Trip Report, March 5-17, 2019

The following trip report is mostly extracted from a post for members of the search team.

I was in the field from March 5-17; others were around before and after. Thanks to the whole team and a couple of guests for their hard work and contributions in the field this trip. We completed the swap out of recording devices in three days, which left a lot of field time afterwards. We were very fortunate in that only one unit was tampered with and only a couple malfunctioned. This is a very low rate of loss for these units.

We continue to have possible encounters in the area, perhaps at a higher rate than in past seasons, though the number of potential observers and time spent in the area has increased this year. And we have gotten some very preliminary results from the first round of deployments.

In addition to the audio deployments, we’re focused on obtaining DNA this season and have been refining the protocol for doing so. On this trip we collected samples from a couple of different forms of feeding sign, one I think is more promising than the other.

Here’s the basic protocol: collect a small quantity of material from places where a woodpecker’s tongue may have been; place it in a vial containing buffer and seal. With luck, genetic material can be obtained from these surfaces, and we can rule in or rule out ivorybill as the source of some kinds of feeding sign.

We also plan to collect samples from the most promising cavities. And are evaluating them following Cornell’s criteria. Cavities are graded:

A: very large cavity in size range of IBWO with irregular oval or rectangular shape (4.0–4.75in [10.2–12.1cm] wide and 5.0– 5.75in [12.7–14.6cm] tall);

B:  cavity larger than typical PIWO cavity but shape is fairly regular, nearly perfect round or oval; or, cavity of irregular shape and within upper size range for PIWO, and lower size range for IBWO (3.5in x 3.7in or [8.8cm x 9.5cm] large PIWO and 4.0in x 5.0in [10.1cm x 12.8cm] small IBWO);

C:  cavity of fairly regular shape, nearly perfect oval or round, in the upper size range for PIWO and lower size range for IBWO. Same dimensions as for B.

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Ivory-billed Woodpecker Cavity (1935 Nest)
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Typical Pileated Woodpecker Cavity

Here are some promising cavities (I’d grade all of them A or high B) I found last trip, plus some we know are being used by other species. I found more cavities this trip than I ever have in the past, mostly because I was paying attention. There’ll be some explanation in the captions. The truth is, no one really knows about cavities; I’ve seen a lot of variation in what PIWOs do; so a lot of this is speculation. I do think scaling or suggestive feeding sign on a tree with a cavity in it may be an indicator, including that the cavity is a former nest.

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Promising cavity, apparently recent

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Promising cavity with a little fresh scaling; however, there were Wood Ducks perched in this tree, which suggests that it may no longer be active.

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Cavities are harder to spot after leaf out. This one looks fairly fresh.

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Older large cavity in cypress stub.

It can be a tough call. The first pair of cavities shown below is being used (and was likely excavated by) Red-bellied Woodpeckers. The size is deceptively large, but the small diameter of the high limb is an indicator.

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The intriguing cavity below was being used as a PIWO roost but would probably have been graded A for its large size and irregular shape. There’s a second, possibly connected, cavity slightly higher and to the the left. Both are oddly shaped. The snag is severely decayed. But again, we have very limited information, so there’s no way to know whether IBWOs might avoid badly decayed snags.

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Regarding feeding sign, extensive scaling on boles, especially of mature trees with tight bark, seems likeliest for Ivory-billed Woodpecker work. Hickories are the highest priority within this category, and we have only found a few such trees over the years. Extensively scaled sweet gums, like the one shown, are worth noting too. A second category, involving smaller sweet gums and branches, is also intriguing. Ambrosia beetles are the prey species involved in this work, which involves extensive stripping and targeted digs into the insect chambers.

In all cases, it’s important to distinguish scaling from shallow excavation with associated bark removal.

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Suspected IBWO hickory chips

The appearance of this work is distinctive. The bark is removed cleanly, and there’s almost no damage to the underlying wood, except for expansion of the exit tunnels on the surface. We hope that DNA can be extracted from these tunnels and that the scaling shown in the first image is fresh enough to be a good candidate. Based on the life-cycle of the beetles involved, I suspect this work is likelier to be found in the latter part of spring and through summer, but keep your eyes open anyway.

We’re finding that Pileateds also feed on hickories and begin by removing bark. They go about it in a different way, however, excavating through the bark and into the sapwood. The appearance of Pileated work on hickories is similar but somewhat different. It tends to be patchier, without less extensive and contiguous bark removal. The chips are smaller, a mix of bark and sapwood, and the appearance of the wood in the areas where bark has been removed is distinctly different, as in the images below.

Extensive scaling on boles of other species is also noteworthy and may have DNA collection potential. There’s more room for overlap between what IBWO and what PIWO might be able to do, since the properties of hickory bark are unique. Look for extensiveness, large to enormous chips, and lack of damage to the underlying wood.

The final category involves sweet gum saplings and small to medium-sized limbs. I have found this distinctive appearing work in only two years, in a small cluster in 2015 and in a single example this season. The bark is extensively, indeed almost entirely, stripped. Chips on the ground should be large. Leaves should be still attached. The beetles’ brood chambers should have been vigorously attacked, and you may see superficial horizontal scratches in the sapwood (not the deeper grooves that used to be mistakenly ascribed to IBWO).

This was a longer trip than usual, and I was wiped out when I got home. We will be returning at the end of April to collect the units. This will mark the end of the deployments for this season, though we will continue to work with the trail cams, with a couple transferred to new locations. I’m hoping to have a guest post from a team member before the next trip.

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