Advertisements

More Recordings from March 15: Approximately Three Hours of Kent-like Calls and Analysis

On March 15, Phil Vanbergen and Matt Courtman recorded numerous kent-like calls at the same location where we heard several calls on March 11 and 12. Phil was able to record two of the March 11 calls. That capture is included in the post, along with Phil’s audio from the morning of the 15th. I heard two of the calls on the 11th; the second one in particular struck me as being consistent with the Singer Tract recordings; the first seemed a little low pitched to my ears, an observation that’s captured on the recording. Steve Pagans and I heard several calls on the 12th, but these were not recorded.

Matt obtained nearly three hours of audio, and to my ears the sounds are coming from 2-4 distinct sources; I had the same impression after listening to some of Phil’s clips. I have now listened all the way through Matt’s recordings several times and will share my analysis below. Matt and Phil are likely to weigh in later with their perspectives. I also have a couple of trip reports pending, so there should be a lot of activity on the blog in coming weeks.

To start with, I counted over 200 kent-like calls in all.

On the long clips posted here, I’ve edited out all of Matt’s ADK (anthropogenic double knock) series, which he did on the half hour. The knocks are very loud, as can be heard from the one trailing sound I’ve left in. I also snipped out several minutes of conversation between Phil and Matt. The ADKs seem to have led to more frequent calling and may have provoked some double knocks, something we may address in a future post.

Edited to add: On further review, there does not appear be a correlation between ADKs and more frequent calling. Clips like the one posted below can be deceptive. One kent-like call that overlaps with a knock has been deleted. There is also one possible knock in response. Caution, ADKs have not been completely spliced out, and they are loud. See bottom of page for brief clip and sonogram.*

Between 6:12 and 6:25 on the last long recording made that morning, there are five calls of differing durations and volumes, followed by what may be a double knock. Similarly, at the end of the full clip, starting at 14:14, 3 calls are bracketed by some potentially interesting knocks, 2 before and 1 or 2 after.

The first four clips below are shorter, amplified extracts on which the calls can be heard easily.

The first two of these are extracted from the final segment described above and include the interesting, tooting sounds and possible knocks.

The third clip includes multiple calls over 2 minutes and nine seconds, along with a wide variety of other sounds.

The fourth is four minutes long (pardon the airplane noise) and should provide additional context while also revealing some of the variations among the calls.

For those, like me, who don’t have professional sonogram software, I recommend using Sonic Visualizer – an easy to use, free program that enables you to watch the sonogram as you listen.

And for those who are unfamiliar with avian bioacoustics, this is a great place to start. I’m on a very steep learning curve myself and am prepared to stand corrected about any misstatements in this post.

Many of the sounds are audible on built-in computer speakers, but playback through headphones, earbuds, or external speakers is highly recommended.

 

I think these calls were likely made by Ivory-billed Woodpeckers. My perspective is based in part on the fact that I have spent all or part of nearly 40 days in close proximity to where the calls were recorded, starting in 2014. A considerable amount of this time was spent sitting quietly, and the total person hours spent in the area is well into the hundreds. We have had occasional kent-like calls, possible double knocks, and possible sightings over the years, but nothing approaching what transpired on the 15th.

Matt spent the morning of the 16th in the same location and did not hear any of the sounds, and Patricia and I spent 4 mornings and one afternoon there between the 23rd and 31st and heard no similar calls. I think this militates strongly against the idea that the source of the sounds is a common resident of the area.

Three alternative hypotheses have been suggested.

On the morning of the 15th, Phil proposed that the sounds might be tree squeaks. There appear to be multiple tree squeaks on the recording, some with similar pitches, but they bear little resemblance to the kent-like calls on the sonogram or to the ear. In addition, the calls sometimes come singly, sometimes in groups, and they vary in pitch, volume, and duration and seem to occur independent of wind velocity (on the 11th we noted that there was no wind.)

Screen Shot 2017-04-04 at 9.29.13 AM

Sonogram of first clip, showing apparent tree squeaks before and and immediately after two kent-like calls – the stacked horizontal lines right of center.

The first sound, at just after 4 seconds on the second clip, seems ambiguous. The sonogram is somewhat similar to the kent-like sounds, but the duration is very short, and it has a creaky quality. It’s also associated with the two creaky sounds that follow. These can be heard frequently over the course of the morning, and their appearance on the sonogram is nearly uniform.

Screen Shot 2017-04-07 at 7.51.16 AM

Sonogram of second clip showing tree squeaks.

One reviewer proposed Wild Turkey and Blue Jay as possible sources. I think turkey can be ruled out due to the absence of other turkey-like sounds associated with these very persistent calls.

Blue Jay strikes me as a more plausible alternative. Blue Jays can be heard at numerous times on Matt’s recordings. And Blue Jays are known to make kent-like calls, some of them very similar to known Ivory-billed Woodpecker sounds. This is likely not mimicry, since the most similar recorded calls I know of were obtained in upstate New York. The recordist noted the similarity. On the sonogram, the resemblance between these calls and either known Ivory-billed Woodpecker sounds or Matt’s recording is not as strong as it might seem to the ear. While they share a strong third partial, the Blue Jay fundamental is higher and some of the higher partials are considerably stronger.

Screen Shot 2017-04-02 at 7.03.13 AM

Kent-like, suspected Ivory-billed Woodpecker calls recorded by Matt Courtman on March 15, 2017. Note the relatively strong base frequency and 3rd partial, and weak 2nd, 4th, 5th, and 6ths.

Screen Shot 2017-04-04 at 11.05.39 AM

Kent-like Blue Jay calls. Note the relatively weak fundamental and strong second through fifth partials.

It’s also important to note that on the Cornell Blue Jay recording, the kent-like calls are intermixed with typical Blue Jay vocalizations. Over the three hours of Matt’s recording, kent-like calls occur during periods when Blue Jays are vocalizing and during periods when Blue Jays are silent.

Some of the kent-like calls have harmonics consistent with Cornell’s recorded playbacks of Singer Tract calls at 145 meters. Many are lower in pitch. Most have a considerably longer duration, although to my untrained eye/ear, some seem close to the 80-100 ms duration on the Cornell recording. More on duration below.

On March 28, I did some playback of Singer Tract calls using an iPhone and a bluetooth speaker. Patricia recorded them on a Roland Edirol R09HR digital recorder. I’m including the recording and the sonogram for comparison. Like Matt’s recordings, the second partial is strong throughout, and the 1st, 3rd, and 4th appear to be weaker than for the Blue Jay shown above.

Screen Shot 2017-04-06 at 12.30.00 PM

At various points, Phil also experimented with doing playback, using calls recorded in 2010 at the old Project Coyote site. (He also played back several other species – Red-bellied, Golden-fronted, and, possibly, Gila Woodpecker to gauge Red-bellied response, and Eastern Towhee out of personal interest.) Examples of putative ivorybill playbacks can be heard over the first 3 minutes of the fourth long clip posted above and also during the first part of the fifth. These sounds are longer but similar in tonal quality to the lower pitched calls. Their harmonic structure is different, however, with a fundamental at around 800 hz, a second partial at around 1600, and a fairly strong higher partial at approximately 5000 hz., and should be readily identifiable on the sonogram.

Screen Shot 2017-04-04 at 2.15.09 PM

Higher pitched playback calls, at middle left and far right.

Phil’s playbacks do not seem to have provoked any kent-like replies. Blue Jays can be heard during the same time frame, but it’s not immediately apparent whether the recorded Blue Jay calls are responses or merely contemporaneous vocalizations. This segment includes some Blue Jay vocalizations.

With regard to Blue Jays and the numerous kent like calls heard from March 11, 12, and 15: to reiterate, many hours have been spent in this vicinity, with close attention being paid to kent-like sounds. These are heard infrequently and never before in such quantity or over such an extended period. If Blue Jays in the area were making these sounds, we almost certainly would have heard and recorded many of them over the years. In addition, both Steve Pagans and Matt Courtman are experienced and skilled ear birders and neither thinks these are Blue Jay calls.

It’s also worth pointing out that another potential confusion call can be heard on the recordings – White-breasted Nuthatch. The sound is similar but much weaker, as should be clear from the amplified March 15 excerpt. On the sonogram, just below the amplified recording, the calls show up very faintly, with dominant frequencies of around 2200-2400 hz and a relatively strong partial at 1700-1800.

 

 

I encourage people to listen through and draw their own conclusions. Input from those with expertise is welcome.

While I can’t say if any of these calls are a perfect match for the Allen and Kellogg recordings (some may be), many of them are close on the sonogram and similar to the ear. It’s important to bear in mind that the Singer Tract birds were likely agitated when those recordings were made, even though Tanner described some them as being good examples of kents. It’s also important to read Tanner’s descriptions carefully, though as is so often the case, his writing can be opaque. Perhaps his most important observation was that “all of the notes have the same nasal, trumpet-like quality.”

According to Tanner, “The notes of the nuthatches are the only bird calls I know that sound like the voice of an ivorybill; the Ivory-bill’s calls are much longer and pitched higher than the calls of a White-breasted Nuthatch, are more in the range of a Red-breasted Nuthatch.” (Emphasis added.) By contrast, Hasbrouck, writing in the 1890’s, described it as being “exactly like the note of the White-breasted Nuthatch” only much louder and stronger.

Tanner’s reference to Red-breasted Nuthatches has always confused me. I’m very much in Hasbrouck’s camp; I think the Singer Tract kents sound far more akin to White-breasted than Red-breasted Nuthatch. Either way, most of the Allen and Kellogg kents are lower pitched than typical White-breasted Nuthatch calls, as are the ones on Matt’s recording. In addition, the Allen and Kellogg kents seem to be of similar in duration to typical nuthatch calls, rather than longer or “much longer”. This too suggests that they are not typical but are more rapid and perhaps higher pitched due to agitation. Tanner wrote further, “[t]he kent note, given in monotone or infrequently, is the ordinary call note. When the bird is disturbed, the pitch of the kent rises, and it is repeated more rapidly, frequently doubled, kent-kent, with the second note lower. The prolonged and slurring, kient-kient-kient call I always heard when two or more birds were together.” This call was never recorded.

According to Allen and Kellogg, “kenting varied a great deal” and a male bird called “loudly and deliberately”, again suggesting that many calls were of longer duration than those on the recording. Tanner’s notes also point to this variability. At one point, he wrote of “1 and 2 syllable yaps”; he has the Mack’s Bayou bird (whose voice he claimed he could recognize) making a “kient-kient” and also transliterated calls with “keent keent” and “yeenh yeenh” (Bales). These renderings all suggest a more drawn out call than those on the Allen and Kellogg recordings. George Miksch Sutton described the Singer Tract birds’ calls as, “strange, bleat like, not quite sharp enough for a woodpecker’s cry. It was slightly nasal in quality and it sounded to me like ‘Gip!’, with a hard g“. Sutton’s description also suggests that many kents had a fairly long duration.

Edited to add: similarly, several observers (Audubon, Beyer, Hoyt)  described ivorybill calls as “plaintive”; this too seems to imply calls of longer duration than what’s heard on the Singer Tract recordings.

Given the resemblance to the Singer Tract recordings and the lack of plausible alternatives, I posit that these calls are at worst highly suggestive of Ivory-billed Woodpecker.

*Possible knock and kent-like calls temporally associated with ADK series. Caution remnant ADKs are loud.

Screen Shot 2017-04-09 at 7.37.53 AM

Advertisements

Trip Report Feb. 20-24, 2015: Still More Smoke

Note: this is a very image-heavy post, and most of them appear ‘below the fold’.

Although we faced significant challenges during this trip, it was nonetheless a very productive one. I was joined by John Henry, the photographer who was with me when I recorded kent-like calls in March 2013. Work obligations kept Frank Wiley out of the field, except on February 24th. A flight delay and 1:20 am arrival at my hotel in New Orleans on the morning of the 20th limited my field time to a couple of hours on that day. I had planned to get in a final half day on the 25th, but wintry precipitation prevented it. Weather conditions were a challenge throughout – skies were consistently cloudy and dark; there was occasional rain; and temperatures fluctuated from the 70s on Friday and Saturday to near or below freezing on Monday and Tuesday.

On the afternoon of the 20th, John Henry and I went to the eastern sector, the most easily accessible part of our search area. This is the vicinity where a visiting biologist, Frank, and I heard double knocks during my last visit, and where we have found a significant amount of feeding sign since 2012. I found some fairly impressive, extensive, and recent bark scaling high on the trunk of a fairly distant tree. I was unable to examine it up close, but from a distance it appeared to be consistent with what I think is likely, if not diagnostic, ivorybill work.

Scaling2:20

On a non-ivorybill related note, the feral hog population seems to be increasing in our area, and they do enormous damage to the habitat, probably not in way that impacts the ivorybills we believe to be present, but their impact on forest ecology is likely severe. While they are hunted by some in the area, and don’t seem to be nearly as abundant as they are in Congaree National Park, for example, they are still a severe problem.

Hogs

 

Edited to add: This poor photograph of large, relatively slow moving terrestrial mammals, the best of several taken at less than 100 yards, illustrates just how difficult it is to obtain good pictures in this environment.

On the 21st, John Henry and I went into the habitat on through the northwest corner. This is an area of fairly recent blowdown, several deep, meandering sloughs, and dense blackberry thickets, making it incredibly difficult to explore. On more than one occasion, we had to retrace our steps and find a different route. I estimate that we were able to cover a quarter mile per hour. Traversing this area is hard on body, boots, and clothing, and it’s very difficult to pay attention to anything except the next step. We finally reached the site of the target tree featured in Frank’s Pros and Cons of Trail Cams and where I recorded a possible DK in response or reaction to an ADK. We decided to do a double knock series. Following Frank’s lead, I did a little pounding on the log before doing any DKs. Then I did a DK (I wasn’t recording, as I was using an external microphone mounted on my camera and figured I’d turn it on when I finished the series). Within approximately 10 seconds, there were 3 extremely loud single knocks that came from east-southeast of us. I’d estimate they were spaced about a half second apart and were no more than a couple of hundred yards away. Nothing else happened in response to the series. Although they didn’t have the resonance of typical woodpecker drumming, they didn’t sound like branches breaking, gunshots, or industrial sounds. There were no hunters in the immediate vicinity, no vehicles parked along the access road on our way in and out of the area, and we heard nothing remotely similar during the rest of the day.

On the 22nd, Frank and I made a pilgrimage to meet J.J. Kuhn’s daughter (known to us as Mrs. Edith) who had honored us with an invitation. We spent a delightful afternoon with her and her daughter, son, and son-in-law. They regaled us with many stories about Kuhn’s life, before, during, and after his time with Tanner. As readers know, we see Kuhn as the true master at finding ivorybills. Mrs. Edith is writing a biography of her father, so we’ll leave it to her to tell the story. During our absence, John Henry visited the northern sector and reported hearing a double knock late in the afternoon. He also spoke to two local hunters who claimed to have seen ivorybills. The elder of the two men said he hadn’t seen any recently but had seen a pair 15 years ago in the area that’s discussed in the first and last paragraphs of my previous trip report. This is the third local person to have claimed a sighting in that general vicinity.

The other person’s claim was of a sighting at the south end of what I refer to as the northern sector, so John and I decided to explore that area (which had not been visited) on the 23rd. As is so often the case, travel was complicated by deep, meandering sloughs, although it was nowhere near as difficult as what we encountered on the 21st. We did not have any possible auditory or visual encounters, but I did find one very impressive looking cavity (although not a fresh one) and a downed sweet gum with very extensive and fairly recent bark scaling.

cavity2:23:13

 

Anotherlimb2:21

HangingBark2:21

John next to the main trunk to provide a sense of scale.

John next to the main trunk to provide a sense of scale.

FullViewMainTrunk

This type of work is similar to work found last year. and while it doesn’t exactly meet the criteria I’ve laid out previously for what’s diagnostic, I strongly suspect that it is Ivory-billed Woodpecker work, beyond the physical capacity of a PIWO. The bark was tight and difficult to impossible to remove without an implement.

Frank joined us on the 24th, and we entered the eastern sector farther north. The hike in at this location is long and difficult, but our efforts were rewarded, and we gained quite a few new insights. Once we were well into the bottomland area, we experimented with doing some playbacks. Frank played some Pileated Woodpecker calls and drums, which stirred up a good deal of activity. One Pileated flew in silently, and several others called with the rapid, “cackle” call and drummed in the distance. He then switched over to playing the Singer Tract recordings, and two more Pileateds flew in to the trees just overhead. They drummed and did the “wok” call, apparently in direct response to the recording. It is at least intriguing that playback of ivorybill calls would produce such a response from Pileateds.

We packed up and headed deeper into the habitat and found a sweet gum with three large, oval shaped cavities.

The lower cavity is the most obvious; the other two are near the top, partially obscured by branches.

The lower cavity is the most obvious; the other two are near the top, partially obscured by branches.

About a hundred yards away, I came across another downed sweet gum with extensive and suggestive scaling and large bark chips underneath; one of the chips, shown below, appears to have strike marks that are suggestive of IBWO, similar to the ones discussed in this post. I failed to get clear photographs showing the extent of the work on this downed tree, partly due to angle and lighting and partly due to the events discussed below.

2:24:barkchip

Large bark chip with apparent bill strike.

Large bark chip with apparent bill strikes.

Detail of downed scaled sweet gum.

Detail of downed scaled sweet gum.

This limb, which was somewhat punky, had been fully stripped of bark, apparently after it fell. Also note the scaling in the background.

This limb, which was somewhat punky, had been fully stripped of bark, apparently after it fell. Also note the scaling in the background.

There was a nearby hickory snag that had been heavily scaled in the manner that I think is diagnostic, although not recently.

Old2:24:15

John had moved some distance away while Frank and I examined the tree, and I started taking pictures. As we were doing so, we heard two distinct double knocks in close succession, roughly from the south. This was at approximately 11:15 AM. We remained in place for 30-45 minutes at which time we played back the Singer Tract recordings. John had moved closer to us. Within 30 seconds to a minute of the playback, Frank and I heard a kent-like call. We disagreed about the direction. Frank had it from the Northwest, and I thought it was from the West. Between 30 seconds and one minute later, a large black bird flew in from the west at about 85 yards. My view was fully obstructed, but Frank saw it for several seconds before it took off, at which point John saw it but could not distinguish any field marks.

We proceeded through some very impressive habitat and found some additional scaling in the vicinity, some on a hanging limb and some more on a downed sweet gum. I have now found five downed sweet gums with this type of extensive work in the past year and nothing similar on other species (I did find similar but much less extensive scaling on a downed persimmon, an uncommon species in our area.) This may be significant

Suspendedscaling

2:24:15scalingnorth

The quantity of suggestive and recent bark scaling I found on this trip relative to time spent was remarkably high, as was the possible encounter rate.

I hope to return the search area in about a month and may do one or two posts on other subjects before then. Stay tuned.


Trip Report – November 27-30, 2014

Frank Wiley and I have spent the past four days in our search area, beginning on Thanksgiving morning. Before getting into the details, it merits noting that this weekend is the probably the peak of deer season in Louisiana. On Thanksgiving, there were perhaps fifteen or twenty people hunting on the edges of the habitat corridor. We encountered a single person in a tree stand that day, at the edge of the potential habitat. The number of hunters dwindled over the weekend, and on Sunday morning, we heard only one or two distant gunshots and saw a lone pickup truck parked along the parish road, nowhere near the bottomlands where we’re focused. On Thursday, we visited the southern sector, where we’ve spent the most time and have had the most encounters, calling it a day in late morning for Thanksgiving. At dinner, a long-time acquaintance of Frank’s described seeing IBWOs at a location about 10 miles from our search area from which we’ve had another credible-seeming report. We spent Friday through Sunday in the northern sector, which contains some extraordinary habitat, much of it old growth or nearly so. In this sector, sweet gums and oaks of 3-4’ diameter at breast height are not uncommon, and larger trees, like the one pictured, can be found from time to time.

Frank w:Chestnut Oak

Frank Wiley with Chestnut Oak. His arm is 32″ from armpit to fingertip. We estimate the DBH to be 5′.

Travel in the northern sector is extremely challenging due to blowdowns and deeply incised sloughs. On Saturday, it took almost the entire day to cover a total of three miles. One impressive feature of the area is the presence of large patches of cane that reaches as much as 15’ in some places. In some parts of the forest, cane is the main component of the understory.

Frank Wiley in Cane Brake

Frank Wiley in Canebrake

Cane understory in second growth pine flat

Cane understory in second growth pine flat

It appears that some places within the northern sector have not been visited by people for several decades. In one apparent old growth area, the only litter we found was a Schlitz beer can and a 16 ounce glass soda bottle, both of which date to the 1980s. There were no shotgun shells or other signs of human presence to be found. Approximately 1/4 mile south we did find a hunter’s flagging that was several years old. This is difficult and seldom visited territory.

At 8:40 on Thursday morning, we heard some distant, intriguing kent-like calls. There were, however, several Blue Jays calling much closer to our location. We then visited the tree shown on the Project Coyote homepage that we found in May 2013. The decay is progressing, and there are many new insect exit tunnels through the remaining bark. It seems significant and mysterious to us that there is no sign of further woodpecker foraging of any kind on the tree. This tree is in within a known Pileated Woodpecker home range, and we believe that if the work were that of a Pileated there would have been multiple return visits by now.

Old feeding sign that has the appearance of the work we believe to be diagnostic is abundant in the northern sector, but we did not find anything that appeared to be fresh. We suspect this may be at least in part a seasonal factor and that scaling of bark is a more central feeding strategy during mating season and until young have fledged. Nonetheless, we were impressed by the abundance of feeding sign. These are several examples. We found the excavation in the last image to be somewhat different from typical Pileated Woodpecker work and therefore somewhat intriguing, although we suspect it was done after the bark had been removed. The wood showed no signs of rot. Oldscaling Old Scaling HiRes Oldscaling2HiRes

Two examples of old scaling found in the northern sector

Examples of old scaling found in the northern sector.

Unusual excavation in a scaled snag

Unusual excavation in a scaled snag

We did not hear anything intriguing on Friday, but at 1 pm on Saturday, deep into the remote, untraveled area, we heard two ambient double knocks. The first of these was perhaps the closest to recorded Campephilus DKs I’ve ever heard in the field. Frank heard an additional DK or two that I missed. We then got two or three single knocks in response to a series of ADKs (anthropogenic double knocks). These knocks appeared to come from two sources, moving from slightly northwest of our location toward the south. On our way out of the area, we found an old snag with an intriguing cavity, as well as one being used by a sub-adult Red-headed Woodpecker. We returned on Sunday morning to place a game camera on the tree. At approximately 8:15 am, prior to setting up the camera, we did an ADK series (this within 200-300 yards of where we heard the DKs the afternoon before). We had several knocks, both single and double, in apparent response.

Red-headed Woodpecker peering out of cavity

Red-headed Woodpecker peering out of cavity at top of target snag

Cavity11:29:14

Cavity in the northern sector found November 29, 2014. Camera trap placed November 30.

As peak search season approaches, we’re encouraged to have three distinct but connected areas where we’ve found suggestive feeding sign and have had putative encounters. While there have been no sightings in the northern sector, the contact rate is extraordinary, as is the abundance of feeding sign. To be continued . . .


The Two Faces of James T. Tanner – A Study in Selective Memory and Blindspots

In a 1936 letter to James Tanner before Tanner began his survey of possible ivorybill habitat in the southeast, Herbert Stoddard wrote, “The area where they (Ivory-billed Woodpeckers) may occur at present is simply tremendous, not restricted as many believe.” Stoddard continued, “. . . if I had the rest of my life for the purpose, I doubt I could cover adequately half the ground I now think worth investigating. When I say adequately I have in mind five days I spent looking especially for these birds with men such as Bob Allen and Alex Sprunt on an area of some ten thousand acres known to be frequented by several pairs of these birds without seeing one. Of course this was due to the element of luck, as others have gone in the same area for a few hours and seen one or two. But it indicates the time one would have to spend in these great river valleys to really be reasonably sure that the birds were absent or even extremely rare therein.” Tanner was one person, and he clearly didn’t have the time to devote to the thorough survey Stoddard suggested, but the later record suggests that he failed even more deeply to take Stoddard’s words to heart. Stoddard’s perspective leaves room for the possibility that Tanner grossly underestimated the ivorybill population in his monograph, something that might lead to very different projections about the likelihood of survival today. It also sheds additional light on the difficulties in searching for ivorybills and on what appear to be some significant blindspots in Tanner’s thinking about the species.

I recently wrote a Facebook post in which I stated Tanner had a “hard time” finding Ivory-billed Woodpeckers. A very prominent American birder and ivorybill skeptic promptly shot back asking for citations, which I provided; I wouldn’t play along with the snarky response, but the exchange gave me the impetus to write this post. To most birders, Tanner is a kind of heroic figure, a pioneer ornithologist, and the author of the only in-depth, definitive study of the Ivory-billed Woodpecker, a bird that, in Tanner’s telling (and even more so in the retelling), was a super specialist that depended on virgin forest for its survival. Tanner is also rightly seen as having played a central role in the development of modern environmentalism, fighting to save the Singer Tract itself and later helping to create Congaree National Park, one of the few remaining substantial old growth stands in the south.

Those who are more deeply steeped in ivorybill lore are likely to have a somewhat different perspective, even as they admire Tanner’s good qualities. In later years, Tanner became increasingly dogmatic about ivorybill habitat requirements and was usually harshly dismissive of  reports from others – including John Dennis in Texas and Agey and Heinzmann in Florida. (This dismissiveness began to take hold in the early 1950s.) By no later than 1985, and probably much earlier than that, Tanner had become convinced the ivorybill was extinct, a conviction that he usually leavened with the statement that he’d love to be proven wrong. Ivorybill aficionados may also raise questions about the 1930s surveys he conducted in the southeast, and the rapidity with which he dismissed almost every place he visited as being unsuitable, sometimes based on a visit lasting a day or two. Most of these visits were made outside of breeding season, at times when finding ivorybills was considerably more difficult.

Tanner may have been right to dismiss many of these areas, but the possibility that he might have missed several populations cannot be ruled out, especially in light of the letter from Stoddard, an established ornithologist with first-hand knowledge of the species. At minimum, Stoddard’s letter put Tanner on notice that ivorybills could be very difficult to find.

Were preconceived beliefs driving Tanner from 1937-1939; was he being cavalier in his dismissals; or was he simply doing his best to accomplish what Stoddard said would take a lifetime in a few weeks spread over three years? It was probably all of the above, but whatever the reason, his mindset became an even bigger problem as time went on, leading him to foment the false impression that ivorybills should be easy to find, a notion that informed the views of my interlocutor on Facebook and of many those who believe the species is extinct.

The fact is that when Tanner was in the Singer Tract, the only birds he could find on a regular basis were the “John’s Bayou Family”, the group first studied in 1935. Their nesting and roosting grounds were approximately 1 mile from Sharkey Road. From 1935-1939, the birds nested in the same general vicinity. Three of the four nests were in very close proximity to one another, and the greatest distance between any two nest sites was 3/4 of a mile. Despite this clustering, it took Tanner five days to find a nest in 1939, when he didn’t have J.J. Kuhn (who had been forced out of his job as Singer Tract Warden) to assist him. While Tanner paid respect to and credited Kuhn, the passage of time has made it increasingly clear that he downplayed the degree to which he depended on Kuhn to find ivorybills. Kuhn had been observing the birds for several years before the 1935 expedition (which also took several days to find ivorybills), and it’s reasonable to infer that the John’s Bayou family was already somewhat habituated to human presence by 1935. Certainly after ’35, they were accustomed to human activity in the immediate vicinity of their nest sites. The only other ivorybill Tanner saw was one he named Mack’s Bayou Pete, presumably a bird hatched in 1935 from a nest that Kuhn found. As with the John’s Bayou pair, this bird was found within a home range that had been roughly delineated in 1935; Tanner believed he could recognize Pete’s voice, but the bird was far more frequently heard than seen.

Edited to Add: I’ve been reminded that the 1935 Mack’s Bayou Nest failed, and that Pete more likely fledged in 1937. The fate of the adult Mack’s Bayou pair is unknown.

Tanner continued to correspond with informants in the Singer Tract until 1948 or ’49 and was advised that one or two birds remained until that time. As Tanner’s temporal distance from his experiences in the Singer Tract grew, so did the distortions in his memory. These distortions are perhaps most dramatically illustrated in an article he wrote entitled “A Forest Alive”, which was published posthumously in Birdwatch (2001), a British magazine. Prominent ivorybill skeptic Martin Collinson mentioned the article and quoted it at some length in a 2007 blog post:

http://proregulus.blogspot.com/2007/12/i-almost-certainly-ignored-this-article.html

Collinson concluded his post with this observation: “As others have pointed out… you can only rationalise the failure of the current searches if you don’t include the words ‘active and noisy’, ‘called frequently’ and ‘easier to see and follow’, in your dataset.”

Of course, Tanner’s observations applied only to the John’s Bayou birds studied in close proximity to a nest. More importantly, Tanner’s recollection was incomplete and inaccurate, and he corrected it in another, humbler, posthumous piece that appeared in Birdwatcher’s Digest (2000) under the title “A Postscript on Ivorybills”. Tanner began by observing that, “Like everyone else’s memory, mine forgets the annoying and unpleasant things and remembers the pleasing; the mosquitoes go but the birdsong remains. Mine is also likely to forget the important and regular events and retain the trivial and unusual.” The article makes it clear that finding even the John’s Bayou birds (which had a known territory and roosting ground) could be difficult and was even harder outside of nesting season. Tanner concluded with this reminiscence: “Hunting in other areas of the Singer Tract for ivorybills was even more difficult and discouraging. My journal is full of such comments as ‘saw old sign, lots of impenetrable vines, and no ivorybills.’ The only other ivorybill we ever found outside of the one nesting pair and their offspring was a single male that we dubbed Mack’s Bayou Pete because of the area he usually inhabited. He was hard to find and once found was soon lost . . . ”  And to reiterate, Mack’s Bayou Pete’s home range was at least something of a known quantity.

By 1985, Tanner was advising the US Fish and Wildlife Service to classify the ivorybill as extinct. He gave the following reasons, to paraphrase:

1) The reports have been unconfirmed and they often describe behavior that is characteristic of Pileateds (flushing from stumps and logs).

Tanner described this as being rare in ivorybills, which may or may not be true, but it’s certainly not unheard of. Allen and Kellogg observed a female feeding on the ground. Moreover, not all reports involved this behavior.

2) There’s so much recreational use of areas where ivorybills used to be present that people should be hearing and seeing them, and there are no extensive areas of former IBWO habitat that are remote and unvisited.

What’s omitted from this analysis is the fact that the beginning of nesting season and the end of deer season are roughly congruent, at least in Louisiana. This means that there’s actually very little human traffic in many prime nesting areas during the times when birds are most active and vocal. And of course, the John’s Bayou area was not particularly remote, although other parts of the Singer Tract were considerably more difficult to reach.

3) Ivorybills are fairly conspicuous birds that, “if present . . . are not hard to find. Furthermore, the feeding sign they made (scaling bark from extensive areas of not long dead limbs and trees) could be easily recognized as a clue to their presence.”

With regard to the feeding sign, I have to wonder what Tanner would say about the sign we’ve found that appears to match this description perfectly. With regard to being easy to find, Tanner’s field notes and his reminiscence in “A Postscript . . .” make it clear that ivorybills were extremely difficult to find, except in extraordinary circumstances – in close proximity to a nest and perhaps with a good deal of habituation to human presence.

Tanner’s story is amazing. His monograph is seminal though not gospel. The in-depth examination of his work in Stephen Lyn Bales’s Ghost Birds is essential reading. Many of his later pronouncements, however, have done a disservice and continue to sow confusion more than two decades after his death.

I’m indebted to Chuck Hunter for alerting me to the Birdwatchers Digest article some years ago, to Fredrik Bryntesson for sharing Herbert Stoddard’s 1936 letter and reminding me of Tanner’s missive to USFWS. This piece is informed by years of discussion with Frank Wiley. He also made a number of constructive suggestions about the specific content. Direct descendants excepted, Frank is undoubtedly J.J. Kuhn’s biggest admirer.


Distribution of Feeding Sign

There may be some value in considering the distribution of the particular type of suspected Ivory-billed Woodpecker foraging sign that I’ve discussed in my recent posts. For the purposes of this analysis, I will limit myself to one very narrow category of bark scaling: extensive work done on the boles of live or recently dead trees (species undetermined in some instances; at least one identified as hickory.) Bark has been tight when examination is possible, and large exit tunnels are abundant. The appearance of the work is consistent – no underlying excavation, no sign of scaling in layers, clean edges.

Two of the trees are in the southwestern section of our search area. This is the general area where I’ve had most of my auditory encounters, although it’s also the area where I’ve spent the most time.

Three of the trees are to the northeast of this pair; two of these were in an inaccessible location and were photographed at a distance of about 40 yards. While they could not be examined for bark tightness, the appearance of the work was consistent with the other examples included in this summary.

Two of the trees are to the east of a parish road (this includes the one discussed in my November update.)

One tree is in the northernmost area we’ve visited and where we’ve spent the least time. Auditory contacts in this area have only involved one source.

The as-the-crow-flies distances involved strike me as being potentially significant. The shortest distance between any two trees is about a quarter mile. The two southwestern area clusters are about half a mile apart at the closest point. From the easternmost tree in these two clusters to the examples east of the parish road, the distance is ~1.35 miles and hence about 2 miles from the westernmost trees. The area to the north is about 2 miles northwest of the easternmost scaling and about 2.8 miles north of the southwesternmost tree.

In 2012, there was a cluster of scaling between approximately .5 miles farther south. The two series of kent-like calls involving two sources heard and recorded in March 2013 came from even farther south.

The distances are much greater than would be expected if a lone pair of Pileateds were engaging in anomalous feeding behavior (there would probably have to be at least three pairs of PIWOs involved.) They’re roughly consistent with the home range Tanner gave for the Singer Tract pairs.


Encounter Rate

      A poster on the Ivory-billed Woodpeckerl Researchers Forum raised a couple of questions about sightings and their quality, and about our encounter rate. I thought I’d take this opportunity to respond here.
      A number of people have had possible sightings in this area. Quality is a subjective term, but it’s safe to say the quality has varied. In most cases, the sightings have been by single observers. A few have involved perched birds. Distinctive features – black crests, malar and dorsal stripes and bills – have been noted in several instances; however, most have been fleeting glimpses of birds in flight. One recent flyover may have involved a pair – field marks were seen on one of the two birds. Just as we see little point in posting additional audio unless conclusive documentation is obtained, we don’t think that posting details of sightings serves much purpose, unless it’s a robust, two-person observation or is accompanied by a clear photograph.
      A little background on the encounter rate. I made my first search trip to Arkansas back in April 2007. Since then I have spent countless days in the field, probably upwards of 100 by now, in Arkansas, South Carolina, Florida, and Louisiana. I’ve learned a lot over the years; I’ve made some mistakes; I’ve written off some possible encounters as wishful thinking and have tried to maintain a healthy self-skepticism. I’ve also been somewhat obsessed with finding a category of feeding sign that is beyond the physical capacity of a Pileated Woodpecker to produce and is therefore diagnostic. As discussed in some of the recent posts, I believe I have succeeded in this, but of course my belief remains just that and is entirely unproven.
      While we don’t count finding suggestive foraging sign in estimating the ‘encounter rate’, which is actually a possible or putative encounter rate, the quantity of scaling that I consider to be Grade A or that is congruent with Tanner’s description far surpasses what I have seen anywhere else. Our old search area was considerably more compact, and in 2009 and 2010, before the adjacent parcel was logged, it was fairly easy to find suggestive feeding sign within that compact area. Since that time, I’ve refined my criteria for Grade A scaling and have made them somewhat more stringent. Nevertheless, this year in the new search area, I have found sign that meets my criteria or fits the Tanner model on virtually every field day. During trips last year, fresh scaling seemed to have been concentrated in one or two locations, and this year it seems to be more scattered. This is purely impressionistic, but whatever the case, there is an abundance of feeding sign that is unmatched by anything I’ve seen elsewhere. And I have never seen scaling that resembles what’s shown in my May, July, and October posts anywhere else, save in the former Project Coyote search area.
      Regarding the encounter rate itself: we include all putative encounters – DKs, whether ambient or in response to ADKs, putative kents, and possible sightings – even weak possibles. We estimate that we have been having one putative encounter for every 20-24 person hours in the field. The rate was considerably higher on my recent trip but probably nowhere near high enough to change the estimate. I should also add that, purely impressionistically, this is the only location where I have heard frequent apparent responses to ADKs. We had a possible attraction in the old search area and did get apparent response DKs from time to time, but nowhere near as often as in the new search area.
      The challenge lies in figuring out where the birds are roosting and nesting, if indeed they are present. We suspect there may be a nesting pair, as auditory encounters in the southern sector have frequently involved two sources of sound. To date, we have no indication that more than one bird is present in the northern sector. We have had very little success finding cavities in either sector, but it has also been difficult to find Pileated Woodpecker roosts in the deeper parts of the swamp, even in obvious, defended home ranges.
      I will be making brief trips in November and December and probably a somewhat longer one in January.