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Author: Nathan Pieplow

The Changes Are In

The Changes Are In

It’s July, and that means it’s time for the annual update to the American Ornithologists’ Union Checklist.  That means the splits I blogged about recently are now official.

Besides the high-profile splits of Winter Wren, Whip-poor-will, and Black Scoter, the checklist committee also did some major rearranging of scientific names, splitting a number of genera and reassigning several species to a new genus.  They do this whenever scientific studies (usually DNA studies these days) make it clear that birds currently classified in the same genus are not, in fact, each other’s closest relatives.  Although most such splits this time around were based on DNA evidence, vocalizations also support most splits.  Below we’ll take a quick survey of what’s changed and how audio was involved.

Species split

  1. Winter Wren is split into three species: Pacific Wren (Troglodytes pacificus) in northwestern North America; Winter Wren (Troglodytes hiemalis) in eastern North America; and Eurasian Wren (Troglodytes troglodytes) in the Old World.  Vocal differences were important in this split; see my older posts on how to separate Pacific from Winter Wrens by song and call.
  2. Whip-poor-will is split into Mexican Whip-poor-will (Caprimulgus arizonae) and Eastern Whip-poor-will (Caprimulgus vociferus). Vocal differences were important here as well; see my earlier post on this topic.
  3. Black Scoter is split into Black Scoter (Melanitta americana) in the New World and Common Scoter (Melanitta nigra) in the Old World.  Once again vocal differences were key, and once again you can hear them in an earlier post.

A couple of Latin American trogon species, the Greater Antillean Oriole, and the Elepaio of the Hawaiian islands were also split.

Changes in Genus

“Brown” Towhees Move to Melozone

Abert’s, Canyon, California, and White-throated Towhees will move from the genus Pipilo to Melozone, where they will join the Rusty-crowned, White-eared, and Prevost’s Ground-Sparrows. This genus split makes sense when you listen to the songs: the “brown” towhees sing with unmusical high-pitched trills and squeals that are very different from the rich, musical series of the “true” towhees.

“True” Towhees Remain in Pipilo

 

These species usually sing songs composed of 2-4 series of fairly musical notes — sometimes highly musical notes.  Some of them can be confused with each other, but rarely would they be confused with any of the “brown” towhee songs.

“Nashville” Warbler complex moves to Oreothlypis

Nashville, Virginia’s, Lucy’s, and Colima Warblers will move to the new genus Oreothlypis, along with the Orange-crowned and Tennessee Warblers.  This group is characterized by songs that are composed of 1-3 rapid (but not buzzy) trills.  The similarities are obvious on the spectrograms and to the ear:

Blue-winged and Golden-winged Warblers remain in Vermivora

These two species, plus their extinct relative the Bachman’s Warbler, remain in Vermivora.  All three are linked vocally by their very buzzy songs, quite similar to one another but quite different from those of the species leaving the genus.

Bachman’s Warbler songs can be heard at the Macaulay Library: [1 2]

Crescent-chested and Flame-throated Warblers move to Oreothlypis

This is one change that doesn’t seem to be supported by vocalizations.  These two Central American species were formerly in the genus Parula with (surprise) the parulas.  And their songs sound very like those species — high and buzzy — not at all like the songs of the other bird moved to Oreothlypis.

These embedded iframes are great, but they take up a lot of space, so we’ll continue on this theme tomorrow.

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Swift Travels

Swift Travels

Where they go, nobody knows: The migration routes and wintering grounds of Black Swifts remain a mystery. Photo composite by Bill Schmoker, Zapata Falls, Colorado, June 2008 (click for link).

Last fall I posted about the project to put geolocators on Black Swifts in an effort to determine, for the first time, where the species spends the months from October to May.  I just got exciting news from Rocky Mountain Bird Observatory’s Jason Beason: on Wednesday night, the team succeeded in recapturing one of the birds wearing a geolocator!

Of course, this success will take a while to bear fruit.  First Jason has to hang the geolocator outside his house for a week so that it can be calibrated according to the sunrise and sunset times at a known location.  (All the geolocators were also calibrated in this way prior to deployment.)  Then, assuming that all has gone well with the device over a year of riding swiftback, the team can download the data and begin the complex task of determining the latitude and longitude of the device every day for the past year based on sunrise and sunset times.  Then, and only then, will the team be able to generate a map of the bird’s travels.

Only four geolocators were placed on swifts last year: three at a cave in the Flat Tops Wilderness and one at a nest at Box Canyon Falls in Ouray.  The geolocator recovered on Wednesday came from the Flat Tops cave. To have recaptured one of only three marked birds there is a tremendous success, but a calculated one, since Black Swifts have tremendously high site fidelity from year to year.  Jason and his collaborators (Kim Potter, Carolyn Gunn, Chuck Reichert, and Todd Patrick) will revisit the cave next month to try to snag one or both of the remaining geolocators at that site, and they will be attempting to recapture the Box Canyon bird tomorrow–it is believed to be attending the same nest as last year.

Thanks and congratulations to the intrepid explorers who are on the verge of solving one of the biggest remaining mysteries of North American bird migration!

The Microphone You Already Own

The Microphone You Already Own

Nine days ago, Eric Ripma found an Orange-billed Nightingale-Thrush singing on territory in Spearfish Canyon, South Dakota.  Assuming the bird is wild and arrived under its own power, it is furnishing a jaw-dropping record — only the third north of the Mexican border, apparently, over 1200 miles farther north than the species has ever been known to venture before.  (See Doug Backlund’s photos here.)

Right now I’m in a hotel in Newcastle, Wyoming, on a trip to chase the Nightingale-Thrush, but that’s not why I felt it was blogworthy.  Rather, I wanted to call attention to a blog entry by somebody else who saw the bird a few days ago.  Cyrus Moqtaderi’s post is mostly about the guilty pleasures of chasing rare birds,  but with a passing remark he sent a shiver down my spine:

I made a few rudimentary audio recordings with my camera’s microphone

Cyrus posted some of this audio to his blog; click on the link above and listen to his recording.  Considering that it was the audio track of a video made with what he called a “dinky point and shoot camera,” it’s really quite excellent.  It’s not going to win any awards from snobby audiophiles, but for the purpose of documenting a sound heard in the field, it’s surprisingly good.

These days, I think it’s safe to say that the majority of birders own a camera capable of taking a short video with an audio track.  That is to say, most birders own a camera with a microphone in it.

That bears repeating: most birders own a microphone.

On a weekly basis, people write me asking for my recommendations when it comes to a cheap starting kit for recording bird sounds.  Also on a weekly basis, I’ve receive mystery bird sounds sent to me for identification in camera-recorded videos.  It took me until now to realize that the second phenomenon might provide a partial answer to the first.  Maybe they won’t produce high-definition audio, but if even half of birders’ digital cameras have the power to match what Cyrus’s camera did, then these built-in camera recordings could help to fill a key gap in Joe Birder’s toolbox.

My ability to identify bird sounds mushroomed when I began recording audio.  There’s something about listening to a recording that you yourself made in the field that really helps set the mental glue, so to speak.  For this purpose, a camera video would work just as well as an expensive parabolic microphone.  Granted, it may not be the most efficient use of your memory card, but then memory’s cheap nowadays, isn’t it?  At the end of the day, if you’re really interested in audio, then by all means buy a recorder — the Olympus VN-5200PC is hard to beat for the price — but if you’re in the field for other reasons and find yourself in sudden need of an audio capture,  remember your camera.  It may be good for more than just boring old visuals.

Wish me luck on that Nightingale-Thrush!

Wings of Thunder

Wings of Thunder

Andrew’s recent post on Spruce Grouse sounds made this YouTube video into a particularly nice find.  Shot by birding guide Khanh Tran in Washington state, it documents the double wing-clap display of the “Franklin’s” subspecies of the Spruce Grouse, which is the form found in the Pacific Northwest, north to central British Columbia and Alberta.  The video will play in high resolution by default; I recommend clicking on the fullscreen icon.  At the end, the wing-clap portion of the video is replayed in slow motion, and appears to show that the bird makes the sound by clapping its wings together above its back as it descends:

These wing-claps, aptly compared to gunshots in the Sibley guide,  have never been documented in the widespread “Taiga” Spruce Grouse (subspecies canadensis).  Most female grouse are thought to be extremely picky about their mates’ displays; males that don’t exactly match their expectations may not get a second look.  Thus, display differences are thought to contribute to reproductive isolation of a couple of other closely related grouse species (Gunnison vs. Greater Sage-Grouse  and Dusky vs. Sooty Grouse).  The presence or absence of a couple of loud wing-claps seem like a reasonable mechanism for separating “Franklin’s” from “Taiga” Spruce Grouse.

Compare the above to this excellent (but lower-resolution) video from northern Minnesota that manages to capture, I think, all the displays of a nominate “Taiga” Spruce Grouse, including all the ones Andrew posted about.  Note the similarity of the display flight as the male comes down from his tree perch — he “stalls out” much like the Franklin’s does and changes wingbeat speed, but resists all temptation to wing-clap.  Instead he makes the much fainter “drumming” recorded by Andrew, which is essentially inaudible in this video.

If that video didn’t satisfy your thirst for watching “Taiga” Spruce Grouse, check out the sequels (1 2 3).

Very little information on the display of Franklin’s Grouse is easily available; Khanh Tran’s video appears to be the only one of its kind online.  The Macaulay Library has a fairly extensive collection of Spruce Grouse recordings (both audio and video), but they all apparently pertain to the Taiga form.  Although Franklin’s and “Taiga” Spruce Grouse were considered separate species at one point, they were lumped in the mid-20th century due to reports of hybridization and introgression in their contact zone in British Columbia and Alberta.  As far as I can tell, no new information on this contact zone has surfaced in the scientific literature for more than fifty years, so there’s not much I can say about it.  However, molecular phylogenies of the grouse by Gutierrez et al. (2000) and Drovetski (2002) both provided genetic evidence for a split of Spruce Grouse, and David Sibley recently listed it as one of the 10 most likely upcoming splits.  But the group hasn’t been as well-studied as the Blue Grouse complex (now split again into Dusky and Sooty Grouse), so the checklist committee may want to reserve judgment for now.

Meanwhile, recordists wanting to make a difference in taxonomic research might schedule a trip to that legendary contact zone in Alberta and northern BC!

lWeoWtEacBE
A Sonoran Sampler

A Sonoran Sampler

One of the most spectacular birds in Mexico, Elegant Euphonias were common at our high camp at Rancho Santa Barbara. Photo by Jerry Oldenettel (Creative Commons 2.0).

Well, I’m back from two weeks in southern Sonora, recording bird sounds with an expedition led by the Sonoran Joint Venture and Western Field Ornithologists in the Sierra de Alamos / Rio Cuchujaqui Wildlife Protection Area.  It was a fantastic trip; I got 10 lifers and accumulated 19 hours of audio to sift through.  It’ll be great blog fodder once I catalog it all.  In the meantime, I’m still struggling to crawl out from under the massive pile of Things To Do Now That I’m Stateside, so I thought I’d just share with you a quick sample of some of the more interesting audio moments from the expedition.

Here’s the sound of a female Rose-throated Becard seizing a cicada, beating it against a tree limb until it quits stridulating, and then consuming it.

Here’s a large colony of bats squeaking in their daytime roost in the skirt of dead fronds below the crown of a palm tree.

If I were to judge a birdsong contest in Northwest Mexico, I’d have to give a prize to Sinaloa Wren, whose contributions to the soundscape were rich and frequent.

But I also love the sweet, soft, musical song of the Rufous-bellied Chachalaca.

No Mexican audio sampler is complete without this bird sound (in fact, much of a recordist’s time in Mexico is spent trying to get away from this species):

Near the El Cajon camp, an adult Gray Hawk fed two young at a nest right above my head:

And here’s the grand finale: the sound of a small group of Black-throated Magpie-Jays driving a Laughing Falcon off his perch.  He isn’t laughing about it, but if you listen closely, you can hear a couple of his faint chuckles.

In the coming weeks, look for some blog posts with a decidedly southwestern flavor!  It’s good to be home.

Off to the Tropics!

Off to the Tropics!

There’s going to be a brief hiatus around here, as both of your Earbloggers are headed south of the border for a little while.  Andrew Spencer is currently in Colombia, and I’m about to leave for two weeks of recording in Mexico.  However, Andrew did promise one blog post from the road sometime in the second half of June.  Other than that, I’ll be back online around the 4th of July, hopefully with lots of new insights into bird sounds!

In the meantime, if there’s nothing new to read here, I recommend getting out into the field and listening to (maybe even recording) some animal sounds!

Boat-billed Flycatcher Feature

Boat-billed Flycatcher Feature

Boat-billed Flycatcher, Horto Florestal de São Paulo, Brazil. Photo by Dario Sanches (Creative Commons 2.0). Click for link.

I just published my first feature article for Xeno-Canto.  I figured I should give their blogging functionality a try, and I’m happy with the result.  My subject is geographic differences in the vocalizations of the Boat-billed Flycatcher (Megarynchus pitangua), a Central and South American species that looks much like the Great Kiskadee of south Texas.

For reasons I explained in my recent post on hybrid flycatchers, vocal differences in flycatchers are likely to represent strong genetic differences.  I noticed some time ago that Boat-billed Flycatchers in Central America make some distinctive sounds that Boat-billed Flycatchers in South America don’t make, and vice versa.  I thought I would be able to write a quick feature recommending a split — a la my Gray Hawk posts [1 2] — but as I started writing, I realized that Boat-billed Flycatchers make a number of different sounds, some of them geographically variable, others apparently not.  It took me far longer to complete my project than I anticipated, which is one of the reasons why you’ve seen Earbirding go so long without a new post!

So head on over to Xeno-Canto’s feature page to check out my work.  As always, I’d love to hear what you think!

Hearing Loss and Bird Sounds

Hearing Loss and Bird Sounds

Happy birthday Earbirding! Photo by Theresa Thompson (Creative Commons 2.0).

In honor of Earbirding’s first birthday (yes, we went live one year ago today), I’m posting on the topic of getting older — and losing your hearing as you age.

Age-related hearing loss, or presbycusis, happens to almost everyone to some degree, although it tends to be more severe among men, and susceptibility can run in families.  It runs in my family, for better or for worse — even though I’m not yet 35, when I go birding with my friend Walter, he can detect chickadees by ear at twice the distance at which I can hear them.  The other day, he and I watched a Blue-gray Gnatcatcher vocalizing at a distance of about 50 meters.  He could hear it distinctly; I watched the bird’s bill opening and closing in silence.

Age-related hearing loss tends to affect high frequencies first, so that the upper frequency limit of a person’s hearing tends to decrease over time.  A European inventor exploited this fact to create a device called “the Mosquito,” a type of sonic “youth repellent” that keeps bus stations and storefronts free of loitering juvenile delinquents by emitting a piercing high-pitched frequency that only young people can hear.  (In retaliation, young people have converted the “Mosquito’s” buzz into a cell phone ringtone that their aging teachers can’t hear when it rings in class.)

In the past I’ve written about some corrective technologies for birding by ear.  Today I’d like to give those of you with perfect ears a chance to experience partial hearing loss.  It’s easy to filter out the high frequencies of bird sounds to get an idea of what you would hear if they were missing.  Some songs, like those of the Golden-crowned Kinglet, would disappear entirely.  Click on the link to test your hearing — if you can still hear the kinglet’s song, then your ears are pretty good.  I can still hear high-pitched songs like this just fine, as long as they are at close range.

But there are other ways that hearing loss can affect our perception of sounds besides eliminating the songs entirely.

Losing Songs in Pieces

Some bird sounds are composed of both high- and low-pitched notes, so that those with presbycusis may hear parts of the sound and not others.  A great example is the typical “fee-bee, fee-bay” song of the Carolina Chickadee, which is one of the best ways to distinguish it from the lookalike Black-capped Chickadee, which sings a simple “fee bee.”  The complete song is easy to identify:

Carolina Chickadee song, McCurtain County, OK, 3/23/2008.

But those with an upper hearing threshold of 6 kHz, which constitutes only a moderate hearing loss, will hear just the two lower notes:

Same recording as above, with all frequencies above 6 kHz filtered out.

And that makes it sound much more like the Black-capped Chickadee:

Black-capped Chickadee song. Larimer County, CO, 5/20/2008

Hearing Loss and Tone Quality

I used to be skeptical that presbycusis could affect the tone quality of sounds, but in some cases it can, especially if the sound is highly nasal.

Here’s a quick reminder in case it’s been a while since you visited the page that explains the nasality of sounds.  To have a nasal tone quality, a sound must be harmonically complex.  Such sounds appear on the spectrogram as vertical stacks of lines.  If the darkest lines in the stack are at the bottom, the quality of the sound won’t be nasal at all.  The higher the darkness climbs, the more nasal the sound.  Thus, the call of the California Gnatcatcher sounds intensely nasal:

California Gnatcatcher, Riverside County, CA, 3/22/2009.

Here’s the same sound, filtered above 6 kHz.  Note that the basic sound remains the same, but the quality changes slightly.  However, I’d still call it “nasal.”

Same sound as above, filtered above 6 kHz.

Here’s the sound filtered about 3.5 kHz.  (This is about the same level of high-frequency filtering forced on all of us by our telephones.  If you’ve ever wondered why people’s voices sound slightly different over the phone, it’s because the phone companies decided long ago that those higher pitches were mostly unnecessary to human speech, so they simply aren’t transmitted.)  This version of the call maintains its basic pitch (because pitch is determined by the spacing between the partials), but the quality is muted, duller, and less nasal.

Same sound, filtered above 3.5 kHz.
A “Skiew!” in the Dark

A “Skiew!” in the Dark

It was a chilly August night on Cameron Pass in Colorado, the most famous site in the southern Rockies to find the elusive Boreal Owl, and Andrew and I were at it again.  Neither of us had lived in Colorado much more than a year, but already we’d made several nocturnal pilgrimages to Cameron, only to stand on the side of the frigid road playing the Boreal Owl tape over and over into the dark, answered by the sound of wind in the trees — or, even more frustrating, the kind of pin-drop silence that might carry an owl call for half a mile or more, if only the owl would call.

Juvenile Boreal Owl, 6/28/2007. Photo by Andy Jones, Cleveland Museum of Natural History (Creative Commons 2.0).
Juvenile Boreal Owl, Dalton Highway near the Jim River, Alaska, 6/28/2007. Photo by Andy Jones, Cleveland Museum of Natural History (Creative Commons 2.0).

Pessimistic but stoic, we crawled out of the car and hit the tape.  The haunting sound went out into the night, over and over again.  And the night answered back with…

SKIEW!

It was an incredibly loud, squeaky bark, like nothing we’d ever heard before — more like a Hollywood ray gun sound effect than anything a bird should say.  We weren’t even sure it was a bird until it started moving from tree to tree, circling the parking lot unseen in response to the tape.

SKIEW!

For fifteen minutes we searched in vain for the source of the Star Wars noise.  Was it a Boreal Owl?  We left that night unsure.

A couple of months later we played the Boreal tape again, this time on a remote road near Summitville in southern Colorado, and again heard the aggressive SKIEW! from the dark.  We managed only a brief and terrible look at the creature in the flashlight beam, but we were finally convinced that we had just encountered our second Boreal Owl.

But were we correct?  The closely related Northern Saw-whet Owl lives in some of the same forests as the Boreal, and according to the BNA account, makes a “ksew” sound that strongly resembles the “skiew” of Boreal — and in fact, Saw-whets have been reported to give their “ksew” sounds in response to playback of the Boreal Owl’s primary song.  (One study got responses to Boreal Owl tapes from three Northern Saw-whet Owls,  seven Great Horned Owls, nine Barred Owls, and one Northern Pygmy-Owl — not to mention a few dozen Boreals!)

Can Boreal Owls be identified by their calls in response to playback, or must you get a look at one to be sure?  According to Phil Mattocks (1988),

The beginner should beware that there are lots of things that go “skiew” in the night. However, none of them sounds exactly like a Boreal Owl, according to those in the know (Bart Whelton, Dick Cannings).

In the hopes of joining those “in the know,” I tracked down an internet gallery of known and possible Boreal Owl “skiew” calls and Northern Saw-whet “ksews”:

  1. Harry Lehto recorded some nice “skiew” calls from Tengmalm’s Owl (as it is known in Europe) in Finland on 19 October 2008.  Although there are some slight differences in vocalizations between the European “Tengmalm’s” and the North American “Boreal” Owl, the two are still considered a single species, and of all the recordings I’ve heard, Harry’s are the best match for the “SKIEW” I’ve heard twice now in Colorado.
  2. Martyn Stewart has posted some Boreal “skiew” calls from the slopes of Mount Rainier, Washington state, from October 2009.  Martyn wrote to me that he didn’t get a visual on these birds, but that they are certainly Boreal Owls.  Note the two different birds giving two different versions of the “skiew,” one much briefer (sharper) than the other.
  3. My recording of an unknown “skiew” — very possibly a Boreal Owl — from Rio Grande County, Colorado, in October 2007, in response to playback of Boreal song.  It’s not quite as high-pitched or sharp as the loud calls I was hoping to record, but it’s a plausible candidate for Boreal.
  4. The audio gallery of the  Birds of North America account of Northern Saw-whet Owl (subscription required) includes a nice recording of the “ksew” call, plus another recording labeled as a “winter” call, which appears to be the same thing.  The “ksew” calls are very similar to the longer version of the “skiew” on Martyn’s recording, and they’re not too far off from the calls in my recording.

According to Dale Stahlecker, the “skiew” call of Saw-whets is “noticeably weaker” than that of Boreals, and I’ve been making the basic assumption that anything as explosive as the “SKIEW” I heard on Cameron Pass has to be a Boreal.  But as the recordings above show, there may be overlap in the “weaker” versions of the call.   Even Bondrup-Nielsen’s original spectrogram of the Boreal “skiew” is too low-pitched and shallowly inflected to match what I’ve heard in Colorado.  Same goes for the recording of the Boreal “skiew” on Cornell’s Voices of North American Owls collection.

When it comes right down to it, how do we know what’s going “skiew” in the dark?  And if we don’t know, how are we going to find out?

Review: Songs of the Warblers

Review: Songs of the Warblers

In 1985, the Cornell Laboratory of Ornithology partnered with the Borror Lab of Bioacoustics and Ontario Nature to produce Songs of the Warblers of North America on LP by Donald J. Borror and William W. H. Gunn.  No other source of that time period could claim to be as comprehensive: it contained no fewer than 280 cuts of song from 57 species of warblers, including mega-rarities from Mexico like Fan-tailed and Golden-crowned Warblers — even the extinct Bachman’s Warbler!  In addition, it included recordings of calls for all but eleven of those species.  For decades, this collection was the last word in warbler sounds.

Now, 25 years later, Cornell has re-released this classic, this time in MP3 format for digital download.  The song recordings are just as high-quality as ever, and I’m thrilled by the idea that their digitization might make them accessible to a whole new generation of bird enthusiasts.  But great though it was in 1985, the collection desperately needs to be expanded and revised — so desperately that I’m not sure I can recommend forking over the fifteen bucks for the download.

Here’s what I like about the collection:

  • The songs sound great. The cuts are nicely edited and, at about 25 seconds apiece, just long enough to stay interesting.
  • They capture the range of variation well in most species.  After listening to the five Borror and Gunn cuts of Olive Warbler song, you’ll be totally confused what an Olive Warbler sounds like — but anyone who listens to Olive Warblers for more than an hour in the field will be equally confused, so I call that a job well done.
  • The coverage of rare species is good.  In particular, those recordings of Bachman’s Warbler are true gems.

Here, unfortunately, is what Cornell should do if it really wants to update this guide:

  • Fill in the gaping holes.  Eleven species lack any recordings of calls whatsoever.  If they were all Mexican vagrants, I might understand, but Wilson’s Warbler?  Black-throated Blue?  You’ve got to be kidding me.
  • Bring the booklet up to snuff.  The accompanying brochure currently includes only the barest minimum of information.  It says nothing of the behavioral context of the vocalizations.  The “Type A” and “Type B” songs of many species are here, but they aren’t labeled as such, nor are subspecies labeled — so I can’t tell whether both “Western” and “Yellow” Palm Warblers are represented, for example.
  • Add flight calls. Andrew Farnsworth and colleages at Cornell have amassed a downright impressive collection of warbler flight calls, including many that don’t appear on Evans and O’Brien’s classic DVD.  Why not stick them on here?
  • Add flight songs.  Even the well-known flight songs of Ovenbird and Common Yellowthroat are missing.
  • Improve geographic coverage and representations of possible splits.  It’s nice that Myrtle and Audubon’s Warblers are treated separately, but where’s “Calaveras” Nashville Warbler?  How about Mangrove Warbler, or at least “Golden” Yellow Warbler?
  • Include common hybrids.  At a minimum, give us a Blue-winged × Golden-winged gallery with a dash of Hermit × Townsend’s.
  • Add Crescent-chested Warbler. The rarity coverage isn’t bad, but by now this species has certainly occurred north of Mexico often enough to merit inclusion.

Nostalgia is great and all, and Borror and Gunn accomplished something truly monumental in their day, but bird sound collections are supposed to be tools, not collector’s items.  And as a field tool, this reissue doesn’t quite meet the modern standard.

Let’s face it: the era of the commercial bird sound collection is pretty much over.  You can pay $15 for Borror & Gunn and listen to four examples of the song of Black-throated Gray Warbler and one example of its calls — or you can head over to Xeno-Canto and download (as of this writing) five examples of song and three examples of calls, completely free of charge.  For better or worse, the internet has democratized bird sound publishing, and anybody who still wants to make money off of sound identification guides has got to add some serious value.

When it published Voices of North American Owls in 2005, Cornell added that value.  The booklet accompanying the two CDs ran to 56 pages and described the behavioral context of each vocalization in detail.  The collection as a whole aimed to catalogue the entire repertoire of each species, and did a pretty darn good job of it.  By and large, the recordings of the common vocalizations were of a higher quality than anything you could download off the internet for free, and the recordings of the rare vocalizations simply weren’t available anywhere else.  Add to that the convenience of having all those sounds in one pre-assembled package, and you’ve got an audio publication well worth the $30 price tag.

With the reissue of Borror and Gunn, the convenience of pre-assembly accounts for almost all the added value.  The quality of the song recordings and the historical significance of the work make up the rest of it.  Whether that totals $15 is a judgment I’ll leave to you.

Here’s my personal judgment.  If I were the Cornell Laboratory of Ornithology, after performing the genuinely valuable service of digitizing this historic collection, I’d generate some goodwill by donating the whole thing to Xeno-Canto, as Bernabe Lopez-Lanus recently did with his colossal DVD Bird Sounds from Southern South America (6100 recordings from over 1000 species).  Barring that, I’d  invest the time and money it would take to really revise and update the project.  Anything less fails to do justice to the original work of Borror and Gunn.