Birds Choose Cavities Near Cutblock Edges
Snags remaining in clearcuts after logging are most useful to birds if left within 100 m of a forest edge. Cavity-nesting birds risk predation when flying further into an opening, so snags there get used less frequently.
Within and near the 30 - 60 ha recently-harvested blocks examined near Prince George, British Columbia, birds prefer making cavities in relatively short snags with advanced decay. Most often these are deciduous trees such as aspen and birch.
Researchers encountered soft snags less frequently in clearcuts compared to the adjacent Sub-boreal Spruce biogeoclimatic zone forest. This may explain why they found active bird cavities to be more prevalent in forest snags.
Kim T. Everett and Ken A. Otter. 2004. Presence of Cavities in Snags Retained in Forest Cutblocks: Do Management Policies Promote Species Retention? The Canadian Field-Naturalist. 118(3): 354-359.