Trip Report: February 5-11, 2016 and More on the Singer TractPosted: February 20, 2016
I flew into Houston on February 4 and arrived at the search area on the morning of the 5th. Frank’s work schedule had precluded him from returning to the search area during my absence, and he was unable to get time off to join me this trip.
Tommy Michot visited on the February 5th; we went to the northern sector, and passed the downed sweet gum top (actually a limb) found in April of last year. Project Coyote had a camera trained on it for some time but took it down due to equipment failure. The main stem, which reaches from the ground to about 20 feet up, had been scaled extensively, down to the base, over the course of the last month. Some of the work had been done no more than a few days prior to my arrival based on the condition of bark chips found at the base.
We have a camera back on this top but have low expectations, since so much bark has been removed that it makes a much easier target for other species of woodpecker. While I don’t believe in the “curse of the ivorybill”, individuals and small groups of self-funded searchers face enormous obstacles and are dependent on equipment that’s often unreliable.
Tommy and I measured a number of the largest trees in the area, and the biggest oaks and sweet gums are around 4’ DBH, with many more in the 3’ range. Here are some of the highlights: two Nuttall oaks: 137 cm/53.94”, 119 cm/46.85″; swamp chestnut oak 110 cm/43.31” four sweet gums: 124 cm/48.82”, 123 cm/48.43”, 110 cm/43.31″, 109 cm/42.91”.
While ours was not a random sample, this table from a 1986 paper by Tanner (on data collected in the Singer Tract in 1938), is interesting for the sake of comparison.
In his 1944 report on the Singer Tract, Richard Pough described sweet gums in the 5’-6’ DBH range as being characteristic of old growth conditions, and such trees were not uncommon in the 19th century. Impressionistically, at least, most of the ~4’ DBH sweet gums in our area are moribund and are likely to have lost their tops. I know of only one gum that appears to be in the 5′ DBH category. As of 2009, the national champion sweet gum had a DBH of 5’4.6″. The tree below could be close to that.
Many, perhaps most, gums have at least some beaver damage. This may be contributing to the earlier mortality, both by stressing the trees directly and by creating the opportunity for beetles to infest them. I have long suspected that the decline of the beaver could have contributed to the IBWO’s disappearance, since beavers directly damage trees by gnawing and also stress or kill them by altering hydrology.
Beavers were extirpated from much of Louisiana by the early 19th century. As of 1931, populations were restricted to the Amite and Comite rivers in the southeastern corner of the state; they were reintroduced in other areas in 1938 and had established themselves in 21 parishes as of 1951. (Wylie Barrow, pers. comm.) Range expansion continued into the 1990s and after. They’re now considered a pest animal and appear to be found in all parishes. A recent paper suggests that the introduction of beavers into Magellanic Woodpecker habitat may have benefitted that species.
I was on my own on February 6th, and I went and staked out the downed top for the better part of the morning. Nothing landed on it except for a Red-bellied Woodpecker that pecked and gleaned but did not scale bark or do any excavating. At approximately 9:30, I did a very aggressive series of ADKs. I heard a couple of loud single knocks that seemed to come from no more than a couple of hundred yards away and also a possible double knock. These came during a period when I was standing, moving around, and doing the ADKs, so I did not hear them very well. In addition, there were a few distant gunshots within about 15 minutes after the series, so I’m not very confident about what I heard. (These were the only shots heard all day.) I found some scaling the next day a couple of hundred yards away (discussed below). This gives me some reason to think the SKs were a reaction, not shots. Still I’d place these in the weak possible category.
One highlight of the day was watching a pair of Red-shouldered Hawks in the act of mating.
I returned to the same area on the 7th, with two cameras to deploy. One is aimed at a large sweet gum stub, about 20’ tall and well over 3’ DBH that I found last trip. The top had broken off shortly before my arrival. While it’s not discussed in Tanner, T. Gilbert Pearson, who was the first modern ornithologist to observe the Singer Tract IBWOs, described this type of “stump” as one of the species’ preferred feeding sites. This is a tree on which I found high branch scaling last year, before the top broke off. I expect this to be a long-term deployment.
I also redeployed a camera on the downed top, although we’re not very hopeful about that location, since the scaling is so extensive and the bark has been loosened in many of the remaining unscaled areas.
I walked south for a couple of hundred yards and found very fresh, large bark chips at the foot of a live sweet gum (there were two large gums ~3’ dbh about 10’ apart). There was extensive scaling on live or recently dead high branches of one or both of these trees. Because there had been a major rainstorm and accompanying minor flooding a week before and the chips were mud free, I can be sure the scaling took place after the rain, and since Tommy and I had spent considerable time in the area examining some other nearby scaling two days before, I strongly suspect this work was done on the 6th. I can’t help but wonder whether the possible single knocks came from whatever was doing the scaling; that would be consistent with my immediate impression when I heard them, both in terms of distance and direction. Nonetheless, my confidence level about the SKs is low given the gunfire.
I don’t think the scaling and bark chips are consistent with squirrel; the chips are large and thick and do not show signs of having been chewed off; the ones collected weighed over five pounds.
There was a little excavation and exit tunnel expansion (visible in the first image above) associated with the scaling; and it has the generally clean edges and lack of layered, flaked off appearance around the edges or on the chips. The leaves and gumballs are attached on most of the limbs, indicating that they’re alive or very, very recently dead, so the bark is almost certainly tight. This is about as good as it gets when up-close examination is not an option
I met Tom Foti, who came in from Arkansas, on the morning of the 8th. Winds were high, with gusts approaching 50 mph. We decided it would be unsafe to venture into the woods, so we drove around the edges of the search area looking at the surrounding upland forest, much of which is impressive and mature. Tom is very enthusiastic about the area, ivorybills or not, and we’re hopeful that steps will be taken to protect and manage it appropriately. The car ride was a running lesson on southern forest ecosystems, and as I told Tom, I’ll count myself lucky if I retain 10% of what I learned.
The next morning, the winds had dropped enough to make it safe to head for the swamps, and Tom and I visited the southern sector, an area where we haven’t spent much time lately. As mentioned in some previous posts, there has been a significant uptick in four-wheeler activity in the area, and it’s heartbreaking to see the destruction these callous individuals are causing. Fortunately, the damage is almost entirely limited to the periphery, and the deeper parts of the bottom are unscathed. The habitat types here are somewhat different, and the logging date is more recent, but it remains very impressive. We walked a long way and went to places I had never been, including a lower-lying flat with tree species I haven’t noticed elsewhere – shagbark hickory, bitter pecan, and overcup oak.
We saw no recent feeding sign in any of these areas, except for some older work on a small sweet gum that I described as being about a grade B-.
We then looped back along a different track, passing the spot where I recorded calls in March of 2013 and where we’d had a concentration of feeding sign in 2012 and 2013. We found nothing until we reached a location farther north that is within 100-200 yards of the tree shown on the homepage. Tom spotted a group of trees with bark scaling, some on boles and some on branches. Once again, this was not “grade A” work, but the concentration makes it more interesting than if it were one isolated example. We did not find any chips at the base of the snag that had been scaled on the bole, and the high branch work is not as extensive some.
It’s worth pointing out that on many days, I’ll walk for hours and see nothing and then find either a dramatic example of scaling or a small cluster of it. Tom and I had probably walked 3.5 miles or more before finding this little cluster.
I was on my own again on the 9th, and I opted to go on a death march to retrieve a trail cam from a tree deep in the swamp and proceed north from there. The tree is a large blown down sweetgum discussed and shown here. There was some fresh scaling on it that I suspect was done by a Pileated Woodpecker. There are nearly six weeks of images to go through, so it will take some time before we find out if there were any captures.
As on the previous day, I walked for a couple of hours without seeing or hearing anything suggestive until I got to a part of the area we haven’t visited since last year, perhaps a quarter mile south of the southernmost point Tommy and I had reached earlier in the week. I found old sign, some of which was fresh last winter and some of which was older. I then found some fresh work on two trees in close proximity to one another. Some of the scaling was on a downed tree but was clearly done by a woodpecker, with chips and other characteristics that I consider to be suggestive. Since the chips were caked with mud, the scaling was a little over a week old. The other work was on one high branch, but conditions made it impossible to look for chips.
On the return hike, I found what I’m quite sure is Pileated Woodpecker work on a recently dead or dying hickory. Since we’ve found a number of hickories that we suspect have been scaled by Ivory-billed Woodpeckers, this was an unusual opportunity to do a direct comparison. In my view the work on hickories is the most compelling for ivorybill due to the density and tightness of the bark and the hardness of the wood. There are pronounced differences in the presumed Pileated and suspected ivorybill work on this species.
The work on the homepage is suspected ivorybill. It is extensive, with huge contiguous areas, perhaps 20% of the entire surface, completely stripped, with evidence of bill strikes targeted at exit tunnels. The Pileated work is spotty by comparison. The bark chunks scaled from the tree on the homepage were large, dense, and thick, and there were no pieces of sapwood among them. By contrast, the suspected Pileated work involves very small pieces of bark that appear to have been removed by digging rather than scaling; there were also a few pieces of punky wood among the chips.
The next morning, I drove to the Wetlands and Aquatic Research Center (formerly the National Wetlands Research Center) in Lafayette and met with Wylie Barrow, Heather Baldwin, Tommy Michot, and Philip and Eric Vanbergen. (Two young enthusiasts who will be helping us out.) Frank joined us briefly, and then Wylie, Tommy, the Vanbergens, and I went out to lunch. It was an exciting and thought-provoking day, and the Research Center is an incredible facility. Wylie and Heather shared their comprehensive and in-depth analysis of conditions in the Singer Tract in Tanner’s day. They’ve amassed an array of materials encompassing land records, Civil War era maps, and stereographic aerial photographs. Their research far surpasses my own speculative effort. It covers the finest details – roads, improved and unimproved, snag densities, tree mortality, conditions around roost and nest sites, as well as conditions in other locations where ivorybills were seen. Tom Foti has done complementary research on hydrology, soils, and vegetation.
Their presentation convinced me that I’ve been too hard on Tanner in some respects. There was a little more old growth in the Singer Tract than I had inferred from the Pough report and some of the historical documents. Nonetheless, the characterization of the Tract as a whole as “virgin” forest is somewhat misleading, since over a quarter of it was second growth, and some of it fairly young. Heather and Wylie have graciously given me permission to summarize some of their findings.
When Tanner began his study, 72% of the Singer Tract was old growth. (Tanner estimated it at over 80%.) Logging in 1938 reduced that percentage to 67%. The ridges, which Tanner deemed to be the best ivorybill habitat, were actually the least likely areas to be old growth. (Tom Foti’s analysis also points to a preference for higher, drier locations.) The regrowth percentages for each landform in Tanner’s day are as follows:
Low ridge (23%)
Total on ridges (32%)
Low flat (4%)
Cypress brake (4.5%)
For the most part, the second growth forests were not particularly old, as has been suggested in previous posts. According to Heather, most of these areas only started to regrow in the 1880s and 1890s, “due to consecutive depressions and low cotton prices”. Thus, parts of the Singer Tract were relatively young second growth, and this included one of the ivorybill home ranges and one that Tanner deemed to be “best” – Mack’s Bayou.
The nature of the habitat in the Mack’s Bayou area is immediately apparent from the 1938 aerial photos, which suggest forest conditions that are present in many parts of Louisiana today. Nevertheless, Ivory-billed Woodpeckers nested there in 1934 and 1935, at minimum, and did so successfully at least once. This fact alone refutes the idea that Ivory-billed Woodpeckers are old growth dependent. Heather informs me that there was an abundance of dead and dying trees on the eastern side of the Mack’s Bayou range, due to a fire caused by logging activities. In any event, the home range Tanner delineated in this primarily second growth area is no larger than the home range he delineated around John’s Bayou, which had more mature forest. In fact, the area he designated as “best” for ivorybills around Mack’s Bayou was slightly smaller than its older equivalent near John’s Bayou.
Tanner knew that a significant portion of the Mack’s Bayou home range was not old growth, since his 1941 map shows “old fields” in the heart of it. He seems to have been unaware of the resurgence of cotton growing during the 1870s and 1880s, so he may have overestimated the age of the forest on that basis. I can’t help but wonder if he glossed over the conditions in the Mack’s Bayou range in part for the sake of protecting the Singer Tract and (as Heather suggested) in part based on what he deemed to be best for the birds from a conservation standpoint, an approach that later ossified into a categorical set of beliefs about old-growth dependence.
As I and others have been arguing for years, extensive forest cover, sufficient dead and dying wood, and enough large trees for roosting and nesting are probably the main requirements, even if old growth or near-old growth conditions are optimal.
I plan to return to the search area in late March and have another post or two in mind in the interim.