I do not count heards. To tick an antpitta is to see one well, otherwise we would have t-shirts with pictures of sonographs.
Iain Campbell
Long before my Earbirding co-author Andrew Spencer went to work for Iain Campbell at Tropical Birding, Andrew introduced me to Iain’s infamous quote about heard-only birds. Being audio fanatics, Andrew and I had a good laugh about it, and resolved to make spectrogram shirts just to spite him.
Someday I will get around to making a T-shirt with a spectrogram on it. But when I do, it won’t be to spite Iain Campbell. Nor will it be to champion the counting of “heards.” (That battle is winning itself — today’s birders are increasingly satisfied with other ways of encountering a bird besides simply laying eyes on feathers.)
When I finally make a spectrogram shirt, it’ll be to celebrate the striking beauty of bird sounds.
Spectrograms are the calligraphy of the natural world. A spectrogram is text, not in metaphor but in fact. As the written representation of an oral communication, a spectrogram is every bit as valid a text as the words on this page. The lines and curves that make up this sentence are standing in for sounds, as do the lines and the curves in a spectrogram — and in both cases, each line and curve carries meaning to those who speak the language in which the text was composed. The correspondence goes beyond the semantic and into the artistic. Some spectrograms match human calligraphy flourish-for-flourish in intricacy, tension, balance, and grace.
The "Bismillah," one of the most famous Quranic texts for calligraphy: "bismi-llahi 'r-rahmani 'r-rahim", "'In the name of God, the most gracious, the most merciful." Remixed from photo by Swamibu (Creative Commons 2.0).Spectrogram of Ruby-crowned Kinglet song, Larimer County, CO, 6/1/2008.
Just as each calligrapher’s work displays its own style, each vocalizing bird traces an individually unique spectrogram when it sings — its own personal signature in sound, the result of a fleeting, even if repeated, intersection of communicator, medium, and meaning. As the Wikipedia entry on Shodo (Japanese calligraphy) puts it, “For any particular piece of paper, the calligrapher has but one chance to create with the brush. … The brush writes a statement about the calligrapher at a moment in time.” In the same way, the spectrogram writes a statement about a bird at the moment it utters a sound.
Shodo (Japanese calligraphy) meaning "intoxicating fragrance," by sensei @ sanbokyodan (Creative Commons 2.0).
Brewer's Blackbird song, Tule Lake NWR, CA, 5/12/2002. Recording by Geoff Keller (LNS 120233). Click to listen
Shodo (Japanese calligraphy) meaning "water bed," by sensei @ sanbokyodan (Creative Commons 2.0).
Dusky Flycatcher trill call, Sierra County, CA, 6/2/1992. Recording by Randolph Little (ML 99326). Click to listen
To celebrate the beauty of spectrograms, I’ve multiplied the images in the header of this blog. Fans of the original Bobolink header need not worry — it’s still in the rotation — but now it’s been joined by seven other spectacular “specs” celebrating a wide variety of bird sounds from different families. One of these eight headers will load at random each time you land on the page. I’ve updated the “Headers” page to reflect this new diversity. If you enjoy them half as much as I do, you might get stuck here hitting “refresh” for hours.
I’ll leave you with two final masterful examples of graphic design, one by a bird and one by a human. I’ll let you sort out which is which.
Arabic calligraphy from a photo by Dr Case (Creative Commons 2.0), remixed with Western Meadowlark flight song, Pueblo County, CO, 5/13/2011.
Northern Mockingbird, Val Verde County, TX, 4/30/2010. Photo by Matthew High (Creative Commons 2.0)
“Mockingbirds are among the world’s most inspired mimics,” writes composer Andrew May. “They learn to imitate other birds’ songs (and other sounds) and incorporate them into their song. Humans, too, imitate and recycle the sounds we hear into our own songs and stories; technologies for recording and manipulating sound have made us even more avid recyclers.”
I like thinking of mockingbirds and other birds that imitate as “recyclers” rather than “mimics,” and so do some biologists. It’s been argued that using the term “mimics” to describe mockingbirds is misleading, because in most branches of biology, “mimics” are organisms that take on or use the characteristics of other organisms in order to be mistaken for them. The palatable Viceroy butterfly, for example, profits from its similarity to the poisonous Monarch only if predatory birds can’t tell the difference. It may not be clear why a mockingbird chooses to belt out the song of a Carolina Wren, but everybody agrees that it isn’t trying to pass itself off as a wren; more likely its motives are closer to those of a human hip-hop artist who creates remixed songs entirely from samples. It’s not mimicking, it’s “appropriating,” to use biologists’ favored term — or “recycling,” to use Andrew May’s analogy.
But May is not content merely to comment on the artistic motives of mockingbirds. He has turned the tables on the mockingbird and “recycled” its already-remixed song into an artistic statement of his own.
May, an associate professor of music at the University of North Texas, has composed a piece of avant-garde classical music called “Recyclers” that centers on a recording of a Northern Mockingbird that I made in Big Bend National Park in 2007. I had forgotten that I gave him permission to use the recording until recently, when I stumbled across his website devoted to the composition. I’m quite taken with it.
The part of the piece I find most fascinating is that May didn’t even use traditional musical notation. Instead he overlaid a spectrogram of the mockingbirds’ song directly onto the musical staff:
I’ve often felt that my own musical training was very helpful in learning to read spectrograms, and I’ve seen people use spectrograms of bird songs to recreate them in musical notation, but this is the first time I’ve seen anyone merge spectrograms and musical notation in this way.
In a live performance, the slowed-down mockingbird sings along on a digital recording while the performers attempt to imitate it, using their ears and their interpretation of the unorthodox score as a guide. It’s not Beethoven, and those unaccustomed to modern classical music may find it unappealing. But I, personally, enjoy it quite a bit. You can listen to a 25-minute performance by the Nova Ensemble below:
As May points out,
The performance may happen anywhere – a concert hall is not necessarily the best environment. Outdoor spaces (especially those populated with mockingbirds) are encouraged.
Wouldn’t it be wonderful to hear a chamber orchestra inviting the local mockingbird population into a joint performance? Unfortunately, the slowed-down playback of the bird sound in May’s recording means it’s unlikely to get a mockingbird’s attention even if performed outdoors — they won’t recognize it as mockingbird song. But knowing mockingbirds, it might not matter. Perhaps they’ll learn something, and repeat a piece of May’s mockingbird-inspired music long after the chamber orchestra is gone.
Baird's Junco, Baja California Sur, April 2006. Photo copyright Dave Krueper. Click to enlarge
Over the entrance to that “intellectual space” in which researchers debate taxonomic limits in the genus Junco, there stands a gate bearing an inscription in fourteenth-century Tuscan:
LASCIATE OGNI SPERANZA VOI CH’INTRATE
Just as Virgil guided Dante through the Inferno, I wish that I could offer you safe passage through the many circles of biological complexity centered on the single hellish question of how many junco species there really are. But there’s no such thing as safe passage. There’s no getting around it: the juncos are devilishly complicated.
Most birders in North America focus on telling the different junco forms apart by sight, which is appropriate, since most North American juncos sing a single high-pitched musical trill that is pretty much the same whether it comes from a Slate-colored, a Pink-sided, an Oregon, or a Gray-headed Junco:
A few of the Dark-eyed Juncos in all of these populations will occasionally sing a slightly more complicated two-parted trill:
And some of the Gray-headed Juncos in the southern Rocky Mountains will sometimes end with a slight flourish of 1-2 different notes:
As one moves farther south in the mountains, the junco songs become gradually more complicated. The “Red-backed” Juncos of northern Arizona sing significantly slower and more frequently two-parted songs than the Gray-headed Juncos they closely resemble:
By the time you reach southern Arizona, the juncos’ eyes have turned yellow, virtually all of their songs have become 2- or 3-parted, the trills have slowed, and terminal flourishes have become common:
Farther south, in central Mexico, the songs get even more complex, with fewer repeated notes, but they don’t last quite as long:
The southward trend towards brevity and complexity continues all the way down to the isolated, fireproof Volcano Junco of Costa Rica and Panama:
“Baird’s” Junco, an outlier
At least one isolated Junco population doesn’t really fit the pattern we’ve just described. At the southern tip of Baja California, high up in the Laguna mountains, one finds birds named after Spencer Baird that closely resemble the Yellow-eyed Juncos of adjacent mainland Mexico, except slightly paler, with a light brown back and soft pinkish flanks. Oh, and they happen to sing an extremely complex song:
Anyone who has ventured into the Sierra La Laguna knows that the endemic Baird’s Junco, currently considered a subspecies of the Yellow-eyed Junco by the AOU, doesn’t sound a bit like most other members of its genus. When we first heard it on the WFO/SJV expedition in 2008, some in our group looked around for a Passerina bunting; I thought I might be hearing a Rufous-crowned Sparrow. Howell and Webb (1995) say the song suggests a small Troglodytes wren, and split the species from Yellow-eyed in large part on that basis.
I recorded enough Baird’s Junco song in Baja California in 2008 for a formal analysis, but I didn’t have the statistical skills to pull it off by myself, so I collaborated with Clint Francis, who was then a graduate student in Alex Cruz’s lab here at the University of Colorado in Boulder, to try to figure out whether Baird’s song was really as different from the songs of mainland juncos as it seemed to the human ear. We wanted to know whether the more complex junco songs from central and southern Mexico might show an intermediate syntax linking the very different-sounding Baja and Arizona populations.
Our results, published this month in the Wilson Journal of Ornithology (subscription required), show that Baird’s sings quite differently than mainland juncos. Figure 1 from our paper illustrates this quite nicely:
Figure 1 from Pieplow & Francis (2011), showing Yellow-eyed Junco songs from Arizona (A–C), Oaxaca, Mexico (D–F), and Baja California Sur, Mexico (G–I). Click to enlarge.
Baird’s Juncos virtually never repeat a note or phrase, and they use far more unique notes and phrases than either Oaxaca or Arizona birds. In these features, the values for Baird’s didn’t even overlap with the values for mainland birds. A discriminant function analysis of 12 features easily distinguished Baird’s from mainland birds, but did not easily distinguish between Oaxaca and Arizona songs.
What does this mean? On the whole, it means that human ears don’t lie: Baird’s Juncos really do sing a highly differentiated song. It is quite possible that this song would reproductively isolate them in the unlikely event that they came into contact with mainland populations, meaning that Baird’s Junco may deserve full species status. We stopped short of recommending a split in our paper until playback experiments and/or genetic analyses can be done. However, a few years from now, Baird’s Junco (Junco bairdi) might just take its place on the AOU checklist as the next new North American Junco species.
Female Blue-throated Hummingbirds may be easier to distinguish from Magnificent Hummingbirds by sound than by sight. Photo by Jerry Oldenettel (Creative Commons 2.0).
Last week I had the pleasure of attending the 2011 Western Field Ornithologists’ Conference in Sierra Vista, Arizona, where the highlight of my trip was the opportunity to view and record huge numbers of hummingbirds. At our first stop, Beatty’s Guest Ranch in Miller Canyon, the legendary row of 15+ feeders was a blur of wings, with at least three or four dozen hummingbirds in view at any given moment, and others whizzing in and out at all times. It took mere moments to rack up a species list that included Magnificent, Black-chinned, Anna’s, Rufous, and Broad-tailed, Violet-crowned, and Broad-billed Hummingbirds.
Shortly, however, it became clear that the huge numbers of hummingbirds were both a blessing and a curse. For one thing, it meant that the number of difficult-to-identify females and immatures was immense. For another thing, it turned rarity-spotting into a search for a hyperactive needle inside a speedy, swarming haystack.
A few minutes into our field trip, one of the leaders, the eminent Kimball Garrett, called out “Blue-throated Hummingbird!”
“Where?” I asked.
“Didn’t see it,” he replied. “Only heard it.”
And then I was able to hear it too: a high-pitched, clear, brief, piping whistle, totally different from the chips, chirps, sputters and buzzes coming from the rest of the hummingbird crowd:
Blue-throated Hummingbird calls, Cochise County, AZ, 8/19/2011.
With my ears more fully open, I began to listen to the other species, and I realized that their vocalizations were distinctive too. In fact, within minutes, I could identify each hummingbird to genus (and therefore usually to species as well) just by hearing it call. After I had mastered the Blue-throated’s unmistakeable “seek!”, the next sound I learned to pick out was the strong, sharp “chip” of the Magnificent, which sounded to me more like the “tewp” call of a Black or Eastern Phoebe than like a hummingbird:
Magnificent Hummingbird calls, Cochise County, AZ, 8/19/2011.
The calls of the Broad-billed Hummingbirds were also instantly recognizable: noisy “chit” and “chittit” notes, much like the calls of a Ruby-crowned Kinglet:
Broad-billed Hummingbird calls, Pima County, AZ, 5/13/2009.
The Black-chinneds took a little more practice to pick out, but their calls were distinctive too, a slightly more nasal version of the standard hummingbird “chip,” reminiscent of tennis shoes on a gym floor:
Black-chinned Hummingbird calls, Pima County, AZ, 5/13/2009.
The genus Selasphorus, meanwhile, which includes Rufous, Allen’s, and Broad-tailed Hummingbirds, tended to give itself away by mixing short electric buzzes with other sounds (a variety of chips and twitters, plus the musical trills of the males’ wings):
Broad-tailed Hummingbird chips, buzzes, and wing trill (in background at about 6 kHz). Larimer County, CO, 5/20/2008.Allen's Hummingbird buzzes and chips, Orange County, CA, 3/21/2009.
And the Violet-crowned Hummingbirds could be identified by their quiet, smacking “tik” notes, so brief that they barely show up on the spectrogram as hair-thin vertical lines:
Violet-crowned Hummingbird calls, Cochise County, AZ, 8/19/2011.
With all these species shooting by at once, it only took me a short time to learn which was which, and arm myself with an identification tool of enormous power. “Black-chinned,” I’d find myself saying, even before the drab female hummingbird came out from behind the bush, much less landed on the feeder for binocular views. Suddenly I was performing feats of identification that had seemed like magic when Kimball Garrett did them a few minutes previously. And all it took was a little ear training!
On May 8th, 2011, Andrew Davis of Winnipeg, Manitoba and his uncle, Tim Davis of Parker, Colorado, were stopped in the picturesque mountain hamlet of Georgetown, about an hour west of Denver, when they heard an odd whistled song that reminded Andrew of a Golden-crowned Sparrow. He later wrote:
As we were tracking it down I remarked to Tim that what it really sounded like was Rufous-collared Sparrow, which I am familiar with from trips to Costa Rica and a trip last fall to Ecuador. Imagine our surprise, though, when that’s what it turned out to be!
Indeed, the two had found a Rufous-collared Sparrow, a common and winsome bird of mountain habitats from Chile to southern Mexico, the only tropical member of the familiar genus Zonotrichia. Several thousand miles north of the species’ known breeding range, the Georgetown bird became something of a celebrity, and birders flocked to see it.
Rufous-collared Sparrow, Fortuna, Alajuela, Costa Rica, 2/9/2010. Photo by Steve Ryan (CC 2.0; click for link).
Naturally, many people wondered about the origin of the bird. Some argued that because Rufous-collared Sparrows are popular as cage birds, the individual in Georgetown was likely an escapee from captivity; others held that the bird might well have arrived in Colorado under its own power. Some in the latter crowd, I suspect, wanted to see Rufous-collared Sparrow added to the official Colorado state bird list; therefore they had a personal emotional investment in the notion that the bird might have flown to Colorado by itself. Different people had different reasons for engaging in or avoiding this debate over origins; see Ted Floyd’s post on the ABA blog for a convincing argument that the bird is “worthy” regardless of its immigration status.
As a birder who appreciates the beauty and behavior of birds no matter when or where I find them, I agree with Ted. However, I am also keenly interested in discovering the sparrow’s origins, not just to provide fodder for the natural-vs.-exotic debate, but because the answer is bound to be interesting from a biological perspective. Is this an opportunity to learn about what happens when a bird’s migration mechanism fails catastrophically? Or is it an opportunity to learn how a (formerly) caged bird can adapt to alien climates and communities? Either way, it’s an opportunity.
Geographic origin
The first thing most people wanted to know was what part of the species’ vast range this individual sparrow had come from. One line of thinking held that if it had arrived under its own power, it most likely came from the geographically nearest population in extreme southern Mexico — and, conversely, if the bird had originated in Mexico, it was more likely of natural origin.
Others argued that it should be the migratory tendencies of populations, rather than their geographic proximity to Colorado, that would provide the best evidence for a natural vagrant. The populations in Mexico and Central America are non-migratory; in fact, they apparently hardly wander even a few kilometers from their breeding territories, making them very unlikely indeed to have sent a scout to the United States. Populations in Chile and Argentina, however, are austral migrants — they breed in austral temperate zones during the southern hemisphere’s summer (our winter) and then migrate north, sometimes thousands of kilometers, when southern winter arrives. Odd as it may seem, even though they are normally found many thousands of miles farther away, austral migrants are much more likely to fly to the United States than sedentary tropical birds. For example, the majority of the 100+ Fork-tailed Flycatchers that have arrived in this country are of the subspecies that breeds in Patagonia, not the subspecies that breeds thousands of miles closer in central Mexico (though that one shows up in Texas sometimes).
In between the sedentary Central American populations and the austral migratory populations are a whole bunch of stay-at-home tropical mountain Rufous-collared Sparrows. Most people interested in the Georgetown sparrow tended to agree that if it was found to come from a distant tropical area — say, Costa Rica or Ecuador — it was most likely an escaped cage bird.
Song sleuthing
When I heard reports that the Georgetown sparrow was singing loudly and often, I immediately wondered whether it might be possible to use its song dialects to pinpoint its birthplace.
Like its relative the White-crowned Sparrow, the Rufous-collared Sparrow in much of its range sings only a single songtype, and these songtypes vary regionally. As it happens, Rufous-collared Sparrows have one of the best-studied songs of any bird species, and a great deal of that research has been done by Paul Handford of the University of Western Ontario. In a 2005 article in Birding magazine, Paul laid out the evidence that different trill speeds at the ends of Rufous-collared Sparrow songs correpond to different habitats. I thought that maybe, given the many spectrograms that he had published, in addition to the vast number of recordings of Rufous-collared Sparrows on Xeno-Canto, we might just be able to find a songtype that matched the Colorado bird.
I made a couple of trips to record the bird, and was able to get its voice on tape on two different days in June. The first time I heard it, it was singing a three-note song without a trill:
Paul said this was typical of early-season breeding songs:
It was giving what we call ‘incomplete’ songs – ones lacking the terminal trill – which is usual for birds very early in the season, before the gonads have reached breeding size.
And indeed, a week later, I found the bird giving the same songtype with a somewhat extended terminal “trill.” It’s pretty darn slow to be called a “trill,” but some populations of Rufous-crowned Sparrows give very slow trills like this, according to Paul’s research.
Paul found slow trills like this in some migratory populations in Argentina. However, since even the “long” form of this song is quite short, it may simply be another version of the incomplete song.
Besides trill type, Paul indicated that repertoire size was the other key factor in trying to determine the bird’s origin:
If the bird is now producing two distinct song types then this suggests to me that the bird is of tropical origins since individual repertoires are only known to be well-represented in Ecuador; in south temperate and subtropical populations, individual repertoire size is one, as usual in Zonotrichia. In Ecuador on the other hand, individuals have been recorded with up to seven very distinctive song types!
Well, guess what? A little later on my second visit, the Georgetown bird started belting out this song:
Interestingly, the last songtype I recorded is the same as the one the bird is singing in the video that Connie Kogler took on May 19:
http://www.youtube.com/watch?v=SDWkk_v5It4
Conclusion? The bird appears to be from an equatorial population with multiple songtypes, NOT a migratory austral population, nor a Central American population, as far as I can tell. What does that mean for the likelihood that the bird got to Colorado by itself? I’ll leave you to draw your own conclusions, but one thing is clear: careful listening (and recording!) is of tremendous help in solving mysteries like these.
— Update —
Got an email from Paul Handford in response to my post, with lots of great additional information. Here’s what he wrote. (Note that chingolo is the name of the Rufous-collared Sparrow in South America.)
Your second recording (the one following the ‘incomplete’) sounds like a bona fide complete ‘theme + trill’ to me. There’s several places that I have encountered songs with such ‘slow’ trills with only 3-4 trill elements, like this one. Nothing about it strikes me as weird or unusual.
On the other hand your third songs are out of my experience — they sound like nothing I have heard before. If I were to hear them in the field, my antennae would definitely waggle about thinking “sounds like maybe a chingolo there”, but they have a quality unknown to me. But then, there’s an entire continent of chingolo songs that I haven’t heard!
The fourth songs again have the quality of incompletes, but also are a bit weird.
All together, there’s only one song that sounds truly ‘kosher’ to me as a complete well-formed song (your second ones). What the 3rd and 4th songs mean is an open question to me: but they don’t impress me as necessarily fully-crystallized songs.
One thing you don’t mention in your discussion is that we can definitively rule out the longest-distance migrant populations, for these have very distinctive head plumage – they completely or effectively have lost the black head stripes (see attached for an in-hand comparison of birds netted in early spring at Lat ~26°S; the stripey one is a local bird and the grey-head is still on its way to the far south).
So my guess coincides with yours: it is a tropical latitude bird; further than that I don’t see us going — without DNA sequencing, at least.
A final thought: there’s a good chance that this is a first year bird; there’s evidence that even nominally single-song birds can continue to learn songs (i.e. there’s not a classic closed learning period) at least into their second year (and, as noted before, Ecuadorean birds can evidently learn over an extended period). All this raises the possibility that, rather than having as it were brought these three song ‘types’ with him, this little guy MIGHT be emulating something local in Georgetown. It seems clear (at least to me) that this bird is counter-singing with local white-crowns; maybe it is also interacting with other taxa? And maybe it learned other notes while it was perhaps living in a cage??
Fascinating possibilities.
Here’s the photo Paul sent with the email:
Rufous-collared Sparrows of the migratory (top, with gray head) and non-migratory populations (bottom, with striped head), near Tolombon, Salta, Argentina, 8/22/2004. Photo courtesy of Paul Handford
In 1989, the American Ornithologists’ Union split the Western Flycatcher into two species: Pacific-slope Flycatcher (Empidonax difficilis) and Cordilleran Flycatcher (Empidonax occidentalis), on the basis of vocal differences, differences in allozyme frequencies, and an area of sympatry in the Siskiyou region of northern California, where they were reported to mate assortatively.
Ever since then, these two species have been causing headaches for birders all across western North America. The conventional wisdom is that they are impossible to identify by plumage or structure, even in the hand. Voice is the only field mark.
Male position note
Most birders use only one clue to identify these two species: the subtle but distinct difference in the position notes of the males. Pacific-slope gives a one-syllabled upslurred whistle, and Cordilleran gives a two-syllabled upslurred whistle:
In “classic” examples like those above, note the distinct kink near the beginning of the Pacific-slope call, and the distinct break in the Cordilleran call (which can sometimes be rather indistinct, as it is in the second call on the right-hand spectrogram above).
However, the situation with these call notes is quite messy. For one thing, the calls are frequently variable within individual males, as in these examples:
Variable calls from a single male Pacific-slope Flycatcher, California Gulch, AZ, 5/13/2009.Variable calls from a single male Cordilleran Flycatcher, Larimer County, CO, 6/1/2007.
Some of the Pacific-slope examples above sound vaguely two-syllabled, and some of the Cordilleran examples sound distinctly one-syllabled. Here’s a more extreme version of the monosyllabic call type from a Cordilleran on territory in Colorado:
Cordilleran Flycatcher calls, monosyllabic variant, from a single male. Larimer County, CO, 6/20/2008.
Note the lack of the distinct kink on the spectrogram that is typical of Pacific-slope. That kink, however, makes little difference to the human ear, and birds that sound like this are likely to be identified as Pacific-slopes in the field.
I believe that’s what happened yesterday when a potential first state record Pacific-slope Flycatcher was reported yesterday in Gregory Canyon, here in Boulder, Colorado. I went to record the bird this morning, and captured a few of its calls on tape:
Cordilleran Flycatcher calls, monosyllabic variant, from a single male. Boulder, CO, 6/13/2011.
Dawn songs
Less well-known than the differences in position note are the differences in the male’s dawn song, which is usually given only before the sun rises. As with the position notes, the differences in dawn song are subtle and subject to both individual and regional variation.
Like the songs of Dusky and Hammond’s Flycatchers, the dawn songs of Pacific-slope and Cordilleran Flycatchers consist of three different phrases usually repeated in an “ABC” pattern:
Pacific-slope Flycatcher dawn song, Orange County, CA, 3/21/2009.Cordilleran Flycatcher dawn song, Larimer County, CO, 5/25/2008.
Compare each note of the songs:
In both species, the first element of the dawn song is a brief, high-pitched, simple whistle of variable inflection.
The second element is the loudest, longest, and most distinctive: in Pacific-slope it usually sounds vaguely two-parted (or at least split in the middle by a consonant), whereas in Cordilleran it usually sounds like a single slurred whistle. (Thus, the distinction in this case is the reverse of that in the position notes.)
In both species, the third song element is a clipped, lower-pitched, two-syllabled note; the second note tends to be higher than the first in Pacific-slope and vice versa in Cordilleran, but this difference is somewhat variable.
When I originally recorded the putative Pacific-slope Flycatcher in Gregory Canyon this morning, I thought I was hearing the standard Cordilleran dawn song from it in addition to its Pacific-slope-like position note. Upon examining the spectrograms of my recordings, however, it became clear that the bird singing the dawn song and the bird giving the position note were different individuals, since their vocalizations overlapped a number of times on the spectrogram. Thus, I do not believe that I heard dawn song from the Gregory Canyon bird this morning. However, I believe it can still be identified as a Cordilleran given the shape of its position note. Furthermore, I heard Cordilleran dawn song and Pacific-slope-like position notes from another individual male about half a mile farther up the canyon this morning.
On the whole, these two species, if they are indeed species, are exceedingly difficult to identify by ear. Spectrograms of the dawn songs or male position notes should be identifiable, however. Thus, decent recordings would be essential to document any occurrence of either species outside its normal breeding range.
Andrew Rush and Arch McCallum are currently researching these birds in great detail, so hopefully we will know much more about taxonomy and identification of “Western” Flycatchers in the next couple of years.
Recently a friend alerted me to a post on the “ID-Frontiers” listserv by Christopher Hill in which he made a statement very dear to my heart:
In this day and age, I’m always surprised at the contrast between the level at which many advanced birders discuss plumage cues and the much more primitive way a lot of us approach sounds. I doubt I could convince many people on this forum of the identity of a vagrant by saying “but it looked just like the picture in my field guide!” (maybe if I repeated it?) but that type of argument is offered much more often, even routinely, in discussions of sounds.
He then apologizes for sounding like a preachy blowhard. (Hoo boy! If those are the words of a preachy blowhard, then I’ve got a lot to apologize for!)
I couldn’t agree more with his argument, which neatly summarizes the raison d’etre of this entire blog. I also wrote a Birding magazine article a few years ago that created a conceptual framework intended to help people describe sounds better. But reading Chris’s comments, I realized that a conceptual framework may not be of immediate use to people hearing bird sounds in the field. What they need are a set of instructions. So I decided to write a few.
How to Describe A Bird Sound in Six Easy Steps
If you can, make an audio recording. Use your cell phone. Use your camera on the video setting. Use a cheap voice recorder. Use your laptop. Use any device that can possibly record sound. If you don’t have one, that’s OK — but if you have any audio recording capability whatsoever, don’t proceed to Step 2 until you’ve done Step 1!
Count the notes. (If they are too fast or too many to count, make a note of that.)
Figure out which notes are repeated, if any. (Remember: trills are made of notes that are repeated, too fast to count.)
Write down nonsense words that sound like what the bird is saying (that is, onomatopoeia). Try not to use real words or phrases, as you’re likely to get closer to the original sound if you let yourself break the rules of English. Spend some time on this, and try to get the transcription as close to the original as possible.
Compare the sound you’re hearing to similar sounds. These could be bird sounds or non-bird sounds — for example, “like a robin song, but without any pauses”; “like the squeak of a shoe on a gym floor”; “like an electronic video game.” Spend some time on this also — come up with multiple comparisons if at all possible.
Sketch the sound. If the pitch of the sound goes up, draw a line that goes up. If it then goes down, draw a line that goes down. You get the idea. Put each note on the page, the way it sounds to your ear.
So, for the record, that’s
Audio
Count
Repeat
Onomatopoeia
Similar
Sketch
Or ACROSS for short.
OK, I know, that’s cheesy. But seriously, these are the steps to follow in the field. Don’t just settle for one of the steps — do them all! Try them with common birds. Try them with birds you don’t know (I’ll be happy to help you identify the results). Try them when documenting rarities.
You don’t need to know any fancy terminology, have any musical training, or use any “conceptual frameworks” when describing bird sounds — you just need to sit down and take the time to do each step carefully. It will change the way you listen, and it will change the way you talk about what you hear.
The American Robin frequently gives both subsongs and whisper songs. Photo by Mr. T in DC (Creative Commons 2.0).
Imagine a male robin, treetop in the early morning, belting out his song for all the world to hear, announcing his territory at the top of his avian lungs. It’s an easy thing to imagine. In fact, it’s pretty close to the stereotypical image of a singing bird.
Now picture that same male robin, deeper in the foliage this time, singing a song somewhat reminiscent of the usual treetop carol, but far, far quieter — so quiet, in fact, that it can’t be heard at 50 yards, and so subtle that the bird doesn’t even open its bill to sing, a slight fluttering of its throat the only clue to the source of the ventriloquial melody.
If you listen carefully to birds at close range, you’ll find that quiet, complex vocalizations like these are not uncommon. Often, they are called “whisper songs.” Some more technically-minded birders might call them “subsongs.” Both subsongs and whisper songs are fascinating, but they are not the same thing. Let’s look at the similarities and differences.
Subsong
The term “subsong” has meant a number of different things since it was first coined in 1936, but I have generally thought of it as The Sound Approach described it:
Subsong…is usually given from dense cover, is often full of mimicry, and may bear little resemblance to familiar adult songs. […] Subsongs are typical of birds with a low sexual motivation, for example adults and first-year birds before the breeding season really gets started, or juveniles after it has finished.
In January and February, the flocks of American Robins that descend into the fruit trees around my home provide ample opportunities to hear and study subsong. I have never made an attempt to age the birds I have recorded, so I can’t comment on whether the subsongs of juveniles and adults are different at this time of year. (Intuitively, I believe that they should be different, since the avian brain changes as birds mature, but I have no evidence for this at present.) What seems certain is that almost every robin in these flocks will sometimes get into the sub-singing mood:
American Robin subsong, Boulder, CO, 1/19/2008.
Compare the spectrogram above with the spectrograms of American Robin songs that I posted a few weeks ago, all of which were recorded in April, May, or June. The January phrases appear more similar to “hisselies” than to “caroling” phrases, but they’re not a perfect match for either one. Nor are they perfect matches for each other — they’re poorly stereotyped. Add that to the extremely low volume, from a bird that doesn’t even open its bill, and you’ve got what appears to be a classic subsong — either the practice sounds of a juvenile that hasn’t yet learned to sing, or the “warmup” tunes of an adult whose neural song circuitry has atrophied over the winter, in the absence of breeding hormones.
The general theory about subsong is that the bird isn’t producing stereotyped phrases because it can’t — it either hasn’t learned how yet (as a juvenile) or it’s physiologically unprepared (as an adult outside breeding condition). Like the babbling of infant humans, subsong provides a window into the process of vocal learning — a complicated, fascinating, messy process that, in a few short months, will result in the crisp, polished performances we know as adult song.
Whisper Song
The term “whisper song” has an even longer history than “subsong,” dating back at least to 1896, when Olive Thorne Miller wrote in the Atlantic Monthly:
A catbird at my back, too happy to be long still, would take courage and charm me with his wonderful whisper song, an ecstatic performance which should disarm the most prejudiced of his detractors.
The phrase appears to have crossed into the ornithological literature as early as 1914, with J. William Lloyd’s letter to Bird-lore titled “The Whisper-Song of the Catbird”:
The performance was like that of a bird in a reverie — like the ghost of a thought of a song. His throat merely trembled, and occasionally the bill parted just a trifle. Yet his song seemed the full repertoire of the Catbird.
Lloyd’s letter seems to have occasioned numerous other published observations of “whisper singing” in other bird species and at other times of year (e.g., Shafer 1916). Quickly, the notion of a “whisper song” gained broad currency among people interested in birds — mostly, it seems, in reference to the same phenomenon we just described as subsong.
I prefer to restrict the term “whisper song” to another kind of quiet, complex vocalization — one that isn’t heard from juveniles or non-breeding adults, but rather from birds at a peak of sexual excitement.
American Robin courtship "whisper song," Mesa County, CO, 5/3/2011.
Note how different this whisper song is from the subsong above. For one thing, it matches the “hissely” phrases we’ve seen from other spring robins. The level of vocal control is much higher; the bird repeats patterns with precision. For example, both the first and second phrases in the spectrogram include elements that are repeated exactly. And the whole third and seventh phrases are carbon copies of one another. This demonstrates that the bird is remembering particular phrases and re-deploying them at intervals, which means that these phrases form a repertoire, a library of remembered behaviors. This robin isn’t “making it up” as he goes along. He isn’t subsinging. He’s singing.
The Sound Approach described such singing as “highly motivated, sexually charged, and ultra-crystallized,” typical of male birds in close-range courtship situations. Indeed I have heard these whisper songs from male robins only during the breeding season, usually in the presence of females — and when no females were visible, I have suspected their presence. This is an entirely different phenomenon than off-season subsong, and it needs a different name. For now, “whisper song” seems like a good way to describe these complex, quiet vocalizations — the avian equivalent of whispering seductively into your sweetheart’s ear.
This past Sunday, which happened to be Easter, I went out to do a little birding near my house in Boulder, Colorado. I was hoping to cash in on the incredible wave of migrants that had swamped the city over the previous couple of days, generating sightings of rarities ranging from Yellow-throated Vireo and Yellow-throated Warbler to Hudsonian Godwit and Sedge Wren. After a fairly uneventful morning of recording Mallards, Downy Woodpeckers, and Black-capped Chickadees, I walked past a bridge over a small canal and suddenly heard what I was looking for — the unmistakable sound of a bird rare in the county — the song of an Eastern Phoebe.
Almost immediately, though, I could tell that something was wrong. The bird didn’t sound quite right — its phrases were clearly variable, not stereotyped like a spring phoebe song should be — and it was missing the really strong burr at the end of the “fee-BRRR” song phrase that is the hallmark (and probable namesake) of the Eastern Phoebe. I realized, with growing excitement, that it could well be a hybrid.
Song of possible hybrid phoebe, Boulder, CO, 4/24/2011.
As I’ve reported earlier, hybrid Black × Eastern Phoebes are on the increase, and have shown up along the Front Range in Colorado before. There was also a hybrid Black × Say’s Phoebe in California a couple of years ago. Hybrid phoebes are among the most interesting of all birds, because they allow us a unique window into the genetic control of song.
While recording audio of its song, I got some decent binocular looks at the singing bird. It looked quite typical of Eastern Phoebes, with a dark brown head; lighter brown upperparts and wings with a slightly grayer tone; faint brownish wingbars; and underparts that were mostly pale, but slightly darker on the upper breast, fading gradually down to the belly, which had a slightly yellowish cream color. From the front the bird had the very vague “vested” appearance caused by the slight contrast between darker flanks and yellow central belly, but this is not unusual on pure Eastern Phoebes. Unfortunately, I can’t recall the precise color of the throat or the level of contrast between throat and face, which would have been a useful mark. Ultimately, if I had seen the bird and never heard it, I might never have suspected anything amiss.
I think there are two lessons to learn here: 1) hybrid phoebes are becoming more and more common in Colorado; and 2) not all of them may be visually identifiable, but the voice gives them away. All the more reason to start recording audio!
Anyone who listens thoughtfully to robins can’t help but bubble with questions about why robins are the way they are.
–Donald Kroodsma, The Singing Life of Birds, p. 37
American Robin along the Platte River, Nebraska, 3/22/2010. Photo by Len Blumin (Creative Commons 2.0).
The American Robin may be the most familiar bird in North America, but for all its abundance and approachability, it remains in some ways inscrutable. Back in 1979, in his classic Stokes Guide to Bird Behavior, Donald Stokes wrote that robin courtship displays remained a mystery, and might not exist at all. The song he called an “enigma,” pointing out that it did not appear to correlate with courtship or territoriality, instead peaking right before the young hatch in any given brood.
Some studies in the 1990s provided evidence that robin song is indeed correlated with courtship and territoriality, but they did not make any attempt to describe the song comprehensively. That task fell to Donald Kroodsma in his popular 2005 book The Singing Life of Birds. Each male robin, Kroodsma explained, has in his repertoire 6-20 simple, whistled “caroling” phrases and 75-100 high-pitched, complex “hisselly” phrases. The familiar daytime song is often made up purely of caroling phrases:
carol carol carol… carol carol carol carol
But at dawn, the male robin often throws a hisselly phrase in at the end of each strophe:
carol carol carol hisselly… carol carol carol carol hisselly
In addition, some robins occasionally give long strings of hissellys without any caroling phrases:
Kroodsma documents all this and more; and yet, after fifteen pages of descriptions, explanations, and explorations, he still finishes with more questions than answers:
“Why have two types of phrases, the caroled and the hisselly phrases? Why have a dozen or two of the caroled phrases and a hundred or so of the hisselly phrases? Do other robins count how many a male sings, and if so, is having more songs better in any way? Why are the hissellys used mainly at dawn and dusk? Why at dawn are three or four caroled notes followed by a single hisselly, and what could it possibly mean to sing 71 hissellys in a row?”
The average American probably hears more song from robins than from any other bird, and yet we still cannot answer any of Kroodsma’s questions. Perhaps it is because we do not listen as carefully as we could; and perhaps it is also because what we call “song” in robins is even more complex than Kroodsma’s work has already shown. Today’s post will push the exploration of robin song a little further, in hopes of facilitating the kind of listening (and recording) that could begin to solve the many mysteries surrounding America’s favorite bird.
Caroling phrases
First, here’s an example of the “caroling phrases,” the familiar short, clear, 1-3 syllabled phrases that we often hear during the day:
American Robin caroling song, Boulder, CO, 4/24/2008.
Hisselly phrases
Kroodsma described the hisselly as “an ethereal whispered note much like the delicate flourish at the end of a Hermit Thrush song”. The hissellys shown below, all from the same individual male robin,have been edited together for comparison. Note that they are much higher-pitched and more complex than the caroled phrases, with a great deal more polyphony:
Ten "hisselly" phrases from one American Robin, edited together. Boulder, CO, 5/26/2008.
Whinnies
The “whinny” is a familiar call of the robin, often given when the birds are alarmed:
Typical American Robin whinny call, Larimer County, CO, 6/19/2008.
But it’s not just a call. At least at certain times, the whinny (or something much like it) becomes an important component of the robin’s song — and each individual male robin knows an awful lot of different whinnies. Here are six that one male robin incorporated into his song within a two-minute span:
Six different whinnies from the song of a single male American Robin, edited together. Boulder, CO, 5/26/2008.
Note the complex and stereotyped fine structure above. These are no mere alarm calls; they are song elements, no doubt about it.
Putting it all together
Here’s a confusing recording of a robin singing with carols, hisselys, and whinnies all mixed together — in fact, he is the sole source of all the hissellys and whinnies on the edited tracks above. I recorded him in late May in Boulder, Colorado, and though there were many other robins in the immediate vicinity, none were interacting with this bird that I could see; he was perched up in a tree just belting out his song. What in the world can he possibly be saying?
American Robin song, Boulder, CO, 5/26/2008.
The beginning of this bird’s song, illustrated on the spectrogram above, follows a pattern like this:
I do not know what is going on with this bird, but its song suggests that anyone seeking to understand robin song should think of the whinnies as a type of song phrase on par with the carols and hissellys. At the same time, it reinforces what you’ve probably already realized: anybody seeking to understand robin song has a lot of work to do.
