Foraging ecology of pileated woodpeckers in Dukes Experimental Forest in the Upper Peninsula of Michigan
Pileated woodpecker selection of foraged trees was studied using a multiple spatial scale study in coniferous and deciduous forests in the Upper Peninsula of Michigan. Most previous works on pileated woodpecker foraging have been conducted in large homogeneous, contiguous tracts of forests of a single assemblage type. These studies found foraging preferences for stand type, tree type, and tree species; specifically, conifers in the western range, and deciduous trees in the eastern range. However, it was unclear if this selection resulted from availability because studied areas were dominated by preferred tree types and species or habitat data was not reported. The availability of suitable coniferous and deciduous assemblages in Dukes Experimental Forest in northern Michigan provided an opportunity to examine foraged tree selection with both habitat types present. Foraged trees were associated with a suite of characteristics: they were declining to moderately decayed (d.f. = 4, χ2 = 10.29 and 297.38, respectively, P ≤ 0.05), injured, and more had conks than expected (d.f. = 4, χ2 = 360.05 and 644.08, respectively, P ≤ 0.05). Coarse examination of the data suggested that deciduous trees in general and aspens and yellow birch in particular were preferred. Further examination suggested that these trees were selected by pileated woodpeckers based on their characteristics alone, which are similar to characteristics of trees inhabited by carpenter ants, the primary prey of pileated woodpeckers.