Feeding sign and cavities are Pileated Woodpecker until proven otherwise, as team member Bill Summerour frequently reminds us. Until comparative studies can be conducted, we are not convinced that one can look at either and say with any certainty that the causative agent was an ivorybill. But some feeding sign and cavities certainly are more suggestive of ivorybill than others. The dead spruce pine cavity tree featured in our October 7 post finally fell, shattering into many pieces and making reconstruction of internal cavity dimensions impossible. The weathered exterior held together better than the rotten interior, allowing for three pieces to be reassembled to allow a close look at the cavities that had been about 30 and 35 feet high. Vertical diameter of the top cavity (above) is 11.5 cm (4.5 inches) and width is 12 cm (4.7 inches). The lower cavity is slightly smaller.
These large woodpecker cavities have no evidence of gnawing by squirrels or other mammals. Although some loss of wood around the rim to wear and weathering may have occurred, both appear to have been chiseled at (or very near) this size. The maximum reported width for nest cavity entrance holes of Pileated Woodpeckers is 9 cm (Bull and Jackson 1995), so this cavity exceeds that by a full inch. Tanner reported the horizontal dimensions of Ivory-billed Woodpecker cavities to be 10.2 cm and wider. Maximum pileated cavity vertical dimension is given as 12 cm, so this cavity does fall within that parameter.
These large woodpecker cavities have no evidence of gnawing by squirrels or other mammals. Although some loss of wood around the rim to wear and weathering may have occurred, both appear to have been chiseled at (or very near) this size. The maximum reported width for nest cavity entrance holes of Pileated Woodpeckers is 9 cm (Bull and Jackson 1995), so this cavity exceeds that by a full inch. Tanner reported the horizontal dimensions of Ivory-billed Woodpecker cavities to be 10.2 cm and wider. Maximum pileated cavity vertical dimension is given as 12 cm, so this cavity does fall within that parameter.
Here is a part of the tree, as it appeared in October (left) and reassembled in the lab at Nokuse Plantation (right). Note the distortion in the left photo caused by the steep viewing angle.
It's hard to resist not showing for comparison the famous 1948 Dennis photo, which may be the last universally accepted ivorybill photo in existence:
Another cavity of interest is this large (yet-unmeasured) one in a living sycamore, found by team member Mike Martin. It shows the oblong dimensions that are more characteristic of ivorybill cavities:
We have several volunteers here this week. Some of the members of our team have considerable Geographic Information System (GIS) experience, and the lab here at Nokuse has excellent GIS and map-printing capability. We are coordinating with Geoff Hill and Brian Rolek to ensure the teams will benefit from the best real-time use of the data that is being collected. There might be a post on that topic a bit later.
We have several volunteers here this week. Some of the members of our team have considerable Geographic Information System (GIS) experience, and the lab here at Nokuse has excellent GIS and map-printing capability. We are coordinating with Geoff Hill and Brian Rolek to ensure the teams will benefit from the best real-time use of the data that is being collected. There might be a post on that topic a bit later.
3 comments:
Curious - no mention of cavity contents or lack thereof. Wouldn't that be a prime concern.
No sign of any inhabitants, but the tree was down for days and perhaps weeks when discovered. It was a pretty old cavity and was probably no longer used by woodpeckers. Due to the ephemeral nature of these dead pine snags, it seems likely that large woodpeckers would use them for no more than a year or two after the death of the tree, and then abandon them.
One more thing, in case this was your question: I looked for feathers, eggshells, etc. among the debris but their absence was no real surprise. Woodpeckers typically keep pretty clean nests, and like the tree itself, a feather would likely not last long in this humid climate.
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