Correlated Ivory-billed Woodpecker Molt and Breeding Phenology; Florida 1968, More Evidence that Ivory-billed Woodpecker Survived Post Singer Tract

Correlated Ivory-billed Woodpecker Molt and Breeding Phenology; Florida 1968, More Evidence that Ivory-billed Woodpecker Survived Post Singer Tract  

Draft 11-10-22

Molt is commonly used by bird banders and ornithologists to gauge a bird's health and age, and aid in specie's identification. The observed molt phenology can be determinate in identification between even closely related species. After recently discovering a synchronous molt on the Ivory-billed Woodpecker in Louisiana (M. Collins, 2008 video, Virrazzi, 2022), I examined the circumstances of the 1968 Ivory-billed feather from Florida associated with those published sightings. 

A correlated molt and breeding phenology was deduced to research the subject feather (see table below). The exact date the specific fresh, secondary feather was found is consistent with the breeding and normal molt phenology for Ivory-billed and not a Pileated Woodpecker.

Change of season or daylight hours stimulates molting, migrating, and breeding. Other factors that influence the timing of the molt include temperature and available nutrition, as well as the bird's general health and reproductive state. In this article the season and date factors only are examined to see if they correlate with the expected date for a normal Ivory-billed Woodpecker molt for the specific feather found.

H. Norton Agey and George M. Heinzman reported eleven detections, including sightings of Ivory-billed Woodpeckers in central Florida from 1967 to 1969 by several people. The sighters became aware of the birds after an inexperienced youngster described a large woodpecker with field marks that only fit an Ivorybill.

Several capable people subsequently saw or heard these birds and identified them as Ivory-billed Woodpeckers. A feather discovered near a fallen nest tree was professionally identified as an Ivory-billed feather. Other feathers from a very young bird were found attached to splinters in the cavity. This was not a one day, one observer event, or one without physical evidence, quite the contrary. The years of evidence were described and published in The Florida Naturalist, 1971.

 

The Ivory-bills were reported from a large cattle ranch with locked gates west of U.S. Route 27 in Hardee and Highlands Counties, north of Highlands Hammock State Park (P. Sykes, 2016). The authors had permission to be on the ranch and the landowner was aware of the Ivory-billed Woodpeckers presence for ~ 10 years prior. Ivory-bills were seen in Highland Hammock State Park several times per reports of multiple witnesses in the 1960's. Birds were reported in the area in the 1930's.

 

Gradually during the multi-year Bald Eagle census for Florida Audubon they began to accumulate insight into the wary birds' movements while hiking this seasonally flooded forest. Ivory-bills are documented to often breed in locations that are flooded (Tanner, 1942). They noticed Ivory-billed sized, fresh tree holes in the general area and bark scaling in certain trees. They heard various Ivory-billed like calls and strong knocks

In 1968 a tree they suspected as recently having a nest was blown down, breaking at the cavity hole. The pertinent tree sections were collected and measured; the hole was comparable to an Ivory-billed nest hole and not Pileated.

Three feathers found at the broken tree were collected and sent to Alexander Wetmore, PhD, ornithologist and Secretary at The Smithsonian Institute. Several taxa of birds have been named in Wetmore's honor. Nothing indicating the feathers or nest hole were not collected in the field on the stated date was noted. The largest feather was identified as the innermost secondary (S8) of an Ivory-billed Woodpecker by Wetmore. Jerome Jackson confirmed prior to 1995 that the feather was indeed an S8 of an Ivory-billed Woodpecker (P. Sykes, 2016).

During a confidential conversation with a professional who had spoken to J. Jackson, Jackson could not recall any details about which Ivory-billed specimen was missing secondary 8. He had not taken or had lost the notes. The professional went to the subject museum and could not find any Ivory-billed specimen missing S8. There was a very old, damaged specimen that Wetmore should have certainly noted the feather condition had he ever seen a feather from that skin.      

 
In this article the molting phenology of Ivory-billed Woodpeckers is examined to see if it coincides with the date this exact secondary feather was found. Feathers are partially consumed in days by bacteria, other animals and other processes.  

 

Top L Dorsal IBWO, Top R Ventral IBWO, 
Bottom L Dorsal PIWO, Bottom R Ventral PIWO, Note that the IBWO wing is not properly 
"laid out" compared to the PIWO's 

NBP-Florida woodpecker holes

The 1971 article was silent on whether the innermost secondary (S8) they found at a fallen Ivory-billed nesting hole in April, 1968 coincided with the proper timing for an Ivory-billed to drop that particular secondary. The feather had been formally identified as an Ivory-billed by an ornithologist as mentioned. Neither the authors nor the ornithologist may have found a reference on the IBWO molting sequence since no summary likely existed in 1968. They may have not realized molt timing can contribute to species identification between the two larger species of SE USA Picidae; regardless they had the S8 feather of an Ivory-billed.


For the first time the 1968 feather is looked at with the benefit of modern literature on the molt timing of Ivory-billeds. The 2008 Ivory-billed video (Pearl River, LA Collins) was found to have a synchronously molting bird.

The molting sequence of Ivory-bills was determined by examining up to 204 specimens; this established that the innermost primary (P1) is dropped soon after the breeding season ends and then innermost secondary (S8) is shed soon after P1 or P2. In this video from March 29, 2008 primary 1 in both wings is missing and that matches well with the expected specific molt sequence as proposed by J. Jackson.

Study Results of Ivory-billed specimens

Highland Hamock State Park details of study 

This was the first announcement of the sightings and proceeded the paper in the Florida Naturalist soon after.  

 

Most North American Picidae also start their flight feather molt right after the breeding season. Pileateds breeding season ends approximately 2 months later than Ivory-bills; for a respective calendar day an Ivory-billed should not have the same feather or feathers molted vis-a vis a Pileated. The same is actually true for molts of other species; the Ivory-billed molts flight feathers earlier than many North American bird species.


The Pearl River, LA 2008 Ivory-billed had both P1s missing on March 29, 2008 (see video showing that above). The S8 Florida feather was found on April 21, 1968.

Both dates are respectively consistent with the known Ivory-billed molt phenology for P1 and S8. This is further and new evidence supporting that the exact feather found in Florida, S8, coincides with the literature for that feather's temporal molt.

The only observed date for Ivory-bills mating is on November 29, 2019. Ivory-bills first clutch eggs have been found in January, February and March.

Note that Heinzman's name is apparently misspelled throughout The Florida Naturalist article, (1971). (Heinzmann [sic] and Agey, 1971; Heinzman’s name is misspelled throughout the article per P. Sykes, 2016)

Ivory-billed Woodpeckers in Florida

Conclusions: Examining evidence of  Ivory-bills should include comparing the observations with the molt and breeding phenology of the species. Molt and breeding phenology can be used to assist in confirming or questioning reports of Ivory-bills.

On April 21, 1968, a secondary 8 feather (S8) of an Ivory-billed Woodpecker was found at Highland Hammocks State Park, Florida by multiple people. April 21 is temporally consistent with the phenology of a normal molt of S8 feather for an Ivory-billed and not a Pileated Woodpecker or many other species.

The presence of feathers from a very young bird and an older Ivory-billed on April 21, 1968, is consistent with the known breeding cycle of Ivory-billeds.   

The feathers found in 1968 are consistent with two separate complex biological cycles which statistically is strong bivariate evidence of Ivory-bills. The feathers' discovery date coincides with the molting and breeding phenology of the species. This adds to the evidence that the Ivory-billed Woodpecker survived well past 1944 in the United States.

 

A synchronous molt of P1 on the Ivory-billed Woodpecker videoed in Louisiana (M. Collins, 2008 video, Virrazzi, 2022), is consistent with the phenology of a normal molt of these feathers for an Ivory-billed and not a Pileated Woodpecker or many other species.  

Both the 1968 (FL) and 2008 (LA) Ivory-billed reports, supported by correlation with breeding and molt phenology are strong evidence that the Ivory-billed Woodpecker survived well past 1944 in the United States. 

Some Reference Excerpts:


Spring--At what time the winter groups of ivorybills break up and spring activities commence is rather difficult to state, for there seems to be considerable irregularity to the breeding season. Judged from published records of its nests, the period of greatest activity would seem to be late March and early April. According to Audubon, (1842): "The ivory-billed woodpecker nestles earlier in spring than any other species of its tribe. I have observed it boring a hole for that purpose in the beginning of March." Scott (1881) reports taking an incubating female in Florida on January 20, 1880, and (1888) of finding a nest containing one young female about one third grown on March 17, 1887. Ridgway (1898) likewise speaks of shooting a male that left its nest hole February 15, 1898, and Hoyt (1905) states that "in Florida they begin building the latter part of January, and if undisturbed the eggs are laid by February 10th."

In 1937 James Tanner discovered a nest in Louisiana from which the fledgling left on March 30, fully 2 months earlier than any previous records from the same locality, and in 1938 apparently the same pair of birds had young the last week in February. In contrast to these dates we find 10 records of April nesting, 5 for May, and 1 (Beyer, 1900) of a young bird just out of the nest in July. The latter records might well constitute second attempts at nesting. The Florida birds, in general, start earlier than those in Louisiana, but at best there seems to be less regularity to the commencement of the nesting period than is found with most of our North American woodpeckers. In this, the ivorybill may register its affinity with tropical birds in general, the ivorybill being the most northern representative of an otherwise tropical or semitropical genus. There is some evidence for believing that ivorybills wander over considerably larger territories in winter than those to which they confine their activities in the spring, but little definite information has thus far been recorded on any of their before and after breeding activities.
Courtship--Nothing seems to have been written on the courtship of the ivorybill except the observations of Allen and Kellogg (1937):

Our only observations were made in Florida about 6 a. m., on April 13, 1924. We had discovered this pair of Ivorybills at about the same time the preceding morning when they came out of the cypress swamp and preened their feathers and called a few times from the top of a dead pine before going off together to feed. They had made such a long flight the previous day that we were unable to find them again, but that night, still traveling together, they had returned to the same group of medium-sized cypress trees which they had apparently left in the morning and In which there was one fresh hole In addition to four or five other old ones In the near vicinity. On the morning of the 13th, they called as they left these cypress trees and flew to the top of a dead pine at the edge of the swamp, where they called and preened. Finally the female climbed up directly below the male and when she approached him closely he bent his head downward and clasped bills with her. The next instant they both flew out on to the "burn," where we followed their feeding operations for about an hour.

Nesting--As before stated, while there are a few records of February nesting, the most definite records are for March, April, and early May, as follows:
April 6, ____. M. Thompson, Okefinokee swamp, Georgia. Laying.
April 9, 1892. E. A. Mcllhenny, Avery swamp, Louisiana. Three fresh eggs.
April 10, ____. Dr. S. W. Wilson, Altamaha swamp, Georgia. Four eggs.
April 15, 1893. A. Wayne, Florida. A young female about 2 weeks out of the nest.
April 19, 1893. Ralph Collection, Lafayette County, Fla. Three eggs.
May 2, 1892. E. A. Mcllhenny, Avery swamp, Louisiana. Three eggs.
May 19, 1892. E. A. Mcllhenny, Avery swamp, Louisiana. Four eggs, a second laying.
May (early) 1894. E. A. Mcllhenny, Avery swamp., Louisiana. Five young, 3 days old.
May 3, 1885. Capt. B. F. Goss, Jasper County, Tex. Three eggs.
July 1897. George G. Beyer, Franklln Parish, La.
March 4, 1904. Brown brothers (Hoyt), feeding young.
March 16, 1904. H. D. Hoyt, Taylor County, Fla. Large young.
March 4, 1905. H. D. Hoyt, Claremont County, Fla. Two eggs, incubation advanced.
March 24, 1905. R. D. Hoyt, Claremont County, Fla. Two eggs slightly Incubated (second laying of the preceding).
April 13, 1924. A. A. Allen, Taylor Creek, Fla. Nest completed. Incubation not yet started.
April (early) 1931. J. J. Kuhn, northern Louisiana. Incubating.
May 13, 1934. J. 3. Kuhn, northern Louisiana. Probably small young.
April 6, 1935. A. A. Allen and P. P. Kellogg, northern Louisiana. Incubating.
April 9, 1935. A. A. Allen and P. P. Kellogg, northern LouIsiana. Building.
April 25, 1935. A. A. Allen and P. P. Kellogg, northern Louisiana. Incubating.
May 10, 1935. A. A. Allen and P. P. Kellogg, northern Louisiana. Small young.Again quoting from the report of Allen and Kellogg (1937):

The site of the Ivorybill's nest seems to vary considerably. Audubon states: "The hole is, I believe, always made in the trunk of a live tree, generally an ash or a hackberry, and is at a great height." There are, however, records of their nesting in live cypress, partially dead oaks, a dead royal-palm stub,"an old and nearly rotten white elm stump," etc., indicating about as great a variety as shown by the pileated woodpecker. The lowest authentic nest of which we have found a record, was that described by Beyer (1900) "about 25 feet up in a living over-cup oak," although Scott (1881) mentions what he considered "an old nest evidently of this species," in a palmetto stub only fifteen feet from the ground. The nest which we discovered in Florida, in 1924, was about thirty feet up in a live cypress and there were other holes in the vicinity in similar trees that had apparently been used in years past. The bark had healed over in some cases and scar tissue was apparently trying to close the wounds. Of the four nests examined in Louisiana, three were in oaks and one in a swamp maple. The maple, seven and a half feet in circumference (breast high), was partially alive, but the top where the nest was located, 43 feet from the ground, was dead and pithy. Of those in oak trees, one was in a dead pin-oak stub about ten feet in circumference and about fifty feet high, standing in more or less of a clearing. The nest was 47 feet 8 inches from the ground. The other two were not measured accurately but were certainly over forty feet from the ground. About the middle of May when it was determined that the first two trees had been deserted, they were cut down, careful measurements taken, and the contents of the holes preserved. The hole in the maple was 5 inches in vertical diameter and 4 1/8 inches laterally, and was slightly irregular at the bottom, as shown in the photographs; that in the oak was more symmetrical with a similar vertical diameter of 5 inches and a transverse diameter of 4 inches. The depth of the maple nest from the top of the entrance hole was 19 1/8 inches, of which 3 inches was filled with chips and "sawdust." This nest cavity was 8 1/8 inches in diameter at the egg level, and the tree itself 18 1/2 inches in diameter at the level of the hole. The nest cavity in the oak was 20 inches from top to bottom with a diameter of 8 1/4 inches at the egg level. The entrance hole went in 3 inches before it turned abruptly downward; the tree at this point was 22 inches in diameter. There was a stub just above the hole in the maple about 4 inches long representing a branch that had apparently died and been broken off years before and started to heal over. The oak was perfectly smooth at the entrance hole, not on either side, slightly above, were the bases of two large branches that could not have given the opening any protection from the weather. The opening in the maple faced north, two of those in the oaks east, and one west. Audubon states: 'The birds pay great regard to the particular situation of the tree and the inclination of the trunk; first, because they prefer retirement, and, again, because they are anxious to secure the aperture against the access of water during beating rains. To prevent such a calamity the hole is generally dug immediately under the juncture of a large branch with the trunk." None of the nests examined by us showed this desire for protection from rain, and the chips at the bottom of the cavity were perfectly dry, though we had had some very heavy rains shortly before they were examined.

Audubon further states: "The average diameter of the different nests which I examined was about 7 inches within, although the entrance, which is perfectly round, is only just large enough to admit the bird." Beyer (1900) says: "The entrance measures exactly 4 1/2 inches in height and 3 7/8 inches in width," and McIlhenny (Bendire, 1895) gives the measurements of a typical hole as "oval and measures 4 1/8 by 5 3/4 inches," and Scott (1888) as "3 1/2 inches wide and 4 1/2 inches high." The corresponding measurements of the nests of Pileated Woodpeckers are given by Bendire (1895) as follows: "The entrance measures from 3 to 3 1/2 inches in diameter, and it often goes 5 inches straight into the trunk before it is worked downward." The additional one to two inches in diameter of the nest hole should he kept in mind when searching for reasons why the Ivorybill has proven less successful than the Pileated Woodpecker in its struggle for existence. Thompson (1885) states: "The depth of the hole varies from three to seven feet, as a rule, but I found one that was nearly nine feet deep and another that was less than two." He also claims that they are always jug-shaped at the lower end.

Of two nests discovered by Hoyt (1905) in Claremont County, Fla., one was 58 feet up in a live cypress about 20 yards from a nest discovered in 1904 by the Brown brothers; the second nest built by the same pair after the first eggs had been taken was in a cypress stub about 70 yards distant from the first and 47 feet from the ground. The opening of the first nest was 6 3/4 inches by 3 1/4 inches, with the trunk of the tree 15 inches in diameter at the nest cavity, which was 14 inches deep. The second nest hole measured 6 by 3 3/4 inches and was likewise 14 inches deep. "The opening in both nests was uneven and rough, and just inside the hollow was much enlarged, being 9 inches across, and unlike the nests of other woodpeckers, was smaller at the bottom than at the top. * * * * One marked feature of the nest tree of which I have seen no mention made is that the outer bark of those I have examined was torn to shreds from a point some distance below the nest site to 15 or 20 feet above it. This made the nest tree noticeable for quite a distance. The last nest taken this season had little of this work done."

             

John Dennis - Tribute, 35 Page Unpublished "Monograph", Cuban Rediscovery; Obituary

John Dennis is one of the most prolific Ivory-billed Woodpecker researchers in the post 1944 era. He is fortunate to have seen both the North American and Cuban Ivory-bills well.  He also had detections of the bird in Texas, Florida and South Carolina. It is likely that he detected more different Ivory-bills than any person after 1944 although George Lamb must be close. 

In 1967, sponsored by the U.S. Fish and Wildlife Service, he reported sightings of ivory-billed woodpeckers in East Texas along the Neches River. Previously, Dennis had rediscovered the Cuban species in 1948. 

With Crompton they had only been on good habitat for a few days, with no detections. A local lumberman insisted that there was spot across the valley where he had encountered the birds consistently. It was hours from the spot they were at, but an Ivory-billed lead must be followed up on----it's basically a birder's golden rule on rare birds. 

The two agreed to go; naturally it was a hot, steamy day, and the steep hills rough and trails nothing more than a rocky rut.

After an executive decision they staged their gear lower down and moved sprightlier up to an unexpected life's highlight.

They laid down for a needed break under some pine trees for a siesta. Dennis was awakened by a noise-----it was the working knocks of an Ivory-billed Woodpecker, on a tree only about 30 feet away.

He tried to get Crompton's attention; who had wandered off. Crompton had been led by sounds to another Ivory-billed and their cavity.

Amazingly Dennis then realized with disgust the camera was down the mountain; this is typical of Lord God bird luck. Rushing down, he was back in an apprehensive hour and snapped some of the often seen Ivory-billed pictures that will linger for centuries (see below).

From Texas Dennis saw a bird well and procured an audio recording of kent calls that were found to be a good match to ivory-billed woodpecker calls, but possibly, also compatible with blue jays. 

At least 20 people reported sightings of one or more ivory-billed woodpeckers in the same area in the late 1960s, and several photographs, ostensibly showing an ivory-billed woodpecker in a roost, were produced by Neil Wright. Copies of two of his photographs were given to the Academy of Natural Sciences of Drexel University. These events helped create the Big Thicket National Preserve.

One of Neil Wright's pictures East Texas

Here is gathered some harder to find details and writings about and by John Dennis. Specially intriguing, with excellent references and rare information that was in government files, is his 35-page "monograph" on the species. 

A Last Remnant of Ivory-billed Woodpecker in Cuba

Cuban Ivory-billed Dennis, see link to paper above for details

Picture from Cuba by George and Nancy Lamb, 1956

John Dennis-Obituary-Washington Post

See the 50 page article with multiple videos of the 2008 Pearl River, LA, Ivory-billed

See the article on the large woodpeckers mating in 2019 in Louisiana  

Captive Ivory-billed, Cuba

Ivory-billed Woodpecker Wingspan and Body Length Measurements and Species Discussion, Drone Footage LA

 

Ivory-billed Woodpecker Wingspan and Body Length Measurements and Species Discussion, Drone Footage, LA

DRAFT

edit 9/20/22

edit 9/16/22

Due to the importance of putative Ivory-billed Woodpecker evidence, public ideas and raw work on the drone footage is being accumulated here. Sections have been written in early August 2022 as evidence, video iterations and ideas are released or appear. Reading this draft in reverse, (bottom up) will show the chronological evolution of ideas and conclusions more clearly.

If anyone wants to propose or present an organizational rewrite, please contact NBP or author. 

------
  

New, different measurement data, deduced from the 2/23/21 0800, drone footage by the C. Principalis Group, obtained in LA is presented. Independent data here, along with prior drone analysis by this author on possible species via plumage and vertical perching indicates this distant bird is an Ivory-billed Woodpecker.

This adds to the original researchers' "lines of evidence" for Ivory-billed Woodpeckers in this area. The body length of the woodpecker in the subject 2021 video was measured on ~ 8/10/22 and several steps were needed to be as accurate as possible on that date. That calculation indicated the length of the bird was 21.4 inches. This obviously closely matches Ivory-billed length and eliminates both Pileated Woodpeckers or Red-headed Woodpeckers if all other characteristics match known Ivory-billed details. Some other non-Picidae species that have lengths substantially different than 21.4 inches are also eliminated.   

Here in late 8/22 is a calculation of 30.3 inches for the wingspan of the subject drone bird. The Ivory-bills' measured wingspan from various specimens is 29 to 31 inches with some sexual dimorphism, females being smaller.  

The 30.3 inches for wingspan is empirical data from the actual video images; it needs to be written up neatly with the exact methods, all intermittent calculations, subtotals and perhaps some screen shots added.  The wingspan measurement was pursued for obvious identification purposes. Careful social media posters were asking about a way to scale the bird.  Good insight by them and a rare, actual question about the evidence.

Another poster experienced in drone photography asked on social media about how the first set of numbers (body length) was derived, and that methodology is similar as for the wingspan here. That person was asked a few short questions by me on any alternant methods; they remained unanswered until ~ 9/18/22. No other plausible method was offered to deduce measurements of the subject bird although climbing the tree with models for reenactment was proposed. That would be expensive, time consuming, slightly dangerous, involve liability and permissions that could be withheld.     

Before doing this latest research, I had deduced a constant, -5% adjustment (C = -5% for now) that is needed to compensate for the slight angle of tree acquisition by the camera that causes foreshortening and influences the actual tree height appearance on a screen to the actual height due to perspective compared to the horizontal measurement of the wingspan on a computer screen, which is not foreshortened. The constant's present value (-5%), and actual estimated range, + - from -5% and weighting in determining the final absolute number is very minimal and is a + - minus 0 to 1 inch from the present final number (30.3 inches) when using C = -5%.  

The exact elucidation of C will intuitively not change the wingspan more than a fraction of an inch or any of the assertions or conclusions in this article.         

To deduce the unknowns of wingspan and body length only one object of known or satellite estimated length is needed. Via caliper on a PC screen, the video's woodpecker wingspan and tree height was measured to establish a ratio using the perch tree height (98 feet estimated) as the utilized height.

The ratio was used to calculate the previously unknown wingspan of the bird. The wingspan measurement was best deduced by using the final in-flight frames of the regular speed sequence of the half flight iteration. There the bird flares out its wings, squared and approximately tangential to the camera lens. Three measurements were made and averaged. Other frames were also measured but not summated; these frames will not change the final results since they were the same as the three measurements used.

Data, Measurements and Derivations for Wingspan

tree height in area equals 98 feet average per authors, and NBP GIS confirmation. Landing tree appears average 

average n = 3, wingspan, 23/128 inch  

tree height is 6 5/8 inches on screen

equals 768 plus 80 (128ths of an inch) = 848/128 inches

 23/848 = .02712      .02712 x 98 ft = 2.658 ft

2.658 ft x in/ft = 31.89 in

31.89 minus (C adjustment of -5 %) - 1.59 in

equals 30.3 inch wingspan in subject bird 

Project Principalis stated the average height of the trees in the study area is 98 feet. NBP checked GIS data bases and examined aerials; the 98 foot height is very close to the actual height of the landing tree.

More ecological correlates support the landing tree height is approximately 98 feet. The maximum heights of the common tree species in the area are in general well over 100 feet. When the species are assumed to be the age of the trees in that area and extrapolated via minimum growth rates, 98 feet is approached.

 
Also you can see in the video that trees of seemingly the same species have varying DBH in the scene. The highest DBH trees and likely the oldest, have heights that are not much more that the smaller DBH trees. This indicates that these older individual trees have recently had more secondary growth (width) than primary growth (vertical). Dominant secondary growth occurs when trees are older and can be approaching 90 feet or more depending on species.


I am highly confident that the estimates of tree height and its derivatives, wingspan and length, are very close to the actual bird's morphology; it is surely not a Red-headed Woodpecker. Color fidelity in the video is adequate. Careful review, frame by frame of relative positions of the white and black during the flight cycle is sufficient to say this bird's dorsal wing pattern is very similar to an Ivory-billed and not a Pileated. The correct species choice depicted in this video leads to only one possible species.

This supports that the drone footage is of an Ivory-billed Woodpecker when combined with other data presented here including an analysis of body length, possible species, wing beat Hz, plumage, etc. below.

Body Length: The average height of the trees in the recently posted drone footage is 98 feet. Using the same methods as above to deduce the wingspan of the bird, the length of the bird is ~ 21.5 inches. This agrees with only one species of Picidae in SE USA.  

Wingspan and Body Length:  30.3 inch and 21.5 inch respectively using the methods described within.  The woodpecker in the drone is portraying measurements that do not agree with almost all SE USA Picidae species. The drone woodpecker's measurements agree closely with known and established Ivory-billed measurements of wingspan and body length measurements. 

Plumage: Careful frame by frame plumage analysis throughout the flight cycle described within eliminates all NA species including known leucistic Pileated plumages. Unknown leucistic plumages of Pileated, which may or may not even exist, are eliminated by the length of the bird being ~ 21.5 inches. In addition, the flight dynamics do not agree with Pileated.     

Parts of Article in Raw Form as of 8/27/22

Poster asks for info, doesn't do the math themselves, yes of course on FB.~ 8/26

"Can you do the same thing using wingspan, careful to include the black wing tips? If you do that I'd like to see if the results are similar. I think the wingspan on a ivory bill woodpecker is about 30"


Update on IBWO Evidence Review, Louisiana 2000-2022 Drone footage

The average height of the trees in the recently posted drone footage is 98 feet. That makes the woodpecker in the drone ~ 21.5 inches long which is right for only one North American species, the Ivory-billed. In addition the bird has largely white wings and black body which only fits IBWO. The bird zooms up for a landing that fits the literature for IBWO (Audubon, et al.). Upon landing the white saddle of an IB is seen. There is also the suggestion of a dorsal stripe.

This area has had sightings for over twenty years meeting the often voiced criteria of "repeated sightings are necessary". Recently game cam photos from the same area depicts birds that are Ivory-bills according to the research group's analysis. Independent review of the photos shows two birds mating in November, an unprecedented time for Pileated Woodpeckers.
Great job by the LA group.

Here is my post a week ago before I knew the height of the trees:

I have scaled the drone bird as follows: using the right landing tree range of possible heights to determine length of bird

if tree is, then bird length

60 feet    12.86 in
70 feet     15.00 in
80 feet     17.14
90 feet    19.28
95 feet    20.35

(note: because tail is unresolved I assumed the tail was average length meaning not an IBWO but RHWO, add ~ 1.0 inch to right column to adjust if bird is the length range of IBWO and well out of the range of RHWO.

From: I wrote this below earlier on 8/17 after the drone footage at regular speed was released. Had not figured out height of trees.

Link to right tree view, and bird is in next comment
It is a standard practice to provide different speeds including actual speed of various videos being used as "record videoes".

An issue for me of the drone half speed, and others a week ago was, what makes it a woodpecker? Many birds can sweep up for a landing on slanted branches.
But now looking more carefully with regular speed at the landing tree, that branch is close to vertical and the bird hitches up, woodpecker-like, and few other taxa other than Picidae do this.

Hz may be of imperfect or of nuanced ID assistance since this bird is mostly not in powered level flight but varied transient flight styles. This can include landing, taking off and possible searching for food or a landing substrate. The bird could also be hesitant if it is parallelling, mimicking or flanking the slight drone movement.

The initial take off includes a drop of ~ the first 50 horizontal feet to the right. Level powered flight is measured in IBWO (8.6 n =4) and PIWO (5.2 n ~ 100) with no overlap for this flight type between the species ever measured. The possibility that this bird is aware of and observing the drone (perceived predator) must be considered in relation to flight type and wing beat Hz.

Still working on this, but subject bird, for at least short sequences of several flaps or less seems high Hz (>6<7 for middle ~ 150 feet) for level flight of any PIWO (5.2). I also do not see the very noticeable wing binding that PIWOs show over ~ 150 feet. But the bird is not flapping completely constant as some binding is probable which may fit the 2006 or 2008 LA video more than any PIWO. The 2008 video seems to show some minimal or more binding.

Also I see the suggestion of wing bowing as Pulliam brought up for Luneau and is in the 2008 LA; this is inconsistent for PIWO which has a deeper wing flex on the downstroke with wing tips almost touching or touching. However comparing this to the powered level (close to level) flight of the Luneau video is not without nuances.

As far as confusing species which have some similar black and white pattern. Why is it not a lost Black-shouldered Kite? Black body might eliminate that but is that cherry picking frames as the black body is not seen in most frames? I do not see it as a kite as far as wing shape, chord width, landing and hitching up a vertical primary branch.

And there is Black-crowned Night-Heron but that should flap much slower than this bird. Also White Ibis and white phase or transforming imm. Little Blue Heron was in the running but trailing badly before these new drone sequences. Seems all 3 are eliminated as this bird Hz is too fast and not landing like or in a substrate like those do.

That may only leave Red-headed Woodpecker or IBWO. The bird seems large but why be subjective on such an important topic.

There is no scale provided with the video at this point although there are multiple ways to provide that. Scaling will provide a method to avoid or address the problem of the inconsistent amount of white in the mantle of this bird from frame to frame.

Since an IBWO is 100% longer than an RHWO that should eliminate one of these species. You provide scale and you may be squarely on Red-headed or Ivory-billed.

Fred Virrazzi 9/11/22 Social Media

Have found more ecological correlates that support the landing tree height is indeed in the 90 to 105 foot range. That height was used in this article to deduce a length and wingspan of the "drone bird".

I have researched the maximum heights of the common tree species in the area and looked at age of the trees in that area against minimum growth rates to establish a minimum tree height.

Also you can see in the video that trees of seemingly same species have varying DBH in the scene. The highest DBH trees and obviously likely the oldest have heights that are not much more than the smaller DBH trees. This indicates that these individual trees have more secondary growth than primary growth (vertical growth) which occurs when trees are older and can be approaching 90 feet or more depending on species.

I am highly confident that the estimates of wingspan and length are close (below)_and this bird is Surely not a Red-headed Woodpecker. Color fidelity in the video is sufficient to say this is not a PIWO. The last species choice is obvious.

But still like to see more about camera specs. end 9/11/22 comment Virrazzi

High Detection Rate of Ivory-billed Woodpeckers in Congaree National Park, SC 2006 to 2009 Indicated Presence

 High Detection Rate of Ivory-billed Woodpeckers in Congaree National Park, SC  2006 to 2009 Indicated Presence  

copyright-Fred Virrazzi

There have been numerous reports of Ivory-billed Woodpeckers in South Carolina subsequent to the last accepted Singer Tract sighting (1944). The Palmetto State sightings were made by many excellent birders, rangers, hunters, naturalists, scientists and citizens.

In 2007, 2008, 2009 and 2011 National Biodiversity Parks, Inc. (NBP) researched, under various federal permits, attraction of Ivory-billed Woodpeckers during Point Surveys in South Carolina. Our field personnel had multiple Ivory-billed Woodpecker (IBWO, IB) detections in multiple years of the 4 field years in SC. These detections included a sighting, a kent, single knocks and  double knocks reported by experienced personnel. 

From 2006 to 2008 various additional formal surveys were performed by other entities and individuals under the umbrella of the South Carolina Ivory-billed Woodpecker Working Group (SCIBWWG).

Over the 4 subject years, 60 or more Ivory-billed reports came from the same ~ 26,000 acre park where NBP had multiple encounters during our research. There is latency for Ivory-billed reports going public due to various formal agreements; it can take many years for researchers to recognize that sightings were tempospatially related. The latency is partially by design.

For the first time, all the Ivory-billed, human detections that the author is aware of is summated in this draft table:

There were also several different IBWO detections by ARUs; these recorded kents and DKs. The ARO detections are not included in the above table but the SCIBWWG summary paper seemed to highly rate these as IBWOs or likely IBWOs. 

There was an unprecedented number of Ivory-billed Woodpecker detections in this one, 26,000 acre park in SC from 2006 to 2009 rivaled only by the Singer Tract, LA after 1900.

This is an incredible number of human detections; no other area post 1944 has 67 detections claimed in any 4 year period. There is likely no single location in the last 75 years with 67 detections let alone 4 years.

At the Singer Tract, from 1941 to 1944 there were likely more than 67 detections claimed as the previously large forest area was attrited, one or more birds lingered and the last birds were somewhat acclimated to tract caretakers. The one, two or more birds there those 4 years were repeatedly seen over and over sweilling the detection number. Congaree (CNP) birds are comparatively harder to see in my experience yet there are many modern sightings.  Without a full tempospatial analysis of these 67 detections it is impossible to say if more than one or two IBs could have been involved.  The SCIBWWG was evidently disinterested in any mapping or statistical analysis of this unprecedented number of sightings.     

The details of the 67 Congaree detections are poorly described and exceedingly vague in the SCIBWWG's final report. 

IBWO Final Report SC

This summary work is done by committee, seems rushed and forced and lacks basic scientific information after mostly volunteers donated several thousand hours of assistance to the group and indirectly the government. Every sighting is only described as "brief" and some of those a "brief fly by". Brief is then never defined in the report. Two sighting may or may not be flybys; the paper is unclear. These 9 sightings demanded more granularity.

As Ivory-billed researchers and literature readers know skeptics have called the 10 minute long, very close Kulivan sighting of a pair of Ivory-bills "brief" (1999, Pearl River, LA). The sighting of a pair was for 10 minutes; this is not brief. Subsequently there were many sightings in that area with supporting video of an IBWO. Kulivan and his sighting were considered reputable; he was on the IBWO Recovery Team Committee.

Rarely has such an inadequate, casual treating of 9 sightings of an uncommon species let alone a species that is considered critically endangered been presented.

Here are the four sentences on the 9 sightings:

"In addition to acoustic encounters, a few visual encounters were reported from Congaree National Park, although all were brief views by single observers. These visual encounters did not provide enough diagnostic field marks to completely rule out other species. In Year 1, four observers reported 7 visual encounters, all of which were brief fly-bys. In Year 2 and 3, single brief visual encounters were reported."


Regardless there are other numerous data sets in the summary paper that strongly support the presence of IBWOs in Congaree if properly interpreted with plausible explanations.

For example, the final report's explanation of the acoustical detections of double knocks as possible duck wings striking, gunshots or Pileateds are implausible and unacceptable to this researcher. The IBWWG also considered some these skeptical explanations unlikely. More information from the past notes and present field (2022) is needed. 

Also, it is unexplained how the report's authors determined there is "likely no breeding population" in Congaree with the 67 detections in Congaree but substantially less in other large open spaces of SC. "However, we believe it is unlikely that a population of Ivory-billed Woodpeckers persists in Congaree National Park due to the absence of firm results despite persistent search efforts for 3 years."

Congaree has superior IBWO habitat to all those other areas. 

Many ecologists use source-sink population models or equivalent to make conservation decisions. There is not a mention of which, if any, assumptions, methods, formulas, theories, models, etc. were utilized to clarify there is "likely no breeding population" in Congaree National Park. 

Source–sink dynamics uses variation in habitat quality to hypothesis on population dynamics. NBP has ground assessed key IBWO habitat in three states. Congaree is superior to any remaining similar sized area in the SE USA.  The COWASEE Basin (see following map) which includes Congaree NP also has some comparative carrying capacity to any similar ~ 200,000 acre area in the SE USA. 

Ivory-bills are noted repeatedly in the literature as being very wary and quiet around their nests. There is no indication that the SCIBWWG designed its effort tempospatially to find nests or seriously research carrying capacity. There is no basis for the SCIBWWG to have concluded Ivory-bills are likely not breeding in the park; the evidence and source-sink dynamics actually strongly supports the possibility of breeding. Obviously more study is needed.               

The results from SC indicate Ivory-billed presence. Repetition of IB detections in one location has often been denied by individuals and departments to have occurred, but serial Ivory-billed encounters has happened. Sightings, kents, double knocks and single knocks, collectively encounters, have been repeated in various SE USA locations besides the one described here.

In 2022 it again became obvious to a very few that two totally unconnected Ivory-billed search efforts had detected the species at least 3 times in the same localized section of the large park in 2009. A third party, a SC resident (G. DeBusk), hearing of the initial two person sighting report, including an avowed skeptic, hiked towards the sighting location. He viewed an Ivory-bill accompanied closely by a similar bird (probable IB pair) in the same exact area a week after the seminal event. He also found dead wood, insect working, immediate to the location of where the IBWO was first acquired. He considered the excavation highly indicative of Ivory-billed based on his past Congaree research.


In 2009 our team, during 7 days of wilderness camping and workman-like point surveying, heard a kent, a double knock and had an IB sighting. The sighting was punctuated with a subsequent double knock using the specially designed Point Survey method.

These three disparate parties had four IBWO detections with two not following or privy to each other's reports or locations; they were unaware of the others exact location within the park during the respective prior efforts. As mentioned another party, G. DeBusk, followed the fresh IB lead.


In science the more times independent experiments or studies are repeated with the same results, the more likely the conclusion is accurate. In statistics, replication is repetition of an experiment or observation in the same or similar conditions. Replication is important because it adds information about the reliability of the conclusions or identifications drawn from the field observations. The statistical methods that assess that reliability rely on replication.


The probability of the NBP detections being a purposefully attempt to mislead, assuming they occurred within the 2 mile square area that includes the seminal sighting can be examined by inferential statistics as follows:

Notes: All 3 detections were in an ~ 2 square mile area. A 2 square mile area is 1.41 mile by 1.41 mile; this is 1/20 of the 26,000 acre park.


Since all three detections were made in ~ the same 2 square mile area, the chance of correctly or randomly picking the area to agree with the prior sightings to better stage contrived detections would be 20 squared, = 400 to 1.


The three separate 2009 Ivory-billed Woodpecker detections that had no knowledge of each other's search location data are as follows:


Detection 1 2/7/2009 Fran Rametta, a NPS ranger along with Corinne Fenner, we’re leading a guided canoe tour.

Saturday February 7, 2009


1:30pm, sunny, 70 degrees


Corinne Fenner and Fran Rametta were leading a guided canoe tour and spotted a very large, chunky bird. It was dark colored and flitting from tree to tree after flying up from near ground level. As it was flying among tupelo trees, we saw a distinct line of white feathers along the back of both wings. There was a black line along the front of both wings. The bird was silent. This sighting lasted approximately 6 seconds. Please see attached map.
(exact author unknown to author but is not either sighters'). and 

"Fran was a jovial skeptic, so the change into an equally jovial believer was fun to witness." (Hunter, C. FB public comment 6/2022). Fran may be retired now (7/22, Virrazzi). Location - Cedar Creek

Detection 2 10/2009 NBP's permitted team had a three person detection within ~ 1 mile of Detection 1. A loud, agitated kent was heard by the entire team. (See official USFWS IBWO comment letter from E. DeVito below). Formal online reports were given to the required and correct jurisdiction; they are password protected with lead researcher access (Virrazzi). Immediate field notes were made and are as of 7/22 unpublished.

Detection 3 10/2009 A few days after Detection 2, NBP's team was hiking east to a survey point when the author saw a largely white-winged, dark bodied bird the size and shape of an Ivory-billed fly from the assumed base of tree surrounded by water. The bird was only ~ 150 feet away, eye level and no take-off disturbance rings were observed, meaning it was not sitting in the water before flushing. The park's ground is very rough and noisy; our team members are directed to space themselves 20 feet apart when we are hiking from survey point to survey point so researchers can better hear any ambient single knocks (SKs), DKs or IB kents. I was not able to get any team members on the bird or raise my binoculars because of the shortness of time in view and the high basal area in this late seral forest.

The team then did an unplanned, permitted ADK survey point at the spot starting several minutes later and had a response DK from a few hundred yards away within the post ADK designed survey waiting period (20 minutes), (see official USFWS IBWO comment letter from E. DeVito below). Formal, required computer reports were given to the correct jurisdiction; they are password protected with lead investigator access (Virrazzi). Immediate field notes were made and are unpublished as of 7/22.

Related Congaree NP Detections that have some details (there are many detections whose details are unknown to the public):


2007 - NBP an incredibly loud, Single Knock of an IBWO was heard ~ 2.5-3 miles S of Detection 1 in 2009 above.

2007 - Cornell University Mobile Ivory-billed Woodpecker Search Team effort. An Ivory-billed Woodpecker responded with a single double knock (DK) to a mobile team's anthropogenic double knock (ADK).

2008 - NBP Multiple single knocks were heard in an area within 1-1.5 miles of Detections 1-3

2/16/2009 George DeBusk, sighted a pair of Ivory-bills within 150 yards of the Detection 1 sighting location several days earlier; he was searching the park because of it. DeBusk is a highly regarded SC citizen with a formal zoology background. By the time of the sighting, he had been searching for the Ivory-billed in the park several times before.

Based on public information in the SCIBWWG's summary report and knowledge of NBP's and others' efforts, it is estimated that 10,000 total field hours were spent; this is one detection per every 149 field hours. In NBP's extensive experience in the field and reviewing modern literature and postings this is a high detection rate per time effort. NBP had an ~ 100% higher detection rate per field hour in Congaree than CLO efforts with different methods.

In NBP's studies this detection rate per hour for NBP is only exceeded at two other SE USA locations. At both those locations substantial evidence of IBWO presence was eventually made public by various researchers.

In general, the photographic possibilities for capturing an Ivory-bill in the Congaree are significantly reduced compared to most other areas because of the topographic conditions, lack of many canoe navigable waters in the forest, mostly wilderness conditions (few trails, noisy to move), superior canopy of 30 to 40 m, causing darkness, high DBH trees and basal area resulting in a dense mid and upperstory, and more.

Any careful Bayesian statistical analysis of Congaree's 67 IBWO detections will come up with a high probability of one or more IBWOs being present in Congaree from 2006 to 2009. 

We recommend that the USFWS review the extensive evidence presented here and the original detection, sketches and recording in all the other federal and state govt. files before determing IBWO presence. 

Regardless the evidence summated in this article, and NBP's USFWS presentation today does not support the extinction of the IBWO in SC.

Acknowledgements to E. DeVito, T. Haydu, L. Shaw, T. Thom, P. and J. Dubois and others for field survey assistance and support in SC.