Large entrances

There are many large cavities in both living and dead trees in our search area.  We measured the size of the entrance holes of 131 large cavities but this was not an exhaustive inventory of cavities in our study area.  We were still finding new large cavities on the last day of our field season and many of the cavities that we found were too high or inaccessible to be measured.  We watched over 40 cavities at sunrise or sunset but our small team felt overwhelmed trying to locate active roost cavities with so many holes in trees to watch.

Many of the cavities that we measured had entrance holes that were outside the size range recorded for the cavities of Pileated Woodpeckers and within the range of nest cavities of Ivory-billed Woodpeckers recorded in the Singer Tract of Louisiana in the 1930s.  The vertical dimension of the entrances of twenty of the cavities that we measured exceeded 12.7 cm (5 inches), and the width of 67 cavities exceeded 10.2 cm (4 inches).  There are surprisingly few published dimensions for the entrance holes of the cavities of Pileated Woodpeckers and many of the published measurements are from the larger western and northern populations of pileateds.  So, we measured 21 large cavities around Auburn, Alabama where pileateds are common but there are almost certainly no ivorybills.  No cavity around Auburn had a vertical dimension that exceeded 12.7 cm and only one was more than 10.2 cm wide.

Cavities can occur alone, as with this cavity in the top of dead sweet gum (at left) or in stacks, as with these cavities in a live water tupelo (at right).

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