Advertisements

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 . . .

Advertisements

Black Woodpecker (Dryocopus martius) Foraging Behavior: More Support for an IBWO Diagnostic?

I’ll be returning to Louisiana in late February and hope to make a couple of more trips during peak search season. Frank has retrieved the cards from our game cams and is in the process of going through several weeks of images. In contrast to the last set, there have been no intriguing hits thus far.

Last month, I came across a very interesting post on the Woodpeckers of the World Facebook group. The link took me to a French website that features some videos of the Black Woodpecker (Dryocopus martius), a Eurasian species, and one of the largest woodpeckers in the world, surpassing the Magellanic in size. In another analogy to the Magellanic, the Black Woodpecker appears to have certain features that are more Campephilus-like than others in genus Dryocopus. This includes flight style; acording to Gerard Gorman’s monograph on the species, Black Woodpeckers don’t generally undulate in flight. More importantly, the size and appearance of the bill certainly evoke the IBWO – generally larger, thicker, and heavier than a Pileated’s. Bill length can reach over 70 mm (although the average is 53-56 mm). According to Tanner, the mean length for ivorybills ranged from 67.8 mm to 74.1 mm depending on sex and region.

For my purposes, this is the most interesting clip. It’s an outstanding sequence that shows a Black Woodpecker scaling bark from a medium-sized hardwood branch. I see the following aspects as being significant and supportive of the hypothesis on feeding sign I’ve discussed in several posts, including here, here, here, here, and here.

For the most part, the bird is removing bark with direct strikes, not the lateral blows of a Campephilus woodpecker. This is possible because the limb is relatively thin, and the bird is able to position herself so that direct strikes will have the same effect that a more lateral blow would have on the bole; she generally engages in lateral movements to flick away bark after it has been loosened. The clip also seems significant insofar as it reveals the amount of effort involved to remove large but very thin strips of bark. In addition, even though the bark is thin, it seems the bird is still removing it in layers, at least some of the time. I think the video tends to support my idea that the work we think is diagnostic – on boles with thick tight bark – is beyond what PIWOs can do physically. At the same time, the footage suggests that the high branch work that Tanner emphasized is likely within the capacity of a Pileated Woodpecker and is indeterminate as we suspect.

In looking at images of Black Woodpecker foraging sign online, it appears that – bill structure notwithstanding – they typically remove bark in layers, just as Pileated Woodpeckers do, and this is true on both hardwoods and softwoods. I have been unable to find any examples of Black Woodpecker work that closely resemble what we think is diagnostic for ivorybill, but examples of the layered scaling are easy to find, for example:

Here

Here

Here

Here

Here

And here.


The Pros and Cons of Trail Cams

Frank wrote this up and asked me to post it.

Recently, we’ve received several messages, and another blogger has mentioned the use of game cameras – also referred to as trail cams, or camera traps – as aids in searching for Ivory-billed Woodpeckers. We’ve been deploying trail cams since early 2009, and have had some intriguing “hits”. They have been useful in many ways, and we have learned a lot about the feeding habits of other woodpeckers – specifically, Pileated, Hairy, and Red-bellied – that were useful in giving Mark insights into the type of feeding sign that we have come to believe is most likely diagnostic for ivorybills. In dozens of deployments, and hundreds of hours of searching with boots on the ground, and sometimes in the water, we have NEVER observed a woodpecker performing the type of scaling that we have come to suspect is diagnostic.

While trail cams are a valuable tool in our arsenal, they are, by no means infallible. There are many pitfalls involved in their use. Firstly, they are not designed to capture birds – in fact many common species of birds are almost unidentifiable in the images. Birds do not set off the motion triggers that these cameras use, and why should they? The cameras are designed for use along trails and adjacent to food plots used by larger mammals – usually whitetail deer. I have tested the Reconyx “Hyperfire” cameras that we use, and even a large Wild Turkey at fairly close range will not trigger one, even at its most sensitive setting, while a relatively small (terrier size) dog will trigger one from a distance of twenty-five or more yards. The manufacturer has indicated to me that there is “something about the way birds reflect light in the visible and infrared spectrum” that makes the cameras’ triggering units unable to “see” them.

As a result, ivorybill hunters must find a camera that will operate in time lapse mode. For all their disadvantages (3.1 megapixels, low resolution among them) the Reconyx cameras offer the best time lapse mode available at an affordable price. This, in and of itself, though, becomes a handicap, as the card for each camera must be programmed, using a proprietary program provided by Reconyx, on a PC. One programs the card, inserts it into the camera, and hopes for the best – there is no way to check and see if the card/camera combination is functioning properly. This has led to many wasted deployments. Additionally, there is the problem of how often should the camera take a photo vs. storage capacity of the card. The cams are designed for 8 gig cards, sometimes they will function with a 16 gig card, but will universally malfunction with a 32 gig card. 8 gigs is usually enough for a ten-day deployment with the camera time constrained to take a photo every twenty seconds for ten hours a day – you do get to select the hours of operation though. While every twenty seconds would seem to be quite often (and a full 8 gig card will store upwards of thirty thousand images), perform a little test for yourself. Go out to your favorite birdwatching location and see how long a bird – any arboreal non-raptor species – stays in one location for twenty or more seconds. Captures of birds on game cams are a relatively rare event – I have looked at nearly a million Reconyx photographs and have picked up birds of any kind in perhaps a thousand images – identifiable birds in maybe two hundred.

The very first thing that has to be done when using game cams is to select a location where you suspect an ivorybill is likely to show up. This could be a tree with scaled bark and other indications that an ivorybill has visited it, or a cavity with features that seem to match photographs of known ivorybill cavities. Both of these are, at best, iffy propositions. One has to find the tree, geotag it (you do have a good GPS unit, right?) then return to the location – often several miles of hiking through some pretty rough and secluded forest, carrying the camera and its mounting system – which weighs around ten pounds. Then the camera and mount have to be positioned to get the target near the center of the frame, which gets easier with practice, and the camera and mount hidden and intervening vegetation trimmed so as not to interfere with the line-of-sight. Once all this has been done the camera can be turned on, armed, and left to do its thing.

Assuming that everything up to this point has been done perfectly, in ten days or so, it’s time to change cards, or retrieve the cam. Now one is faced with the daunting prospect of going through some thirty-thousand photos looking for anything “interesting”. Often, several days of images will pass without a single “hit” of any kind. It’s often a relief to spot even a small woodpecker or squirrel, to remind one that the target is part of a living ecosystem.

The series shown here is exceptional in terms of quantity of images, quality, and our ability to place the camera. (It may be significant for what it doesn’t show, a Pileated doing the type of scaling we think is diagnostic.) Even so, it was not possible to cover the entire target tree.

As I stated earlier, these cameras, within their limitations, are useful tools, but for my money, nothing really beats the good old MK I MOD I human eyeball. But at this point, that’s just not enough …

In addition to the suggestive photos we’ve already posted, we recently obtained some pictures at the site where last week’s double knock was recorded. Because we find some of these pictures intriguing but inconclusive, we have deployed two cameras in hopes that the double placement will yield an identifiable photograph. The first picture, taken under good lighting conditions, clearly shows a Red-headed Woodpecker (there is a roost at the very top of the snag); the others are ambiguous. We are posting them unedited and leave it to you to speculate about what they may be. We recognize that none of these are of anywhere near good enough quality to be identifiable as ivorybills, but we are doing some further analysis to get a clearer sense of scale. The camera placement is 85’ from the tree; the branches behind the tree are an additional 15” away. My preliminary estimate of the diameter of the tree just above the jug handle on the right is approximately 18”.

I have taken careful measurements using a camera with known lens settings and a rangefinder – when the weather is more congenial, I will make comparison shots at the exact measured ranges. This should give a margin of error of ~1″ or less.

IMG_7153

IMG_4142 IMG_4195 IMG_4313 IMG_4399
IMG_7926 IMG_7927


Trip Report – December 26, 2014-January 3, 2015

Weather conditions were poor for a good part of this trip, but we did the best we could under the circumstances.

I flew from New York to Louisiana on Christmas Day. During a layover in Dallas, I was uninterested in the food offerings in the terminal from which my puddle-jumper flight was slated to depart. I hopped on the tram to the international terminal and found a place to have lunch. There was a young guy sitting at the table next to mine, and we started talking while waiting for our checks. It turns out he grew up within 15 miles of our search area and thinks he saw an IBWO while hunting near his childhood home about ten years ago. I did not press him for details, but it was clear from the conversation that he knows Pileated Woodpeckers; I was also confident that he was sincere. Leaving the coincidence aside, it’s astonishing how many people in this part of Louisiana claim to have seen IBWOs in hardwood bottoms.

During this trip, we also encountered a couple of duck hunters who were already aware of our search. One of them said, “If I saw one, I wouldn’t tell anybody,” which is considerably less worrisome than what I’ve heard people say in other places. The big concern for most is that finding IBWOs means the end of hunting in the area. We assured him that would not be the case. The thing for searchers to stress in this context is that success will mean that more forest is protected.

On Friday, December 26th, Frank Wiley and I went to the northernmost sector, traversed a swath of tornado blowdown, and went to the site of our game cam. There is nothing of great significance to report from that day, except finding the somewhat unusual excavation discussed in this post.  There is a good deal of old suggestive feeding sign in this area, but we found nothing fresh.

We returned to the same location on Saturday and aimed two Reconyx cameras at the target tree that will be shown and discussed in an upcoming post that Frank is writing and will complete when he recovers from the flu. We hope that having two cameras in one location, with different orientations and shooting cycles, will yield better results than deploying just one.

At a little after noon, Frank heard a single knock coming from the blowdown. It was followed by calling from a Barred Owl, a Pileated Woodpecker, and a Red-shouldered Hawk. On the full recording of the ensuing events, I can be heard saying “I thought I heard a knock out that way.” I had forgotten about this until I listened to the recording. Weak possibles are so frequent in our search area that I tend to dismiss them. The knock I heard must have come from the blowdown as well, since I pointed my camera in that direction. Frank did a double knock, and I recorded the “response” discussed in my December 27th post.

We left the swamp ahead of the rain on the 27th, and it rained heavily through the 28th. On the 29th, we were joined by several biologists and divided into two groups. I tried to take my group to the area where I recorded possible ivorybill calls in March 2012, but water levels were too high to do much, so we went to explore some new territory to the northeast. A map of the logging history suggested that some of these woods would be very impressive, but in comparison to some of the other patches, we did not find this to be the case. There is a large area of blowdown that merits further attention, and we know the habitat south of the blowdown to be outstanding; there was a good concentration of old feeding sign near the edges of the blowdown. There are several other bottomland areas in the northern and northeastern sectors that we haven’t visited yet and that appear not to have been logged since the early 20th century (1905, 1910, and 1916).

Frank took the other group into an area that has been surveyed a little more. One member of his team heard a weak possible double knock.

On the 30th, the weather was cloudy, windy, and cold. We took our three remaining guests to the site of the game cams to give them a sense of the scale and the context for some of the images to be discussed in Frank’s post. The general view was that the blowdown might be an important area. We hiked out at a little after 1 pm, and two of our guests departed. We took our remaining guest to the easternmost sector, a narrow corridor of mature bottomland hardwoods around a smaller stream. This area has had concentrations of fresh scaling in past years. At around 3:30 pm, after doing an ADK series, Frank heard two double knocks a couple of minutes apart. Neither our guest nor I heard them, but approximately two minutes later, we both heard a distinct DK that Frank missed. We disagreed about direction but both thought it was more consistent with typical Campephilus double knocks than the one I recorded on the 27th, with a shorter intra-knock interval and a softer second knock. We had no doubt that it was a double knock on a woody substrate.

On the 31st, Frank and I explored a mostly unvisited area, to the south of what Frank calls “Jurassic Park”. This is one of the widest swathes of bottomland hardwoods in the area, and it is very impressive; there are many patches of open canopy forest, with massive superdominant oaks and sweet gums like this one, which has a DBH of 4’2”.

Frank Wiley with massive sweet gum

Frank Wiley with massive sweet gum

We’ve only scratched the surface in this very large sector (which includes Jurassic Park) that our history suggests was last logged in 1908.

There was abundant scaling scattered throughout, mostly old, with one sweet gum (?) showing a large area of fresh work fairly high up.

Old scaling with large exit tunnels

Old scaling with large exit tunnels

Recent scaling that is intriguing but does not quite meet our diagnostic criteria because it shows some signs of layering and has a couple of small foraging pits

Recent scaling that is intriguing but does not quite meet our diagnostic criteria because it shows some signs of layering and has a couple of small foraging pits

While this fresh scaling does not quite match the criteria for what we think is diagnostic, since it shows some signs of layered working and has a couple of small foraging pits, it is still quite extensive, and at least from a distance, the limb appeared to be live or very recently dead. Some large exit tunnels are visible on close examination.

Also, while in this sector, we did an extended playback of the Singer Tract recordings. The playbacks did not generate any suggestive sounds, but several American Crows and two Red-Shouldered Hawks came in to investigate. The crows called, but the hawks did not vocalize. We don’t know whether the response of other birds to ivorybill sounds or imitations thereof is an indication of presence, but we are intrigued by it. It happens frequently in our area. Red-shouldered Hawks, in particular, react strongly to double knocks.

Weather was a severe problem on this trip, preventing us from going into the field on December 27th, January 1st, 2nd, and 3rd. On the 2nd I made a brief visit to the area described by the man I met in the Dallas airport. I was reluctant to go off the main gravel roads in my small, 2-wheel drive rental, and there was no obvious public access to the narrow stream bottom. I drove through a recent clearcut of about 40 acres. This looked to have been a stand of mature hardwoods. There is some measure of connectivity with our search area, and there are numerous smaller riparian corridors in the region. If birds are breeding in this part of Louisiana, there are ample possibilities for movement and dispersal through habitat that is not quite as impressive.