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Author: Nathan Pieplow

Curve-billed Thrasher Identification

Curve-billed Thrasher Identification

The AOU checklist committee recently rejected a proposal to split the Curve-billed Thrasher into two species: the “Palmer’s” Thrasher (palmeri group) in Arizona and West Mexico, and the nominate or “Eastern” Curve-billed Thrasher (curvirostre group) in the rest of the bird’s range.

"Palmer's" (Western) Curve-billed Thrasher, Desert Botanical Garden, Scottsdale, AZ. Photo by Patrick Coin (Creative Commons 2.0).Nominate (Eastern) Curve-billed Thrasher, Colorado, by Fort Photo (Creative Commons 2.0).

Although very similar, the two groups can usually be distinguished by sight. In the photos above, note that the eastern bird (right) has a much whiter background color to the breast, resulting in stronger contrast with the breast spots; it also shows sharper and bolder white highlights in the wings and tail.  The stronger throat pattern, with a more distinct dark line bordering the white throat, may also be significant.  However, the much colder, grayer tone to the plumage overall is likely an artifact of photo lighting.

Interestingly, one of the committee members who voted “yes” on the split did so in large part because of differences in the call notes between the two forms, which I hadn’t seen discussed anywhere before:

YES. I now favor splitting palmeri – the clincher for me is that palmeri has distinct call note differences, a clear upslurred whit-wheet, as opposed to a two note whit-whit in which both notes are the same.

I have investigated this difference, and it seems to hold up across (at least) most of the species’ US range.  The vast majority of the call recordings I could find from well inside the range of “Palmer’s” Thrasher showed the same typical pattern: two upslurred whistles that started at the same pitch, with the second one ending much higher:

"Palmer's" Curve-billed Thrasher call, Catalina State Park, Pima County, AZ, 2/23/2008.

Whereas the call of eastern curvirostre-group Curve-billed Thrashers consist of nearly identical notes, both upslurred across a wide frequency range like the second note of the “Palmer’s” call:

Nominate eastern Curve-billed Thrasher call, Carlsbad Caverns National Park, Eddy County, NM, 3/30/2008.

Both groups of Curve-billed Thrashers give versions of this call with 3 or more notes, particularly when they are excited.  When the eastern curvirostre group does so, as you can see in the spectrogram above, all the notes tend to be similar.  When western palmeri birds extend their calls, the first note is usually of the stunted variety.  The third note (and any subsequent notes) tend to be like the second, but a little softer, so that the second note ends up getting the emphasis: “wit-WEET-weet”:

"Palmer's" Curve-billed Thrasher calls (3-noted version), Alamos, Sonora, 7/3/2010.

Some Curve-billed Thrashers in southeast Arizona give multi-note calls that are difficult to classify.  Here’s a bird from a few miles south of Eloy in Pinal County, where I believe the palmeri subspecies would be expected:

Atypical Curve-billed Thrasher calls recorded south of Eloy, Pinal County, AZ, 2/22/2008. Recording by Andrew Spencer.

Here’s some more from the same individual bird:

The two-note versions of this individual’s call tend to seem like the reverse of the typical palmeri pattern, with the second note quieter and less extensively upslurred than the others.  One might suppose this could be an intermediate bird, since the palmeri and curvirostre groups apparently overlap in southeast Arizona, but most educated guesses that I’ve seen have placed the overlap zone farther east, between Tucson and the New Mexico border.  I don’t believe this bird was identified visually to subspecies, so it remains a question mark for now.

Just to whet the appetite of the curious, here’s a Curve-billed Thrasher call from the Oaxaca valley in southern Mexico, which preliminary DNA studies showed as being distinct from either the palmeri or the curvirostre group (though apparently more closely allied with the latter).  Note again the “WEET-wit” pattern, which is the reverse of palmeri’s:

Obviously, more sampling is needed to fill in the many gaps in our knowledge of the Curve-billed Thrasher and its vocal variation.  Amateur recordists of the southwestern US and Mexico, this is your cue.

Gear Recommendations

Gear Recommendations

This past weekend I made my annual field trip to the Western Field Ornithologists’ conference in Palm Desert, California. Unfortunately, I had little opportunity to get out and make recordings in the field – it was a particular shame to miss out on recording at the Salton Sea, where (if you find the right spot) the most disruptive background sound usually comes from other birds, not from humans or vehicles. However, I did get to use a microphone a little bit during the Field Sound Recording Workshop that I ran on Saturday morning. While demonstrating the use of a parabola for some of the workshop participants, I was able to record these interesting sounds from a nervous flock of Gambel’s Quail:

In preparation for the workshop I drew up a brief list of equipment recommendations for those who would like to get into sound recording. I had long hesitated to do this, because I’m really not a gearhead at all – I basically know just enough about audio recording equipment to use it properly. But requests for gear recommendations are probably the single most common question that I field, and I felt it would be of use to readers if I posted the resulting info to my blog.

So, from now on you’ll see a “Recording Gear” page among the links above. Besides the equipment recommendations, the real value of the page is probably the quick links to other online resources. Please let me know if you find it useful, or have anything to add or subtract!

Got Grosbeaks?

Got Grosbeaks?

If this is a common sight at your feeders, Aaron Haiman wants to hear from you. Ontario, Canada, 11/11/2007. Photo by Mike Mills (Creative Commons 3.0).

Aaron Haiman is a Master’s student in Tom Hahn’s lab at the University of California, Davis.  For his thesis research, Aaron is following up on the paper that Tom published with Kendra Sewall and Rodd Kelsey in 2004, the one that described five call types of Evening Grosbeak.

As you will recall, Joseph Grinnell in 1917 recognized five subspecies of Evening Grosbeak on the basis of plumage brightness and bill morphology.  In 1974, the American Ornithologists’ Union decided that some of these subspecies were not distinctive enough, and so they lumped them into the three subspecies currently recognized.  However, the five call variants described by Sewall et al. match up quite well geographically with Grinnell’s original five subspecies.  So Aaron is setting out to determine whether Grinnell’s original taxonomy should be reinstated.  Eventually, he wants to answer lots of interesting questions:

  • do birds of different call types look any different from one another?
  • have they diverged genetically?
  • do other vocalizations vary along with the flight calls?
  • do they have different habitat requirements?
  • do they prefer different foods?
  • do birds of one type respond to the flight calls of other types?

In order to answer all these questions, Aaron needs grosbeaks.  And a great place to find themis at backyard bird feeders.  Aaron has already visited the properties of eight homeowners in three states who reported Evening Grosbeaks at their feeders, and with their generous cooperation, he has set up nets to capture the birds.

Once he captures a grosbeak, Aaron measures it, bands it, takes a sample of its blood, and releases it back into the wild.  Of course, he also audio records the bird’s flight call.  On his recent trip to Colorado, Aaron banded 19 Evening Grosbeaks — which isn’t a bad haul, but much more data is necessary to unravel the mysteries of the biology of this remarkable nomadic finch.

If Evening Grosbeak is a regular visitor to your backyard, and you are willing to host a banding and recording session, please  e-mail Aaron at anhaiman@ucdavis.edu describing where you live and how many Evening Grosbeaks are coming to your feeders.  So far, Aaron has gotten wonderful support from several generous people willing to open their yards to his research — and if you’re willing and able to help, he would love to hear from you.

Humming Their Own Tune

Humming Their Own Tune

In the bird world, there’s usually a pretty big difference between vocalizations that are learned and those that are not learned. By and large, learning birds can produce much fancier songs than their learning-impaired cousins – perhaps because coding music directly into the DNA takes up a lot of genetic “disk space,” introducing limits on the complexity of genetically-determined vocalizations.

Like many members of its family, this Anna's Hummingbird sings an extremely complex, learned song. Photo by Nathan Rupert (Creative Commons 2.0).

If you flip through a North American field guide, you might notice that the birds in the front half of the book (ducks, hawks, owls, gulls, woodpeckers) tend to have pretty simple vocalizations, whereas all the most acclaimed avian singers (wrens, thrushes, finches, mockingbirds and thrashers) are in the second half of the book. This is no coincidence. First, birds in the order Passeriformes (the huge order that encompasses the second half of the field guide) sport a uniquely complex set of muscles to control their syrinx, enabling them to perform much more spectacular feats of vocal gymnastics. Second, with the important exception of the flycatchers, most North American passerines learn their songs.

However, the learning of complex songs isn’t restricted to the so-called “songbirds.”  In fact, some of the best examples of learned, complex songs come from a family that isn’t in the Passeriformes at all: the hummingbirds.

To people in most parts of North America, this may come as quite a surprise.  That’s because our most widespread and familiar hummingbirds — Ruby-throated, Black-chinned, Broad-tailed, and Rufous — actually don’t sing songs at all; their vocalizations are limited to a variety of chip notes and buzzes, and produce their territorial sounds mechanically, with trilling wings or chirping tails in display dives.  But to those who live along the West Coast or in the southwestern deserts, the soft but astonishing song of the Anna’s Hummingbird is a familiar sound:

And Anna’s is no fluke.  Behold the vocal stylings of a Green-throated Mountain-Gem, a Central American relative of the Blue-throated Hummingbird:

Laboratory experiments have demonstrated that at least Anna’s Hummingbirds learn their songs, and as one would expect, the songs vary regionally as a result.  Although not all hummingbird songs are as complex as the examples above, the variation in songs can be tremendous.  Check out Xeno-Canto’s collection of recordings of Reddish Hermit, a lekking hummingbird from South America.  A quick perusal of nearly two dozen spectrograms will show that no two songs are alike.  Now, South America is a huge continent, and a species as wide-ranging and vocally variable as Reddish Hermit might well be split in the future — but take a look at these three recordings, all from the same biogeographic region (the Guianan Shield):

All show a similar repeated downslurred series, but each is spectrographically unique, and those differences are easily detected by the ear.  The differences are evidence of song dialects — local variants that we would expect to see in any population with learned songs.  (Anna’s and other singing hummingbirds have these song dialects too, but the differences between dialects are a little easier to see in a hummingbird with a simpler song.)

Many species of North American hummingbirds sing, including Costa’s, Blue-throated, Magnificent, White-eared, Broad-billed, Violet-crowned, and probably also  Buff-bellied.  In the tropics, the chorus of singing hummingbirds can sometimes be absolutely bewildering.  Next time you’re in singing hummingbird territory, keep your ears peeled for these all-too-often overlooked, underestimated melodies.

Automatic Song Recognition Online

Automatic Song Recognition Online

Hermann Redies and the folks at Xeno-Canto have just launched an ambitious project called Pai-Luiz, which attempts to automatically identify recordings of unknown bird sounds by looking through the entire Xeno-Canto database for matching syllables.  It’s just a prototype system at the moment — not particularly user-friendly yet, nor particularly accurate, but it still represents a huge leap forward in online automatic sound identification.

To give Pai-Luiz a try, you have to log in as a Xeno-Canto user, upload two different WAV files of the sound, and specify a precise bandwidth — as Hermann explains in the online documentation, you need to be pretty familiar with sound editing and spectrograms in order to do all this.  Once you upload a sound, Pai-Luiz takes up to an hour to process your request and email you a long list of recordings that might match yours.  The list is only a group of best-guess suggestions and there’s no guarantee that it contains a match — the actual identification still falls to you, the human user.  But when it works correctly, Pai-Luiz cuts down a lot on your workload — instead of having to listen to tens of thousands of recordings, you only have to sort through a few dozen possible matches.

Hermann is looking for users to try out the system and give feedback so that he can improve it.  If you’ve got a little extra time, you might want to feed it some known and unknown sounds to see what it kicks back.

(By the way: Hermann is a co-founder of Association “Mãe-da-Lua”, which purchased a Nature Reserve for the birds of the threatened caatinga habitat in northeastern Brazil, but can no longer afford to keep it open.  The reserve is looking for buyers or donors; for more information, see Hermann’s website.)

What’s That Screeching?

What’s That Screeching?

Independent young Great Horned Owl, Louviers, Colorado, 5/26/2008. Photo by Thomas Halverstadt (Creative Commons 2.0).
Barn Owl, Herefordshire, England, 8/16/2006. Photo by Stevie-B (Creative Commons 2.0).

Around this time of year, I tend to get a lot of questions from people who want to know what kind of bird might make frequent loud harsh screeches at dawn, at dusk, or in the middle of the night.  In most of the cases I’ve been able to solve, the culprit has turned out to be a young Great Horned Owl — one of the most vocal youngsters in the avian world (though one of the least vocally skilled, if I may be so bold as to say so).

However, back when I first started tracking these screeches to their source, I was usually hoping for a Barn Owl.  And in areas where both species are possible, I think that a number of birders may regularly misidentify the shrieks of young Great Horneds with the “shhhhk!”  of the Barn Owl.  Thus, it seemed like a good idea to post on how to tell these two (rather unpleasant) sounds apart.

Great Horned Owl

I tend to associate the shriek of Great Horned Owl with young birds, but according to the BNA account, it can also be given by adult males and, especially, adult females.  Juveniles shriek while still in the nest, and continue shrieking on a regular basis until at least December or January.  The shriek is usually short (half a second or less), typically slurred either up or down, and almost always sounds at least partially squeaky (as evidenced by the banding on the spectrograms):

Presumed juvenile Great Horned Owl, Walla Walla County, WA, 8/20/1990. Recording by Dave Herr.

(Click here to listen to the above recording at the Macaulay Library.)

The above recording is typical in that the sound is mostly noisy, but partly voiced — in this case, even slightly polyphonic.  The end result is a call that sounds like an inhaled hoarse scream.

Here’s a fairly similar example, from a bird still in the nest (with a Say’s Phoebe in the background):

Great Horned Owl juvenile begging from nest, Baca County, CO, 4/23/2005.

Meanwhile, the following recording helps demonstrate how variable this vocalization can be, even within individuals.  It was recorded from a bird that appeared to be an adult, though given the late date it may have been a first-year bird that had recently acquired adult plumage.

Great Horned Owl, Minnehaha County, SD, 9/2/2007.

Besides being strongly upslurred instead of downslurred, these calls (particularly the first one) are also less noisy, dominated by bands on the spectrogram, giving them a tone quality that is squeakier and less like television static.  The “squeaky” quality and the strong inflection are two of the best ways to tell a Great Horned Owl from a Barn Owl.

Barn Owl

Although Barn Owl vocalizations are just as variable as those of Great Horneds, the “classic” Barn Owl screech is fairly distinctive: longer than a Great Horned shriek (up to a second long or more), and consisting mostly of noise, neither upslurred nor downslurred, perfectly horizontal on the spectrogram and very lightly banded, if at all.  The call may sound like loud television static that is abruptly turned on and then off.

Barn Owl, San Joaquin County, CA, 5/13/1990. Recording by Geoff Keller.

(Click here to listen to the above recording at the Macaulay Library.)

Note that each call above ends with a very brief squeak, distinctly audible in this close-range recording.  Many Barn Owls, but by no means all, sound this way.  Here’s an example of shorter calls devoid of squeaks:

Two Barn Owls, Miami-Dade County, FL, 12/28/2004. Recording by Gerrit Vyn.

(Click here to listen to the above recording at the Macaulay Library.)

As always, we should beware individual, geographic, and age-related variation when identifying owl shrieks.  Here’s a bird from Ecuador that sounds much higher-pitched and distinctly upslurred.  It still has the hissing, non-squeaky tone quality typical of the species, but if such a bird were to vocalize in North America, it would make identification somewhat more challenging:

I hope this post is helpful for those wishing to make sense of the shrieks they’ve been hearing in the night.

http://www.xeno-canto.org/embed.php?XC=17270&simple=0
The Coolest Bird

The Coolest Bird

The Coolest Bird, by Rich Levad. Click for link

I’ve posted a couple of times before [1 2] about the Black Swift, one of the most unique and mysterious birds in North America, but this news was too good not to report: Rich Levad’s book “The Coolest Bird” has been published online by the American Birding Association.  Click the link for the 152-page PDF.

I had the privilege of knowing Rich before his untimely death in February 2008 from ALS (also known as Lou Gehrig’s disease).  He was such a force of nature that even though his career as an amateur ornithologist didn’t begin until after he retired from teaching, he still managed to move our knowledge of the Black Swift forward as much as any other individual in the past three decades.  “The Coolest Bird” is part memoir, part historical narrative, part monograph.  Rich meant it to be a book for the masses — the story not only of the bird but of all those who have pursued it, including their rivalries and prejudices, their flashes of insight, their daring climbs to nest locations, and above all their passion for the bird.  It’s a fast and absorbing read — if you have any time to spare, I highly recommend it.

Spectrograms on the iPhone

Spectrograms on the iPhone

Screenshot of the Spectrogram application for iPhone, showing how it renders Killdeer vocalizations. Click for link.

An email from Denise Wight alerted me to the Spectrogram application for the iPhone, which is a pretty neat little app indeed.  It uses the iPhone’s built-in microphone to create realtime scrolling spectrograms of any sound you’re hearing.  This means you can see spectrograms in the field, at the very same time that you’re listening to the bird sound.

Why is this exciting?  Because now those with hearing loss can see the sounds that their ears can’t hear!

Here’s an example.  Ted Floyd, editor of Birding magazine and author of the Smithsonian Guide to Birds, is Colorado’s recognized guru of nocturnal migration study.  Ted and I have gone out together many times to listen to nocturnal migrants giving their quiet “seep” and “tsit” notes high overhead in the dark, and every experience has been frustrating for me, because Ted invariably hears ten times more flight calls than I do, and that’s no exaggeration. My ears simply aren’t good enough to register such high-pitched sounds at such low volume.  I can only hear the lowest, loudest migrants, and for a while I suspected Ted might be making up the rest.

No such luck.  I realized the phantom flight calls were real when I carted my laptop into the field, plugged my shotgun microphone into it, and started recording with Raven.  Voila: a realtime scrolling spectrogram showed me the sounds of the night sky, even the ones I couldn’t hear.  The scrolling spectrogram gave me a chance to identify sounds visually that I couldn’t even detect by ear.

Now anyone with an iPhone can have the same experience, for the low price of $4.99, without having to lug a laptop and a microphone into the field.

The Spectrogram application has its pros and cons.  The gain is adjustable, which is nice.  You can adjust the frequency scale to run from zero to 8 kHz, 22 kHz, or 44 kHz — the 8 kHz setting should work best for most bird sounds — but you can’t zoom in or out on the time scale, which means those flight calls aren’t likely to be visually identifiable.  This may be better in future versions.

One thing that drives me absolutely nuts is the color scheme.  You can’t change it to grayscale — you’re stuck in the odd red-and-blue mode.  Personally, I can’t stand spectrograms in colors.  They may be nice for other purposes, but when it comes to identifying bird sounds, the colors get in the way.  Birders don’t need much information about loudness; for us, a spectrogram is text, and it’s meant to be read.  Therefore it needs to be in black and white, for the same reason that books need to be printed in black and white — anything else hurts the eyes after a while.

I could say more, but I’ll dismount my soapbox. Before signing off I should note that Pete Schwamb, the creator of Spectrogram for the iPhone, has also created a couple of other cool audio-related iPhone apps — including CricketSong, which uses the chirping of Snowy Tree Crickets to determine the air temperature.  Check it out.

The Genus Formerly Known as Aimophila

The Genus Formerly Known as Aimophila

Recently I explored some of the recent AOU species splits by comparing birdsongs.  Today I want to look at a genus that the AOU dramatically chopped and reshuffled: the sparrow genus Aimophila.

Aimophila has long troubled taxonomists.  On the one hand, it has traditionally included certain pairs of species — for example, Cassin’s and Botteri’s Sparrows, or Rufous-crowned and Rusty Sparrows — that look nearly identical.  On the other hand, it has also included birds that look radically different from one another.  In fact, taxonomists have never been able to establish a definitive set of features that distinguishes Aimophila from other sparrows.  Unsurprisingly, it turns out that not all the species in the genus share a common ancestry.

Still in Aimophila: Rufous-crowned Sparrow. Photo by Jerry Oldenettel (Creative Commons 2.0).Moved to Peucaea: Sumichrast's (Cinnamon-tailed) Sparrow. Photo by Jorge Montero (Creative Commons 2.0).Moved to Peucaea: Stripe-headed Sparrow. Photo by Len Blumin (Creative Commons 2.0).

A DNA study by DaCosta et al. (2009) recently showed that the members of Aimophila were not all each other’s closest relatives — a finding that typically portends a taxonomic rearrangement.  Largely on the basis of that study, the AOU recently split Aimophila three ways:

Remain in Aimophila

  1. Rufous-crowned Sparrow (Aimophila ruficeps)
  2. Rusty Sparrow (Aimophila rufescens)
  3. Oaxaca Sparrow (Aimophila notosticta)

Move to Peucaea (a resurrected genus)

  1. Cinnamon-tailed Sparrow (Peucaea sumichrasti)
  2. Rufous-winged Sparrow (Peucaea carpalis)
  3. Stripe-headed Sparrow (Peucaea ruficauda)
  4. Black-chested Sparrow (Peucaea humeralis)
  5. Bridled Sparrow (Peucaea mystacalis)
  6. Botteri’s Sparrow (Peucaea botterii)
  7. Cassin’s Sparrow (Peucaea cassinii)
  8. Bachman’s Sparrow (Peucaea aestivalis)

Join Sage and Black-throated Sparrows in Amphispiza

  1. Five-striped Sparrow (Amphispiza quinquestriata)

I’m going to save Five-striped Sparrow for another day, since it’s a complex topic — but let’s take a look at how the vocalizations of the other two groups give a clue to their taxonomic relationships.

Aimophila nasal chatters

A hallmark of the three species remaining in Aimophila is a short nasal call that often runs into a long fast chatter.  Here are examples from two of the three (the Rufous-crowned Sparrow chatter is at the end of the recording):

I couldn’t find online examples of the Oaxaca Sparrow chatter, but Howell and Webb say that it has one:

A slightly nasal, dry, scolding chatter shasha… or chehcheh… suggesting a wren; also a harsh, more excited, often prolonged chattering chii-i-i-i-i-i-ir, accelerating and slowing.

Peucaea rhythmic twitters

The species now in Peucaea don’t appear to give nasal chatters like those above, but many of them do give a unique “rhythmic twitter” — a rapid series of chip notes in which every fourth note or so is audibly different than the majority, giving the whole thing a unique rollicking rhythm.  The Black-chested Sparrow of Mexico provides perhaps the best example:

In its complexity, this call sounds much like a song, but the actual song of Black-chested Sparrow is described in Howell & Webb as a separate vocalization:

Song typically a single note followed by a rapid, liquid series of 8-16 notes sometimes accelerating into a trill: swiet, swieswieswieswie… or psu, susususu…, etc.

You can hear one strophe of Black-chested Sparrow song here (the very first vocalization on the cut; the rest is the rhythmic twitter).  Howell surmises that the rhythmic twitter may actually be a duet between two birds, and spectrographic analysis seems to support this view: in several examples on the Macaulay Library cut linked above, it seems that one bird often starts or finishes before the other.

Several other species of Peucaea apparently have rhythmic twitters (apparently often or usually duets) in addition to musical songs:

Cinnamon-tailed Sparrow

Rhythmic twitter:

Song:

Rufous-winged Sparrow

Rhythmic twitter:

Song:

Stripe-headed Sparrow

Rhythmic twitter:

Song:

Bridled Sparrow

Rhythmic twitter:

The song can be heard here.

The remaining species in Peucaea are more familiar to American birders: Bachman’s, Botteri’s and Cassin’s Sparrows.  They apparently don’t give rhythmic chatters quite the way their Mexican congeners do — or at least not as often — but the literature on all three species describes “excited songs” and/or “pair reunion chatters” that may well correspond to the “rhythmic twitters” above.  (There well may be a difference between “excited songs” and “twitter duets” in some of the above species, although I didn’t really draw the distinction this time around.  In particular, I know for a fact that only one Cinnamon-tailed Sparrow individual was involved in the production of the “rhythmic twitter” example above, and it was responding aggressively to my playback of the same vocalization — which sounds more like an “excited song” type of behavior than a “twitter duet.”  You know what that means — more study needed!)

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Rattles, Claps, & Burp-clicks

Rattles, Claps, & Burp-clicks

Buff-collared Nightjar. Photo courtesy of Manuel Balcazar Lara (click for link).

Perhaps the single species I most wanted to audio record on my recent trip to Sonora was the Buff-collared Nightjar.  I posted last year about the mystique of hearing this bird north of the Mexican border, where it is extremely local and rare.  In southern Sonora, by contrast, it is abundant, and I heard its préstame-tu-cuchillo song every single night of the trip.

Although the song of the species is well known, its other sounds are not.  The Birds of North America account on this species says “Calls, typical of genus, are various chuck or clucking notes; and quirr. Calls very similar to those given by Whip-poor-will. No known recordings of calls. Female known to give only chuck calls or clucking; no song. … Not known to wing-clap as other caprimulgids do.”  Howell and Webb’s Mexican field guide says that calls include “a low, clucking chuuk and kruk kruk, kruk…, and harder, clucking chatters.”  These descriptions give the impression that Buff-collareds may have a pretty impressive call repertoire, but without recordings, of course, it’s difficult to be sure.

I am pleased to share with you a couple of cool audio clips that may help resolve (or perhaps merely deepen) the mysteries surrounding the calls of the Buff-collared Nightjar.  The first was recorded in 1986 and resides in the archives of the Macaulay Library.  It was recorded by Geoff Keller, one of the foremost nature sound recordists in America, and the first four minutes of it are probably the finest recording I’ve heard of Buff-collared’s primary song.

Right at the end of the cut, something remarkable happens:

(Click here to hear the original)

The first time I heard this, I thought that Geoff’s microphone had rolled downhill right in the middle of one of the bird’s song strophes.  It sounded like a mechanical failure of the sound equipment.  But after listening carefully a second time, I realized that the crickets in the background keep chirping undisturbed throughout the disturbance and after.  I did a little research and discovered that Curtis Marantz, another fine sound recordist, had listened to the same cut before me and added some notes to Cornell’s database: “The recording concludes with what appears to be a series of wing-claps and some clucking or clicking calls (if not a noise produced by the wings).”

At first I was somewhat skeptical of this claim, since wing-clapping hadn’t been reported from the species, and also because of the bizarre nature of the sound, which alternated low “claps” with higher “rattles.”  But then I contacted Geoff Keller by email to ask him about the circumstances surrounding this recording, and he replied:

You have hit upon one of my most memorable recordings of my entire career….  As for the sounds at the end of the recording, I too agree they are wing-claps. I have now since heard many similar wing-clap sounds from other members of the Nightjar family.

Even more interesting is what Geoff witnessed after the end of the recording:

After the bird ended his series of territorial calls, the presumed male flies away (that is when the wing-claps are heard). However, the bird wasn’t finished. It circled around and landed once again just a few meters in front of me. There apparently was a female present, and the two nightjars began yet another series of most unusual sounds, which almost certainly would have been courtship vocalizations. This series of vocalizations were very different from the display/advertisement call of the male … I seem to remember “purring sounds” and “gurgling” like noises. I am presuming there was a female close by in the darkness, but I do not really know for sure. I do know for certain that the nightjar was unaware of my presence, as I had been holding tight under the cover of a mesquite tree for many minutes, and had entered this position while the bird was calling from the opposite end of his breeding territory some 100 meters away.

Unfortunately, we don’t have recordings of the courtship sounds that Geoff heard in the field that night.  But when I was in southern Sonora, I had my own remarkable encounter with a Buff-collared Nightjar, which resulted in another interesting recording.

It was about 9:00 PM, quite a while after sunset, and my Mexican guide Rene and I were hiking by headlamp down a trail through some scrubby forest on the north slope above Rancho Santa Barbara.  We had just stopped to listen (successfully) for Spotted Owls, and I had my recording equipment ready to go, although it was turned off, when Rene came around a corner and a bird flew up in front of him, clucking and growling.  I immediately recognized the vocalizations of a nightjar, as I’d heard similar sounds from Common Poorwills and Mexican Whip-poor-wills in distraction displays.  I turned my recorder on, and as I did so, the bird flew away from Rene and closer to me — landing about 10 feet in front of me on the path.  It took me a couple of seconds to find it in the headlamp and point the microphone at it properly, and during that time it made a bizarre series of quiet sounds, alternating burps and clicks and low gulps.  When I finally got a look at the bird in the headlamp, I had just a moment to marvel at how obvious the buff collar really was.  For these few seconds (the second half of the recording below), the bird was sitting on the ground without visibly moving, so it definitely was not making any of these sounds by wing-clapping.  Then it flew off at the end the way it had flown in, with a couple of gruff clucking calls.

Over the next week, I tried many times to record more calls from Buff-collared Nightjars, but I had scant luck.  However, I did hear these odd burp-clicks again on a number of occasions, from many different individuals — always at the beginning of a song bout.  When a male nightjar was about to start singing for an extended period, he would give a series of these burp-clicks for about 10 seconds, which would lead right into the first rendition of his normal song.  After that, he would repeat the song for a long time without any calls in between — only the first song in each bout had the special introductory notes.

Perhaps the most interesting thing about what I recorded is that when I asked Geoff Keller to listen to it, he didn’t seem to think it was a very good match for the presumed courtship sounds he heard in 1986.  In other words, the species probably makes even more sounds than can be heard on this page.  Geoff’s recording and mine, I think, establish Buff-collared Nightjar as by far the most vocally versatile nightjar in the western United States — but that’s just based on the tiny bit we know of it.  What else do Buff-collareds say?

If ever there was a bird I desperately wanted more recordings of, this is surely it.