Imbolc Incident

It is the last week of January—which to my mind can be the epitome of the doldrums of winter. Well, maybe not the worst of it. The worst is more like late February, when I become very disheartened, because winter seems to be interminably stuck and refuses to yield to spring. 

What we experience in late January or early February is the cross-quarter day called Imbolc. It is a Celtic day of observation that falls halfway between winter solstice and spring equinox. The solstices and equinoxes occur at precise astronomical dates, which designate when the Earth is at a specific location in its orbit around the sun. Their timing is known; even to the exact minute. The cross-quarter days, however, are imprecise, because their timing depends on local weather; thus Imbolc, for example, falls on about February 1, or maybe a few days on either side.

Imbolc's significance is that it signals the very first signs of the quickening of life in the spring. While we may look around and see no discernible change at this time of year, plants and animals at Imbolc time sense the change coming on and begin to stir. Deep underground, seeds begin to swell, getting ready to pop open. Cows begin to lactate again (Imbolc means “with milk”). While we humans can watch the calendar and note that cross quarter time is here, animals and plants sense it. 

I heard a great example this morning that showed me that Imbolc had arrived—even though the weather lately has been extremely cold and snow coats the ground. I was having no thoughts of spring—only my lamentations over the frigid conditions. Stepping outside, I heard the call of a titmouse. I immediately stopped and listened. Was I really hearing a titmouse call in late January? These birds call in spring, during mating season, and occasionally during the summer—but never in fall or winter. They might chatter scoldingly on frigid days, but they do not sing.

That's what halted me so abruptly. I had not heard a titmouse call for five months or more. Was I imagining it? No, the call came again. It was way off in the woods. An hour or so later I heard the call yet again—this time from another direction, again off in the woods. That told me that the first call did not come from an addled bird, who was maybe suffering from hypothermia. This was another titmouse. I later heard a third... then a fourth.

Why this untimely singing, on such a frigid morning? The sole explanation I could come up with was they were responding to Imbolc. Something was stirring deep in the breast of these birds—a primeval urge that the earliest hints of spring were causing. I wondered if underground seeds might also be showing the slightest hint of swelling—getting ready for the new year. I would remain ignorant about that, however, since the ground is coated with a thick, ice-covered coat of snow. Icy winter is in no hurry to depart, but that first sign of spring is here!

Whippoorwill Wrangle

As I sat in the outdoor tub recently, I heard two whippoorwills who seemed to be vying with each other—at least that's how it sounded to me. Conversations and competitions between animals can get quite complex. We humans—with our complex languages and our big brains—tend to belittle the forms of communication we hear going on in the animal world. Caught within the narrow confines of our own kind of information transfer, we are apt to look upon animal communication as primitive and simplistic. We miss the subtle details of how they talk to each other.

So I sat there in the tub, tuning into the dialog that these two birds seemed to be having with each other. The whippoorwill's call is an onomatopoeic one—meaning that their song is essentially identical to their name. These birds sing out—not with the usual “tweet tweet”—but with a robust “WHIP-poor-WILL.” The first two syllables seem to be emitted on the inhale of breath, with the last strong syllable exhaled with gusto. Because the bird calls out on both inhale and exhale, he can go on and on, uninterrupted. And sometimes whippoorwills do—much to my chagrin. They can repeatedly call out through the night, drilling their calls deeply into one's ear and brain.

The two birds I was listening to this night would each sequentially sing out a dozen or so phrases and then fall silent, as if waiting and listening to the other bird, to see what the response was. They called back and forth several times, before they both paused for a while, as the forest silence once again returned. In a few minutes their call-and-response routine would begin afresh—with now one of them having shifted to a new location in the forest.

There obviously was some kind of communication going on. I became absorbed in their game—trying to fathom what the rules were. It was rather like traveling to a foreign country, where I was ignorant of both the language and customs, and was observing a dialog between people and trying to guess what they were talking about.

Was I listening to a whippoorwill contest? If so, were they contesting territory? This late in the season, they were unlikely to be seeking mates—the broods of all of our local birds had already been fledged, so there was no need to vie for a mate. Well, maybe they weren't competing for territory; maybe it was simply to see which one had the more appealing and accomplished call. Or maybe they were discussing some aspect of forest life... such as the lack of mosquitoes to eat tonight.

So, if it was a territorial contest, I wondered which bird might be the challenger and which one the defender. One bird's pitch was a little lower than the other's. Does pitch convey information? Does the more aggressive bird sing at a lower pitch? I also tried to guess which bird's call seemed to be more eloquent than the other. Would the challenger or the defender sound more impressive and resolute? I know that birds often try to bluff each other, and maybe a kind of deceit was going on.

When, after a pause, one changed position, I tried to guess if he was yielding and backing off, or maybe losing interest in the game and simply moving on. On the other hand, birds will sometimes alter the quality of their call—in order to signal that they are possibly acquiescing, when actually they seek to deceive the other into believing they are closer and more intimidating that they really are. It's part of the game.

As in most cases when I am treated to the calls and exhibitions of our wildlife, I am left wondering—with more questions than answers. Their sophisticated communication is yet beyond my comprehension. I've reposed in the tub for a couple of decades now, eavesdropping on their conversations. Bit by bit, I sometimes begin to understand what they are up to. Maybe in another half century—when I am a hundredtwentysomething—I may get it.

Complex Bird Calls

Sitting in the outdoor tub with the stillness of night stealing in, I love to listen to the evening bird calls, as each species takes its turn, before flying off to the night's roost. I can almost predict the sequence of calls, as the titmice and goldfinches begin the evening's sign-off, followed by a tumultuous Carolina wren. Then the wood thrush and the cardinal vie to see which one closes off the day's symphony, before the whippoorwill ushers in the night chorus.

I love to listen carefully to the various calls, trying to discern if birds of different species seem inclined to listen to each other—if only to determine when their own song can be offered by slipping it in between the calls of others, so as to minimize the overlap and maximize the chance that each of them will be heard. The intent of their singing is not to compete with a different species, but to signal any nearby birds of its own species that it's here and deserves respect. (In a similar fashion, it has been shown that birds singing in cities modify their calls, in an attempt to be heard above the din.)

Most of the calls I recognize come from old friends, with whom we've cohabited in this clearing in the woods for a few decades now. I have come to expect their voices each evening. But now and then I hear an unfamiliar call and wonder who it is. Might it be a visitor who's testing whether it might find a home here? Might it just be passing through and stopping on a pleasant evening, to join the chorus?

This particular evening brings a new, rather complex call. It seems to me that it's two different birds—one shouting out a high-pitched melodious squawk, sort of like a soprano bluebird. The second call is a lower-pitched “burp, burp, burp.” It must be two different species, I think, with such contrasting calls. They even seem to be coming from two different directions in the woods.

But as I listen over several minutes, I begin to become suspicious about my first impression. These two different calls are precisely synchronized. They quickly follow one another in the same succession, but never overlap. When I normally listen to two different species of birds calling out, they seem to be trying to fit their calls into each other's gaps, but inevitably get a little sloppy and overlap each other just a bit. These two calls tonight never overlapped.

So maybe I'm listening to just one bird that sings out with two very different calls—one a high-pitched squeal and the other a low-pitched burp? That could be. The wood thrush has a three-part call—each part having a very different quality. And I've written here before how the different parts of the wood thrush's call even seem to emanate from different locations in the woods. I have decided that the wood thrush's song appears to come from different directions, because one part of the call reflects off trees leaves, while the other part penetrates deep into the woods.

So what am I listening to this evening—two birds who have an uncanny ability to perfectly synchronize their calls, or a single bird with a two-part call? I do seem to hear the call coming from two different locations in the woods. The answer will not come tonight, as the calls soon ceased. The bird (or birds) will hold onto their secret for another day.

Pileated Patter

By dint of living out in the woods for over 30 years, we have been able to enjoy many varieties of bird calls. Because we live in such a quiet place, we can hear birds calling from far off in the woods. Thus, we rarely see some birds who we long ago identified by their calls, because they are so shy. Sometimes, trying to get a glimpse of one of these bashful birds, I try to sneak up on them in the woods, but they always detect my advances and withdraw even deeper into the trees.

One bird that is unique in both its appearance and call is the pileated woodpecker (see photo below). We have about five species of woodpeckers hereabouts—from the tiny downy (7 inches or 18 cm long) up to the pileated (17 inches or 40 cm long). Woodpeckers forage for ants and other bugs inside live or dead trees, as they hop up and down the tree trunks—bracing themselves with their stiff tail feathers. Their call can be heard from far off in the woods, as they forcefully thump on tree trunks, bashing their long, hard beaks against the bark, as they excavate holes, seeking a buggy lunch.

Pileated woodpeckers have two other sounds that travel well through the woods. One is a call that sounds like a derisive laugh, as the bird flies to and fro, as if in paroxysms of guffaws, brought on by observing some hilarious event. Their merriment seems to last for several minutes, as they fly around, convulsed by their self-derived chortles. I like to think this loud display is simply a way to express their joy at being alive.

The other distinctive sound the pileated woodpecker emits is when he drums on a hollow tree trunk or limb. While the slower-paced pounding (for a meal) is heavy and thudding, the drumming is fast and loud. The bird is intending to send out a message, which is meant to travel a long distance. A woodpecker drums—not for food, but for communication. The hollow sound is intended either to attract a mate or to declare territory and warn off male rivals.

Over the several decades we have lived here we have often heard the large pileated woodpecker off in the woods—drumming away, as he signals others of its species. We've also watched their showy flight, as their brilliant black and white wings flash out, topped by their bright red head.

A pileated woodpecker recently offered me a first-time, long-sought view of it, as it drummed on a hollow snag. (A snag is a standing dead tree—usually broken off at some height, into which woodpeckers and other creatures drill holes and construct dens. Even though a snag may provide good, dry firewood for us, we like to leave them standing—as they offer a sort of high-rise critter hotel.)

This special evening was my first time to watch a pileated woodpecker, as he drummed on a hollow tree. Usually I hear them drum far off in the woods, and wonder what resonating limb or trunk they've chosen to beat upon. This time I could see. Excitedly, I watched this woodpecker hop up and down the tree trunk—looking as if he was seeking bugs, but his search this night was instead to locate a good drumming spot. (Woodpeckers, when they are after bugs, will forage much closer to the ground—as that is where their prey is more likely to be located.) This bird hopped around near the top of the snag, looking for a promising spot, where he rapidly banged away. It was very loud and very fast paced. I watched his head whap back and forth in a black/red blur.

I watched the bird drum, then pause, and move to a new spot, where he drummed again for a couple of seconds—as if seeking a louder spot. Seemingly satisfied with his performance, he finally flew back into the deep woods. I was thrilled to be able to watch the action!

Now, if I could someday watch a male deer rub his antlers against a tree, or an owl carry food to its babies, or a fox pounce on its prey, I'd feel just that much more privileged. With patience and persistence, I might just do so one day.

Bird Ruminations

I'm sitting in my outdoor tub as twilight approaches, listening to the unfolding of the bird sounds and activities, as dusk begins to come over the land. There is such a variable chorus of birdsong all through the day—from the first pre-dawn hesitant outbursts, to the glorious morning ensemble of messages, to the midday business announcements of daily bird goings-on, to the late afternoon showy serenades, to the evening sign-offs that precede their settling in for the night.

As dusk approaches the calls become more like individual solos, as some of the birds retire, while others can't resist a few last pronouncements. After awhile, I find myself listening to what at first seems to be the last two birds calling out, into the approaching gloom. As I tune into their songs, I begin to realize that they are far more in sync with each other than I first thought. How do they coordinate their songs so well? But I soon come to understand that what seemed to be two birds singing from two nearby locations is really one bird, with two distinct calls.

Then I realize that what is really going on is that this single bird has both a lower-pitched song that I can associate with its true location, and a second, higher-pitched song that is being scattered back to me from the leaves of trees up in the woods. My acoustics training helps me to understand that the lower frequency song travels through the woods, unmindful of the trees leaves, so I can discern the bird's true position: over there in the clearing. But the higher-pitched part of his song has much shorter wavelengths—wavelengths that I realize are about the size of the leaves, so these shorter waves “see” the leaves as much bigger than the low-frequency waves. They reflect off the leaves, back to me, making me think that the bird is somewhere up in the woods where the trees are, rather than over in the clearing.

It's similar to when you drive at night with your headlights on. On a clear night your beams penetrate into the distance, illuminating the road ahead. You can see far off, knowing where the road ahead is, and see the distant oncoming cars by their headlights. On a foggy night, however, the air is saturated with water droplets whose size is “seen” by the waves of light from your car's beams—just like the tree leaves for the high-frequency birdsong. The result: your headlights' glow is reflected back to you, dramatically altering your view. Your eyes are dazzled by your own headlight reflection and you lose perspective of where you really are, or even where those approaching cars are.

This phenomenon (for birdsong or headlights) is called “backscatter.” It can disorientate you—even make you think there are two birds out there, rather than one late caller who is about to retire for the evening. A closer listen helped me tune in to see what's really happening. “One bird in the ear is worth two in the tree.”

Fading Thrushes

I have written before (“Wood Thrush Encounters,” 7/19/08 and “Foreign Bird Call,” 10/31/12) of how thrilled I get when the wood thrush sings out from the forest. Most species of thrush have beautiful songs, and of the handful of thrush varieties we are blessed with around here, the wood thrush is clearly the winner. Its call is melodic, inventive, artistic, and exquisite—like a Bach étude.

The bad news is that wood thrushes are on a steep decline. Their habitat—both in the summer in the US and over the winter in Central America—is dwindling, along with their population. I am keenly aware, as their gorgeous songs become scarcer in our woods, that the days we may listen to their melodies are limited.

Maybe the dwindling process is even going on very locally now. The last couple of years we have heard their calls much less often. We once were regularly regaled in early morning and after sunset with their repeated songs—never once tiring of them. Now we seldom hear them. I caught the old familiar call a few nights ago, for the first time in weeks. How it thrilled me! I stopped in my tracks and gratefully tuned in.

I wonder what will happen on the nature scene, after the wood thrush is gone—as seems rather inevitable. For a few million years the bird has filled its niche—fulfilling many more functions than simply singing for human pleasure. How will its disappearance upset the exquisitely balanced ecosystem? It will leave a hole—one that undoubtedly will be filled by an opportunist, who I'm sure will not be able to sing nearly as beautifully.

Nature, over the eons, has attained a robust yet fragile equilibrium; a sacred stability that we only barely understand. In the process, a divine natural art has been created. We blundering humans are defacing that scared art—for no good reason. We will wake up someday and face the results of our devastation—but how much will we have permanently lost by then?

Noisy Night Jar

Sometime in mid-April we will hear our first whippoorwill call out into the night air. They have arrived in the northern Shenandoah Valley from Florida or Central America and are getting ready to gobble up countless insects and beget their next generation of chicks. No bird is quite as emphatic and clamorous as the whippoorwill. They begin to call, as deepening dusk settles over the area—the first calls of the season being primarily from the males, showing off their vocal skills to all available females within aural range.

The whippoorwill's scientific name—Caprimulgus vociferus—aptly captures this bird's insistent song. It is in the night jar family and is an onomatopoetic name—meaning that its call has essentially the same sound as its name: whip-poor-WILL. (Although I think a closer rendition of our local bird’s accent is something more like per-for-REAL. If you’ve ever heard one of these birds, try singing out these alternative renditions in a falsetto and see which seems closer… just be sure you are alone, or accompanied by congenial people.) 

One of these guys will begin to call out, and quickly seems to get seized by an urge to keep going, without pause, until he threatens to bring on himself a serious case of laryngitis. In fact, one intrepid ornithological accountant once recorded a performance of 1,088 continuous calls!

Recently sitting in the tub, as nightfall came on, I could make out three whippoorwills simultaneously calling—trying to outdo each other in the vociferousness department. As they repeatedly called, I wondered how they could be aware of their competitors presence. If you don't shut up and listen now and then, how can you know that you have rivals in the vicinity?

Because of its nocturnal habits, there is a lot of mystery about the behavior of the whippoorwill. Its coloring is cleverly cryptic. In the daytime they rest on the ground, so well camouflaged that you could step on one and not see it. In the dark they become really hard to spot. In fact, here's a cute bit of whippoorwill lore: while you might catch sight of a gaggle of geese, you'd more properly refer to it as an “invisibility” of whippoorwills.

So a whippoorwill is far more often heard than seen. Although I may hear a whippoorwill call anytime during the night, they are most active at dusk and just before dawn. Their gut has an amazing capacity—they can consume up to 2,000 small insects in one night! The female whippoorwill lays two eggs, which are timed to hatch as the moon is waxing. (Can they really read a moon almanac?) That way, the parents can see bugs all night, to catch and feed their ravenous youngsters. Or maybe they need the bright moonlight to see their own cryptically-colored chicks in the dark?

I sat there soaking, listening to the three insistent whippoorwills call—seemingly ignorant of each other. At least that's how it seemed to me. Their repetition rate varied all over the place, so they sounded like three tin-eared musicians, oblivious to the fact that their calls were both out of sync and out of tune with each other. It was a lousy trio! They lack the harmonizing skills of katydids that I'll be hearing in another couple of months, when a dozen or more of them will call out and gradually get in sync with each other, until the woods literally throb with the pulse of their calls.

Foreign Bird Call

Thrushes are our most accomplished singers around here. Their songs are complex, variable, extremely melodic, and endlessly fascinating. The three thrushes we have, in decreasing order of song beauty are the wood thrush, Louisiana water thrush, and the good ol’ American robin. Thrushes are also migrating birds, so we eagerly await their calls each spring and joyfully exclaim our first hearing. 

For years, we’ve thrilled to listen to our best thrush caller—the wood thrush—coming from various places off in the woods. They are the first to call just before dawn and again the last to call after sunset. Their song is a three-part symphony, always repeated in the same order: (1) two low stutter tones, (2) followed by three flute-like liquid notes in varying order, and (3) capped off by a high-frequency trill or tremolo. The third part comes in at least half a dozen varieties, and the bird delightfully mixes them up. I can listen to a wood thrush call out 20-30 times and he never exactly repeats his song.

This year was different, however. There seemed to be only one thrush out there in the woods, and his song was not the same as in the past. Most of the time this guy left off the first and third movements—curtailing it to singing the middle three notes. At other times he’d just sing the final trill. I don’t think it was the same bird we’ve had on the past… moreover, it was only one bird calling from out in the woods during the season. Where were the other thrushes this year? Was this a new guy—either from another territory (with another accent) or maybe a juvenile just learning the song?

Ornithologists know that America’s wood thrush population is alarmingly declining. They breed in the eastern United States and winter in Central America. In both regions, their habitat is disappearing, as forests (its only home) are cut for agriculture and other commercial uses. We feel very fortunate to have had a viable population of wood thrushes around here, these last several years. But maybe they’re dwindling and we’re hearing the last of them now? This year’s lone caller was unsettling. It’s just a matter of time before we will no longer be thrilled by their wonderful song.

I wonder if this year’s single thrush’s different song is because he’s not one of our local birds, but one who has moved in from someplace else. Birds develop regional accents in their calls—especially if they tend to hang around the same location. They learn the local dialect and stick with it. But if a juvenile doesn’t get exposed to its species’ normal song, it’ll develop its own distinctive—and very much simpler—song.

So this lone caller could be a lonely juvenile who did not have mentors around to teach him. Or he could be from another region, and has moved into our territory—either because his native habitat has disappeared, or even that climate warming has driven him a little north this year. (Maybe that’s a Georgia accent I’m hearing?)

We also had fewer Louisiana water thrushes calling out this year, and the calls we did hear were also a little different from the past. So I wonder if we may be experiencing the same thing with both kinds of thrushes: a decrease in population and a subsequent change in calls. I hope not.

When the number of birds declines in an area, the lesser-skilled or less aggressive males begin to predominate for a while. In a normal situation, the best singers prevail, causing the poorer singers to slink off and lose their chance to mate. In any given year, most of the birds who could mate, do not do so, because they get shoved to the margins. But as the population drops off, the less talented (and maybe less fit and healthy) birds get their chance. Maybe that’s what’s going on here?

I can only guess how lonely it must feel to a bird, as the population declines and they find mates increasingly scarce. At first, maybe the less fit birds would flourish, because they have a chance to claim territory they’d otherwise be pushed out of. But as time goes by and the population further decreases, even those who persevere can’t find mates. What’s it like, for those last few birds, as they search in vain? How does the last bird feel? Does he or she sense something wrong?

After a few weeks of the strange-calling wood thrush singing out with his truncated song, we no longer heard him at all. Did he fail to attract a mate? Did the local females reject his call as being just too foreign? Did he move on to yet newer territory, seeking better luck? Later, we heard a few hesitant wood thrush calls far off… too far off to discern which bird it might be.

I pray that this year was just a weird experience, and we may once again hear that old, thrilling call next spring. At some point, however, we (or our survivors) will hear the last thrush call. The termination of a natural phenomenon that’s continued for hundreds of thousands or even millions of years is very sad.

New Bird Call?

A few months ago I was soaking in the tub when I heard what appeared to be a new bird call for me. Over the years, I’ve been able to identify most all of the calls of our local avian residents, and even a few who are traveling through. It’s neat to get to know the calls, so when I hear one sound off in the woods where I can’t see him, I can imagine who the caller is and what he looks like.

But this call was a new one for me. The bird was just out of sight, so there was no chance of spotting him, without stepping out of the tub… a move I’m extremely reluctant to make, after I get soakingly settled. I was curious about this call, but not that curious.

The call had two parts to it, it was very simple: a kind of trilly “brrr,” followed by a higher pitched whistle. Over and over he called, as the mystery deepened. What kind of bird was it? I closed my eyes, as if that might help me guess. He continued to mystify me.

Then suddenly the caller landed on a branch just above my head, continuing to sing. I opened my eyes and saw it was a common chickadee… just a little ol’ chickadee. I’ve never heard them sing like this! In fact, there were three of them, cavorting around, each one in turn calling out.

It was if they were demonstrating for me: “Look! Here’s our new song that we just learned. How ‘bout that? Yes, it’s us, your chickadee buddies. We’re not singing for territory or mates, just goofing off and seeing what we can do. Don’t you know it’s almost a full moon? We’re gonna have a party!” With that, they gaily flew off, still belting out their new song.

One more lesson for the giant, water-logged, two-legged, non-flying creature. It’s nice to know that the local critters are kind enough to keep teaching me. There is so much to learn from them.

Close Calls

Listening to a bird’s call when he’s off at a distance in the woods can be quite a different experience than when he is close by. If the song propagates through the forest for some distance, the high-frequency content becomes absorbed by the leaves, leaving the lower frequencies to carry on alone. Some information is lost.

Every now and then, I will be treated by a bird singing out from a perch close to me and I can hear much more in his song. This is more likely to occur in the early morning or at dusk, when competing noise sources (wind, distant airplane, barking dogs, local vehicles) are absent. If I am also still (such as sitting pensively in my outdoor tub), I can hear subtleties in his call that I’d otherwise miss.

When the bird calls from back in the woods, what I tend to hear is a purer sound, more like a clean whistle… it’s a simple call. When he lands nearby and sings out, however, I am amazed at all the additional sounds and complexity I can pick up.

For instance, the distant call of the mourning dove is like a soft, low, pure whistle. It’s a clean, cooing sound. Last evening, however, a dove perched on a branch close by, as he called out. I could hear a breathiness to his call, that gets absorbed when he’s calling from back in the trees. This close-by dove sounded to me like he had a wheeze—as if his air passages were constricted, or he had a bit of a cold. And his melodic “coo” sounded more like a yodel, as if he had flipped into a falsetto voice—whereas it sounds more like a smooth, melodic slur when he’s deep in the woods.

When the bird is close, those softer, high-frequency sounds can be distinguished. A bird may quietly lisp, buzz, whisper, rattle, hiss, whir, and rasp, as part of its call. When he’s close by, all these gentle, high-frequency sounds can be heard. They make his call far more interesting and informative.

When we humans talk (or sing) to each other, most of the information that we hear is contained in the high-frequency subtleties. Consonants create clicking, popping, hissing, and buzzing sounds that convey most of the message. Our throat cavities, lips, tongue, and nasal passages create many inflections that add a wide range of sounds. A bird has none of these sound shapers—his complexity comes from incredibly intricate muscle twitches of his bronchial and syrinx regions, deep in his throat. It’s a simpler sound, but still can be loaded with information.

Birds do manage to accomplish a lot of communication with each other—despite the lack of mouth parts to modulate their song. I’m wondering if all the additional sounds I hear when a bird calls from close by are what they use to relay all that information to each other. What difference might he be signaling if that familiar song of his is preceded by a sift gurgle or rattle, or if he tacks on a bit of a whir or buzz at the end, or even if he has a bit of a cold? I’m sure they are telling each other things that I’m usually missing.