Personal matters have kept me out of the field for much of this summer, and will do so at least through the end of September. I haven't been back to my study area since the 2nd of July when I downloaded audio from my long duration recorder, then left it redeployed with fresh batteries. I hope a bear hasn't found it and ripped it off the tree by now. It's got another 6 weeks of hanging out before I'll be able to go back and check on it.
But I couldn't stand not having a recorder in the field so I ordered a new one, the Olympus WS-510M, bought a new set of mics from Giant Squid Audio Lab, and went for a hike deep into a regional park not far from my house. I like the looks of this park because its sandwiched between a large river and a sprawling neighborhood of housing developments. The rivers edge is completely undeveloped for miles in either direction and thickly forested with large, old growth timber. There are a number of hiking, biking, and horse trails through the park, but they're closed at night and a lot of the park is strictly bush whacking if you want to get in to see it. The river defining one edge of the park is broad, but wade-able at many places and has several uninhabited islands in mid-stream. On the opposite shore of the river is more parkland, a wildlife management area full of swamps, and miles of undeveloped farm land (as opposed to the neighborhoods on my side of the river).
Its only 20 minutes from my house so I figured, what the heck. You never know until you go. So yesterday afternoon I hiked a half mile in on foot trails and then bush whacked a hundred yards off trail and into a thick understory of white oak saplings. I stopped at the end of a finger ridge that looked out over the heavily forested river bottom. I could hear the river rapids below, about a quarter mile away, and the occasional passing aircraft engine.
I deployed the recorder in one of the saplings with the left channel mic pointed toward the river, and the right channel mic pointed back toward the parking lot where I'd come from. It was about 7 p.m. with plenty of day light left, but before walking away I did three whoop and wood knock combinations.
This morning I returned before lunch to pick up the recorder. The battery appeared to have run out by the time I picked it up, which is the norm. The recorder indicated 14 hours of audio had been captured, so I was pleased that I would have plenty of recording to search through. But when I got it downloaded onto my computer I was dismayed to see that something strange had happened. The recorder captured about 55 minutes of audio, then seemed to pause for a dozen hours, and then continued recording two more hours of audio early this a.m. Not sure why this happened but hope its not a flaw in this new recorder.
Anyway, after going through the three hours of audio it did capture, I managed to locate a couple of interesting clips to share.
The first is a pair of faint whoops that occurred early in the morning hours, right around sun up. They're faint (as are many of the calls I seem to capture), but they were noticeable in the spectrogram software I use to review audio (I would have completely missed these if it weren't for the spectrogram. The first whoop seems to be preceded by a soft wood knock, the repeating down note of a yellow-billed cuckoo appears, and at the end the second whoop sounds nearly the same as the first, just fainter. I put this into a youtube video with annotations to hopefully make it more discernible to your ear (looping the video can help you hear the whoops more clearly):
The second recording might not be a vocalization at all, but its note-worthy enough that I want to share it, and some examples of similar recordings. I call it a "horn" like vocalization. It sounds rather mechanical in origin, but its also very similar to other horn-like vocals recorded by Galahad in Washington State. His recordings sound like a car or fog horn at first, but sometimes waivers in a distinctly biological fashion, sounding natural and not mechanical in origin. The horn-like sound my recorder captured this morning was some time before sunrise, seems to be preceded by a deep wood knock, and also seems to evoke a wood knock response about 15 seconds later (its that wood knock that made me look closer at the possible vocal).
Warning, this horn-like sound is such a low frequency, 265 Hz, that your computer speakers may won't be able to reproduce it (my laptop speakers can't). So head phones are probably required in order for you to hear the note at all (but the wood knock at the end of the clip is easily heard).
Here's a link to the youtube video of this sound in a spectrogram:
And here's a couple of links to Galahad's horn vocals from Washington state, for comparison (these are higher frequency and easily discernible on most computer speakers):
http://sites.google.com/site/mongahela/galahad/GHB-R09_0091-AMNRLPAM-StrangeHowl.mp3
http://sites.google.com/site/mongahela/galahad/GHB-R09_0060-AMNRLPAM-HornVocal.mp3
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