As we put the finishing touches on Larkwire Water Birds of North America, I thought some of you might enjoy a little peek inside the process.
For months we have been building the library of recordings. Even for some common calls (e.g., the contact call of American Bittern), it’s suprisingly tough to get material we can use. For many species, we’ve combed literally every recording Macaulay and Borror have, and then reached out to other recordists, as well. We’ve rejected hundreds of samples because there’s too much background noise, overlapping vocalizations, or they’re just not typical enough.
Thankfully, for most species, we manage to find a good selection. In fact, in many cases, we accumulate more than the “typical three” that we feature in most levels of the game. (Only at Master level are you challenged with more than three samples per call.)
Once we’ve assembled all these samples, Michael O’Brien listens to all of them again and picks the “top three.” It helps to be one of the best earbirders on the planet! To give you some insight into this process, here are Michael’s comments on our samples for American Coot Anxiety call. At this point, we had three samples, but as you’ll see, Michael wasn’t completely happy with them:
It seems that we probably have two call types here. The 1st FL cut is a good example of the Anxiety call, but the other two in that section are something different, though related and also common calls. I think, for our purposes, we can lump them, but there’s another more classic variation of the Anxiety call that we need to get. A good example of this is ML Audio 43003, 0:19-0:22. This will give us three cuts that represent a good range of related calls.
Note the word “probably”! One of the things I’ve learned from Michael is to be absolutely humble in the face of how much we don’t know about bird sounds. Also, we quite often find that calls don’t fit as neatly as we’d like into simple boxes; often they exist on a continuum (e.g., alarm calls that are a more intense version of contact calls). For all of these reasons, and more, it’s invaluable to have Michael’s extraordinary field knowledge—and every time you use Larkwire, you’ve got that at your fingertips.
Here’s the final set of cuts we used in the product. The MB cut is the “classic variation” that Michael didn’t want you to miss.
I’ve always thought that nest parasitism (e.g., cuckoos laying eggs in other species’ nests) seemed particularly evil and wondered what defences species have evolved against this. An amazing study from Australia has just come out showing that Superb Fairy-Wren mothers basically teach their chicks a food password. If the nestlings don’t give the password, they aren’t fed! Presumably, nest parasites (such as cuckoos) haven’t evolved the ability to learn the password and therefore won’t succeed.
The mothers actually vocalize these special calls to their eggs and the study shows that the babies learn the calls before hatching. Once hatched, the chicks’ begging calls include the “password call” that the mother gave. Different mothers give different calls and the study shows that these variations are not genetic but learned. It would be very interesting to know more about the call variations used by the mothers.
The other thing that would be amazing to observe would be a nest in which both alien and native babies were present—in order to see whether mothers actually feed their own babies and ignore the others.
The New York Times has a fascinating piece called The
Sound of a Damaged Habitat. In it, musician and soundscape recordist
Bernie Krause describes a before-and-after experiment that he did to measure
the effects of selective logging on a stand of old growth forest in the Sierra
On a June morning prior to the logging, Krause recorded the rich variety of
bird songs and other sounds, a dawn chorus that included Lincoln’s Sparrows,
MacGillivray’s Warblers, Williamson’s Sapsuckers, Pileated Woodpeckers,
Golden-crowned Kinglets, robins and grosbeaks, as well as squirrels, spring
peepers and numerous insects.
In the ensuing years after the logging, Krause returned over fifteen times to
record in the same location. Visually, the forest is unchanged, however the
soundscape has never approached its original richness. He writes,
“I’ve returned 15 times since then, and even years later, the density and
diversity of voices are still lost. There is a muted hush, broken only by the
sound of an occasional sparrow, raptor, raven or sapsucker. The numinous
richness of the original biophony is gone.”
Using the natural soundscape, especially bird sounds, as a measure of
biodiversity and ecological health makes good sense and has been supported
As with all birding, earbirding and conservation go hand in hand.
One of the fascinating challenges to creating a new Larkwire songpack is organizing the sounds into similarity groups. With landbirds, for instance, we have a group such as “Robin-like,” which includes tanagers, several vireos and other species whose songs are confusable with the song of American Robin.
With waterbirds, these groups don’t cross taxonomic families quite as much. Grebes are mostly grouped with grebes, rails with rails, herons with herons, and so forth. But one of the groups that I find fascinating is “Wing sounds,” which includes several ducks and swans. Differences in pitch and quality give very distinct clues to species identity. Here are a few samples:
Mute Swan wing sound
Trumpeter Swan wing sound
Tundra Swan wing sound
Northern Shoveler wing sound
Common Goldeneye wing sound
Surf Scoter wing sound
We’ve been hard at work on our Larkwire waterbirds songpack and it’s coming together nicely. Despite the fact that none of these species are “songbirds,” there’s wonderful variety and beauty in the sounds that they make.
There’s the strange harrumphing of the Long-tailed Duck:
Of course, the wailing of the Common Loon:
And how about the haunting, whistling trill of the Long-billed Curlew:
Have you bought your Duck Stamp yet?
If you’ve heard of Duck Stamps at all, you probably think of them as a hunting license for waterfowl. And while they are that, they are much more, too. Duck Stamps represent one of our most successful conservation programs.
Duck Stamps were established in the 1930′s as a way to fund the acquisition of waterfowl habitat. At the time, they may mostly have been thinking of hunters, but the habitat preserved has become our National Wildlife Refuge system, enjoyed and appreciated by millions who are not there to shoot ducks. As pointed out by Barbara Volkle of Friends of the Migratory Bird/Duck Stamp, some of the most diverse and wildlife-rich refuges in the nation have been acquired primarily with Stamp funds.
For $15, you get an annual pass to all refuges. In my neck of the woods, this pays for itself with a few trips to Nisqually NWR.
What a great way to support conservation!
Kenn Kaufman and Rick Wright have each done a good job parsing this year’s taxonomic revisions (PDF) from the American Ornithological Union. They agree that in some ways the biggest change this year is the shift in how we view the falcons, which are now seen as much more closely related to the songbirds than to the hawks, kites and eagles.
Intuitively, this is very surprising! One could certainly explain the similarities in form as the result of convergent evolution (ie., similarities in function and behavior have led to the evolution of similar physical “solutions”). In fact, completely unrelated species can share the same form, which is why anteaters and aardvarks both have long, sticky tongues (for eating ants).
What I find interesting about the hawks and falcons is that many of their vocalizations are so similar as well. For example, listen to these two cuts of a Prairie Falcon and a Northern Goshawk. If these species are only distantly related, then perhaps the similarity of sound quality and structure represents convergent evolution as well. That’s a fascinating thought, because it suggests that theses sounds are not arbitrary, but in fact highly adapted to the constraints of each species’ environment.
Over on the ABA blog, Ted Floyd has nice series about documenting rarities with field recordings.
Ted shows that you don’t need an expensive rig to capture audio snapshots of bird sounds. As with photos, the pros will haul around heavy, expensive equipment and get top quality; but in the digital age, anyone can capture remarkably good audio. (In part 2, he discusses audio editing on the cheap, which will make your recordings even better.)
The key point is not just how easy it is, but that (as with birding in general), we so often hear birds rather than see them. For documenting rarities, or just sending out a “twitpic” of your latest find, recording the bird songs and calls that you’re hearing is becoming another regular part of birding.
Researchers at Duke have shown an interesting new form of selective pressure on bird sounds: juvenile birds learning their songs prefer sounds that they can hear clearly. In some ways, it’s an obvious finding, but still has interesting implications.
Hand-reared Swamp Sparrows were exposed to a variety of recorded adult songs. Some of the recordings had been degraded by being re-recorded at a distance in typical habitat. Other recordings were not degraded. As adults, all of the sparrows sang clear songs; none learned songs that had been degraded.
Why is this interesting? In part, because many other studies have shown that birds are adapting their sounds to cope with human noise pollution. This is the first study that shows how it might be happening.
On a deeper level, this finding adds insight into how bird songs came to sound they way they do to begin with. They are adapted to habitat.
The full paper is in Biology Letters, but you’ll need a subscription.
It’s always great to remember that many birds make a rich variety of sounds, in addition to (or instead of) the songs that we hear during courtship and breeding season. These “other” sounds we lump in the category of “calls” and one of the fascinating things about calls is that we often don’t really know what they mean. The fact that many birds have a rich variety of calls suggests that they communicate a rich variety of meanings.
Case in point: Recently at my local patch I heard two crows giving loud, rapid, throaty caws—I figured they were mobbing something. Looking around for a hawk, I noticed a third, subdued crow in the same tree. Occasionally it gave a weak, nasal caw—the sound of an immature crow.
After a while, the immature flew to another nearby tree. The two adults followed it and continued their loud cawing. They did not physically attack it, but kept up a racket. Once again, it flew a bit further, and they followed.
The meaning of all this? It seems possible that they were chasing away their own offspring from a previous season. Time to make it on your own. It’s also been suggested to me that they were encouraging a young crow that was having trouble foraging on its own.
Always nice to have mysteries.