Electric flowers and platform plants

…a hidden world of communication

Many plants produce flowers as a way of attracting animal visitors that can pick up pollen and move it to another flower. Flowers come in an array of colors—all the wavelengths we can see plus UV (which most humans cannot see). A yellow flower with a UV pattern is readily distinguishable from other yellow flowers—to the many kinds of animals (including insects and hummingbirds) that can see UV. That’s been known for many years.

However, flowers actually have (at least) two ways of enhancing their distinctiveness that humans generally cannot detect without special equipment. More recent research has found that plants can exploit another sensory system of animals. 

There is a natural electric gradient from the ground (negative) up into the atmosphere (positive). And around every plant and its flowers there is a weak electrical field. Flowers have a negative charge (like the earth they come from), but they bloom in positively charged air, creating a little electrical field. Around the flowers that electrical field is strengthened: the electric effect is best developed around edges, such as the rims of petals and the inner (sexual) parts of the flower. So the size and shape of the flower is emphasized and made even more distinctive.

Bumblebees and other insects can detect the presence and shape of the floral electrical fields and use the information to decide which flowers to visit. Bees detect the electrical fields with their fuzzy hairs. The floral electrical fields are weak, but they are strong enough to deflect the hairs (just a wee fraction of a degree) and set off neural signals that the bees can interpret. Bees’ antennae can detect the fields too but no neural signal is sent on. Experiments with artificial flowers (identical in color, shape, and size) with and without nectar rewards and with and without electrical fields around them showed that bees quickly learn to choose the rewarding, electrical flowers.

Further research revealed that hoverflies, which are also important pollinators, can also do this well. Their body hairs are deflected by small electrical fields and a neural signal is sent. The flies learn to read the signal and their efficiency and speed of finding floral nectar rewards increases.

This hoverfly can perceive electrical fields around the edges of the petals, the big white stigma, and the stamens of this fireweed flower. Photo by Bob Armstrong

Electricity also helps move pollen from floral anthers to insects, because insects have a positive charge and the flower a negative one. So loose pollen can actually jump small distances from anther to insect, even before the bug lands. If the plant is lucky, the insect carries the pollen to another flower. If not, a bee may groom the pollen off its body and packs it away in its pollen baskets to feed bee larvae.

Plants are commonly used as platforms for transmitting vibrational signals, usually among themselves. For example, treehoppers suck plant sap, often gathering in considerable numbers on plants. The treehoppers contract their abdominal muscles very fast, creating surface vibrations that move over the plant. We can’t hear them without the aid of special devices, but the vibes are picked up by the legs of other treehoppers. Those vibrations are like songs, varying in pitch and tempo, and are clearly interpreted by the receivers.

Some songs are used for courtship, drawing male and female closer together; a second male can jam the first male’s songs and decrease a female’s response, thus interfering with the courtship. Baby treehoppers (called nymphs) emit cries of alarm when danger is perceived; this elicits defensive behavior of the mother, who signals after evicting a predator, calming thenymphs. 

Lots of other insects (and spiders) can communicate with each other using plant vibrations. Many female insects use variation in male vibrations to choose the right species and the best male to mate with. It goes the other way too: males can use female vibrations to discriminate among females. Insects such as katydids make sounds we can hear, but they also make vibrational signals that indicate body size, and females prefer larger males. Leaf-cutter ants create vibrations when chewing into leaves; if it’s a really good leaf for growing fungi to feed the colony, the distinctive vibrations can recruit other foraging ants to exploit the good resource. The larvae of some insects use vibrations to attract others of the same kind or to keep competitors away.

A typical range of transmission for most of these vibrational signals is up to about two meters, although it can be longer for large insects and spiders. All vibrational calling is energetically expensive, and some studies have shown that an insect that calls a lot is not likely to live as long as one that calls infrequently. The host plants that provide the platform have different vibrational properties, so they differ in their signal transmission capacity. 

Some plant-based vibrations are not meant as communication among members of the same species. Vibrations produced by feeding, for instance, can be risky if it attracts predators—and lots of potential predators can track such vibrations. For example, a feeding caterpillar inadvertently gives vibrational cues to a predatory stinkbug and perhaps to parasitic wasps. In contrast, some butterfly caterpillars vibrate along with chemical signals to call in mutualistic ants to provide protection from predators. And there’s a spider that mimics the vibrational signals of the males of other species, to lure females of those species into hunting range for the mimicker.

Clearly, plants do far more than most of us ever imagined! That’s just a sample of sensory worlds that humans cannot experience directly. We miss a lot!

The stories of electric flowers and singing tree hoppers came mainly from a fascinating book about the sensory world of animals (An Immense World, by Ed Yong).

Fall fungi

…and some assorted flowers

It’s been a good fall for mushrooms and other fungi; the trail-sides have been decorated with a variety of forms and colors. One day, on the Horse Tram trail, I noticed a beautiful fungus on tree, a species of Pholiota (known as scaly-caps), probably the golden-fleece scaly-cap. It’s a wood-rotting saprophyte. Several days later, those golden caps had matured, opened, and turned gray. Most of the rest of the fungi have now deteriorated into messy lumps, but it was good while it lasted.

The golden fleece scaly-cap decorated this tree trunk for several days, before turning gray. Photo by Mary Willson

Some sharp-eyed hikers called attention to some strange-looking mushrooms that most of us have never noticed at all. These turned out to be not one but two different fungi in close association. A local mycophile identified one of the fungal participants as a species of Hypomyces. The many members of that genus are parasitic on other mushrooms, growing over the surface of the host, changing the surface color (to red or green or yellow or…), sometimes changing the shape of the host and even preventing the mushroom cap from opening for spore dispersal. The parasite sends filamentous hyphae into the body of the host and extracts nutrients.

A parasitic fungus in the genus Hypomyces covers another fungus, probably Russula. Photo by Deana Barajas

Each species of Hypomyces parasitizes just certain kinds of fungi—some on Amanita, some on Russula, some on Helvella, and so on. Many, perhaps most, of the hosts are mycorrhizal, forming mutualistic connections to various plant species and often connecting one plant, of the same or different species, to another. Those connections move materials among all the participants. When the parasites tap into those connections, it opens up the possibility that some nutrients from plants might end up in Hypomyces—which thus might be indirectly parasitic on plants. This adds a whole ‘nother layer of complexity to existing connections.

Of course, there are lots of questions to be asked about these complexities. Could the parasite, by drawing nutrients from the mutualistic host fungus, perhaps increase the movement of nutrients from the plants? How does that possibility affect the mutualism? Do the species of plants connected to the host fungus have an effect on growth and reproductive success of either the host or its parasite?  Hmmm, the ecology of Hypomyces is rife with unanswered questions!

In early September, a cheery little roadside plant was still flowering. It’s called eyebright, for its medicinal applications, and belongs to the genus Euphrasia. When I tried to look for more information about this genus, I found that the taxonomic complexities daunting. There are many species in the genus; they often hybridize and populations have evolved in different directions rather rapidly. Furthermore, the genus (with its many relatives such as paintbrush, lousewort, yellow rattle) has been transferred from one taxonomic family (Scrophulariaceae) to another (Orobranchaceae). So we need to update our field guides!

Eyebright blooms for many weeks, well into the autumn. Photo by Mary Willson

Like its just-named relatives, eyebright is hemiparasitic. It has green leaves and can photosynthesize its own energy-yielding sugars but it also makes connections between its roots and the roots of various host plants, often grasses and other herbaceous species. The host plant can affect the size and the time of flowering of eyebright, and perhaps other aspects of its life history.

Our local species is known as Euphrasia arctica. It’s a tetraploid (with twice the usual amount of DNA in its nuclei), so it may have originated as a hybrid. An annual, it often colonizes roadsides and other disturbed sites. The little white flowers are probably self-compatible but potentially out-crossing. The flowers may be visited by insects, but I’ve seen little visitation on the plants I’ve looked at. The fruit is a small capsule, with many tiny wind-dispersed seeds.

Thanks to Jenifer Shapland for identifying the fungi.

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.

Beavers

family-oriented rodents

Beavers (Castor canadensis) live in monogamous pairs (unusual for mammals) with their offspring. There may be several kits of the year plus some one- or two-year olds. Mating occurs in winter, gestation lasts about three months, and kits are born furry and active. They may nurse mother’s milk for a month or so but start eating solid food at an early age. Both parents and the older offspring help take care of the kits, who soon start swimming with the others to find food and observe the repair of dams. Offspring stay with their parents for two or three years before dispersing to find a mate and start their own family. Some have been known to disperse for many miles, including in salt water.

Each family is territorial, claiming a space and defending it against other beavers. Intruding beavers may be treated aggressively, but scent mounds at the water’s edge are used to announce ownership and warn off strangers. The mounds are built of vegetative debris and mud, anointed with urine that isscented by two kinds of glands that secrete oily stuff into the urine just before it leaves the body. Every beaver has its own combination of scents, permitting identification of individuals. Scents on the mound may be renewed frequently, especially if strange beavers are known to be wandering nearby.

Each family typically has one lodge, although sometimes additional simple burrows are used (for example, the male of a pair may move out, temporarily, while the young are being born). Lodges are constructed out of a pile of sticks in the middle of a lake or pond or modified bank-burrows with added sticks on top and near the entrance. A lodge commonly has an underwater entrance leading up to a platform used for drying off and then up to a living chamber, often floored with soft, dry vegetation. The sides of a lodge are usually plastered with mud, inside and out, and there’s a vent at the top (where hoar frost may develop in winter). Lodges in northern regions are quite well insulated, capable of keeping the inside temperatures near freezing even when outside temperatures plunge to minus thirty or forty degrees F.

Dams are built to create ponds deep enough that they don’t freeze to the bottom. They are built of sticks, mud, and vegetation. All members of the family work on building and on repairing breaches in the dam. In flat country, dams can be many meters long; in steep canyons, they can be over five meters high.In addition, sometimes beavers dig canals from the home pond out into the surrounding wooded area; this facilitates dragging branches from the woods back to the pond.

Trailcam photo
Photo by Jos Bakker

In regions where ponds are ice-covered in winter, beavers make caches of branches for winter food. Caches may poke up above the ice but the animals have access to the branches under the ice, and they seldom do much wood-cutting in winter. Although they can use any kind of tree or shrub, willows and aspens or cottonwoods are favorites. They eat the twigs and inner bark, with the aid of special bacteria that break down cellulose (in wood). In summer, however, they depend a lot on softer, herbaceous vegetation.

Beavers are the largest rodent in North America (and second largest in the world). They commonly weigh up to seventy pounds but occasionally exceed a hundred pounds. They’re heaviest in fall, after putting on fat for the winter. The muscular body is capable of hauling large branches for many meters.

Beavers have a very specialized way of life, maintained by behavioral adaptations (building dams, etc.) with a variety of physical adaptations to suit. They can stay underwater for fifteen minutes, if they have to, swimming more than half a kilometer. Their lungs are very efficient, capable of exchanging 75% of their capacity (three or four times more than humans) with each breath. Oxygen storage capacity is not outstanding but they have a high tolerance for carbon dioxide. The mammalian diving reflex works well; when submerged, the heart rate slows and most blood is shunted to brain and heart.

The big incisor teeth grow constantly; chewing wears down the back side of the teeth but leaves a sharp edge where the iron-hardened (and orange colored) front side of the teeth endures. When biting into wood, they commonly anchor the top teeth and actively chew with the lower jaw, which is moved by a powerful muscle in the muzzle. They can close their lips behind the front teeth, keeping wood chips out of the throat. The jaw joint is high on the skull, allowing the hard-ridged molars to meet in parallel for grinding vegetation. Eyes and ears are also high on the skull, so a swimming beaver can sense the upper world; ears and nostrils can be closed while underwater, and a protective nictitating membrane slides over the eyes.

Toes on the big hind feet are webbed, giving good thrust for swimming. The front feet are quite dexterous, the fingers adept at handling small items; they also carry wads of mud and vegetation while a beaver is swimming or walking. The wide tail is a multi-purpose appendage: a rudder when swimming, a brace when standing to chew a tree trunk, a stabilizer when walking on hind feet, sometimes a cushion for sitting on cold or lumpy ground, and the well-known tool for slapping the water to give the alarm signal.

Much of a beaver’s diet consists of woody material that is hard to digest. Beavers (and some other herbivores) have a special sac (a caecum) at the junction of the small and large intestines that houses symbiotic bacteria that break down cellulose. Partially digested food enters the sac, is further digested by the bacteria, and is eventually excreted as a soft pellet that beavers re-ingest, getting the benefit of the break-down activity of the bacteria. Regular pellets of material that did not go into the caecum are excreted as firm lumps of mostly sawdust.

The double coat of fur has long guard hairs covering softer, fluffier fur; the underfur is good insulation, trapping air and keeping water from the skin. The outer fur is waterproofed by grooming the fur with oils from anal glands; toes on the hind foot are modified to improve combing the fur while spreading the oils. That luxurious fur led to rapacious trapping for at least two centuries, resulting in near-extinction of beavers in North America. Sometime in the 1900s, better sense began to prevail and beavers have been re-introduced to many areas in order to reap the many benefits of their activity. Of course, such activities also conflict with some human activities, requiring some compromises. But that’s another long story…

Cavity-nesting birds

…seekers of snug places to rear their young

Nesting in a cavity—a hole in a tree, a burrow in a bank, or another enclosed space—gives a bird significant advantages. Cavity nests are generally safer than open-cup nests. The nest contents are concealed from predators (to some degree), although some predators can sniff out the nests anyway (think of snakes, monkeys, squirrels, marten and weasels, and so on). The cavity opening may be easier to defend than a wide-open cup. The eggs and chicks, and an incubating or brooding adult, get some protection from inclement weather, be it cold or hot or wet or whatever. For birds raising chicks in a nest (not applicable to ducks), nest-tending and food-delivery activities of the adults makes the nest a focus for observant predators; reducing the length of time needed for such activities reduces the risk of being observed and attacked. So open-cup nesters are in a hurry to get their chicks out of the nest, while cavity-nesting birds generally have longer incubation and nestling periods. 

If you put a dot for every cavity-nesting bird species on the evolutionary tree, the dots would be scattered all over the many branches of the tree. Clearly, cavity-nesting has evolved many times, appearing in such disparate groups as ducks, falcons, woodpeckers, owls, puffins, petrels, chickadees, nuthatches, bluebirds, flycatchers, and others.

In many cases, these birds depend on finding an existing cavity, perhaps in a rotting or storm-damaged tree, perhaps in a rock crevice, or perhaps in a hole made by another animal such as a rabbit or a woodpecker. Interestingly, sometimes closely related species differ in their use of nesting cavities: for example, common mergansers nest in existing cavities but red-breasted mergansers (in the same genus) make open nests on the ground. Birds that are dependent on existing cavities often face intense competition for suitable, available spaces, which can be limited in supply. For example, there are many observations of European starlings displacing bluebirds or tree swallows from cavities. Likewise, tree swallows and chickadees sometimes contest ownership of a nice cavity.

There are two ways around that problem. One is for each bird to excavate its own cavity. The most familiar excavators (to most of us) would be woodpeckers. All of the birds we call woodpeckers excavate holes in trees or tall cacti, but some of their relatives in the southern hemisphere or the Old World do not.

Hairy woodpecker. Photo by Bob Armstrong

Another excavator familiar to us is the belted kingfisher, which digs tunnels in earthen banks. There are many kinds of kingfishers; not all eat fish, but all are reported to excavate their nesting tunnels in earthen banks or termite mounds. A related group of many species, called bee-eaters, are also burrowers, often nesting colonially in earthen banks.

Other examples of excavators are found among the penguins, shearwaters, and petrels. The three species of puffin are usually dig burrows, the Atlantic and tufted puffins in soil and the horned puffin commonly in rocky places. All parrots make cavities for nesting, usually in trees, but one species stands out: the burrowing parakeet of Chile and Argentina regularly digs nesting burrows in limestone or sandstone cliffs. Three of the four species of North American nuthatches can excavate their tree nests from scratch, although all four more commonly use existing holes, modifying the cavity as needed. Our chickadees can excavate holes in soft rotten wood but often use existing holes.

The swallows, some of which are cavity nesters, provide an example of marked variation of nest type within one taxonomic group: Bank swallows (called sand martins in Europe) excavate tunnels in earthen banks, but rough-winged swallows generally depend on finding old holes in the banks. Tree swallows are not known to excavate but need cavities; cave swallows and barn swallows make open-cup nests. Cliff swallows, however, make covered nests of mud, stuck onto a vertical surface—which leads me to the second way of avoiding competition for nesting cavities:

Some birds aren’t cavity nesters (strictly speaking), but achieve some of the advantages of cavities by constructing a covered nest. The cover may be made in different ways, but it serves to conceal the nest-contents to some degree. Here are some examples: In Latin America, a large set of species typically constructs covered nests, often of clay; the resemblance to old-fashioned adobe bake-ovens earned them the sobriquet of ovenbirds. They are not, however, related to the North American ovenbird (a warbler), which builds a ground nest woven of plant material, with an entrance on the side. Marsh wrens and sedge wrens weave semi-globular nests of grasses and reeds; dippers, too, make bulky, more-or-less spherical nests of moss and plant parts, with a side entrance. Then there are the oropendulas and caciques of Latin America, the penduline tit of Europe, the orioles of North America, some weaver birds of Africa, among others, who weave bag-shaped nests, suspended from branches.

American dipper. Photo by Bob Armstrong

It would be wonderful if it were possible to unravel the genetic and ecological events that led to each evolutionary twig or branchlet with one or more cavity-nesting species, diverging from their open-cup relatives.

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.

Flower colors

variations in our local blossoms

The flowers of any species are typically controlled by genes and are usually of a certain color: bog cranberry typically has pink flowers, starflowers are white, forget-me-nots are blue, and so on. Biologists often think that deviations from those norms would break up the important relationships with the usual pollinators of each species, causing failures of reproduction. And perhaps that often happens. However, over the course of thousands of years of evolution, there must have been many mutations of flower color (including UV) and many of them must have found an adequate pollinator—otherwise we would not see the array of flower colors that we do. Natural selection favored some of those mutants, and they persisted, then becoming more common (and eventually the norm) in a population.

So it may be interesting to consider flower-color variation in some of our local species. In some species, flower color is almost constant across the population: e.g. lupines are blue, with occasional pink- or white-flowered individuals; northern geraniums are pink, with rare white-flowered individuals. In other cases, there’s a continuous range of hue: wild iris flowers are usually deep, rich purple, but some are paler, even lavender, while others are various shades of reddish purple. Rice-root (chocolate lily to local folks) flowers are usually maroon-brown, but some plants make flowers that are mostly yellow with brown lines, and there are many intermediates. On the road above Eaglecrest, there’s a stand of white-flowered river-beauty, not just one individual but an aggregation of them, quite unlike the usual pink-flowered ones.

Photo by Denise Caroll
Photo by Deana Barajas
Photo by Denise Carroll

That raises obvious questions about the pollination of these variants. Are the variations determined simply by genes or are there environmental effects too? Who pollinates the variants? Do pollinators favor the normal deep purple irises, or the brown rice-roots, thus reinforcing the norms? How well do the variants reproduce: Do pink or white lupines reproduce (as either pollen donors or pollen receivers) as well as blue ones; do yellow rice-roots do as well as brown ones? If so, could the variant colors spread? Could the white-flowered river beauties show how a variant could spread more widely?

There are cases of environmental effects on flower color, with potential consequences for pollinator interactions. The hues themselves are presumably determined genetically, but the environment affects gene expression—which genes are turned on or off, for instance. The best known, perhaps, is that in certain species of hydrangea the colorful sepals can be blue, or red, or something in between. Flower color in this hydrangea is sensitive to soil conditions: in acid soils that contain aluminum ions, the flowers are blue, but if the soil is alkaline or neutral, the flowers are pink or red. The color change may affect visitations by pollinators, but so far I have found no information about this.

However, in two other, less well-known, instances, flower-color changes on individual plants are associated with pollinator changes:

Moricandia arvensis is a type of mustard that grows in semiarid and arid ecosystems in the western Mediterranean area. Recent studies have found that the difference between spring climate conditions (mild, wet) and summer conditions (hot, dry) produce quite dramatic changes in the flowers produced by each individual plant. In one set of conditions, the flowers have large, purple petals that reflect UV light; in the other set of conditions, the petals are small, white, and UV-absorbing, with a different shape as well. Experiments showed that the floral changes are a response to changes in temperature and photoperiod that correspond to the seasonal shift. Conveniently, there were corresponding changes in the pollinators of the flowers (from long-tongued bees to small bees, small beetles, and butterflies) and seed production was achieved.

Equally intriguing is a recent study that found effects of herbivory on floral traits. Black mustard (Brassica nigra) is native to parts of the Old World and considered to be invasive on the Pacific coast of North America. Individuals of this species altered many floral characteristics in response to insect herbivory—reflectance of the petals, morphology, composition of volatile compounds, nectar and pollen production. If that’s not sufficiently amazing, then consider that the particular floral response varied with the specific insect herbivore. The pollinator fauna shifted too and successfully effected seed production.

These two examples, both from the mustard family, raise interesting questions. They are present-day examples of pollinator shifts; individuals of these two are sufficiently flexible to engage different sets of pollinators under different conditions. By so doing, they may extend their reproductive seasons or overcome some effects of herbivory. What is it about these plants that allows them (but not many others) to do this, and do any other plants do so? Maybe they do–and have yet to be discovered? It’s a fertile area for more research.

Fun in Gustavus

Swarming toadlets and mayflies, fungi-eating gnats, and other wonders

In the first part of July, I went to Gustavus for a short visit, and there was much of interest to be found! A walk near a shallow lake was the highlight. Thousands of tiny toadlets had recently lost their tadpole tails and were dispersing into the countryside.They thronged the lake edges, the gravel road that circles the lake, and the thick herbaceous vegetation on the far side of the road. Fortunately, that road had been temporarily closed to traffic, giving the little adventurers a chance to pursue their lives as terrestrial animals. Now, instead of filtering bits of aquatic vegetation, they’ll eat insects and worms and such. My companion and I walked that road very carefully, watching every footfall.

Toadlet. Photo by Bob Armstrong

Above the hordes of venturesome toadlets, the air was full of gossamer-winged mayflies. Adults had recently emerged, leaving their old exoskeletons on the lakeside vegetation. They danced up and down, occasionally landing on our caps. The adults don’t live very long, only a day or two (hence their name of Ephemeroptera); after the mating dances, females lay hundreds of eggs on the water and die. 

Mayflies have an unusual life cycle, with two ‘adult’, winged stages (Why??). The aquatic nymphs go through many molts as they grow, obtaining oxygen from the water through the integument primarily and, in older nymphs, through gills on the sides of the abdomen. The last nymphs empty their guts, fill the mid-gut with air, let go of the substrate and float to the surface. There, the exoskeleton splits open and wings come out, and the subadult floats for a day or so, until it is ready to fly. Then it flies to nearby vegetation, where it molts again, becomes sexually mature, and lives its brief life as a full adult.

Mayflies. Photo by Kathy Hocker

Along other trails, many of the hemlocks had yellow needles mixed in with the normal green ones; they were afflicted by the hemlock needle rust, a relatively harmless fungus. The life cycle includes alternate hosts of blueberry (Vaccinium) species—spores from hemlock develop on the leaf litter of deciduous Vaccinium species but on the live leaves of evergreen species, and send the next generation of spores to hemlocks. When we looked closely at the undersides of some of those sick needles, we found tiny (about one mm.) critters, probably fungus gnat larvae, nibbling at the fungal pustules. They were transparent but the innards were reddish.

On the Nagoonberry Trail, we noticed clumps of sodden white fluff at the bases of several spruce trees. These turned out to be piles of cottonwood catkins with burst seed capsules; when not sodden with rain, the cottony fluff lets the seeds disperse on the wind. In the piles I inspected, there were almost no remaining seeds attached to the fluff. That suggested to me that red squirrels had collected the catkins when they fell to the ground and stashed them, eating most of the seeds and leaving the fluff in a small midden. In fact, one pile of fluff was on top of the customary spruce-cone midden. A bit farther on, we found catkins scattered singly all over the ground, as they had fallen. In some of them, the seeds were gone, as if a roaming squirrel had snacked en route, not collecting them. All of that was my squirrely notion, but my companion was skeptical.

A gigantic spruce had developed a monstrous crack up its trunk, letting the tree topple over to lean on a neighbor. It had been so thoroughly infected by dyers’ polypore fungus that the entire trunk was rotten, falling apart in chunks.

We snacked on wild strawberries as we strolled along and saw plenty of signs that bears and coyotes had done the same, leaving scats containing seeds and sometimes whole berries. On the subject of strawberries, but not related to their seed dispersal: I was surprised to see them growing along the roadsides in the company of grass-of-Parnassus, an unusual association.

Plants of alpine bistort (Polygonum viviparum) were common along the trail. Toward the top, the flowering spike bears small whitish flowers that are capable of setting seed but reportedly seldom do so. The lower part of the spike bears fat little bulbils that develop directly into young plants, sometimes producing green leaves even before the bulbil falls off the parent. That’s what gives this plant its specific name ‘viviparum’—producing ‘live’ young (as opposed to seeds)—as if seeds or the eggs of animals aren’t really alive until they sprout or hatch.

Extra tidbits: Chickadees were rearing a second brood in a nest box. Juvenile ravens were caught by a trail cam as they scavenged fallen cottonwood catkins and carried them away (would they eat them or just play with them?). Leaf-roller moth larvae had left their alder leaf-rolls full of digestive products (politely called frass) after the larvae had (presumably) dropped to the ground to pupate. And the so-called Indian paintbrush posed its usual puzzle about variation in flower color, ranging from yellow to orange.

Diverse musings

on oystercatchers, pinesap, and spittlebugs

At the mouth of Cowee Creek, sometime in mid-June, we’d found a vigilant pair of black oystercatchers, presumably with a nest nearby. A couple of weeks later, a small group of hikers stopped at the same spot and quickly noted that the adult oystercatchers were tending two tiny, downy chicks. The chicks had hatched quite recently; their legs and especially their bills were still very short (it would be impossible to fit an adult-size bill inside an egg). One adult guarded them closely while the other made short forays down the beach for food.

Oystercatcher chick. Photo by Bob Armstrong

Black oystercatchers are beach-nesters; both male and female construct the nest, which is usually made of rock and shell fragments. There may be one to three eggs per clutch, incubated for about four weeks by both parents. Eggs are reported to be tolerant of flooding by high tides. The chicks can walk and swim well three days after hatching; after about five days, they start to peck at possible food items. Very young chicks are fed mostly by the male, while the female broods or guards them. Later, when chicks can follow adults to feeding sites, the female takes a more active role in feeding them. Young ones may begin to forage for themselves at about ten days, but they are just learning, taking fewer and poorer items than the adults. They gain weight quickly, but elongation of legs and bills takes longer. Even at seven weeks, chicks get much of their food from the parents, mostly marine molluscs, the large ones cut up into conveniently small pieces. They can fly, then, but in general they are not fully skilled at foraging until they are about three years old. Human disturbance can lead to prolonged incubation and fledgling times.

The trail down to Cowee Meadow provided a nice surprise—a small, yellowish-pink, peculiar-looking plant with no green color at all. This plant is called pinesap, and we don’t see it very often. Without green pigments, it is not capable of photosynthesis and making its own nutrition. It is indirectly parasitic, tapping into the mutualistic mycorrhizal fungi that connect many green plants and carry nutrients from one to another. Connections to those nutrient-transporting fungi turn out to be essential for growth and flowering, and even seed germination of pinesap. The plant is subterranean except for the inflorescence, which pushes its way up above ground. The flowers contain nectar, and bumblebees are thought to be the main pollinators (although there may be some self-pollination too). At first, the flowers are pendant, but they tilt upward when the seed capsule is mature, thus facilitating seed dispersal.

Pinesap

By the end of June, the herbaceous vegetation in many meadows was decorated with the foam ‘houses’ of spittlebugs. Adult spittlebugs (a.k.a. froghoppers) can fly as well as hop, and they forage by sucking sap from the fluid-conducting tissues of plants. Stealing sap from plants can reduce the health and reproductive output of the plant, so gardeners and farmers don’t like spittlebugs. The bugs are also known to transmit certain diseases from plant to plant.

Spittlebug sign on fireweed

There are many species of spittlebug; the best-studied species lays eggs in plant tissues in late summer and fall; the overwintering eggs hatch in spring. The larvae (called nymphs) are sap-suckers too. They disperse from the hatching site, and once they get to a good feeding spot, they tend to stay put, molting several times as they grow inside that foam ‘house’. They produce the foam by mixing air and excess fluid from the gut with secretions (from the end of the abdomen) that stabilize the bubbles. The foam helps protect them from predators and parasites, perhaps various micro-organisms, temperature extremes, and desiccation. Sometimes several nymphs share a foam ‘house’.

Sap is not very nutritious, but spittlebugs (and many other sap-feeding insects) have help: inside certain abdominal cells are very specialized symbiotic bacteria that provide amino acids and vitamins that are used by the host insect for growth and maintenance. These helpful bacteria are apparently passed from mothers to offspring.