During a leisurely hike through the forest, one might encounter an unusual sight nestled among the treetops: a witches’ broom. This peculiar formation, resembling a broom due to its dense cluster of twigs and shoots, is a common occurrence in various woody trees and shrubs, including the Douglas-fir and ponderosa pine.
The instigator of these formations in such trees is often dwarf mistletoe, a parasitic plant that extracts nearly all its required water and nutrients from its host. This parasitic relationship can lead to the formation of a witches’ broom.
Traditionally, both the mistletoe and the resulting witches’ brooms have been considered undesirable, primarily because they can propagate among trees and potentially lead to the death of a stressed host tree.
However, there’s a silver lining to this natural phenomenon. Recent studies suggest that witches’ brooms play an integral role in supporting wildlife. They contribute to forest structure by providing cover, shade, nesting sites, and sustenance for various creatures. Birds, for instance, use these formations for nesting, roosting, and hunting insects. Notably, the Mexican spotted owl favors them as a habitat.
Other forest inhabitants, such as squirrels, porcupines, and skunks, utilize witches’ brooms as warm and protective nests, as well as storage spaces for cones and seeds. Remarkably, a biologist once observed evidence of a mountain lion in a particularly large broom situated low in a Douglas-fir.
Thus, witches’ brooms might not be as ominous as their name suggests. Recognizing their ecological benefits could guide land managers in making informed decisions about tree management to foster healthier forests and wildlife habitats.
This Earth Note was written by Rose Houk and produced by KNAU and the Sustainable Communities Program at Northern Arizona University.
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