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Repost with Addendum: Ivory-billed Woodpecker Sightings and Evidence 1944-2003: The Partially Hidden History

I’m reposting an entry from February 2015 with some new commentary as prologue.

I recently received a Google alert about a new paper on statistical approaches to extinction relying on sight records. According to the paper, which has not yet been peer reviewed:

We have shown that the rate of sightings is the strongest indicator to infer extinction, and too much information about the quality of the sighting can actually be detrimental. Ideally a sighting record would be a list of certain and uncertain sightings only.

I’m curious as to how this model might treat the ivorybill, using the sighting data compiled and analyzed by William C. Hunter in the U.S. Fish and Wildlife Service’s Recovery Plan, a document with which many extinction modelers seem to be unfamiliar.

I’m not trained in statistics, and the literature on this subject is often over my head, but I’m familiar with the concept: “garbage in, garbage out”. Unfortunately, when it comes to the ivorybill, information that is repeated in the statistical papers is often inaccurate:

“For example in 2005, based on a brief sighting and a pixelated image, the ivory-billed woodpecker was declared to have been rediscovered (Fitzpatrick et al., 2005), resulting in the mobilisation of resources for management strategies and recovery plans (Gotelli et al., 2012). However, based on the evidence its rediscovery was brought into question (Sibley et al., 2006), and subsequent extensive searches have failed to result in further sightings (Gotelli et al., 2012).” Roberts DL, Jarić I. (2016) Inferring extinction in North American and Hawaiian birds in the presence of sighting uncertainty. PeerJ 4:e2426c 

An example of a species with a high false detectability is the ivory-billed woodpecker. After 2006, when the US Fish and Wildlife Service offered $10,000 for information leading to an ivory-billed woodpecker’s nest, it was ‘observed’ 14 times and audio recorded 300 times. Nonetheless, the reward remained uncollected (Newton 2009). Lee, T. E. (2014), A simple numerical tool to infer whether a species is extinct. Methods Ecol Evol, 5: 791–796.

Neither of these papers applied the models described to the ivorybill, and I’m not commenting on the validity of the models themselves. I’m pointing to how peer-reviewed literature can sometimes function as an echo chamber in which inaccurate information gets repeated as fact.

While it’s true that extensive searches have failed to obtain indisputable proof, the Luneau video, however controversial, cannot be characterized as a “pixelated image”. There were many more sightings in Arkansas and elsewhere, and in Arkansas, numerous kent-like calls and double knocks were heard and recorded over several seasons.

The book by Newton cited in Lee is Hidden Animals: A Field Guide to Batsquatch, Chupacabra, and Other Elusive Creatures, clearly not a serious scientific treatment of the ivorybill and apparently not a very well-researched one. There were in fact 15 Arkansas sightings between 2004 and 2005 and 14 in 2005-2006. The reward, which was for $50,000, applied to Arkansas only and was offered by the Nature Conservancy, not the USFWS, in June 2006. The source of the claim that audio was “recorded 300 times” is not clear, nor is the meaning. Inaccuracies aside, it’s an enormous logical leap to base an assertion about high false detectability on the inability of an unknown number of bounty hunters to locate a nest in ~500,000 acres of forest.

It may well be true that the ivorybill is more prone to false detectability than some other species; its iconic status makes this seem likely. It’s also true that there have been a number of organized searches for the ivorybill and that the number of sightings has increased as a result of publicity and search activity, at least during the first decade of this century. Nevertheless, many of the records between 1944 and 2003 listed in the USFWS Recovery Plan were unrelated to publicity or organized searches and were incidental to other activities, including bird surveys. In addition, the Recovery Plan tally included some qualitative analysis of the sightings, and an unspecified number of reports were excluded as probable false detections.

I find it odd that Appendix E of the Ivory-billed Woodpecker Recovery Plan is seldom if ever referenced in the recent literature, including Birdlife International’s species account (which I’m honored to say does reference the post below). It’s an official government report and is the most extensively researched document of its kind. I suspect that many readers will be unfamiliar with it and think it merits quoting at length; I’ve bolded some important passages.  I encourage people to click on the link above and read the rest.

Here, a potential encounter is defined as a report not easily explained as something other than an Ivory-billed Woodpecker on the basis of description of the bird, the type of habitat in which it was encountered, and distribution. After the Arkansas announcement was made, post-1944 reports were compiled prior to the 2005 announcement of an Ivory-billed Woodpecker being sighted in Arkansas. A map was produced of these potential encounters in Service brochures. These potential encounters were based on those discussed by Jackson (2004) or otherwise in Service files as “probably reliable,” defined here as not obviously another species. A review of other published literature and files maintained by some State working groups included other potential encounters that are cited and used in this treatment (both before and after 1950). Excluded from further consideration were reports that likely described other species (especially Pileated, but also Red-headed and sometimes other woodpecker species), as well as those reports outside the historical range of the species (as depicted in Tanner 1942) and in unlikely habitats such as golf courses and backyards. The reports between 1945 and 2005 considered further vary in detail, with some accepted based solely on the credibility and reputation of the observer. Reports since April 2005 (i.e., the Arkansas announcement) are similarly treated, but at least one diagnostic field mark had to be observed (most often the white trailing edges on a flying or perched large woodpecker).

It is important to understand the type and level of documentation accepted for this species’ persistence at the time when most collecting of specimens began to trail off (i.e., after 1900) compared with those reports which were accepted without question previously. While most previous treatments break down reports by State, here it is believed that important insights can be made by comparing reports, type and level of documentation, by decade starting with the 1800 and ending with the present. References for those reports besides those of Tanner himself prior to 1940 are provided in Tanner (1942, with cross-reference to location on his maps, his figures 3-10) and are so noted here.

Results and Discussion

The number of locations with Ivory-billed Woodpecker reports peaked between 1880 and 1910, the same period when most specimens were collected (Figures 1, 2). The number of locations with potential reports after 1940 generally dropped below the number of locations with all reports between 1900 and 1940. However, when including only potential encounters between 1900 and 1939, the range in number of locations among decades was roughly similar to the number of locations with potential encounters in the decades between 1940 and 2009, only dropping below 10 locations during the 1990s. The number of locations within each decade with multiple reports among years never exceeded 10 per decade prior to the extensive efforts underway after 2005 to search for this species.

Prior to 1940, only a small percentage of locations from decade to decade provided the source of reports from multiple years within any one decade, ranging from 12 to 28 percent of all locations with birds reported within each decade (Figures 3, 4). After 1940, there was a slight increase in the percentage of locations with multi-year reports in the later decades, ranging from 9 to 51 percent of all locations with birds reported within each decade. Despite this increase in locations with reports from multiple years there was no definitive documentation of persistence at any of these locations. Similarly, a very low percentage of locations with reports spanning more than one decade is documented in the historical record, but again with a slight increase during the latter decades (Figures 5, 6). Reports continue to come from most of Tanner’s regions into the present day with an obvious shift from those regions that included Florida to regions elsewhere (Figure 7).

In summary, there is no evidence that the Ivory-billed Woodpecker was ever widely or consistently relocated in the same areas from year to year or from decade to decade prior to 1940, despite the impression one may have about birds at the Singer Tract during the 1930s. Actually, during Tanner’s study the chore in locating birds often took days or weeks even where pairs or family groups were known to occur from previous years (and actually only one nesting pair at John’s Bayou was consistently relocated during his entire study). Whether the birds were truly more nomadic than previously thought, or whether the low percentage of repeated locations historically has been due to the search patterns of ornithologists and collectors is unclear. What is clear is that the present pattern of reports that do not effectively document occurrence of the species has been repeated from decade to decade for more than a century and that the number of locations with potential encounters within the same decade has varied little since the 1870s.

Whether or not many or all post-1944 reports pertain to actual Ivory-billed Woodpeckers will continue to be debated in some circles, and it also is possible that some of the reports dismissed for purposes of this treatment perhaps should not have been discounted so lightly. However, the pattern of credible-sounding reports accepted for this treatment from locations without firm documentation was from decade to decade slightly lower between 1940 and 2009 than the pattern recorded between 1890 and 1939. Most interestingly, the exceptional increase in locations with potential encounters during the present decade is on the surface similar to what was recorded during the 1930s, given both of these decades experienced a notable increase in amount of effort to firmly document the persistence of this species (with similar results despite substantially fewer observers involved in the 1930s than in the present decade).

 

RecoveryPlanE1&2RecoveryPlan3-4RecoveryE5-6RecovE7

One caveat about this material: the specific information in Appendix E is potentially subject to change in the future, but the overall patterns are likely to stay similar or the same.

Here’s the February 2015 entry.

This post is inspired in large part by an exchange of emails with Chris Sharpe, an ornithologist who is working on an IBWO literature review. Our correspondence revolved around the IUCN’s species account, which describes the ivorybill as “possibly extinct” and cites recent statistical analyses that suggest extinction is likely, as well as one that indicates survival is possible and another that concludes “very large search efforts are needed to detect small populations.”

Chris pointed out that there are many other species on the Red List that fall into a similar category with many unverified reports but in more remote habitats and nowhere near the search effort that has been expended on the ivorybill. While there’s some validity to this assertion, I think the reality is considerably more complex and that the ivorybill is in fact sui generis.

Many of the specifics of ivorybill history are little-known, and the statistical studies seem badly flawed. One focuses on collection rates but may not adequately address changing attitudes toward conservation in the early 20th century among other factors. Another is perhaps even more problematic for a number of reasons – most importantly its focus on “verified sightings”, which is a particularly complicated issue when it comes to the ivorybill. It omits numerous controversial sightings and does not include post-Singer Tract instances in which physical evidence was obtained, although the authenticity of that evidence has been contested. “Sidewinder” posted the abstract and a good summary of the findings on ibwo.net a few years ago:

Roberts, D. L., C. S. Elphick, and J. M. Reed. 2010. Identifying anomalous reports of putatively extinct species and why it matters. Conservation Biology 24:189–196.

As species become very rare and approach extinction, purported sightings can stir controversy, especially when scarce management resources are at stake. We used quantitative methods to identify reports that do not fit prior sighting patterns. We also examined the effects of including records that meet different evidentiary standards on quantitative extinction assessments for four charismatic bird species that might be extinct: Eskimo Curlew (Numenius borealis), Ivory-billed Woodpecker (Campephilus principalis), Nukupu`u (Hemignathus lucidus), and O`ahu `Alauahio (Paroreomyza maculata). For all four species the probability of there being a valid sighting today, given the past pattern of verified sightings, was estimated to be very low. The estimates of extinction dates and the chance of new sightings, however, differed considerably depending on the criteria used for data inclusion. When a historical sighting record lacked long periods without sightings, the likelihood of new sightings declined quickly with time since the last confirmed sighting. For species with this type of historical record, therefore, new reports should meet an especially high burden of proof to be acceptable. Such quantitative models could be incorporated into the International Union for Conservation of Nature’s Red List criteria to set evidentiary standards required for unconfirmed sightings of “possibly extinct” species and to standardize extinction assessments across species.

Here are the Ivory-billed Woodpecker sighting data they used:

Physical evidence: 1897, 1898, 1899, 1900, 1901, 1902, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1913, 1914, 1917, 1924, 1925, 1932, 1935, 1938, 1939

Independent expert opinion added: 1911, 1916, 1920, 1921, 1923, 1926, 1929, 1930, 1931, 1933, 1934, 1936, 1937, 1941, 1942, 1943, 1944

Controversial sightings: 1946, 1948, 1949, 1950, 1951, 1952, 1955, 1958, 1959, 1962, 1966, 1967, 1968, 1969, 1971, 1972, 1973, 1974, 1976, 1981, 1982, 1985, 1986, 1987, 1988, 1999, 2004, 2005, 2006

Data were from Tanner (1942), Hahn (1963), Jackson (2002, 2004), Fitzpatrick et al. (2005), Hill (2006), and Floyd (2007).

Some conclusions: For the Ivory-billed Woodpecker, the prior sighting record suggests that even by the time of the first controversial sighting, the species was relatively unlikely to remain extant (ca. 21% chance), regardless of the level of evidence (physical or independent expert opinion) used…the effect on the predicted extinction date will depend on the details of the sighting record. Including controversial sightings will, by definition, move expected extinction dates forward in time. An ever-increasing burden of proof should be required with increasing time since the last verified sighting. The burden of proof also should be greater when there is a pattern of frequent sightings prior to the last accepted record and lower when long periods between sightings are common in the historical record.

A second paper published in 2012 reached the same conclusion using 39 sightings “classified as certain and 29 classified as uncertain”.

The insistence on verification is problematic because it’s founded on an appeal to authority, and for much of the time frame in question, the primary if not sole authority was James T. Tanner. Tanner had a strong predisposition to dismiss every post-Singer tract report he received and was somewhat cavalier about reports he investigated in the late ’30s as well. (In fairness, Tanner did accept a number of post-Singer Tract sightings in an unpublished, late 1980s update to the records section of monograph.)

Tanner likely underestimated the population IBWO population in the late 1930s. At minimum, he missed six pairs in Mississippi, according to Jackson ( In Search of the Ivory-billed Woodpecker, pp. 60-62.  These details reinforce the point made by “Fangsheath” of ibwo.net that, for the ivorybill at least, demanding verification leads to “a rather vicious circularity”. In a recent email, Fangsheath also pointed out that “the Roberts et al. scheme fits tidily into the narrative created by Tanner, that the Singer Tract was the last hope of the ivory-bill, and that when that: wilderness was lost the bird essentially became extinct . . . Tanner searched across several states for the bird and found none elsewhere, yet he himself believed that the bird survived in a number of areas. And so we have a curious contradiction – on the one hand an appeal to authority is being used to exclude many sightings, and on the other hand that same authority is saying the bird exists in areas where sightings are excluded. The mythos that the bird had very specific habitat requirements clouded every search effort and every sighting evaluation, before and after 1944.”

Fangsheath’s observation about the impact of Tanner’s narrative on future search efforts is profoundly important. Tanner’s ideas about habitat, which were in large part a product of his cultural background and the “myth of the frontier”, hardened over time. In later years, he ignored some of the caveats he set forth in his own monograph. But even his approach to reports from the 1930s reflected a set of beliefs about habitat requirements that had no scientific basis. Many people, myself included, are prone to reflexively accepting these assumptions about “habitat quality” because the conventional wisdom is so deeply engrained.

Fangsheath also reminded me that in the years before Tanner, the species was being written off and had been for decades. Florida was believed to be the last stronghold; the Singer Tract and Atchafalaya basin were not considered, nor were the large tracts of overcup oak/water hickory forest (where Beyer found ivorybills in 1898), many of which were untouched until the 1940s. Unlike the Singer Tract, these areas were often roadless and very difficult to penetrate; the Tract was bisected by a road, had few deep bayous, and was largely free of undergrowth, making it much easier to search. I’ve already discussed Tanner’s difficulty in finding ivorybills anywhere besides John’s Bayou. In this context, it’s worth noting that Bick’s 1941 sighting (from his car on Sharkey Road) involved two birds feeding in a lower lying “ash flat” in which overcup oak predominated.

In addition to these conceptual flaws, the papers grossly underestimate the number of post-Singer Tract encounters within the historic range. While it is impossible to quantify the controversial reports, it’s clear that the 26 or 29 referenced in the studies are the tip of the iceberg. There are well over four times that many on record for the 1944-2003 time period. And no doubt, numerous encounters never made it into the literature.

I initially posted a brief comment about this on Facebook and ibwo.net, with a link to Jerome Jackson’s 2002 Birdwatching Daily article listing 20 pre-Arkansas and post-Singer Tract encounters (some just auditory and one from Cuba) and a reference to Michael Steinberg’s Stalking the Ghost Bird catalogue of 85 sightings during the same time frame. A commenter wrote, “Yes but no confirming photos”. That also led me to think it would be worthwhile to explore this subject in a somewhat more depth, since there is physical evidence, albeit contested, related to several post-Singer Tract and pre-Arkansas reports.

Before turning to the physical evidence, it’s worth reiterating that the 1944 date for the last “verified sighting” is fundamentally flawed and arbitrary. The 1944 date is for the “Say Goodnight” encounter that involved artist Don Eckelberry and two local boys, Billy and Bobby Fought, and the purported last lone female IBWO in the Singer Tract. This poignant story was retold in The Race to Save the Lord God Bird, and it has become central to the popular lore about the species. There’s no doubt that the encounter took place, and Eckelberry no doubt believed that the bird was the last of her kind. Roger Tory Peterson apparently received and accepted a report that a single bird, presumably the same one, was still present in 1946. Tanner was likely aware of this and had an additional reason to think that birds persisted in the Tract well after 1944. His papers include a letter stating that Singer Tract game warden Gus Willett saw a pair in November 1948 at North Lake #1 (I have been unable to identify this lake). According to the letter, the “[b]irds are moving over a much larger area than formerly.” The letter mentions that there had been several other sightings during this time period. There’s no reply from Tanner in the archives and no further correspondence about the Singer  Tract birds. It appears that this is the letter from Tanner’s former student, Arthur MacMurray, that is referenced in Jackson, but Jackson’s account does not mention Willett, who would have been familiar with ivorybills. The strong possibility that a pair of birds remained in the Tract for more than four years after it was cut should itself raise questions about Tanner’s narrative.

Jackson’s list of 19 US reports between 1944 and 2003 was undoubtedly not intended to be comprehensive (and his book includes many others). Instead, it focuses on sightings by professional ornithologists and/or people who were familiar with the species. These include: Allan Cruickshank, John Terres, Herbert Stoddard, John Dennis, Davis Crompton (Dennis and Crompton studied ivorybills in Cuba), Whitney Eastman, and William Rhein. Jackson doesn’t mention it, and was perhaps unaware when he wrote the article, but Rhein had filmed the Imperial Woodpecker in Mexico several years prior to his 1959 Florida ivorybill sighting. It strains credulity to think that every one of these experienced observers, most or all of whom were familiar with the species and all of whom knew pileateds well, would be mistaken. Jackson points out that Terres kept his sighting to himself for more than 30 years out of “fear of being scorned.” Such was the climate surrounding ivorybill claims, even in 1955.

Steinberg lists 85 sightings between 1944 and 2003. His list includes most, if not all, of Jackson’s reports, breaking them down into individual incidents. Jackson treated repeat encounters in the aggregate. Nonetheless, most of Steinberg’s reports do not appear on Jackson’s list. Many of them are from less illustrious sources and quite a few are anonymous, but some of them are from game wardens, field biologists, and graduate students in ornithology.

The Ivory-billed Woodpecker Recovery Plan, prepared by the U.S. Fish and Wildlife Service and completed in 2010, includes an even more detailed compilation of records, some of which are of course also included in Jackson and Steinberg. It lists approximately 100 reports of varying quality between 1944 and 2003. Some of these are aggregates, involving multiple observations. The number of observations is sometimes enumerated and sometimes characterized as “numerous”, “multiple”, or “several”, so it’s impossible to arrive at an accurate tally, but the total almost certainly exceeds 150.

Although the Steinberg and the Recovery Plan compilations are more extensive, they are undoubtedly far from comprehensive. For starters, the climate of intimidation around reporting ivorybills was strong enough to deter John Terres in 1955, and that climate of intimidation only grew more toxic over time, as the Big Thicket and Fielding Lewis incidents, not to mention the battle over the Arkansas reports, make clear. In addition, there’s good reason to believe that countless reports from local people, hunters, and amateur birders have been discounted, dismissed, or ignored by authorities, at least prior to the “rediscovery”. Steinberg writes of his first visit to the Louisiana Department of Wildlife and Fisheries Baton Rouge office in 2003,“ . . . few people took the book, or more important the larger issue very seriously. The typical response from many in the office, other than Nancy Higginbotham, seemed to be, ‘Don’t you have anything better to do?’” (Higginbotham claimed two sightings, one of male in 1986 and one of a female in 1987, both in the Pearl River area.) We’re personally familiar with several instances in which reports were dismissed or ignored. One involved the landowner in our old search area, who came forward after the Kulivan sighting and was deeply offended by the way he was treated. As far as I’m aware, no one has done a comprehensive review of records committee submittals within the historic range of the ivorybill; I know of one such submittal from Texas in 2002 that came from unsuitable habitat, outside the historic range, but there may well be others that are more robust.

I’d like to turn to three examples of physical evidence obtained in the post-1944 era. Some of this is fairly well known – the Agey and Heinzmann feather and the Fielding Lewis photographs. The other is somewhat more obscure, but no less interesting for being so.

The Agey and Heinzmann observations took place between 1967 and 1969, in Polk County Florida. They obtained two recordings that Tanner dismissed. There was evidently some very poor communication about it that was compounded by an obvious error on Agey and Heinzmann’s part. They mistakenly thought that calls on their first clip were consistent with some ivorybill sounds from the Singer Tract; they clearly are not. The second clip, which is dominated by a Red-shouldered Hawk, recorded March 3 1968, does have some faint kent-like sounds, but the quality is extremely poor. They are most easily heard on the amplified version that begins at 3:14. The RSHA calls were not what interested Agey and Heinzmann, but they failed to make this sufficiently clear.

I believe Tanner wrote the notes that accompany the recording:

“Well, I’m not sure what to say here. As far as I can determine, there are only four original sound clips here. The recordings at 0:04-0:32 and 0:49-0:57 are certainly flicker-like, especially the continuous series at 0:04-0:21 and 0:26-0:32, but I am less certain about the latter part of the first series (0:21-0:23), which appears to have been recopied twice at 0:41-0:48. A similar vocalization is included at 0:49-0:57 (recopied at 0:59-1:06). Given the very different quality of these sounds relative to those in LNS #6784, combined with the close similarity of the calls to those of Colatpes auratus, leads me to doubt that any of these sounds were given by C. principalis. The recordings from 3 March 1968 (2:45-3:07) represent the calls of Buteo lineatus. Quality unchanged (2;3 – the signal is not bad for the first part, but terrible for the rest, most of which seems to represent copies of various recordings)”

Agey and Heinzmann found several feathers near a cavity, and one was identified as the innermost secondary of an Ivory-billed Woodpecker. Oddly, Jackson wrote that “ . . . some shadow of doubt is cast over these records because Agey and Heinzmann also tape-recorded what they said were Ivory-billed Woodpeckers, and personnel at the Cornell Laboratory of Ornithology identified the birds on those tapes as pileated woodpeckers.” Given that one of the recordings does include kent-like calls, this criticism is not entirely warranted, and the misidentification seems irrelevant in light of the physical evidence (and ironically Tanner seems to have failed to correctly identify the calls on the first clip). Jackson also alludes indirectly to rumors that the feathers were taken from a specimen. These have circulated for years but are unsubstantiated. Agey and Heinzmann published their findings:

Agey, H. N., and G. M. Heinzmann. 1971a. The Ivory-billed Woodpecker found in central Florida. Fla. Nat. 44 (3):46–47, 64.

Agey, H. N., and G. M. Heinzmann. 1971b. Ivory-billed Woodpeckers in Florida. Birding 3:43.

To the best of my knowledge neither publication is available online at this time.

The next event, chronologically, started with a series of encounters in east Texas in the late 1960s. John Dennis obtained a recording that Tanner initially dismissed, in part for the patently absurd reason that a Pine Warbler is also heard on the clip, but later described as “a real mystery” when confronted with the sonograms and analysis that were suggestive of ivorybill. That recording is now catalogued as IBWO.

Additional slides, taken in 1970 in east Texas by a man named Neal Wright, were turned over to the Museum of Natural History in Philadelphia which also houses the Fielding Lewis photographs. These were made public after the rediscovery, and since writing this in 2015, I obtained permission to post them on the blog. They show what appears to be a female Ivory-billed Woodpecker in a nest cavity. When I first viewed the Wright photographs, I was quite skeptical, but later, I was struck by the resemblance to this image from the Singer Tract.

Wright was apparently quite a local character, and I remain somewhat suspicious, as he may have had ulterior motives; however, the similarity to one of the unpublished images from the Singer Tract is strong, and in the pre-internet era, it seems unlikely that a Texas woodsman would be familiar with any of the ivorybill images that did not appear in Tanner’s monograph.

The Fielding Lewis photographs, taken in South Louisiana in 1971, are far better known, although Lewis wished to remain anonymous. His identity was not revealed until more than three decades later, and he was identified at the time only as “the Chief” (Jackson was unaware of his identity in 2004, though it was made public soon thereafter.) George Lowery presented these images at the American Ornithologists’ Union annual meeting and was attacked by many of his colleagues who deemed them to be a hoax. It’s worth pointing out that there have been hoaxes in recent years (these were swiftly and easily debunked), so there’s legitimate reason for skepticism about any claim. In the case of the ivorybill, however, skepticism has frequently been replaced by a virtually irrebuttable presumption of fraud (or error).

In a letter to Tanner, Lowery (who, unlike most of his detractors, had actual field knowledge of ivorybills) wrote: “I know the man in question very well and I am sure he would not pull something like that. In the first place, where would he have gotten the mounted specimen? Why would he have two photographs of the birds way up on two separate trees? Both of considerable diameter and not subject to being shinnied. Also, assuming he might have had a mounted bird to photograph, why didn’t he get a better picture while he was at it?”

The most common reasons given for believing that Lewis hoaxed the photos are that the bird is similarly positioned in both images (similarly but not identically, a neat trick with a specimen) and that the bill and feet are not visible. Bear in mind that these pictures were taken with a Brownie or Instamatic camera, and the quality is very poor. Nonetheless, I believe a foot is very faintly visible in both photos, positioned in a manner that would be expected of a live Campephilus woodpecker. I worked from scans of the originals and made some modest enhancements in Photoshop. Note also that in the first picture, both a cavity and bark scaling can be seen on the tree.

fieldle1-enlarg-scan copylewisphotoarrow

Regardless of whether my analysis is correct, the foundation for claiming that these photographs were faked is shaky indeed – not only for the reasons Lowery gave but also because of Lewis’s reticence about revealing his identity, insistence on keeping the location secret, and lack of any discernible motive.

The recovery plan mentions two other pieces of physical evidence. One is a feather that was purportedly found in a nest or roost cavity in 1985, and the other is a photograph supposedly taken in Georgia in 1975 (correction, 1965).

It’s not my intention to fault the IUCN or to quarrel with the “possibly extinct” designation, although I think Bill Pulliam’s analysis of the Luneau video in light of Rhein’s Imperial Woodpecker film should be dispositive. My main purpose is to call attention to the fact that there’s considerably more evidence for survival than is popularly recognized or than appears in the scientific literature. There are multiple instances of people, often outstanding birders, hesitating to come forward with reports and hard evidence – for decades. Terres waited 30 years; in the cases involving physical evidence, only Agey and Heinzmann went fully public and identified themselves in making their claims; in Stalking the Ghost Bird, Steinberg includes detailed 2005 field notes written by a Louisiana “birder for more than forty years” who “has also worked as a contract ornithologist conducting bird surveys on rice and crawfish farms for more than ten years.” This individual too requested anonymity. To a significant extent, the shortcomings in the literature are directly related to the controversy that has surrounded this species for nearly a century (remember Mason Spencer who went so far as to obtain a permit and kill an ivorybill to prove the species persisted) and the accompanying climate of unhealthy skepticism that has, if anything, grown even more unhealthy since the rediscovery. This sets the ivorybill apart from other possibly extinct species.

I’ll be heading for Louisiana at the end of the week and will post a trip report when I return.

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Trip Report: April 26-May 1, 2017

I returned to the search area last week and spent as much time as I could in the field. The trip was generally uneventful, and conditions – strong winds, rain, and high water – limited my field time. Woodpeckers are getting quieter generally; full leaf out, heat (temperatures in the high 80s on the 26th, 27th, and 28th), and abundant mosquitoes make things even more difficult at this time of year; nevertheless, I’m planning one more trip before summer.

On the 26th, I hiked to hickory stub that currently has two cameras trained on it, as one camera needed securing. There were no signs of woodpecker activity on the stub. This beautiful Great Egret in a beautiful spot was a highlight. There were Little Blue Herons in the vicinity too, but I couldn’t get a clear shot, too much mud and intervening vegetation.

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On the 27th, I arrived at the “listening point” (where the March recordings were made) shortly after sunrise. I opted to sit quietly, rather than doing playback or ADKs. I did not see or hear anything.

I met up with Steve Pagans at around 10 am. Since water levels were low, we were able to get closer to the snag with the cavity that I found last month. I spotted a second cavity higher on the stub, on the opposite side. IMGP4571 (1)

These cavities are large, similar in size, shape, and unusual appearance. While I suspect they are no longer active roosts, we will put a camera on the snag in June, if it’s feasible to do so. The nest John Dennis found in Cuba appeared to have two entrance holes, although Dennis thought one might be too small.

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On the hike out, I spotted this wolf spider with her young on her back.

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On the 29th, Steve and I visited one of the less accessible parts of the search area. It is an impressive patch of forest, with some oaks and sweet gums approaching or surpassing 5′ DBH. The sweet gum below is probably the largest single trunked gum we’ve found.

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Reminiscent of the Singer Tract.

Predicted wind speeds were 15-20 mph, and the gusts were undoubtedly stronger, so birds were not very active. The gusts were often unnerving, and a couple of large limbs fell, uncomfortably close to us, while we were stopped for lunch.

The forecast for the 30th was for even stronger winds, with thunderstorms in the afternoon. We decided to play it safe and stay out of the woods. Steve went home, and I spent part of the day driving scouting a large patch of nearby forest by car, but I wasn’t able to reach the bottomland area that had intrigued me on Google Earth.

The rains didn’t arrive until evening, but they were very heavy, with 3-4″ overnight. Thunderstorms continued until mid-morning on the 1st, so I didn’t venture out until about 10:30. Conditions were cool and cloudy, and everything was soaking wet. My movements were limited by high water levels; these continued to rise during the four hours I spent in the field. Avian activity was again minimal. Coming across this rattlesnake, the third or fourth I’ve found over the years, was the day’s highlight.

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On May 2nd, my last field day, I spent the early morning trying to get to the hickory stub and trail cams. Water levels were too high, so I returned to my car and drove to a more accessible location. While I have been concentrating on it less this season, there have been a number of possible contacts in this area, and we have found abundant sweet gum scaling there every year. As has been discussed in several recent posts, classic, ‘Tanneresque’ high branch scaling on freshly dead sweet gums is not necessarily inconsistent with Pileated Woodpecker.

Still, I found some very dramatic work on the dead fork of a dying gum. Phil and I first found this tree in February, but most of the scaling has taken place since then. Of particular note were the enormous bark chips found at the base, again all removed since the end of January. My hat, which is shown for scale, is 12.5″ x 12″. Note that this scaling involves some of the largest limbs. Since some gum balls are still attached to the dead limbs, I think it’s safe to assume that the bark remains relatively tight; the scaling also looks generally clean, something that I find suggestive of ivorybill. To the best of my recollection, the bark chips are the largest I’ve ever found from sweet gum limbs.

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Later that morning, I found a mildly intriguing cavity in a small sweet gum (~18″ DBH). While it’s almost surely PIWO, I’m including it because the shape and skewed angle are somewhat interesting and also to illustrate that even smaller trees can host substantial cavities. The original image was badly backlit, so I’ve brightened it and rendered it in black and white to make the cavity easier to see. Referencing Dennis again, he estimated the diameter of his Cuban nest tree at 12″. While DNA evidence suggests the Cuban IBWO is/was a different species, more closely related to the Imperial than to the US IBWO, the conditions under which Dennis found a breeding pair seem relevant to the survival of the North American species, and the ‘old growth specialist’ caricature:

There was a sprinkling of deciduous trees, some quite large. Although this region had been heavily logged and burned over as well, growth was quite luxuriant in spots. A watercourse, as well as the generally rugged terrain, had prevented a clean sweep of all the timber. The pine  trees, on the whole, were limited to less than five inches in diameter.

There may be more on this in an upcoming post.

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Ivory-billed Woodpecker Sightings and Evidence 1944-2003: The Partially Hidden History

This post is inspired in large part by an exchange of emails with Chris Sharpe, an ornithologist who is working on an IBWO literature review. Our correspondence revolved around the IUCN’s species account, which describes the ivorybill as “possibly extinct” and cites recent statistical analyses that suggest extinction is likely, as well as one that indicates survival is possible and another that concludes “very large search efforts are needed to detect small populations.”

Chris pointed out that there are many other species on the Red List that fall into a similar category with many unverified reports but in more remote habitats and nowhere near the search effort that has been expended on the ivorybill. While there’s some validity to this assertion, I think the reality is considerably more complex and that the ivorybill is in fact sui generis.

Many of the specifics of ivorybill history are little-known, and the statistical studies seem badly flawed. One focuses on collection rates but may not adequately address changing attitudes toward conservation in the early 20th century among other factors. Another is perhaps even more problematic for a number of reasons – most importantly its focus on “verified sightings”, which is a particularly complicated issue when it comes to the ivorybill. It omits numerous controversial sightings and does not include post-Singer Tract instances in which physical evidence was obtained, although the authenticity of that evidence has been contested. “Sidewinder” posted the abstract and a good summary of the findings on ibwo.net a few years ago:

Roberts, D. L., C. S. Elphick, and J. M. Reed. 2010. Identifying anomalous reports of putatively extinct species and why it matters. Conservation Biology 24:189–196.

As species become very rare and approach extinction, purported sightings can stir controversy, especially when scarce management resources are at stake. We used quantitative methods to identify reports that do not fit prior sighting patterns. We also examined the effects of including records that meet different evidentiary standards on quantitative extinction assessments for four charismatic bird species that might be extinct: Eskimo Curlew (Numenius borealis), Ivory-billed Woodpecker (Campephilus principalis), Nukupu`u (Hemignathus lucidus), and O`ahu `Alauahio (Paroreomyza maculata). For all four species the probability of there being a valid sighting today, given the past pattern of verified sightings, was estimated to be very low. The estimates of extinction dates and the chance of new sightings, however, differed considerably depending on the criteria used for data inclusion. When a historical sighting record lacked long periods without sightings, the likelihood of new sightings declined quickly with time since the last confirmed sighting. For species with this type of historical record, therefore, new reports should meet an especially high burden of proof to be acceptable. Such quantitative models could be incorporated into the International Union for Conservation of Nature’s Red List criteria to set evidentiary standards required for unconfirmed sightings of “possibly extinct” species and to standardize extinction assessments across species.

Here are the Ivory-billed Woodpecker sighting data they used:

Physical evidence: 1897, 1898, 1899, 1900, 1901, 1902, 1904, 1905, 1906, 1907, 1908, 1909, 1910, 1913, 1914, 1917, 1924, 1925, 1932, 1935, 1938, 1939

Independent expert opinion added: 1911, 1916, 1920, 1921, 1923, 1926, 1929, 1930, 1931, 1933, 1934, 1936, 1937, 1941, 1942, 1943, 1944

Controversial sightings: 1946, 1948, 1949, 1950, 1951, 1952, 1955, 1958, 1959, 1962, 1966, 1967, 1968, 1969, 1971, 1972, 1973, 1974, 1976, 1981, 1982, 1985, 1986, 1987, 1988, 1999, 2004, 2005, 2006

Data were from Tanner (1942), Hahn (1963), Jackson (2002, 2004), Fitzpatrick et al. (2005), Hill (2006), and Floyd (2007).

Some conclusions: For the Ivory-billed Woodpecker, the prior sighting record suggests that even by the time of the first controversial sighting, the species was relatively unlikely to remain extant (ca. 21% chance), regardless of the level of evidence (physical or independent expert opinion) used…the effect on the predicted extinction date will depend on the details of the sighting record. Including controversial sightings will, by definition, move expected extinction dates forward in time. An ever-increasing burden of proof should be required with increasing time since the last verified sighting. The burden of proof also should be greater when there is a pattern of frequent sightings prior to the last accepted record and lower when long periods between sightings are common in the historical record.

A second paper published in 2012 reached the same conclusion using 39 sightings “classified as certain and 29 classified as uncertain”.

The insistence on verification is problematic because it’s founded on an appeal to authority, and for much of the time frame in question, the primary if not sole authority was James T. Tanner. Tanner had a strong predisposition to dismiss every post-Singer tract report he received and was somewhat cavalier about reports he investigated in the late ’30s as well. This likely resulted in his underestimating the population at the time. At minimum, he missed six pairs in Mississippi, according to Jackson ( In Search of the Ivory-billed Woodpecker, pp. 60-62.  These details reinforce the point made by “Fangsheath” of ibwo.net that, for the ivorybill at least, demanding verification leads to “a rather vicious circularity”. In a recent email, Fangsheath also pointed out that “the Roberts et al. scheme fits tidily into the narrative created by Tanner, that the Singer Tract was the last hope of the ivory-bill, and that when that: wilderness was lost the bird essentially became extinct . . . Tanner searched across several states for the bird and found none elsewhere, yet he himself believed that the bird survived in a number of areas. And so we have a curious contradiction – on the one hand an appeal to authority is being used to exclude many sightings, and on the other hand that same authority is saying the bird exists in areas where sightings are excluded. The mythos that the bird had very specific habitat requirements clouded every search effort and every sighting evaluation, before and after 1944.”

Fangsheath’s observation about the impact of Tanner’s narrative on future search efforts is profoundly important. Tanner’s ideas about habitat, which were in large part a product of his cultural background and the “myth of the frontier”, hardened over time. In later years, he ignored some of the caveats he set forth in his own monograph. But even his approach to reports from the 1930s reflected a set of beliefs about habitat requirements that had no scientific basis. Many people, myself included, are prone to reflexively accepting these assumptions about “habitat quality” because the conventional wisdom is so deeply engrained.

Fangsheath also reminded me that in the years before Tanner, the species was being written off and had been for decades. Florida was believed to be the last stronghold; the Singer Tract and Atchafalaya basin were not considered, nor were the large tracts of overcup oak/water hickory forest (where Beyer found ivorybills in 1898), many of which were untouched until the 1940s. Unlike the Singer Tract, these areas were often roadless and very difficult to penetrate; the Tract was bisected by a road, had few deep bayous, and was largely free of undergrowth, making it much easier to search. I’ve already discussed Tanner’s difficulty in finding ivorybills anywhere besides John’s Bayou. In this context, it’s worth noting that Bick’s 1941 sighting (from his car on Sharkey Road) involved two birds feeding in a lower lying “ash flat” in which overcup oak predominated.

In addition to these conceptual flaws, the papers grossly underestimate the number of post-Singer Tract encounters within the historic range. While it is impossible to quantify the controversial reports, it’s clear that the 26 or 29 referenced in the studies are the tip of the iceberg. There are well over four times that many on record for the 1944-2003 time period. And no doubt, numerous encounters never made it into the literature.

I initially posted a brief comment about this on Facebook and ibwo.net, with a link to Jerome Jackson’s 2002 Birdwatching Daily article listing 20 pre-Arkansas and post-Singer Tract encounters (some just auditory and one from Cuba) and a reference to Michael Steinberg’s Stalking the Ghost Bird catalogue of 85 sightings during the same time frame. A commenter wrote, “Yes but no confirming photos”. That also led me to think it would be worthwhile to explore this subject in a somewhat more depth, since there is physical evidence, albeit contested, related to several post-Singer Tract and pre-Arkansas reports.

Before turning to the physical evidence, it’s worth reiterating that the 1944 date for the last “verified sighting” is fundamentally flawed and arbitrary. The 1944 date is for the “Say Goodnight” encounter that involved artist Don Eckelberry and two local boys, Billy and Bobby Fought, and the purported last lone female IBWO in the Singer Tract. This poignant story was retold in The Race to Save the Lord God Bird, and it has become central to the popular lore about the species. There’s no doubt that the encounter took place, and Eckelberry no doubt believed that the bird was the last of her kind. Roger Tory Peterson apparently received and accepted a report that a single bird, presumably the same one, was still present in 1946. Tanner was likely aware of this and had an additional reason to think that birds persisted in the Tract well after 1944. His papers include a letter stating that Singer Tract game warden Gus Willett saw a pair in November 1948 at North Lake #1 (I have been unable to identify this lake). According to the letter, the “[b]irds are moving over a much larger area than formerly.” The letter mentions that there had been several other sightings during this time period. There’s no reply from Tanner in the archives and no further correspondence about the Singer  Tract birds. It appears that this is the letter from Tanner’s former student, Arthur MacMurray, that is referenced in Jackson, but Jackson’s account does not mention Willett, who would have been familiar with ivorybills. The strong possibility that a pair of birds remained in the Tract for more than four years after it was cut should itself raise questions about Tanner’s narrative.

Jackson’s list of 19 US reports between 1944 and 2003 was undoubtedly not intended to be comprehensive (and his book includes many others). Instead, it focuses on sightings by professional ornithologists and/or people who were familiar with the species. These include: Allan Cruickshank, John Terres, Herbert Stoddard, John Dennis, Davis Crompton (Dennis and Crompton studied ivorybills in Cuba), Whitney Eastman, and William Rhein. Jackson doesn’t mention it, and was perhaps unaware when he wrote the article, but Rhein had filmed the Imperial Woodpecker in Mexico several years prior to his 1959 Florida ivorybill sighting. It strains credulity to think that every one of these experienced observers, most or all of whom were familiar with the species and all of whom knew pileateds well, would be mistaken. Jackson points out that Terres kept his sighting to himself for more than 30 years out of “fear of being scorned.” Such was the climate surrounding ivorybill claims, even in 1955.

Steinberg lists 85 sightings between 1944 and 2003. His list includes most, if not all, of Jackson’s reports, breaking them down into individual incidents. Jackson treated repeat encounters in the aggregate. Nonetheless, most of Steinberg’s reports do not appear on Jackson’s list. Many of them are from less illustrious sources and quite a few are anonymous, but some of them are from game wardens, field biologists, and graduate students in ornithology.

The Ivory-billed Woodpecker Recovery Plan, prepared by the U.S. Fish and Wildlife Service and completed in 2010, includes an even more detailed compilation of records, some of which are of course also included in Jackson and Steinberg. It lists approximately 100 reports of varying quality between 1944 and 2003. Some of these are aggregates, involving multiple observations. The number of observations is sometimes enumerated and sometimes characterized as “numerous”, “multiple”, or “several”, so it’s impossible to arrive at an accurate tally, but the total almost certainly exceeds 150.

Although the Steinberg and the Recovery Plan compilations are more extensive, they are undoubtedly far from comprehensive. For starters, the climate of intimidation around reporting ivorybills was strong enough to deter John Terres in 1955, and that climate of intimidation only grew more toxic over time, as the Big Thicket and Fielding Lewis incidents, not to mention the battle over the Arkansas reports, make clear. In addition, there’s good reason to believe that countless reports from local people, hunters, and amateur birders have been discounted, dismissed, or ignored by authorities, at least prior to the “rediscovery”. Steinberg writes of his first visit to the Louisiana Department of Wildlife and Fisheries Baton Rouge office in 2003,“ . . . few people took the book, or more important the larger issue very seriously. The typical response from many in the office, other than Nancy Higginbotham, seemed to be, ‘Don’t you have anything better to do?’” (Higginbotham claimed two sightings, one of male in 1986 and one of a female in 1987, both in the Pearl River area.) We’re personally familiar with several instances in which reports were dismissed or ignored. One involved the landowner in our old search area, who came forward after the Kulivan sighting and was deeply offended by the way he was treated. As far as I’m aware, no one has done a comprehensive review of records committee submittals within the historic range of the ivorybill; I know of one such submittal from Texas in 2002 that came from unsuitable habitat, outside the historic range, but there may well be others that are more robust.

I’d like to turn to three examples of physical evidence obtained in the post-1944 era. Some of this is fairly well known – the Agey and Heinzmann feather and the Fielding Lewis photographs. The other is somewhat more obscure, but no less interesting for being so.

The Agey and Heinzmann observations took place between 1967 and 1969, in Polk County Florida. They obtained two recordings that Tanner dismissed. There was evidently some very poor communication about it that was compounded by an obvious error on Agey and Heinzmann’s part. They mistakenly thought that calls on their first clip were consistent with some ivorybill sounds from the Singer Tract; they clearly are not. The second clip, which is dominated by a Red-shouldered Hawk, recorded March 3 1968, does have some faint kent-like sounds, but the quality is extremely poor. They are most easily heard on the amplified version that begins at 3:14. The RSHA calls were not what interested Agey and Heinzmann, but they failed to make this sufficiently clear.

I believe Tanner wrote the notes that accompany the recording:

“Well, I’m not sure what to say here. As far as I can determine, there are only four original sound clips here. The recordings at 0:04-0:32 and 0:49-0:57 are certainly flicker-like, especially the continuous series at 0:04-0:21 and 0:26-0:32, but I am less certain about the latter part of the first series (0:21-0:23), which appears to have been recopied twice at 0:41-0:48. A similar vocalization is included at 0:49-0:57 (recopied at 0:59-1:06). Given the very different quality of these sounds relative to those in LNS #6784, combined with the close similarity of the calls to those of Colatpes auratus, leads me to doubt that any of these sounds were given by C. principalis. The recordings from 3 March 1968 (2:45-3:07) represent the calls of Buteo lineatus. Quality unchanged (2;3 – the signal is not bad for the first part, but terrible for the rest, most of which seems to represent copies of various recordings)”

Agey and Heinzmann found several feathers near a cavity, and one was identified as the innermost secondary of an Ivory-billed Woodpecker. Oddly, Jackson wrote that “ . . . some shadow of doubt is cast over these records because Agey and Heinzmann also tape-recorded what they said were Ivory-billed Woodpeckers, and personnel at the Cornell Laboratory of Ornithology identified the birds on those tapes as pileated woodpeckers.” Given that one of the recordings does include kent-like calls, this criticism is not entirely warranted, and the misidentification seems irrelevant in light of the physical evidence (and ironically Tanner seems to have failed to correctly identify the calls on the first clip). Jackson also alludes indirectly to rumors that the feathers were taken from a specimen. These have circulated for years but are unsubstantiated. Agey and Heinzmann published their findings:

Agey, H. N., and G. M. Heinzmann. 1971a. The Ivory-billed Woodpecker found in central Florida. Fla. Nat. 44 (3):46–47, 64.

Agey, H. N., and G. M. Heinzmann. 1971b. Ivory-billed Woodpeckers in Florida. Birding 3:43.

To the best of my knowledge neither publication is available online at this time.

The next event, chronologically, started with a series of encounters in east Texas in the late 1960s. John Dennis obtained a recording that Tanner initially dismissed, in part for the patently absurd reason that a Pine Warbler is also heard on the clip, but later described as “a real mystery” when confronted with the sonograms and analysis that were suggestive of ivorybill. That recording is now catalogued as IBWO.

Additional slides, taken in 1970 in east Texas by a man named Neal Wright, were turned over to the Museum of Natural History in Philadelphia (search Ivory-billed Woodpecker, registration required to view image) which also houses the Fielding Lewis photographs. These were made public after the rediscovery. They show what appears to be a female Ivory-billed Woodpecker in a nest cavity. When I first viewed the Wright photographs, I was quite skeptical, but later, I was struck by the resemblance to this image from the Singer Tract.

Wright was apparently quite a local character, and I remain somewhat suspicious, as he may have had ulterior motives; however, the similarity to one of the unpublished images from the Singer Tract is strong, and in the pre-internet era, it seems unlikely that a Texas woodsman would be familiar with any of the ivorybill images that did not appear in Tanner’s monograph.

The Fielding Lewis photographs, taken in South Louisiana in 1971, are far better known, although Lewis wished to remain anonymous. His identity was not revealed until more than three decades later, and he was identified at the time only as “the Chief” (Jackson was unaware of his identity in 2004, though it was made public soon thereafter.) George Lowery presented these images at the American Ornithologists’ Union annual meeting and was attacked by many of his colleagues who deemed them to be a hoax. It’s worth pointing out that there have been hoaxes in recent years (these were swiftly and easily debunked), so there’s legitimate reason for skepticism about any claim. In the case of the ivorybill, however, skepticism has frequently been replaced by a virtually irrebuttable presumption of fraud (or error).

In a letter to Tanner, Lowery (who, unlike most of his detractors, had actual field knowledge of ivorybills) wrote: “I know the man in question very well and I am sure he would not pull something like that. In the first place, where would he have gotten the mounted specimen? Why would he have two photographs of the birds way up on two separate trees? Both of considerable diameter and not subject to being shinnied. Also, assuming he might have had a mounted bird to photograph, why didn’t he get a better picture while he was at it?”

The most common reasons given for believing that Lewis hoaxed the photos are that the bird is similarly positioned in both images (similarly but not identically, a neat trick with a specimen) and that the bill and feet are not visible. Bear in mind that these pictures were taken with a Brownie or Instamatic camera, and the quality is very poor. Nonetheless, I believe a foot is very faintly visible in both photos, positioned in a manner that would be expected of a live Campephilus woodpecker. I worked from scans of the originals and made some modest enhancements in Photoshop. Note also that in the first picture, both a cavity and bark scaling can be seen on the tree.

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Regardless of whether my analysis is correct, the foundation for claiming that these photographs were faked is shaky indeed – not only for the reasons Lowery gave but also because of Lewis’s reticence about revealing his identity, insistence on keeping the location secret, and lack of any discernible motive.

The recovery plan mentions two other pieces of physical evidence. One is a feather that was purportedly found in a nest or roost cavity in 1985, and the other is a photograph supposedly taken in Georgia in 1975 (correction, 1965).

It’s not my intention to fault the IUCN or to quarrel with the “possibly extinct” designation, although I think Bill Pulliam’s analysis of the Luneau video in light of Rhein’s Imperial Woodpecker film should be dispositive. My main purpose is to call attention to the fact that there’s considerably more evidence for survival than is popularly recognized or than appears in the scientific literature. There are multiple instances of people, often outstanding birders, hesitating to come forward with reports and hard evidence – for decades. Terres waited 30 years; in the cases involving physical evidence, only Agey and Heinzmann went fully public and identified themselves in making their claims; in Stalking the Ghost Bird, Steinberg includes detailed 2005 field notes written by a Louisiana “birder for more than forty years” who “has also worked as a contract ornithologist conducting bird surveys on rice and crawfish farms for more than ten years.” This individual too requested anonymity. To a significant extent, the shortcomings in the literature are directly related to the controversy that has surrounded this species for nearly a century (remember Mason Spencer who went so far as to obtain a permit and kill an ivorybill to prove the species persisted) and the accompanying climate of unhealthy skepticism that has, if anything, grown even more unhealthy since the rediscovery. This sets the ivorybill apart from other possibly extinct species.

I’ll be heading for Louisiana at the end of the week and will post a trip report when I return.


George and Nancy Lamb’s 1957 Cuban Ivorybill Study

I have been re-reading George Lamb’s 1957 report on the Cuban Ivory-billed Woodpecker. A number of items struck me as potentially significant for North American searchers, some for how they diverge from Tanner and others for their level of detail. Since this report is likely unfamiliar to many, I thought I’d do a quick post listing some of the more interesting observations

Lamb references a number of local sightings of “groups” of ivorybills, with one report to John Dennis that involved six birds. Notwithstanding, Lamb estimated the population density in Cuba to be much thinner than in the Singer Tract, at one pair per 12-25 square miles. He also pointed out that “ . . . the Cuban Ivory-bills are living for the most part in a cut-over pine forest where only small and deformed trees remain.”

The Cuban ivorybills fed on pines and hardwoods more or less equally, although most of the feeding sign was found on pines, due to the difficulty of searching for sign in the denser hardwood habitat. Roosts and nests were found exclusively in pines (one unused cavity was found in a hardwood), which is interesting in light of the fact that hardwoods were also available. Cavities were found at heights ranging from under 20 feet to nearly 60 feet. Cavities were higher in mature forest; Lamb suggested but did not conclude that the preference was for higher cavities and that the lower ones reflected an adaptation to cut-over conditions.

Lamb describes a female scaling bark: “At this point she was only about 25 feet away while she was feeding around the base of a small pine. She began ‘barking’ this tree about 30 inches from the ground and slowly worked up to the top.” Dennis too had observed birds scaling small pines. They found more scaling than excavation.

This apparent preference for pines, including small ones, may be significant, particularly since the hardwood areas were “relatively untouched”.

An estimated 17 birds were killed by humans over a ten year period, a huge number for such a small population. And it seems an open question whether the thinner population density noted by the Lambs was due to habitat quality, hunting pressure, or a combination of the two.

Regarding flight style: “. . .the flight of the Cuban Ivory-billed Woodpecker was always level and purposeful. They are strong fliers, capable of covering considerable distance in little time, as indeed they must to live successfully in cut-over woodlands. Although the Ivory-bill did not seem to undulate in its flight, the wing beats were not steady, having an almost imperceptible 2-3-2-3 rhythm.”

There’s no mention of double knocks, but calls are discussed. Lamb describes the sound as like the “note of a penny tin trumpet . . . short and usually repeated in a series of single-double-single beats, or it may begin with a double call: that is a high nasal “pent, pent-pent, pent”, or just “pent-pent”. On several occasions the female Ivory-bill most frequently observed made a few long and very loud calls, soon after leaving here roost tree in the early morning. The notes were of greater duration than normal and were repeated in a series of sixteen to twenty-two kients.”

Food for thought . . .


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 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 was undoubtedly J.J. Kuhn’s greatest admirer.