Note: Based on thousands of hours of reviewing and analyzing field recordings, I now think these sounds are squirrel vocalizations. In my experience, Eastern grey squirrels are the most challenging confusion species, both in the field and on sonograms. Modest attenuation by distance can make them sound quite ivorybill like, and fundamental frequencies can sometimes be in the range of the Singer Tract ivorybill kents.
Since summer is here, and things are slow, I’ve reconsidered my decision not to post audio obtained in the course of our searches (although I’m not sure I’ll repost old audio from the original search area.) We did not record anything of note during 2013-2014, although we did have a number of auditory encounters. It’s not feasible to keep a recorder running at all times, so when interesting ambient sounds occur, it’s only possible to capture them when they go on for an extended period. In these situations, it’s a judgment call as to whether to approach the source of the sounds, try to record them, or a mix of the two.
These recordings were made on March 2, 2013, and I have included my notes to provide details and context (location redacted.) On the morning clip, the calls can be heard at approximately 0:03, 0:17, 2:04, 3:36, and 3:47 (two calls in very close succession with the interval almost indiscernible to the ear but evident in the sonogram). On the afternoon clip, the only call captured is at approximately 0:52. On the morning clip, there are toots on a clarinet mouthpiece at approximately 0:25 and 1:30, so beware if you’re listening on headphones. The first clip can be played directly from this page. Click on the link to play the second in its own window. I can only hear the call on the second clip with headphones.
Although the duration of the calls appears to be consistent with the Singer Tract recordings, the base frequency is considerably higher, approximately 920 hz.
John Henry and I were ***** on Saturday March 2, 2013. Conditions were mostly cloudy and cold.* Winds were strong (gusts probably around 20 MPH and not many birds were calling). The morning had been active, but as winds picked up, birds went quiet. At approximately 10:15 am, several crows were calling loudly, but I heard 2 intriguing calls behind the crows. I asked John to stop and be quiet. The calls continued, sporadically, for the next 30-45 minutes. I was able to record some of them. We both estimate the distance at around 200 yards and agree that two birds were involved. We both agreed that the calls were mobile and over the course of the sequence, they came from at least three directions. We tried to follow the calls but did not see anything.
Most calls were singles, but in a couple of instances, a first call was followed by a second one within a couple of seconds. The pitch of the second call seemed lower. The duration of the calls seemed to be short. They lacked the intensity of the Singer Tract recordings, but were clearly not Blue Jays, nuthatches, or tree squeaks.
I blew on a clarinet mouthpiece. The calls continued, but neither of us had the impression that there was a response.
At the end of the sequence, John heard two additional calls that I missed, and we found large bark chips at the base of a tree that was in the vicinity from which he had heard the calls. We had walked through this exact location before the calls began and had not noticed the chips (which I normally would have done.)
Between us, we heard a minimum of 18 Ivory-billed Woodpecker-like calls in the morning.
We left the area and returned late in the afternoon. At approximately 5 pm, we were at the spot where we found the bark chips. At this time we heard approximately a dozen more of the same calls and were able to record a couple. The first call I heard seemed a little off, as the note seemed to be doubled, one in immediate succession after the other.** This only happened with the first one. The others were virtually identical to those heard earlier in the day. A white-breasted nuthatch called during this sequence, and there was no possibility of confusion.
*The two nearest weather stations reported lows of 27 and 30 and highs of 47 and 49 respectively. Temperatures in the search area were likely slightly lower. When the morning calls were recorded, temperatures were in the mid-30s.
**This was what I wrote at the end of the day, without consulting any literature. Of course doubled calls are described by Tanner and occur on the Singer Tract recordings.
We are not claiming these as Ivory-billed Woodpecker calls, but several ornithologists have been unable to identify them. The sound and base frequencies are consistent with calls recorded in the old Project Coyote search area.