Band-winged Nightjar (subspecies decussatus), Rafan, Lambayeque, Peru. January 2010, copyright Christian Nunes
I’ll admit I was crushed when Nathan wrote a feature for xeno-canto before I did. I have no one to blame but myself; it was pure laziness on my part that kept me from doing one. After I got over the bruised ego from him being first I got my act in gear and wrote one of my own. So if you want to read about the vocal variation in Band-winged Nightjars, check out my first xeno-canto feature.
Like Flycatchers and other suboscine passerines, Nightjars don’t learn their voices. So distinct vocal variations may well have taxonomic implications. In Band-winged Nightjar in particular there seems to be a good case for further study, and potentially splitting the species. For example, note how the differences in Whip-poor-will vocalizations recently played a role in the split of that species.
Finally, if any of you have recordings of Band-winged Nightjars you could upload to XC, especially of the decussatus, roraimae, or patagonicus subspecies that would be of great help!
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.)
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.
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:
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.
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 (123).
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!
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 [12] — 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!
Copyright Andrew Spencer, April 2010, Boot Cove, Maine
Or so I’ve been told. Supposedly the only way that Spruce Grouse can get away with being so remarkably “stupid” is the fact that since they eat spruce needles they taste absolutely vile, vaguely reminiscent of turpentine. Since, obviously, I haven’t actually tried Spruce Grouse myself I can’t comment on what they actually taste like, but it certainly sounds like as good an explanation as any… However, despite their not tasting very good this is still a highly sought-after species, with a well developed reputation as a hard to find bird. Here is my take on how you can find one…
Depending on who you ask, how to actually find a Spruce Grouse is a matter of debate. Some people say it’s easiest in the winter, when deep snow forces birds to the edge of the road. Others may say it’s in the later summer, when females herd their young through the spruce-fir. If you ask me, though, I would say that it’s in the early spring, when the muffled wingbeats of displaying males echo softly through the forest.
First off, though, I should correct a common misconception about Spruce Grouse displays. They do NOT include extremely low pitched hooting, as has been reported in many sources (e.g., Sibley). This misconception apparently has its roots in and article by Greenwalt (1968), and this error has been echoed through many field guides until recently. The displays of Spruce Grouse (the males at least) are entirely non-vocal, and the low pitched vocalizations referred to in most sources apparently are in reference to Dusky or Sooty Grouse.
I should also note that all the displays I write about below are in reference to the nominate subspecies of Spruce Grouse. The taxon found in the northwestern part of the lower 48 and adjacent Canada (“Franklin’s” Grouse) has a different display, and one I am not familiar with.
The main display of male Spruce Grouse (and the loudest, and thus easiest to hear from a distance) is simply the sounds of the wings whirring as it flies from a perch about 15 feet in a tree to the ground, and then back up to the tree. The specifics of the wing noise varies, though, between the descent and the ascent: during descent the bird flies normally, until it nears the ground, when it suddenly rears up nearly vertically in the air and the pace of the wingbeats picks up noticeably. During the ascent the wingbeats are more powerful and faster, but even in pitch throughout the flight.
While neither of these wing noises are especially loud, in the early spring boreal woodland (where there tends to be very little noise) it can carry for quite a distance and be a good way to find them.
Spruce Grouse flight display descent, Boot Cove, Maine, April 2010Spruce Grouse flight display ascent, Boot Cove, Maine, April 2010
Once you’ve located the displaying grouse, if you watch it long enough you may well notice some other, quieter and more subtle displays. One that was frequently given by a bird I observed for a couple of hours in Maine consisted of the bird lifting both its wings about a quarter way to horizontal and then beating them against the sides of its body, producing a muffled but quite audible “thump”. This sound is apparently not described in BNA, but seems to be a quieter version of the two loud “gunshot-like” thumps of the display of “Franklin’s” Sprcue Grouse.
Spruce Grouse wing thump, Boot Cove, Maine, April 2010
The other display that I observed from Spruce Grouse in Maine is what BNA calls the “tail-whoosh”, where the bird opens its tail and closes it rapidly, producing a slightly metallic swishing noise. It is also surprisingly loud for a sound being given by just the tail of an otherwise stationary bird. Compared to the flight displays and wing thumps, the tail-whoosh is a rarely given noise, at least during my observations – I heard perhaps a half-dozen total during two hours.
Spruce Grouse tail-whoosh, Boot Cove, Maine, April 2010
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, 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”:
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.
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.
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.
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?
"Eastern" Whip-poor-will. Painting by Louis Agassiz Fuertes, from The Birds of New York (1910). Public domain.
According to the grapevine, the AOU Checklist Committee has voted to split Whip-poor-will into two species. This split has been long anticipated, as the eastern and southwestern forms breed a thousand miles apart in different habitats, show slight average differences in size and plumage, and (most importantly for this blog) sing slightly different songs.
One of the primary lines of evidence cited in the split proposal was the recent publication of a molecular phylogeny of the nightjars by Han et al. (2010). Among many other species, the study looked at the two populations of Whip-poor-will (the eastern vociferus group and the arizonae group of the Mexican highlands), along with their close relative the Dusky Nightjar of Costa Rica (Caprimulgus saturatus). The study says that the three taxa “form a group… but their inter-relationships remain unresolved. This suggests that these three taxa should be given equivalent taxonomic status.” In other words, they recommend either splitting the Whip-poor-will, or lumping it with Dusky Nightjar.
Evidently the committee preferred the former option. No word yet on what they chose for names, so I’ll call them “Eastern” and “Mexican” for now. Here is a sampling of the songs of both forms, plus the Dusky Nightjar for comparison:
"Eastern" Whip-poor-will, Madison County, AR, 4/26/2009. Recording by Andrew Spencer.
"Mexican" Whip-poor-will, Cochise County, AZ, 5/11/2009.Dusky Nightjar, San Jose province, Costa Rica, March 2010. Recording by Arch McCallum.
The three song samples above progress through the taxa from north to south. Note how with each successive southward jump, the song elements become longer, more widely spaced (both within and between strophes), and burrier (more squiggly on the spectrogram). It’s clear that these three taxa are closely related, but it’s also easy to tell them apart, even by ear, primarily by speed and level of burriness. However, it seems to me that the Dusky Nightjar is more different from the two North American forms than they are from one another; in addition to being much slower, it is also significantly higher-pitched.
Note that if the AOU accepts the recommendations of Han et al. when it comes to splitting genera, then the whole Whip-poor-will group (along with Chuck-will’s-widow, Buff-collared Nightjar, and possibly Common Poorwill) will be moved from the genus Caprimulgus into Antrostomus — but no such proposal is currently before the committee as far as I know.
Eastern & Western Marsh Wrens sing slightly different songs, and may well be two different cryptic species. Many birders are aware of this in the vague sense, but haven’t taken the time to figure out how to tell the two forms apart.
Western Marsh Wren, Marin County, CA, 4/18/2009. Photo by Len Blumin (Creative Commons 2.0).
Eastern Marsh Wren, Rockingham County, NH, 5/2/2007. Photo by Scott A. Young (Creative Commons 2.0).
As the above photos show, identification by ear is going to be much easier than identification by eye — although these photos do nicely illustrate the slight average differences in crown color (browner in the west, blacker in the east).
So far, no one has reported any differences in the calls that the two Marsh Wrens make outside the breeding season, so this post will focus on songs. At first listen, the two forms can sound extremely similar. They both sing with the same pattern (that is, a couple of introductory notes followed by an unmusical trill):
Western Marsh Wren
Eastern Marsh Wren
Introductory notes
The easiest and most reliable way to separate the two forms is to listen to the introductory notes. The introductory notes of Western Marsh Wrens almost always consist of two quick, low, noisy “tuk” sounds. The second “tuk” usually runs right up against the start of the trill: “tuk tukRRRRRRRRRR.” Eastern Marsh Wrens, by contrast, very often start with a single nasal and/or buzzy note, which might be transliterated as “beer” or “bzt.” Listen for the difference in the songs above.
Some Eastern birds sing more complex introductions, giving 2-4 different kinds of introductory notes before the trill. Some of them — particularly in the far eastern part of their range, and especially coastal birds — can include so many different kinds of introductory notes that the overall impression is of a half-second warble preceding the final trill. They also frequently include some of these notes after the trill. Here’s a great example from upstate New York.
In another example from Florida, the bird goes crazy with high-pitched frantic warbles both before and after the trill; they may sound like distant fighting Killdeers, but they’re all Marsh Wren notes.
Tone quality
The tone quality of trills provides another important distinction. Western birds sing mostly noisy, unmusical notes, almost all of which sound like they could have been made by a typewriter or a stock ticker. The trills of an Eastern bird, meanwhile, tend to be more musical, although it’s a stretch to apply the word “musical” even to an Eastern Marsh Wren, since, at their loveliest, their trills tend to sound like someone rapidly shaking a fistful of coins. Nevertheless, listen closely to an Eastern trill for semi-musical “clinking” sounds or “piping” notes mixed in with other kinds of sounds.
Repertoire size
Both Eastern and Western Marsh Wrens sing with a repertoire of multiple song types, and they almost never sing the same song type twice in a row, preferring instead to cycle through almost their entire repertoire before repeating. According to Kroodsma & Verner (1997), Western males sing far more song types (100-200) than do Eastern males (40-60), but don’t bother trying to count them; instead, listen to the quality and complexity of the introductory notes and the trill.
Those familiar with Sedge Wrens may notice that Western Marsh Wren songs can be quite similar to songs of Sedge Wren, while Eastern Marsh Wren songs are less similar. However, Sedge Wrens can often be distinguished by their tendency to repeat one song type over and over again before switching to another. Unlike Marsh Wrens, they only cycle through their repertoires when excited, “during the dawn hour or during intense countersinging” (BNA). Here’s a Sedge Wren for comparison:
