Tree Girdling for Potential Bat Roost Creation in Northwestern West Virginia

Abstract

Cavity/crevice tree-roosting bats in North America face an uncertain future with many factors impacting their populations. To benefit crevice/cavity roosting bat species, forests are often enhanced with the use of tree girdling. In October 2015, 20 maples, 22 oaks, and 18 hickories were girdled using a method with fell cut and herbicide (frilling) or double-girdling with a chainsaw. From 2016–2021, targeted trees were observed and the tree’s decay state was collected. The average time for trees to display suitable roosting characteristics for frilling trees was 3.23 years while it was 4.46 years for double girdling. The average time frilling trees contained suitable roosting characteristics was 3.20 years while it was 1.63 years for double girdling. The frilling method resulted in a quicker kill of trees than double girdling and frilling trees had suitable roosting characteristics for a longer duration. Frilling was effective killing all three types of trees, while the double girdling was less effective, especially on oaks. When grouping species and treatment in analysis, only average decay states between maple frill and oak double girdling and hickory frill and oak double girdling were significantly different. This evaluation demonstrates that roost tree creation relating to tree species and girdling methodology has a temporal component that should be considered when managing for crevice/cavity bat roosts and multiple habitat creation methods should be used in conjunction with snag creation to provide sustainable bat habitat over longer time periods.