmental and demographic conditions are different, but it remains to be seen to what extent this is true for mountain goats.

Detailed genetic analyses by Canadian researchers has shown that mountain goats probably survived the last major glaciation in at least two refugia. Fossil evidence had previously supported the idea of a southern refugium, perhaps in southern British Columbia or thereabouts. But the more recent molecular data show that another refugium probably existed in northern BC or Southeast Alaska; goats from northern areas tend to be different genetically from those of the southern areas. In the thousands of years since the Pleistocene glacier began to recede, some movement of goats must have occurred, because some populations now consist of both northern and southern genetic types. Similar historical differentiation of northern and southern population is known for other mammals as well, including ermine, red fox, and mountain sheep.

North Douglas Rainforest Trail

mostly musings on tree bark

I have walked the rainforest trail on North Douglas I-don’t-know-how-many times, but every time there is something worth noticing—including some things that I’ve missed or just didn’t think about on past walks there. In mid January a friend and I strolled that trail again, just to see what we could see. It was a productive stroll! Here are some of the things of interest.

The hemlocks in that area commonly have ‘fluted’ trunks, with pronounced, rounded ridges running up from the base. This ropy-looking growth feature (no relation to the musical instruments!) is common in Southeast Alaska but less common farther south, for reasons unknown. The fluting apparently results when lateral transfer of nutrients is restricted, so some parts of the trunk get more nourishment than others and therefore grow better. Several factors, such as root or branch damage, have been shown to have temporary effects on lateral transfer of nutrients, but damaged trees can overcome the effects as they continue to grow. One study reported that trees exposed to mechanical bending by the wind are more likely to develop flutes than trees not subject to much bending; thus, trees on windy coasts or unstable substrates are more likely to develop flutes than inland trees. An experiment that stabilized the trunks of young hemlocks by running guy lines out to nearby trees showed that stabilization reduced flute development (as judged by growth rings) only in some years. So other, still unknown, factors must be involved as well.

The red alder trunks near the trail often bear belts of dark, rough bark with short vertical fissures. Some belts are only a few inches wide but others may be a foot or more in width. According to the forest pathologists (Paul Hennon and Robin Mulvey) at the Forestry Sciences Lab, these areas have been infected by the so-called rough-bark fungus that does not damage the wood but rather affects only the bark layers. Young alders are particularly susceptible to infection, but the rough bark remains as the tree ages. Scanning several trunks, I thought I could detect newer infections, just beginning to develop, that had bands of small vertical fissures round the trunk, without the dark color. Although this fungus seems to be common along this trail, a search for it in the Amalga Harbor area failed to find it, so the distribution appears to be localized.

We noticed that some of the rough-bark belts had several old, oval divots in the bark, above or below the belt. The divots bear a resemblance to the sap wells made by sapsuckers and we wondered if the birds had sampled these trees in the earlier stages of the infection. Or could the birds have helped to disperse the fungus by drilling wells, some of which are now covered by the rough bark?

Many of the hemlocks out here have rows of deep conical pits around the trunk (not at all like sapsucker wells). In addition, lots of the trunks have had the outermost layer of bark flaked off, exposing paler bark layers below. All of this is evidence of woodpecker activity—in search of bugs living in the bark crevices or burrowing under the thick bark. Some of the activity was quite recent, because flakes of outer bark lay on top of the snow. Who dunnit?? Not sapsuckers, because they are gone for the winter. Maybe three-toed or black-backed woodpeckers. Neither is common in our region—in fact, except for sapsuckers, woodpeckers are strangely uncommon in our forests. But why? One speculation is that local predators such as goshawks keep woodpecker populations down.

We found at least two vertical scars on older trees; the scars had been made a long time ago, because the trees had grown healing tissues over the edges, reducing the openings to narrow slits. Both scars were about four feet long and very similar to each other, located about eye level. Inside the slit we could see the flat, gray wood. We wondered if these scars could have had an anthropogenic origin and, if so, then what was the reason for people to make them. Or perhaps an adjacent tree had fallen along the trunk, stripping off the bark—a fairly common occurrence, but these scars were so similar to each other that this seemed unlikely. There’s more to be learned…

This walk was not just about trees, however. Large flocks of pine siskins swooped over the canopy. A mixed flock of golden-crowned kinglets and chickadees foraged on the beach fringe, talking all the while. A lone horned grebe in winter plumage dove in the bay, ignoring the mallards that nibbled at the water’s edge and the goldeneyes loafing near the point. Most interesting to me was a chance observation: I happened to turn around in a lucky spot and something caught my eye. A tuft of moss and grass stuck out of a niche in a tree trunk, so I went over to check it out. ‘Twas a bird nest—but maybe not just one! There were three layers piled one atop the other, as if three nests had been built here (I did not tear the structure apart to be sure). Perhaps some small bird had really liked this spot. Birds don’t usually renest in a site where their previous nest failed, so (if this was the same individual), she had been successful here before. Who was it? Possibly a junco…

On Bessie Creek Trail

a soggy slog and crossbill thoughts

I tried to second-guess Juneau weather the other day. The Parks and Rec hike was scheduled for Mt Roberts, up to the tram and the cross. I figured that trail would be a nightmare of ice, so I (with a friend) opted to go out the road—where it is usually colder, they say. So we hoped that the rain-and-snow mix that was falling in town would be just nice falling snow in the colder zone out the road. Ha!

Wrong! Out the road it was raining. The temperature was several degrees warmer than in town. And there was even less snow on the ground out there. It doesn’t pay to try to second-guess our weather!

Nevertheless, there we were—way out the road. So we went up the Bessie Creek trail, which starts just past Adlersheim. The quagmires that mess up the beginning of the trail were largely frozen and elicited none of the usual bad words from us. The route through the forest was quite passable: some snow, a little ice, and some open ground. Cleats were useful but not absolutely necessary.

I think Bessie meadows are at an elevation of about six hundred feet. Alas, the new-snow line was tantalizingly just out of reach, about a hundred feet or so higher. However, the existing snow was plenty deep for good snowshoeing.

We put on our snowshoes when we reached the beaver pond and the main meadow and then we strolled around the beautiful, rolling meadow in the rain. Someday I’d like to do the whole route from the Bessie meadows down along the south fork of Cowee Creek to the mainstem of Cowee Creek, and thence back to the road.

Early morning snow and all-day rain had blurred most of the animal tracks, unfortunately. A series of paired, rounded paw prints, with about four or five feet between pairs, suggested a large sort of weasel-relative. Some other creature had plunged deeply in the snow, lunging forward, but I couldn’t be sure who it had been.

We found a horde of pine siskins on the ground at the edge of the forest. They were busily picking up fallen seeds and chattering to each other. There could easily have been a thousand of them. Our approach sent them flying, but they returned to the feast as soon as we went by.

I heard a gang of red crossbills, foraging in the treetops. I’d never really understood how the crossed bill-tips served to pry open cones. But a good video is available online from the Cornell University Laboratory of Ornithology; this makes it all very clear. Once the cone scale is pried up by the crossed bills, the bird extracts a seed and removes the wing by holding the seed in a palatal groove while the tongue helps work the wing off the seed.

These crossed bills are somehow also capable of picking up seeds and grit from the ground, just as do birds with ordinary, straight bills.

Red crossbills are widespread in North America, and may comprise a group of closely related species. Different types of crossbill are adapted to forage specifically on certain species of conifer cones; some have large bills and large palatal grooves for large cones with large seeds, and others have small bills and small palatal grooves for small seeds. Each type of crossbill can also feed on other species of conifer, but they are most efficient on their own type of cone. Their calls are also distinctive, to the trained ear, and they seldom seem to interbreed. Red crossbills, and the related white-winged crossbill, move around seasonally, appearing in large numbers in a certain place and then moving on in search of better foraging.

After several hours of soggily tramping around, we got back to the car, wet but happy. And the Mt Roberts hikers? Well, it seems I was not far wrong in thinking that trail was a misery.

On the Lemon Creek Trail

porcupine sign, hemlock observations, and singing birds

For weeks I’d been wanting to explore the Lemon Creek Trail, in hopes of enticing Parks and Rec hikers to go there again, after a hiatus of several years. I know the first part of the trail well—up over the saddle behind Home Depot, from many excursions to a dipper nest site that’s approachable from upstream (after a short bushwhack from trail to creek). But just over the saddle is a small swampy area and another small creek, and the continuation of the trail on the far side of the swamp eluded me.

So, one day in late March, I headed up the Lemon Creek trail with two friends, one with two feet and one with four feet. The trail was pretty icy, and we met a guy who had turned back, but our ice cleats proved themselves once more. Near the swamp, we crossed the little creek on a snow bridge, but –of course—missed the spot where the trail resumed.

So we floundered on down to some alder thickets close to Lemon Creek where the snow was still pretty deep. Soon we noticed a series of elderberry stems that had been nipped off. Sometimes the nipped-off stem was still there, and then we saw that the leaf buds had been nibbled away. Aha! So that’s what the porcupines were after. Cut off the whole stem to get a few bits of budding leaf. Most of the elderberry bushes in this area had been pruned by foraging porcupines. I have to wonder why they like the stuff—it smells bad (to me). I think elderberry has defensive chemicals intended to deter munchers, but porcupines seem to be able to deal with them, or else they are desperately hungry.

After plunging through the snow for a little while longer, I said that I had a faint memory that the trail should be a bit up the slope in the conifers. So we peered up the steep hillside, well decorated with devils club and, indeed, it looked like a trail up there. Up we scrambled, and there it was. Now I knew we could follow it back and find where it connected to the little swamp. It was a decent day, with just a little misty rain from time to time, so, having regained the trail, we went on. And the rest was ‘cake’. The trail is clear and easy to follow, probably because the research teams that go up to the glacier have kept it open.

Along the way, we commented that porcupines seldom seem to completely girdle the hemlock trees from which they eat bark; usually they just sample a patch on one side. No sooner had we said this than we came upon a twenty-foot hemlock that was completely de-barked all the way around from about one foot high to about fifteen feet above the ground. What made that little hemlock so tasty, apparently? It was outcompeted (for light) by its much taller neighbors, so maybe it didn’t have a lot of energy to allocate to defensive chemicals.

We trudged and slid along, eventually dropping back down to a broad sand flat with lots of alders and the remnants of an old log bridge. Just upstream from here, the creek makes a ninety-degree turn, and so does the trail, which goes on up the valley.

Several years ago, Parks and Rec used to be able to walk up the road through the gravel pit on the opposite side of Lemon Creek, cross a bridge, and thus get to the wooded valley that comes down from the glacier. But nowadays, one gets to this point by almost two miles of trail from the trailhead behind Home Depot. After numerous side excursions to look at things, by the time we reached the sharp angle in the stream, it was time to turn around. So we perched on a log to share a snack while gazing at the creek and wistfully contemplating another day when that upper valley could be explored.

Our return trip was uneventful, although the snow bridge that held both of us on the outward-bound trip only held one of us on the way back. But at least I didn’t get my feet wet in the little creek!

The conifers were full of talkative pine siskins and a few crossbills. Juncos flirted around in the brush by the big sand flat. Varied thrushes sang all day. Kingfishers rattled up and down the stream, no doubt checking out cutbanks in which to dig a nest hole. A dipper put on a concert down in the creek. Best of all, we heard our first winter wrens trilling enthusiastically. But technically, we can’t call them winter wrens any more. The taxonomists have decided that the western winter wrens are genetically distinct from winter wrens in the east (and Europe, where they are called The Wren). Although the plumage differences are subtle, and the songs are not very different, the calls are reported to be distinctive. So now our wrens are known as Pacific wrens.

All in all, a good day. Mission accomplished, most pleasantly. Now to see if Parks and Rec will try this trail, come summer.

On the water

a whale watch trip stirs up questions

I don’t get to go whale-watching very often, but when I do, I usually see something interesting and new questions frequently get stirred up.

One trip gave us a good view of humpback whales doing their locally famous bubble-net feeding. Most of us here have seen this behavior at one time or another, but somehow it has not become ‘old hat’. How does a group of whales decide which one will create the rising, circular curtain of bubbles that rings a school of little fish? How did they invent this foraging tactic in the first place? Did it really originate here, and get carried to Prince William Sound whales by a wandering Juneau whale? How do they coordinate the upward rush of several whales through the panicking fish and avoid crashing into each other?

Another trip brought a troop of Dall’s porpoises, cavorting around the bow of the ship. The group grew, as additional individuals came zooming in from who knows where. They played there for some time, to the great delight of all on board. Then they disappeared, apparently on some magical signal; suddenly they were simply gone, vanished out of sight. Why did they all gather by our ship? And why did they go?

Then, in early September, we watched a small pod of orcas cruise by Little Island, where hundreds of Steller’s sea lions, of all sizes, had hauled out. Even the few sea lions that happened to be in the water a few feet from their dry confreres on the beach did not seem to be alarmed at the orcas passing nearby. Mammal-eating orcas don’t use their sonar to find prey, because mammals can hear the beeps. So we thought that these must be a resident, fish-eating bunch of orcas, using their sonar to find fish and therefore no threat to the sea lions.

As the orcas went on down along Ralston Island, we learned that this was actually a group of transient, mammal-eating predators, identified by a known mark on one of them. Nevertheless, no prey was visible and they acted (to our eyes) as if they were hunting fish: sudden, brief changes of direction and quick dives. This led to the question of whether mammal-eating orcas might sometimes snack on fish as well.

Then a small band of juvenile sea lions came into view from the opposite direction, seemingly oblivious of the jinking-around orcas—until the two groups of animals were very close. Then the sea lions really freaked out, caught between the rocky shore and the orcas. Much frantic splashing and churning about! As the orcas placidly went on their way, the sea lions calmed down and swam toward Little Island. What was going on here? Mammal-eating, transient orcas with already full stomachs? Just fun and games for the orcas? Mistaken identification by the sea lions?

Later that same afternoon, we encountered a scattered group of humpbacks doing nothing very exciting. But alongside our boat there appeared a solitary sea lion with something in its teeth. That sizable something was tossed and thrashed about until it was just a rag (and a few loose bits for the attending gulls). Finally we got a closer look and saw tentacles with sucker discs, just before the whole thing disappeared down the gullet of the sea lion. The octopus was caught at depth of over four hundred feet, not a very deep dive for a sea lion.