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On the off-chance someone may have a sense of this, will toss out a question I once had but then failed to ever pursue:
For his multi-year study of Ivorybills Tanner spent a very few days in a great many locales (in addition to his lengthy time at the Singer Tract), but even when there had been rumors of IBWOs elsewhere he would often emerge pessimistically saying that he saw no foraging work that would be indicative of IBWO presence (let alone seeing or hearing the species), and therefore concluded the species was not present. (because presumably the birds have to eat every day ;))
So I’m wondering how much vigorous ground-searching (in terms of time/hours) Tanner thought was adequate, finding NO IBWO-like work, to reach such a conclusion… 5 hrs? 10 hrs.? 20 hrs. or more? How often was he seeing fresh tree work at the Singer Tract, where he pretty well knew the locations and travels of a few IBWOs? Every day or couple of days? In short, how much time should a modern-day searcher expect to spend in a given locale before seeing potential IBWO foraging IF the birds are there (or, in reverse, after how many hours of searching should one be discouraged if encountering NO such foraging evidence?). Granted it will depend somewhat on the size and habitat of the locale, but nonetheless Tanner dismissed fairly quickly some rather large areas.
Perhaps those too who took part in the larger-scale Big Woods and Choctawhatchee searches could say/guesstimate how often interesting bark-scaling was being seen in those studies?
If you have an answer, or at least a thought, feel free to write in "comments" below or send directly via email (if you don't wish to appear in 'comments').
p.s.... will just add that even if Tanner had a strong notion of how many hours spent in an area seeing no physical evidence of IBWOs were adequate to conclude they weren't present, it doesn't mean he was right!
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7 comments:
Won’t go into details (and haven’t heard from anyone else) but my own rough back-of-the-envelope estimate is that Tanner would’ve found 25 hours of ground searching, without seeing possible IBWO work, adequate to rule out their presence — an adjacent, as yet unsearched area, might still harbor the species, but the area being actively searched likely could be ruled out… with the cautionary proviso that the birds (strong flyers) might forage in areas completely separate from where they actually roosted/bred.
I believe the time of year is a very important factor in answering your question. I have located a very significant number of scaled trees in one of my search sites. During winter when the leaves are off such scaled trees stand out since the scaled trunks and limbs are white in a dark winter woods background. Depending upon the size of area searched one could cover quite a bit of ground over the course of a few days. Assuming you are searching the best looking or prime part of the forest one could avaluate it pretty quickly. Tanner leaned upon local guides to take him to those best locations, descibing to them what type of areas he was seeking. I am not a Tanner expert and am a searcher still learning. But based upon what I have found, which matches very closely the trees Tanner described and the one photo I am aware of, these types of trees are best located in mid to late winter. Leaves obstruct ones view later in the year and the birds may be feeding significantly upon grown insects or vegetable material. One thing I am curious about is whether Tanner only limited himself to areas with significant presence of Sweetgums and rejected other forest types such as Pines or hardwoods lacking significant numbers of Sweetgums. If large Sweetgum trees presence was a requirement I can see him rejecting certain locations very quickly and out of hand. I consider that to have been a mistake if so.
Tanner could have learned a lot from the dozens of searchers who can't even get a single photo of the bird.
It is still to be seen whether the scaled trees I have found are due to work of IWBO. All I know is that they match the description. And I know how I located them. See Allan and Kellogg's paper about Ivory-bills feeding on young pines. I do not believe one should limit one's search locations to only those with large Sweetgums when evidence indicates maybe more variability. Whether Tanner did that or not I don't know.
One additional bit of information so there is no confusion.... The scaled trees I have located are mostly Hickories still retaining small limbs and twigs and a few still having leaves from the previous growing season.
Hey Scott, while Tanner was very favorable toward sweetgums for IBWO I don’t think he considered them a “requirement” (for example he referenced the predominance of cypress in some Florida habitat)… he more clearly thought pines unfavorable, but did still stress “variability” in potential IBWO habitat.
As you likely know things to look for with any scaling you find include the tightness of the bark, possible ‘chisel’-like beak-marks, and possible tunnels of borer-beetles (and hey, always look for any discarded feathers at base of such a tree!). I’d be curious as to where on the trees you are mostly seeing scaling, high, low, middle or all over?
Hello Cyberthrush. Most of the Hickory trees I have located have very tight bark. I have photographed some of the chisel marks with a small ruler for reference. The trees have multitudes of bore holes. I have photographed the beetle larvae under the bark. I use GIS/GPS with ESRI Field maps I have created for use in the search. Last year at one of my sites I mapped via this technology 16 scaled trees at the end of April and in May. A number were other species than Hickory and scaled a small amount. But many were Hickory trees scaled from around chest high on the trunk up into the upper limbs of the trees. Some trees almost denuded of all bark. One particular tree still had green leaves but a significant amount of scaling (more about this tree later). In later trips I noticed what I thought were older dead trees which had been scaled the previous year(s). It appeared that the trees in this location were being utilized over several years. So it was my hope to find actively scaled trees this winter and set up trail cams to surveil them. Last Saturday (2/10/2024) I located an additional 6 trees. One was a very impressively scaled Hickory with probably half of it's bark removed and piled at the base. While there were small pieces of bark there in the 2 or 3 inch range, there were also many in the 6 inch plus range. This was very thick bark and tightly held to the tree. 165 feet away was another large tall Hickory which appeared to be at the beginning stages of being scaled. Last Saturday I had set up a trail cam on the impressively scaled tree I just described and one on the tree I found last year which still had leaves. It had recently scaling and the tree was being once more worked. All of the trees I found last year at the end of April were not scaled anymore that spring and summer. They appeared to only be worked during the winter and then what ever did it moved on. The area I have found these trees (so far) is approximately 1 mile wide by 1/3 mile deep. It is somewhat consistent with the maps Tanner created to illustrate the nest/roost holes and feeding sites he found in the Singer Tract. Whether this is the work of an Ivory-billed Woodpecker is still to be seen. Hopefully I will soon have some identification of what is doing the scaling. Part of the reason I put in my first comment and have written what I have is to maybe help other searchers. If what I have found is Ivory-billed Woodpecker work then the time is now for searchers to be in the woods seeking out extensively scaled trees, because now is the best time to locate them. When you find one then search for more in the immediate area. Look for similar but older trees in the area to indicate it has been a feeding area in the past. Cyberthrush, I have posted photos and descriptions on one of the Ivory-bill searcher Facebook groups. It is a private group and not available to the public. If you want to join it and are approved to do so (I am just a member and am not involved in the approval process) then you can take a look at what I have posted and decide for yourself if it is of any value. Let me know and I can provide you with the name of the Facebook group.
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