Singing

birds sing for many reasons!

A mid-August walk finds the woods almost silent. A raven talks, a jay complains, an eagle titters, a squirrel chatters. If you are lucky, a little group of chickadees will come by and visit. But bird song is over for the year. Warblers are on the move, singly and in small groups, ready to spend the winter down south.

Why should the absence of bird-song make me think about singing? Maybe when the spring chorus is in full swing, I’m too busy listening, but now I have time to notice the emptiness.

It has long been known that male birds sing to attract mates and advertise their nesting territories. Songbirds commonly learn at least part of their breeding season songs by listening to their fathers’ songs and perhaps also those of their neighbors. In some cases, localized dialects develop, in which all the males sing very similar songs and females tend to prefer males that sing the local version. This is apparently more likely in birds that are year-round residents; examples are heard in the songs of white-crowned sparrows along the west coast. Sometimes song learning in migrants also occurs on the wintering grounds where populations can mix and hear each others’ songs as they warm up for the spring season. And some birds, such as mockingbirds and starlings, readily mimic the songs of other species.

Something different has happened with the white-throated sparrow, which nests all across northern North America. Its characteristic song consists of two notes followed by three triplets, rendered in English in the U. S. as “Old Sam Peabody, Peabody, Peabody. Over a decade ago, however, a change was noted in the song of males in western Canada (where the song is said to say “O sweet Canada, Canada, Canada”). But those western males weren’t singing the triplets anymore; they were now singing duplets instead. And, strangely, this new version of the song spread gradually eastward, to Quebec (as of 2020). No one really knows why the new song is taking over; one suggestion is just that the females like the novelty of it, which raises the question of what the next novelty might be!

In other cases, changing conditions may cause birds to change their songs so as to be heard more clearly by each other. Several studies have shown than birds in cities sing at a higher pitch than their country relatives, perhaps to be heard over the background cacophony of city noises, many of which have low pitches. Social context also matters: birds tend to sing longer and faster songs in areas where their populations are denser and there are more potential territory intruders.

Many studies have shown that singing has huge effects on emotional, mental, and even physical well-being of humans. Those of us who have enjoyed choral singing with local groups know well some of those benefits. More recently, research has found that birds probably get similar benefits. Now it seems that, in addition to attracting mates and advertising territories, they may also sing for the pure pleasure of it, as Darwin once suggested.

Starlings gather in large flocks when the nesting season is over. In those flocks, both males and females sing a lot—not the songs of the breeding season, but more unstructured, less ritualized songs. In studies with captive starlings, researchers had found that, given a choice, the birds preferred to be in aviaries where they had previously participated in group singing—perhaps because it was pleasurable. Then the researchers experimentally manipulated the levels of the birds’ natural opioids; opioids are the chemicals that induce feelings of well-being and pleasure and they also reduce pain. Their production can be stimulated by certain conditions, such as being in a safe place with friends, and activities, such as eating and singing. So we—and birds too, perhaps–feel good when those things happen. And feeling good may, in turn, favor more associations with safe places and more eating and singing.

The researchers demonstrated that, using drugs, they could stimulate the production of natural opioids by the body and trigger lots of group singing, simultaneously reducing stress-related behaviors. Conversely, when the production of natural opioids was experimentally reduced, group singing was also reduced…and the birds no longer preferred to be where they had experienced group singing before. There may be more to the emotional life of birds than we give them credit for!

Two trails

…and some bird stories

A group of friends went up the Granite Basin trail in mid-August. Lots of work has improved the trail mightily, and big boards stashed alongside indicate that more work may be planned. Snow still covered the trail at the place where spring avalanches always dump their icy loads. That was perhaps a measure of how unseasonably cold this ‘summer’ has been.

Salmonberries were ripening at trailside, but in one place skimpy, pale leaves made it clear that the canes had only recently come out from under snow cover. Purple fleabanes (or daisies) and grass-of-Parnassus flowered. White mountain-heather and partridgefoot were in full bloom. We found odd red structures on one mountain-heather and did not have the least idea what they are; we found out that they are a result of a fungus infection that makes the plant turn leaves into false flowers, with nectar(!), to attract insects that then spread the fungus.

Mountain-heather “false flowers”. Photo by Kerry Howard

Clouds hung low that day, obscuring any long vistas. They lifted, just slightly, about midday; not enough to even say there was watery sunshine. But that was enough for the marmots to come out and ‘sun’ themselves on the rocks. Folks watched a dipper foraging in the pool above the falls, where we often see them. Those who ventured farther into the basin saw ptarmigan, including chicks.

Ptarmigan chick. Photo by David Bergeson

The previous week I went to check out the Horse Tram trail. From the Boy Scout trail, the route goes up the hill a bit and then there’s a junction (with a yellow marker).  The original tram route went down over the saddle into Amalga Meadow, but the newer route heads up the hill to a little meadow and then down to a cove and toward the Eagle Valley Center in Amalga Meadow. Some work had been done on the stretch going up the hill but then there was a long, muddy, squishy reach to the small meadow (but work was in progress). From the meadow on down toward the EVC, the trail is now in great shape.

Parks and Rec hikers used to do a loop, from the Boy Scout trail up the (then-unimproved) Horse Tram trail to the little meadow, down to Amalga Meadow, and back up over the saddle where the bent and twisted tram tracks are still visible in places to the junction and on down to the Boy Scout trail. The old tram-track trail over the saddle is now badly eroded and overgrown, and it’s hard to pick up that trail from Amalga (even when you know, in general, to aim for the saddle). If a hiker wants to do the loop, it’s easier to do it in the other direction: over the saddle from the junction down into Amalga, where it is possible to pick your way by several damp routes over to the trail up to the small meadow and back down the hill.

As we hiked down on the good trail from the little meadow recently, a family of chickadees flitted around our heads, quite fearlessly. So we wondered if they sometimes got treats from people at the EVC. Sapsuckers had made a double row of sap wells up the side of a damaged spruce –not a usual place for their wells. In the wet meadow, a bear had dug up one skunk cabbage out of thousands that grow there; so we had to ask Why that one in particular?

Here are some bird stories: A friend sent me a video of a raven following a marmot, pecking at its tail; the marmot continues to browse, the raven continues to pester its tail. Pure mischief!! Not at all like ravens and crows pecking at an eagle’s tail to distract it from a captured salmon. Ravens also destroy the padding on car-top canoe carriers; is that just for fun and something to do when bored? A friend tells of watching a raven carefully selecting a spot to cache something held in its bill. The raven could see the observer well, but it completed the cache and flew off. My friend went to the cache and found—a small, smooth quartz pebble. Trickster, indeed!

Finally, one day in August, I came up the steps into my living room and, as always, glanced out the front windows. There was a fair-sized, brownish lump on the railing, looking a bit disheveled. Huh?? Oh. That heap of stuff is a juvenile goshawk! It was glaring at a cat crouched a few feet away in the living room. The bird was ‘mantling’—displaying by hunching over, raising the feathers on its upper back (its mantle), and spreading its wings. Typically used as a display to protect a captured prey from challengers, it can also be a defensive display, it seems (it held no prey). So it was a stand-off—neither cat nor bird liked the other one. I later saw the goshawk perched in a nearby tree. What drew it here in the first place? Maybe a duck or two on the pond (I once saw a goshawk take a duck there), but perhaps more likely the hairy woodpeckers that frequent my peanut-butter feeders. Goshawks commonly forage by dashing through tree canopies, snatching squirrels and woodpeckers from branches and tree trunks; at least in some places, woodpeckers are a common prey.

Animal percussionists

diverse ways of communicating through rhythm

The percussion section of an orchestra is usually stationed behind the other performers. The percussionists move smoothly from one noise-making instrument to another, banging, rattling, swishing, clacking and clicking, and thumping. They coordinate with the other performers and the conductor, to create a unified production.

The animal kingdom has its percussionists too, although they are certainly not orchestrated to coordinate with each other. Each type does its thing for its own reasons, on its own time, and in its own place. Nevertheless, in a broad, ecological perspective, they are part of a unified whole, and the world would be a poorer place without them. Here’s a sampling of percussionists among the animals.

Some critters use tools, of a sort, to make a percussive noise. Woodpeckers drum on trees (preferably hollow) or rain spouts to advertise their territories and availability for mating. Beavers slap their broad tails on the water as a warning signal. Monkeys and bears clatter and snap branches as a threat to potential enemies. Horses may stomp their feet on the ground in a confrontation with other horses.

More commonly, animals use various body parts as noise-makers. Annoyed rattlesnakes give warning by shaking their tail rattles. A displaying male peacock may rattle and swish the feathers of his gaudy train. Click beetles have a spine on one segment of the thorax that can be snapped into a notch on the adjacent segment when the beetle flexes its body; a loud click is made when the spine is released. Release of the spine quickly straightens the flexed body and flips an escaping beetle into the air; the click startles a would-be predator .

Many insects, some spiders, and even some birds drag a scraper over a ridged surface to make noise; this is called ‘stridulation’. Crickets rub one wing against another; grasshoppers rub a hind-leg on the forewing; a moth rubs a leg on a swollen part of the hind wing; some ants rub two abdominal segments together. Insects stridulate for various reasons, including mate attraction, territorial defense, as a warning signal, or (in ants, for example) a call for help from colony members. A species of neotropical manakin has two modified feathers on each wing, one with ridges and a stiff one to rub over the ridges. A displaying male raises his wings and shakes them back and forth very rapidly (perhaps 100 times a second!), to attract females.

A freshwater fish called a ‘drum’ has special muscles that rub on its swim bladder, making a grunting sound. Cicadas have special organs in their abdomens that make a buzzing sound when muscles pull them in and out of shape; the abdomen is mostly hollow, which intensifies the sound. When mature cicadas emerge from their larval life underground and ‘sing’ to attract mates, the racket can be deafening.

Snapping shrimp make a loud pop with one enormous claw. A very quick closing of that claw forces out a rapid jet of water. There is then a drop of pressure behind the jet and a bubble forms; this is known as cavitation. The bubble implodes with a loud pop when pressure from surrounding seawater rapidly rises again. The sonic shockwave from the popping bubble is used to stun or kill potential prey, such as a small fish or crab.

A ruffed grouse male advertises his territory and attracts females by standing with the tail braced on a log or small mound. He ‘drums’ by repeatedly cupping the wings forward and then quickly pulling them back. The sudden compression and release of air pressure produces low-pitched sound as air rushes into a momentary vacuum (cavitation again). It’s a high-energy display, starting slowly and speeding up to a continuous thunder.

Bird tails

versatile appendages

I recently watched a brown creeper hitching up a little spruce tree just outside my window. Brown creepers typically forage for invertebrates by moving vertically up a tree trunk, hooking their sharp little claws into the roughness of the bark. They actually hop upward, moving both feet at the same time, while the body is braced by the tail. The two central tail feathers are strong and somewhat pointed, although the outer tail feathers have softer tips. The tail is essential to the creeper’s upward locomotion.

That elementary observation made me think more generally about the tails of birds. Their tails are made of feathers supported by a bony structure comprised of fused tail vertebrae. The feathery tails are obviously important in aerial locomotion and maneuverability; that role has been well-studied and we easily see it when watching eagles or gulls swooping back and forth. But here I want to focus on some particular uses of the tail that have special functions, such as seen in the brown creeper.

Like brown creepers, our wood peckers climb tree trunks by hopping upward while braced by a strong tail. The strong, pointed tail feathers are also very important when the woodpecker is excavating a cavity, bracing the body while the bird hammers away. Three-toed woodpeckers have especially strong central tail feathers, allowing them to rear back on tiptoes and put the whole body behind the strike. In contrast, sapsuckers excavate chiefly by using just head and neck movements, and their central tail feathers are not quite so robust.

Red-breasted sapsucker. Photo by Kerry Howard

Both creepers and woodpeckers molt their tail feathers in an unusual pattern. Most birds are said to shed the central ones before the outer ones. But creepers and woodpeckers keep the central ones until the new outer ones have fully regrown, to maintain at least some tail support for their climbing activities while the new central tail feathers are growing in.

The little aerial insectivore called Vaux’s swift (and its eastern relative, the chimney swift) is unable to perch on twigs. It clings well, however, to vertical surfaces such as the interiors of hollow trees (or chimneys) where it nests. Aiding the vertical cling are its spine-tipped tail feathers that press against the walls, helping support the bird in that orientation.

In other birds, raising and spreading the tail fan makes the birds look bigger. Male turkeys, for example, display their spread tails when they puff up and strut to impress females and other males. A ruffed grouse male raises his tail fan during the drumming display that advertises ownership of the display site and attracts females. Female grouse may use a raised tail fan when defending a brood of chicks.

Some birds have turned tail feathers into sexual adornments. Males of some of the African widowbirds and whydahs have tail streamers several times longer than the body—aerodynamically somewhat disadvantageous but apparently alluring to females. Similarly, males of certain manakins in the neotropics and birds-of-paradise in New Guinea have long, decorative tail feathers with odd shapes useless for flight.  

Ring-necked pheasants, native to Asia but introduced elsewhere, have colorful, long tail feathers that they spread, raise, and orient toward another bird during courtship or intimidation of other males. There are many kinds of pheasants in Asia, often with fancy tail displays… including, of course, the biggest, most famous pheasant of them all—the peacock, a native of India but domesticated around the world. All that beautiful color and shimmer of a peacock’s ‘tail’ display is not made by tail feathers at all! The real tail feathers are dull, stiff things supporting the gaudy display from behind. The display itself is formed by upper tail coverts—body feathers on the rump that have become decorative and long. Perhaps the fanciest true tail belongs to the lyrebirds of Australia. Male superb lyrebirds have huge, ornate tails used in courtship. Some of the feathers are fluffy, some are wiry, and two elaborate ones make the lyre-like shape. Males display on a cleared mound on the forest floor, raising the elaborate tail, and dancing, while mimicking the sounds of many other birds. That display is better seen and heard than just imagined; videos are readily accessible on the internet.

July explorations

subalpine and sea-level explorations

Toward the end of July I hiked with some friends around Cropley Lake at Eaglecrest. It was the first full day of sunshine after something like three weeks of nearly continuous rain and cool temperatures. We reveled in the dazzling light and warmth. Some of us hoped we’d find yellow fireweed and sky-blue gentians blooming on the soggy back side of the lake, but apparently we were too early. Maybe the unseasonable weather slowed them down.

Swamp gentian. Photo by Bob Armstrong

But there were other things to be seen. Millions of swamp gentians starred the meadows, interspersed with the tiny pink dots of bog cranberry. As we approached the elevation of the lake, there were clear signs of late spring: the last of the spring violets and Jeffrey’s shooting star, and swathes of bog laurel. Late spring mingled with summer: little iris-like Tofieldia and leatherleaf saxifrage, with inflorescences of varied shades of red, were common; grass of Parnassus was about to bloom. Pink paintbrush prefers this habitat to the lower-elevation gravelly flats occupied by the yellow paintbrush species. The big treat was seeing dozens upon dozens of butterworts in bloom. Sometimes called ‘bog violets’ for a supposed resemblance to true violets, butterworts are not related to violets at all (although they both may have purple flowers). Butterworts are insectivorous, catching bugs on their flattened, sticky, yellowish leaves that are not a bit like violet leaves.

Paintbrush. Photo by Bob Armstrong

Earlier in the month, during all that rain, we made a special trip to Cowee Meadow. On a previous visit, we’d finally discovered what the female inflorescences of sweetgale looked like when they were in flower, and now the goal was seeing the mature form. By luck, our timing was good—the female inflorescences made slim, brown, cone-like structures, whose scales opened up to release seeds. By traipsing around for a while in the meadows, we also found more female plants than we’d found earlier, so females aren’t quite as rare as we thought (although still vastly outnumbered by male plants).

We happened to look at some fireweed flowers. I don’t know what attracted our attention, but when we looked attentively, we noticed that many of the flowers had no visible female parts. Fireweed flowers are both male and female, with a set of stamens with pollen-bearing anthers around a conspicuous, white, four-branched stigma for receipt of pollen. But some of these flowers seemed to be missing the big stigma.

After much closer attention, we found that the female structure was there, but small and drooping and apparently with the four branches both short and closed up tightly, as if they’d never fully matured. Fireweed inflorescences bloom from the bottom up, so older flowers are borne below younger ones, with unopened buds up at the top. But age of flower did not account for the development of female parts; both young and old flowers often lacked fully developed stigmas.

What is going on here? Is this just something I should have noticed long ago? Or could the long spell of un-summery weather have made the plants decide not to even try to receive pollen and make seeds?

Everywhere we wandered in the meadows, we found recent bear digs, usually for angelica roots. In some cases, the edible root-nodules of chocolate lily (rice-root) had been incidentally dug up too, but were left uneaten.

Back in the middle of July, on the Crow Point/Boy Scout trail, I watched a hummingbird visiting yellow paintbrush. It dipped in, then floated (or so it seemed) high into the air before coming back down to try another flower in the same patch. It tried a few flowers but soon zipped away, as if to seek better foraging elsewhere.

Red fruits of baneberry decorated the sides of the berm edging the goose flats. The felwort that we often see later in summer wasn’t blooming yet. But the wide meadow between the trail and the river was covered with white arctic daisies (Chrysanthemum arcticum), not to be confused with the weedy, alien white daisies on the roadsides.

A search for Salicornia in the big goose flat was futile for what seemed like a long time. But finally we struck the right microhabitat and found a lot of it—a tasty snack! This highly salt-tolerant annual plant is known as glasswort or saltwort or sea asparagus, among other common names.