SparrowFest at The Arsenal + more on recording in the wind

[Ted Floyd]

Hey, all.

With Pete Christiansen, Jason Zolle, Jeff Percell, and Michael Ward, I enjoyed a nice day yesterday, Sat., June 13, of eBirding and iNatting at Rocky Mountain Arsenal National Wildlife Refuge, Adams Co. The weather was pleasant: temps a bit below the seasonal average, with some clouds rolling in by mid-day, and winds kicking up after sunrise. More on the wind in a bit.

The highlight was an excellent showing by several passerellid species. We detected 37 Cassin sparrows, 80 grasshopper sparrows, and 87 lark buntings. And those were, of course, just trailside and roadside detections; Lord knows how many are out there altogether. An eclecticism of other avian highlights included: a male black-chinned hummingbird, seemingly on territory; a Virginia rail, singing the male-song in the middle of the day; a western cattle-egret strutting along the shore of Lower Derby Rez; two Mississippi kites swooping and sailing over Lower/Little Havana; just one burrowing owl (I think they're mostly down in the their holes right now, tending young and out of sight); a cordilleran flycatcher giving the "position note" in Upper Derby woods; one audio-supported presumptive eastern warbling-vireo and four unsupported, and unsupportable, warbling-vireos (more on this below); a sage thrasher, in ideal breeding habitat (sandsage + saltbush) at Big Blue Stem; and three dickcissels, one at Big Blue Stem, two singing along the wildlife drive. In the one-that-got-away category: a brief apparition from a scolopacid that likely was a white-rumped sandpiper. And as to non-avians, at least four prairie racerunners, Aspidoscelis sexlineatus viridis, in a New Mexico locust grove.

The Cassin sparrow show at The Arsenal is impressive. Check out this eBird output, indicating some combination of: (a) legitimate species biology; and (b) the pernicious positive feedback loop of observers going to places where birds have previously been reported. As Andrew Floyd casually inquired, on seeing this result: "Did you contribute to this bias?" Lol, guilty as charged: We ticked the species at 10 "daughter" hotspots at the "mother" hotspot for The Arsenal. Anyhow:

Okay, recording birds in the wind. Nathan Pieplow recently recommended recording from our wind-baffled trousers pockets. I remember an incident, eons ago, on a windy winter morning in Boulder when Bob Zilly yanked off one of my mittens, wrapped it around my recorder, and voilà, the peak meter, indicating wind noise, dropped to near-zero. That's cool. But if you want the ultimate wind baffle, try a CAR. 🚘 Here's one of yesterday's Cassin sparrows, out on the windswept wildlife drive at The Arsenal:



You can tell from the almost perfectly straight flatline on the waveform function (bottom panel). Srsly, if recording from within a pocket or mitten does the trick, doing it in a car, as above, takes things to a whole new level of acoustic purity.

Here's a grasshopper sparrow, atop windy Rattlesnake Hill yesterday at The Arsenal:

Something poignant for peeps, like me, with deleterious alleles for the LOXHD1 and TRIOBP genes (tl; dr— you got age-related high-frequency hearing loss), is the strong signal at the 0.77-sec. mark. First, a plea for birders to examine not just the popular sound spectrogram output (top panel), but also the richly informative waveform function, or oscillogram, output (bottom panel). Look at all those millipascals reaching the defective cochleae of my inner ear at around 0.77 sec.; given that the powerful signal has a carrier frequency just under 6 kHz, I can still totally hear that sound, and I've disciplined myself in recent summers to be consciously attuned to it. Which means I typically get on a singing grasshopper sparrow 300–500 ms before the kids do. Even if it's the only part of the song I can hear on a grasshopper sparrow singing at any distance. 😬

Next up. There are Brewer sparrows out there! Not nearly as many, this summer, as there are Cassin and grasshopper sparrows. To find a Brewer sparrow at The Arsenal, try the sandsage–saltbush admixtures, as, for example, at Big Blue Stem. Here's one singing in the wind:

Although the recording is acoustically noisy, with "white noise" (actually, gray noise in all such outputs) throughout, it's not all that bad, for the perhaps counterintuitive reason that the bird was singing out in the open. Open environments are, on the whole, acoustically simple, having the useful effect of driving wind noise down into the lowest registers. That's suboptimal if you're trying to hear (and record) owls, pigeons, and subwoofers, but not so bad for sparrows, katydids, and dog whistles.

More challenging, and where the Pieplow–Zilly Theorem really comes into play, is in acoustically complex environments like the decently dense grove at Upper Derby. Here's a presumptive eastern warbling-vireo yesterday at Upper Derby:



Lots of "white" (gray) noise in that one, even though, subjectively, it didn't seem bad, as we were "out of the wind." So we were, in terms of broadband activation of our epidermal mechanoreceptors. But the wind's sound energy (those pesky millipascals) don't magically go away. Hello?—First Law of Thermodynamics? The wind is still there, but it's distributed everywhere in the environment, manifested as this sort of dull reverb that we don't consciously pick up on but that nevertheless diminishes our sensitivity to discrete sounds in the environment. (Cf. the well-known problem of struggling to discern sibilant phonemes at cocktail parties.)

Two other things:

1. Nathan issues a plea for longer(ish) cuts of birdsong, and that's especially advisable, I would say, in the case of variable vireos. Ed Pandolfino has a paper in Western Birds, a while ago, on the songs of Cassin and plumbeous vireos, and he makes the point that it's actually impossible to identify—or, at least, credibly attempt to identify, haha—those two species from audio cuts less than about a minute in duration. Sorry, this cut from The Arsenal is only 15 seconds, presented here as COBirds-suitable imagery, rather than Pandolfino-compliant output. Father Ed: Forgive me.

2. You've all been waiting for the other shoe to drop. 👠 Yeah, we all need to provide such support for our species-level warbling-vireo IDs in Colorado. Pete, Jason, Jeff, Michael, and I actually heard five (n=5) candidate eastern warbling-vireos yesterday at The Arsenal, but we got spectrogram-supported audio on just this one. Therefore, we eBirded one eastern and four "spuhs" (eBird taxon "Eastern/Western Warbling Vireo") for our visit yesterday at The Arsenal. There's no shame in that! Indeed, it signals that you are a competent, science-based birder. Just do it. Or, I suppose, don't do it. 

Ted Floyd
Lafayette, Boulder Co.

P. s. Two more things on warbling-vireos. I cannot help myself.

First, for peeps keeping tabs on the presumptive easterns at Walden Ponds, Boulder Co., catastrophe struck back on Wed., June 10! Check out this audio and, especially, the comments appertaining thereunto:

macaulaylibrary.org/asset/659462219

Second, while we're all excitedly adding presumptive eastern warbling-vireos to our county lists, let's not overlook the coolness of presumptive western warbling-vireos. They can get amped up ("a vireo on speed") like easterns, they are super-variable, and they'll sometimes sneak in a terminal "squirt!" note in the song. For the ultimate surround-sound experience with presumptive western warbling-vireos, ride the gondola at Telluride, San Miguel Co. For the poor man's experience, try Gregory Canyon in Boulder Co., full of songsters like this one, singing up a storm back on Mon., June 8:

macaulaylibrary.org/asset/659334751