Forest Age and Cavity-nesting Birds

Scientists sampled 60 stands of forest in Quebec with varying time since their last fire to determine the abundance and characteristics of snags; fallen trees used as habitat for various wildlife but especially cavity nesting birds such as woodpeckers, chickadees, nuthatches and creepers.

These findings are especially relevant for federal and provincial land and wildlife managers, and NGOs concerned with forestry and wildlife. The findings could have implications in commercial forestry practices to ensure that managed forests support biodiversity.

Forests older than 200 years provided the best habitat for secondary cavity nesting birds like the red breasted nuthatch, boreal chickadee and brown creeper. This is likely due to an abundance of large snags in old growth forests in combination with the amount of time they have been standing, increasing their use by many species and variety in levels of decomposition.

Interestingly, scientists found that primary nesters, such as the black-backed woodpecker, were not necessarily more abundant in recently burned forests, but found somewhat consistently in all forest ages. However scientists acknowledge this may be due to a low detection rate and to a broader definition of ‘recently burned’ forests as under 50 years old, as woodpeckers prefer one to five year old post fire forests, and decrease in areas of older burns.

Snag abundance and characteristics in the samples were typical of unmanaged boreal forests; the most snags were found in young forests that had experienced a fire 50 years ago or less, followed by a transition period of few snags, then an abundance of snags again once the forest aged beyond 200 years