Seeing scenery

the benefits of immersion

Photo by Kerry Howard

Most of us appreciate beautiful scenery, be it driving the Going to the Sun Road in Glacier National Park or driving through the upper Midwest when the fall colors are at their best. Maybe we even stop here and there, to feel the breeze on our faces and sniff the fresh air.

When I’m in a beautiful place, however, I usually want more than that. Post-card pretty and fresh air are good but not entirely satisfying. I want to walk around in that place, hearing the local sounds, smelling the local flowers, touching the rocks and tree bark, as well as feasting my eyes on the local geology, plants, and animals. Basically, I love to experience some of the details of an area, not just the big picture but also the things that comprise it.

But to get the full experience of a place, I have to immerse myself in it. This takes a while, perhaps two or three days. On my solo canoe trips in the canoe country on the Minnesota/Ontario border, years ago, the first day out was a sort of shake-down cruise, getting used to packing and unpacking the canoe at portages, remembering how best to set up my tent, getting the feel of the paddle again. By the second day, my ‘civilized’ life was beginning to fade into the background, temporarily of no concern. Then on the third day, I could wake up in the morning and be totally IN the experience. And there I could stay for days on end, paddling to new lakes and new campsites, seeing and listening and feeling. Unbeatable!

When I cannot achieve that full experience, I can settle for a walk-about in some interesting place. But I have also learned that when I look at a lovely bit of scenery, I am often aware of some of the things that under-pin the scene. Not a fully conscious awareness– I’m not thinking actively about how the trees grow, or what the glacier did, or what birds might be nesting there. But at some level, I am aware of those kinds of things and they deepen my appreciation of what I’m seeing.

In a way, that is a little like listening to a fine piece of classical music (for me, who is not a musician, by any stretch of imagination). I’m not capable of being analytical of what I’m hearing—the modulations, the counter-points, and so on. The top of my listening mind usually dwells on the melody, but I’m very aware, at another level, of the bassoons and horns making the foundations and the middle voices breathing life into the piece. All of it has to be there.

Photo by Mark Schwann

However, there is yet another level of appreciating scenery (or the music, for a musician): looking for the underlying patterns and thinking about their meanings. There are some who say that the close focus often needed for science and analysis gets in the way of appreciation. Indeed, there are folks who habitually ‘can’t see the forest for the trees’, and that is no doubt true for all of us some of the time. But it is possible to see both the trees and the forest—to see the trees as part of the intricate network of the whole forest, not isolated beings but part of a complex set of interactions. In fact, recognizing the interconnectedness that makes the network often leads to better science, while simultaneously enriching the experience of viewing the scenery.

Every scenic place has stories to read and music to hear, if one chooses to do so.

Golden-crowned kinglets

tiny, but mighty

Female golden-crowned kinglet. Photo by Mark Schwann

Golden-crowned kinglets have appeared in these essays several times, but never as the main feature. So I decided to devote most of one essay to these tiny birds. I was prompted to do so on an autumn walk on the Outer Point/Rainforest Trails, when I saw a few golden-crowns right at eye level, fossicking about (and talking ) in the understory. Golden-crowns nest and often forage in the tree canopies but, especially in winter, they may come down to search for semi-dormant arthropods on the twigs.

They are resident here, staying all year (but migratory elsewhere), in contrast to the ruby-crowned kinglets, which nest here but migrate south for the winter. Golden-crowns are generally a tiny bit smaller than ruby-crowns (averaging 6 g vs 6.5g, respectively). Both species forage chiefly by gleaning arthropods from leaves and twigs, but golden-crowns occasionally eat fruit, and are usually higher in the trees, more often in conifer than deciduous forest, usually farther out on branch tips, and they are said to be surface-gleaners more than ruby-crowns, which are often hover-gleaners. The soles of the feet of golden-crowns have grooves that are thought to be adaptations for foraging on conifer needles and twigs, facilitating clinging and hanging downward. Golden-crowns have slightly shorter hind toes and lower legs, and their bills are slightly smaller; those morphological differences may (or may not) be related to the different foraging habits, in ways yet to be determined.

Both kinglet species belong to the genus Regulus (‘little king’), which is widespread in the northern hemisphere, with six or seven species (depending on who is counting). All these species have colorful crests that can be erected at will. The ruby-crown, however, is the only one that lacks black stripes around the crest, and it is sometimes classified in a different genus. So our two kinglet species are not each other’s closest relatives. The nearest relative of the golden-crown is thought to be the goldcrest of Europe. Kinglets were formerly considered to be classified with the European warblers (taxonomic family Sylviidae), based on very similar appearance (but without the crests on warblers), but now it seems that the kinglets are classified in their own family, the Regulidae, on the basis of nuclear and mitochondrial genetics.

In winter, golden-crowns often join mixed-species foraging flocks, usually with chickadees and nuthatches, occasionally with downy woodpeckers and brown creepers. Golden-crowns may huddle together in small groups, somewhere in the conifer foliage. In the eastern U.S., there’s even a report of them going into leafy squirrel nests. They don’t have especially good insulation from their plumage, and they don’t put on fat in the fall; although they can gain a little weight by foraging each day, they lose it overnight. In cold conditions, they don’t become hypothermic, although ruby-crowns do. Instead, apparently they just gear up their metabolism and generate heat. However, bad winter storms can bring high mortality, possibly because foraging is difficult.

There are few detailed studies of breeding biology, in part because golden-crowns typically nest high in dense conifer foliage (however, they are reported to nest in willow scrub on an island in Alaska). Both male and female build the nest, which is suspended from stems or twig forks near the end of a branch, and protected overhead by foliage. Many different types of materials are used, including twigs, moss, feathers, hair, lichens and so on. The nest is deep with thick walls; the inside diameter is about four cm, while the outside diameter is about seven cm. In that tiny cup are laid eight or nine miniscule eggs, usually, which the female incubates for about two weeks. The male brings food to her while she does this. The nest gets crowded when the chicks hatch and grow, and their activities stretch the nest walls. The chicks fledge in about two and a half weeks, fed by both parents; they become independent of their parents after another two and a half weeks. Remarkably, the parents are reported to be capable of producing two broods of chicks a year, the pair staying together for both broods. The average life span is probably rather short, but some have been known to live about six years.

Male kinglets erect their flashy crowns during aggressive encounters and when alarmed, showing the orange-red center surrounded by the gold. I found no information on possible use during courtship nor on female displays of the golden crown. The intensity of crown color is likely to be linked to successful foraging and a supply of carotenoids that come from the diet; its possible role in mate choice is not known. Researchers in Ontario, where golden-crowns are migratory, suggested that more colorful crowns might reflect body condition, because more colorfully ornamented birds left earlier on southward migration.

Male golden-crowned kinglet. Photo by Gwen Baluss

The nesting density of golden-crowns was greater along stream reaches with salmon runs than along streams without salmon, as has been shown for other species too. Golden-crowns strongly prefer intact tree canopies—their density went down after logging clear-cut various-sized patches of trees, and they avoided buffer strips, being almost absent from strips twenty meters wide.

There is much to be learned about this diminutive insectivore, both in terms of basic natural history and its ecological requirements.

Observers with good hearing may hear golden-crowns talking with their very high-pitched notes as they move through the canopy. Then it’s fun to see if one can spot them in action, way up there.

December bricolage

a familiar woodpecker, eagle art, and an assortment of snow-loving bugs

A female hairy woodpecker visits my suet feeder regularly, and I’d bet any money that she is the same one that came all summer long, as a juvenile, in the company of a male, presumably her father. She learned well from her dad, and she still comes.

One day in mid-December, I spotted her wrapped around the suet feeder, her tail curved around one end as she pecked away at the other end. A sudden fluttering caught my interest, as another woodpecker landed briefly, to snatch a quick bite. The new arrival stayed just long enough that I could see her small bill and also see that she was much smaller than the hairy woodpecker. So there was no doubt about it; it was a downy woodpecker. I’m told that they seldom nest in our area but we sometimes see them in the off-season.

On a gray and foggy day, I turned on to the road by the Pioneers’ Home, where the line of young cottonwood trees is often used for perches by eagles scrounging from the nearby dump. On this day, half a dozen eagles were hanging out on the cottonwood branches. In the fog, the eagles were black, the graceful branches were black, the whole array artistically displayed like silhouettes on a silvery backdrop. Splendid!

A few days later, I wandered down the east shore of Mendenhall Lake, then cutting over to the Moraine Ecology Trail. Some post-holing, some bush-whacking, a wet foot from finding a soft spot in the ice—but the quietness was pleasing. The sound of Nugget Falls and scattered raindrops tapping on my cap—that was it. Aaah—maybe a red squirrel chattering over in the woods. I found a thriving, bright green patch of stiff clubmoss, poking perkily up out of the snow, still bearing immature cones. Surprisingly, there were no hare tracks, but beavers had been busy in a couple of places, packing down a trail between ponds, dragging a few branches over the snow, and starting new cuts on some big cottonwoods. An ermine had bounded from one clump of brush to another. The only observable activity was provided by two small, flying insects, maybe midges.

Seeing those little fliers reminded me of other ‘bugs’ that come out on the snow, at least on days of mild weather (although some caddisflies spend the whole winter as winged adults). Several kinds of arthropods, from many different taxonomic groups, can be active in winter; here are some of them: a variety of tiny flies known as midges are active in winter; most fly about but others are flightless.  Males of a moth called Bruce’s spanworm fly in late fall and early winter, mating with wingless females that lay their overwintering eggs in protected sites such as bark crevices. There are winter-active craneflies that dance in swarms, mostly in fall and spring but also in winter, and stoneflies that emerge in late winter, crawling onto land to mate. A fungus gnat can tolerate very low temperatures because it has an antifreeze protein in head and thorax (but not the abdomen, which can freeze and apparently thus reduce evaporative water loss). The famous iceworm (it’s really a worm, somewhat related to earthworms) lives on glaciers, crawling down into cracks and crevices where the temperatures are said to stay about thirty-two degrees Fahrenheit; so they don’t freeze and can go on feeding on microscopic algae and detritus.

Springtail. Photo by Bob Armstrong

And then there are the springtails, non-insect arthropods, most of which can hop about using a forked appendage on the abdomen. Several kinds can be found hopping or crawling over the snow, looking for microscopic bits of food or dispersing to new places. Their predators are out too, including spiders, beetle larvae and danceflies (see photos). A study of one kind of dancefly found that males swarmed near selected landmarks on sunny, windless days in winter, at temperatures as low as eight degrees centigrade. The males carried captured insects to lure females to the swarm, presumably eventually using the prey as a courtship gift.

A dance fly with a springtail. Photo by Bob Armstrong

Thanks to Bob Armstrong and John Hudson for guidance about winter arthropods.

Ice and quiet

exercises in active stillness

One day in early December, a friend and I set out to check part of the West Glacier trail and the route along the lakeshore. It was raining, of course, as it had been for days seemingly on end, but the fierce winds had abated. We thought the several creeks that flow across the beach might be flooding (as lots of other creeks were) and too deep to cross happily with just hiking boots on our feet. But the first couple of creeks were no problem; that was encouraging. We eventually got to a deep, wide creek that was too much for us, so we detoured up to the main trail, crossed a convenient bridge over that stream, and went right back down to the beach.

Walking along the cobbly beach allowed us to have what little light was available on that dark, dismal day. As we approached the north end of the beach, we began to see huge, thick plates of ice stacked up on the shore, perhaps the works of those terrific winds a few days earlier. In some places, the ice plates were stacked up four or five deep.  Some ice plates, maybe shoved by the slabs arriving behind them, had plowed into the gravelly beach, raising a berm about a foot high.

Photo by Kerry Howard

I know nothing about the physics of ice fracturing. Many of the slabs had well-defined corners; only a few were very rounded. It seemed that quite a few of those corners made a nearly perfect ninety-degree angle. That was probably  just a random happening; I’d need a big sample to find out!

Lunchtime at the end of the beach, before straggling up the muddy cut-off trail to the main West Glacier trail. It was very quiet out there—just the roar of Nugget Falls across the lake, the tapping of some rain drops on my cap, and an occasional clunk of one slab of ice lightly hitting another. We talked about what ‘quiet’ means.

Those of us who live in town often think of our places as quiet. There are sounds of traffic on the roads, airplanes overhead, boats on the channels, the garbage truck dumping the trash can, sometimes people talking while passing by, not to mention the ordinary sounds of the fridge or the furnace turning on. We learn to tune out the noises that are familiar and ignore the temporary intrusions. And we call that ‘quiet’.

Although almost no place in the real world is totally silent, I thought it might be interesting to find out what we can hear in places and times when all human-caused noises are absent and no tuning out is needed. Fortunately, here in Juneau, we can find suitable places and times for this exercise rather easily. So I enlisted the aid of a couple of friends to do a little sampling. The ‘game’ was to find a place and time devoid of anthropogenic sounds and then spend four or five minutes just listening. To do this requires some (brief) concentration, allowing no potential mental distractions, such as an eagle flying high overhead or a mink running across a beach or any worries you may have brought with you.  

For the record, here are a few of the listening samples we obtained, in the middle daylight hours, in early winter.

–Eagle Beach: wind rushing through the tops of spruces while lower branches rustle more gently; rain drops plinking on the water surface and thudding on rocks, waves lapping the shore, a raven calling overhead, a red squirrel chattering in the woods.

–Boy Scout beach: distant call of a gull, faint sound of gull wings just offshore, wavelets coming onto the beach.

–Nugget Falls trail: roar of the falls, ravens calling from the slopes of Thunder Mountain, a gull’s call, sound of ice cracking on the lake surface.

–Basin Road: a flock of chickadees conversing in the trees, the creek rippling over rocks, a gentle breeze stirring spruce branches, raindrops on the observer’s hood.

–Auke Rec: surf, wind in the trees, rain hitting the rocks, raven calling, Barrow’s goldeneyes calling.

–Horse Tram Trail meadow (two observers): distant waterfall on Peterson Creek, distant water to north, ravens to west and north, unknown bird near the meadow, a crow, companion dog walking and breathing.

Not very exciting, eh?  It was about as quiet as it can be, out there. That’s part of the point. A poet called such a time of conscious attention an ‘active stillness’. The exercise is a little like a short meditation, with the focus directed outward, but I find that the peaceful effect is internalized—a little relief from other concerns and whatever tensions were building. A moment of calm that, for me, is similar to the peace that comes with some well-loved pieces of classical music, with the addition that there is a feeling of connectedness to the natural world.

It’s not an exercise for everyone, of course. You have to be ready for it.

Early winter walks

confluence tracks, a caddisfly on ice, and an orphaned bear

A visit to the lower reaches of the Herbert and Eagle rivers usually turns up something of interest. A recent warm spell meant that looking for critter tracks in snow would be a vain endeavor. However, the sands were well-decorated by several animals.

Deer tracks old and new went every-which-way. One trackway went right to the last bit of sand and disappeared, so that deer probably swam the river. Maybe it took advantage of the current to arrive at some point well downstream. There were mink track and a good print of a small otter. Beavers had trekked back and forth over the sand bar, one of them recently toting a twiggy branch that left a well-defined pattern. Local beavers had a big cache of small branches for feeding little, growing beaver-lets through the winter.

Perching on a convenient log and pulling a snack from a backpack had the often-predictable result of attracting a black-feathered opportunist. This raven was obviously an experienced moocher and stood expectantly less than fifteen feet away. So the snack was shared. As experienced as that bird was, it approached tidbits tossed only three feet away with the characteristic sideways hops, ready for a quick dash to safety if needed. Just as the supply of snacks ran out, another raven came in and missed the fun.

The west side of Mendenhall Lake caught the brunt of some very strong winds in early December, piling up big plates of broken ice. I went back out there a week later, when a light snowfall had brightened everything. The ice plates were still there, but this time one of them featured the only wildlife seen on that walk: a caddisfly. One of the big chunks of ice was tilted up, and the critter was walking down the steep edge. As it did, a small bit of ice broke off below its feet—I like to think that the insect kicked it off. Someone said it looks like the critter is climbing down its own Denali.

A winter caddisfly, sometimes called a snow sedge, walks down an icy ridge on the shore of Mendenhall Lake. Photo by Kerry Howard

This caddisfly has a name (probably Psychoglypha subborealis) and a nickname (snow sedge). It is winter-active: both males and females have been found at times of very cold temperatures—as low as minus twenty or thirty degrees Centigrade, having emerged from their freshwater larval stage in the fall. When they emerge, they are adult in form but sexually immature. They mature gradually during winter, using up stored body fat in the process and females developing their eggs. They mate and lay eggs (in open fresh water) in early spring, and then apparently die, after a life span of roughly six months.

This caddisfly is not unique among insects in having a life history involving winter activity, but there are not many spend an entire phase of their life history in winter. I wonder about the ecological pressures that led to the evolution of such an unusual habit. Certain kinds of stoneflies customarily emerge, as adults, from fresh water streams in late winter, as soon as the streams aren’t completely covered with ice. Temperatures are often below freezing, but these winter stoneflies have ways to cope with the cold. They are interested in mating at that time, maybe getting a head start for their larvae in the streams?

On a group hike to Crow Point and Boy Scout beach in mid-December, when there was nice, fresh snow on the ground, I found some mouse tracks, a vole highway between grass clumps and some wanderings, and a set of squirrel tracks. Weasel tracks were all over the place—maybe hunting was not-so-good and lots of searching was needed? Or are there lots of weasels out there? We watched a small black bear cub in the tall grass, where it was digging persistently for some time, apparently finding edible roots. There have been reports of an orphaned cub in this area (and elsewhere), and this one was all alone. However, it seemed to be fending for itself reasonably well, and although it was not very chubby, we hoped it could eventually hibernate successfully.

An orphaned bear cub forages in the meadow near the boyscout camp. Photo by Denise Carroll

Splash power

using raindrops for dispersal

Some weeks ago, I wrote about spore dispersal in bird’s nest fungi, in which the mature spores are held in a small cup and when a raindrop falls into the cup, the spores are splashed out. I decided to learn more about what other species use raindrops for dispersal. It turns out that raindrops have been put to work, so to speak, to disperse spores, seeds, little asexual propagules, and even sperm.

Splashcups are apparently the most common means of using raindrops. Seed dispersal from splashcups has been reported for many genera of plants, including some that grow in our area: Veronica (brooklime or speedwell), Sedum (stonecrop), Sagina (pearlwort), and Mitella (bishop’s cap). However, I’ve not been able to confirm that our particular species of these genera have this adaptation. Something to look for!

Splashcups for seed dispersal are typically small, just a few millimeters across, and more or less funnel-shaped, with the sides of the funnel not too steep and not too spread out. Small seeds are splashed out at various speeds, up to a meter or so away from the parent plant. Splashcup plants are generally small, herbaceous species; they grow in a variety of habitats.

Some mosses use splashcups too, for dispersal of sperm from male individuals. The raindrops give the sperm a head start on their way to receptive females, but once started, they have to swim to their final destination (thus needing a film of water to complete the journey). The juniper haircap moss (Polytrichum juniperinum) here in Southeast is one of these, and other local haircaps may also do things this way. Other moss genera in Southeast with this adaptation for sperm dispersal include Atricum, Plagiomnium, and Mnium, but again I’ve not succeeded in confirming that our local species do.

Another moss uses splash cups made of modified leaves to disperse ‘gemmae’, which are asexual clusters of cells that can germinate and form new individuals. This moss is called pellucid four-tooth moss (Tetraphis pellucida); it disperses its sexual spores by wind. Although it is found in south-central Alaska, Yukon, and B.C.—that is, all around our area, but there’s apparently only one record, so far, for Southeast (in Sitka).

The lung liverwort (Marchantia polymorpha) occurs all over Southeast and belongs to a genus known for gemmae dispersal by splashcups and raindrops. In addition, males bear their sex organs on little, stalked ‘saucers’ (not the technical term!) and sperm are released onto these saucers. When a raindrop hits the loaded saucer, the sperm can be dispersed as much as sixty centimeters away. Then they have to swim, in a film of water, to a female.

A familiar lichen genus is Cladonia, some of which are known as ‘pixie cups’. These make stalked cups that contain little asexual granules (technically called soredia) composed of bits of fungus and algae that are enough to start a new lichen individual. These tiny granules can be splashed up to a meter away by a raindrop, but they may also travel by wind.

Another type of raindrop-assisted dispersal is thought to occur in Tiarella (foam flower), which we often see here. The seed capsule is shaped like an old-fashioned sugar scoop, with a long lower lip. A rain drop hitting the lower lip could flip out the seeds. This spring-board mechanism is also seen in some club-mosses (Lycopodium, including our local L. selago), which disperse little vegetative, non-sexual propagules (called bulbils) this way.

Fungi have a couple of other unusual ways of using raindrops or at least water drops for dispersal. Some of the puffballs release spores when the tender top of the mushroom is struck by raindrops. Certain fungi (not specified in the available literature) release spores by a water-drop-driven catapult: There is one drop (apparently produced by the fungal spore) at the base of a spore and one (source not given) along the side of the spore. These two drops merge, creating a big enough drop with reduced surface tension so it breaks open, pushing the spore from its attachment and popping it loose.

See this video by Bob Armstrong for an example of fungal dispersal by raindrop.

Raindrops even get involved in pollination of flowering plants. In some buttercups (Ranunculus) and marsh marigolds (Caltha), rain splashes pollen from the anthers (where pollen is produced) to the receptive stigma of the same flower.

All those splashcups and springboards and catapults are evolved adaptations of the respective species. They function to the benefit of the plant or fungus by increasing reproductive success via successful dispersal.

However, raindrops may also have non-adaptive effects, such as transmission of foliar diseases. If a raindrop hits a leaf infected by bacteria, viruses, or fungus, it bounces, potentially carrying the infective agents with it in a water drop. The distance carried depends on many factors, including water-drop size, leaf shape and orientation and its motion when hit by the rain drop, and location of the original infection on the leaf. A complicated matter, indeed, but of some importance especially in agricultural monocultures. 

Armored defenses

hard shells and prickly exteriors

Organisms that can’t run away or hide from would-be predators often defend themselves with some sort of armor that deter access to the soft bodies inside. Clams, cockles, and mussels are enclosed in hard shells. Turtles and armadillos wear hard body-armor.  Butternuts and black walnuts are famously tough nuts to crack. In some cases the armor is not a hard shell but a covering of sharp spines. But for every armored defense, there is a counter-measure that allows some predators to get at the edible parts inside.

The sharp teeth of rodents can gnaw a hole in the side of a seed. Years ago, I sometimes used cherry pits as bait in live traps for mice: the mice could neatly carve a hole in the side of that seed and extract the nutritious nugget inside. Fox squirrels in the eastern deciduous forest harvest and cache black walnuts for later consumption, gnawing open the tough shell (note: these are not the domestic thin-shelled “English” or Persian walnuts we buy in the store). Brazil nuts are notoriously hard-shelled, but agoutis can open the big enclosing fruit and extract the very hard seeds, which they cache, to be opened and eaten later.

The strong bill of a blue jay can hammer open an acorn. Oystercatchers sometimes pound on a mussel shell to break it, then sever the shell-closing muscle, allowing the shell to open. However, our black oystercatcher is said to prefer just to jab its long bill into open shells and then sever that muscle.

Hard shells can be smashed by dropping then onto a hard surface. This seems to be a popular method for a variety of predators. Crows and gulls often do this with shellfish—carrying the prey high above a rocky beach and letting it fall, then coming down to extract the flesh from the broken housing. Sometimes it takes several drops. And there’s often a sneaker nearby who’ll try to snatch the meat before the original bird descends. Some gulls are reported to select hard surfaces for dropping big clams but can use softer mudflats for smaller clams.

Several kinds of eagles are said to carry turtles aloft, then letting them fall onto rocks and smash open. New Caledonian crows drop candlenuts onto anvil stones; then they pry out the edible nut. Coconut crabs eat many things, but when a coconut is on the menu, the crab may climb a tree and drop the large nut to crack it, then finishing the job with its big claws.

Sometimes a tool is used as a hammer to open a food item in a hard shell. Chimpanzees (and a few other primates) are well- known for this behavior, teaching the method to their offspring. Sea otters hold a shelled prey on their chests as the float about, using a rock to beat on and crack the shell. Egyptian vultures may crack ostrich eggs by throwing stones at them.

Or maybe you get somebody else to do it for you. There’s the famous situation in Japan, in which carrion crows have learned to exploit traffic patterns to open hard-shelled walnuts. The crows are reported to wait for a traffic-stopping red light and then place walnuts in the roadway before the light turns green. When the traffic moves on again, the vehicles pass over and crack the nuts, and the crows zip down to grab the kernels. They are also said to drop the nuts in front of moving cars. Similar behavior has been reported for American crows in California, except that there the behavior is not timed to the traffic patterns.

Octopuses have at least two means of opening clam or mussel shells. One method is using the suction cups on the arms to pull the two shells apart. Another method is to drill through the shell (octopuses have two kinds of drills for this purpose), sometimes injecting a venom that relaxes the shell-closing muscle. Different kinds of octopuses have their favorite points of where on the shell to drill. Sometimes an octopus uses its beak to chip off thin parts of a shell, giving access for injection of venom.

Whelks are big, carnivorous snails that drill through shells to get at the meat, using the file-like radula. Lots of insects also can drill through hard seed coverings. Weevils provide good examples; the females of one kind of weevil bore into acorns of various species of oak, chewing channels with mouthparts at the end of the long snout. They then lay eggs in the acorn and eventually the larvae feed on the nutritious material inside (which the oaks intended for their seedlings).

Pinching can do the trick too. The big claws on crabs and lobsters can crack the shells of other crabs and some molluscs. The hefty bill of a grosbeak can crack hard seeds and beetle carapaces.

The ultimate insult to armored or spiny defenses might be just ignoring them and swallowing the prey whole. Gulls and crows gulp down small molluscs and cough up the shells later. These birds can also swallow small sea urchins, somehow sliding that spiny body down their gullets (see photo). Hard, prickly sea stars can be crammed down a gull’s gullet too (photo). Ouch?

Photo by Bob Armstrong
Photo by Bob Armstrong

A few vertebrates are defended by armor plates or spines. How do predators deal with these defenses? Armadillos carry a suit of hardened plates, and one kind of armadillo can roll up into an armored ball. How predators gain access to the vulnerable parts isn’t clear—perhaps a cougar or bear just gives the victim a big swat with a paw to tip it over and disorient it, exposing the vulnerable underparts?

When threatened, European hedgehogs roll up into a ball, erecting their spines to present a predator with a spiky mouthful. European badgers can wedge open the spiny ball and get at the tender belly. Foxes eat hedgehogs too, but they are said to be less successful in attempts to disarm them.

The spines of an American porcupine are a formidable defense—the beast turns its back with raised spines, brandishing its spiny tail. Many an ignorant or over-eager dog can attest to its effectiveness. If it can, the porcupine hides its face between tree roots or its paws. For good reason! A fisher commonly attacks a porcupine by grabbing and injuring its unprotected face, then flipping the damaged victim over to attack the belly and kill it. Other carnivores can use these techniques too.

There is no perfect defense.

How to carry a lunch

when you don’t have a brown paper bag

A human day-hiker usually carries a lunch in a backpack and may require a canine companion to do likewise. However, other animals carry lunch internally, in special storage compartments. Here are some examples.

Some birds have gular pouches that start under the tongue and extend down the throat. Clark’s nutcracker reportedly can carry a hundred or more pine seeds in their gular pouches, to be cached for future lunches. Blue jays can carry several acorns in the pouch, and Steller’s jays can pack many sunflower seeds into theirs. Townsend’s solitaires, both male and female, have pouches just during the breeding season, presumably to carry bigger loads to the chicks; several caterpillars can be stored there for delivery to the nest. Pinyon jays have, not exactly a pouch, but a distensible esophagus that can carry several dozen pine seeds for the jays to cache. A bird with a full gular pouch shows a noticeable bulge on the throat. (Note: gular pouches have other functions too, but those are not part of this story.)

Many birds have crops (or craws)—an enlarged, thin-walled, distensible part of the lower esophagus that can accumulate considerable amounts of food. The size and shape of bird crops varies greatly among species, from just a stretchy portion of the esophagus (e.g., in fish-eaters such as cormorants) to a bag-like expansion. Most omnivorous and seed-eating birds have storage crops. For example, parrots, as well as canaries and other finches, store food in their crops to regurgitate for their chicks. Chickens and turkeys have crops, but not geese. Even many raptors are said to have crops, but not owls. Scavengers such as turkey vultures can store a lot of carrion in a bulging crop. A foraging hummingbird may fill up its crop with nectar and then sit quietly for several minutes. It’s not doing ‘nothing’; it takes a few minutes for the nectar to move on to the stomach and make room for more. Hummers can store nectar, and perhaps insects, in their crops, to deliver to chicks in the nest.

Bohemian waxwings eat a lot of fruit of many species; mountain ash is reported to be a favorite. They can pack several mountain ash berries into their crops at a time. A little flock of these waxwings was perched in an alder tree outside a window, where an observant friend watched them. A waxwing with nothing in its bill suddenly held a fruit that was quickly swallowed. Up came another fruit; it was dropped, probably accidentally. Then another one was regurgitated and swallowed. As one fruit after another emerged, the size of the lump in the throat area got smaller and smaller.

One day on my pond this fall, I saw two mallards that looked most peculiar. Viewed from the front, the lower neck and upper chest were totally lopsided, bagging way out to the right. Both birds had clearly been foraging very successfully, storing lots of goodies in their crops. And they were back to get more!

The strange hoatzin of South America eats mostly leaves; its crop has been modified to do double-duty, becoming used for digestion as well as storage. Hoatzins are the only birds known to have foregut fermentation (as cows do): The modified crop houses special bacteria, which ferment the ingested leaves. When they load up this crop with big meals to be processed, hoatzins would bulge so much they’d tip over but, conveniently, they have a big callus on the breastbone that braces them upright.

Lots of insects have crops too, near the beginning of the digestive tract, just after the junction of thorax and abdomen. As is the case for birds, in some insects, the crop is like a bag, but in others it’s just a wide place in the esophagus. It may be used only for storage, but in some insects digestion may begin there, before the food passes on the stomach. In honeybees, the crop is sometimes called the ‘honey stomach’. A foraging honeybee gathers nectar from flowers, stores it in the crop, and the loaded bee flies to the hive, perhaps digesting a bit of the nectar to fuel its own activity. In the crop, an enzyme breaks down some of the sugar into simpler sugars and compounds that resist invasion by microbes. (Sucrose breaks down to glucose and fructose, and glucose is further broken down to make protective compounds). In the hive, the load of nectar is passed from the forager to worker bees, who move the liquid around in their mouths, making bubbles that allow water to evaporate. They may also place water droplets on the honeycomb and fan them with their wings, evaporating more water. So, at each step, water is removed from the nectar, leaving thicker liquid with a high concentration of sugars and some protective compounds, to be stored in the cells of the honeycomb. That’s how they make honey to feed the larvae.

Bird song

corvids are songbirds… so why don’t they sing?

One day in early November, after a morning of plonking about on snowshoes for the first time this year, I sat myself on a snowbank and leaned against an old alder tree—time out for a snack. My companion perched at the base of another alder a few feet away. We’d spent the morning looking at animal tracks in a meadow. As soon as we opened our packs to dig out our lunches, we were visited by a raven, who called and attracted another one. But they ignored our (admittedly) small offerings and departed.

Thinking about the raven calls reminded me of some recent reading about the singing behavior of birds and a lingering question. First, some background: ravens, crows, and jays are classified as songbirds on the basis of both morphology and genetics. But their singing behavior differs from that of other songbirds in an interesting way.

Most songbirds sing during the nesting season, sometimes all day long, sometimes mostly in the morning. Males may use one song before dawn and another after sunrise, and there is usually a dawn chorus of many species all vocalizing at once. Morning bird songs are something that lots of folks, not just birders, look forward to in temperate-zone springtime and even sometimes in the tropics.

Bird song has many functions. Males advertise their territory ownership, telling others of that species to stay away. Sometimes, two males face each other aggressively at a territory border and have song duels, each one trying to out-shout the other. Males’ songs also attract females to their territories, the vigor of their songs indicating their state of health and motivation. Female songbirds may sing too—telling other females to stay away from that territory. Or, in some cases, a female might sing to tell her mate to bring her a snack.

The ‘voice box’ of birds is totally different from that of humans, other mammals, and reptiles. We have a cartilaginous larynx at the upper end of the trachea (windpipe). The larynx is thought to have evolved from a valve involved in swallowing (and when we swallow, the larynx moves). We sing or talk by moving air out of the trachea and through the larynx, causing vocal membranes to vibrate; muscles linked to the cartilages control the sound. The closest living relatives of birds are crocodiles and they too use a larynx for vocalization. However, although birds have a larynx, it’s not used for making sounds; they use another structure, called a syrinx. The avian syrinx is located at the lower end of the trachea where it branches into two passage-ways (bronchii) going to the lungs. The syrinx apparently evolved, not from a valve, but from structural supports for the branching airway, and very different muscles are involved in control of its vibrating membranes.

Because the syrinx is in two parts, at the beginnings of the two bronchii, songbirds can sing two distinct notes at the same time, something a larynx cannot do. This is not the same as Mongolian throat singing, in which singers learn to exploit the harmonics (overtones) of the fundamental note. The two distinct notes sung by a songbird are not harmonically related. Air is moved from the lungs into the trachea, as most song is produced by exhaling; but birds can also produce some song when they inhale. Loudness and pitch are changed by altering air pressure and by changing the tension of the muscles that control the elastic, vibrating membranes of the syrinx.

Jays, crows, and ravens have the avian syrinx, but they don’t use it in the same way as other songbirds. They can make a huge variety of sounds; the loud, raucous ones are most familiar to us. But they are perfectly capable of making musical sounds and do so, quietly, upon occasion. If you listen carefully, you might hear them! But these songbirds have no dawn choruses, no song-battles for territory, no lovely singing to attract mates. That begs the question: Why not?

The underground ecosystem

complex and under-appreciated

The ground: we stomp all over it, dig holes in it for buildings and alien plants, scrape it off and discard it for access to minerals. That’s the meaning of being ‘treated like dirt’.

Nevertheless, a lot goes on underground in the layers of soil. It’s a very complex ecosystem. Sometimes called the rhizosphere, it’s the realm of roots.

This essay includes several topics that have appeared here before, but this time I’ll try to bring them together, if briefly, in one context, while expanding on some of them.

Vascular plants have roots that help stabilize the upper parts of the plant and carry soil nutrients and water to the rest of the plant. Thus, roots make possible the forests and grasslands in which we and other terrestrial critters walk or crawl around.

In some species, roots are a means of vegetative propagation, spreading away from a parent plant and sending up new shoots that look like separate individuals but that are all part of one. Aspen is a classical example among the trees, making groves of tree trunks that are all one individual, genetically. Perennial grasses, such as beach rye, can spread rapidly in this way by means of underground stems called rhizomes.

Tree roots sometimes graft to each other, linking their vascular systems and sharing nutrients (and, potentially, pathogens). Grafting is relatively common among neighboring individuals of the same species but is also known to occur between individuals of different species (e.g., pine and spruce).

Neighboring plants of all sorts are also often connected by mycorrhizae—fungi that carry nutrients from plant to plant and from soil to plant. Their networks can be very extensive, connecting plants of different species. As many as eighty or ninety percent of all plants may use mycorrhizal connections. Mycorrhizae are said to be especially dense in perennial grasslands.

Mycorrhizae even make connections to mosses and other rootless plants. Mycorrhizae contribute significantly to growth, survival, and reproductive success of many plants (some orchids even need them for seed germination). However, these useful fungi are inhibited by agricultural fertilizers containing inorganic nitrogen and water-soluble phosphorus. 

There’s plenty of nitrogen (N) in the atmosphere but it is, nevertheless, often a limiting factor for plant growth and development. Nitrogen is also used in plant defenses against pathogens and herbivores. Plants can’t use atmospheric N directly, but N becomes available via a process called N-fixation; this process is catalyzed by enzymes that transform atmospheric N to ammonia and thence to various amino acids that are usable by the plants. This work is done only by various kinds of bacteria and some other one-celled organisms, which have been around, somewhere, since long before plants evolved. Some of these N-fixers live freely in the soil, others associate with the outsides or the insides of roots, and still others are housed in special nodules on plant roots. Within these nodules, the process of N-fixation uses energy provided by the plant’s photosynthesis.

The legumes (peas, peanuts, etc.) are well-known for their nodules inhabited by bacteria called Rhizobia. These nodules are induced by the bacteria in response to chemical triggers from the plant. These bacteria can only fix nitrogen when with a suitable host. Some of these symbioses between plant and bacteria are highly specific—each partner associating only with the other one; and if a different type of bacteria gets into the nodule, it can usurp energy and cause the plant to die. But some Rhizobia are much less fussy, associating with several plant species. In our area, beach pea and lupines (for example) have Rhizobia nodules.

However, many other kinds of plants form symbiotic relationships with N-fixing bacteria of a different type, mostly known as Frankia. These filamentous ‘actinorhizal’ bacteria produce hormones that mimic certain plant hormones and force the root cells to proliferate rapidly, causing swellings (nodules) to form. Local examples of this symbiosis include alders and sweetgale.

Plants with N-fixing bacteria use that nitrogen for better growth and defense. In addition, plants with enhanced nitrogen levels may provide nitrogen to other plants via grafts or mycorrhizae. Many plants with N-fixing bacteria are also mycorrhizal—a three-way symbiosis! In agricultural settings, nitrogen-enhanced plants are plowed down into the ground to improve the next crop. A little N-fixing water-fern is sometimes cultivated to be used as green manure for other crops. Plants with symbiotic N-fixers are sometimes also planted near human-favored trees (e.g., Douglas fir), so that the products of leaf and rootlet decomposition enter the soil and enhance the growth of the favored neighbor.

Roots have all those helpers (so to speak) that contribute to supporting the plants. They also have enemies. Roots are eaten by some above-ground consumers; geese dig the roots of silverweed, bears dig the roots of lovage, angelica, hemlock parsley and the bulb-like tubers of northern ground cone. Some invertebrates (including nematodes, insect larvae) nibble roots or suck their fluids. And there are root-rot fungi that can demolish a root system and cause a tree to collapse.

That’s just the root-y part of the complex soil ecosystem. Fungal hyphae pervade the soil, sometimes reaching high densities. There’s a teeming community of invertebrates: mites, earthworms, millipedes, nematodes, springtails, spiders, isopods, insects….as well as astronomical numbers of bacteria and other one-celled organisms creating complex food webs. It’s an ecosystem that’s not as well-studied as some others but surely has many interesting stories.