Conservation planning for the more than one thousand animal species that use tree cavities around the world should start with identifying the role of old, standing trees. In North America, woodpeckers produce the majority of cavities for tree-cavity-using vertebrates (77% of nesting cavities). Elsewhere, damage and decay are the main producers of cavities used (74% in Eurasia and South America; 100% in Australasia) -- a much slower process. Most trees are more than 100 years old before decay cavities even begin to form.

Researchers tracked nearly 3000 tree cavities in Canada, Poland, and Argentina. Each year of the respective studies, they confirmed whether the cavities were in use and by which species. In North America, woodpecker and decay-formed cavities had similar lifetimes.  However, on other continents, decay-formed cavities tended to last much longer than those created by woodpeckers, and provided homes for multiple species over years or decades.

Globally, therefore, most cavity nesters are critically dependent on slower-forming cavities and require forest policies that stem the current rate of loss of old trees.

Source: Kristina L Cockle, Kathy Martin, and Tomasz Wesołowski. Woodpeckers, decay, and the future of cavity-nesting vertebrate communities worldwide. Front Ecol Environ 2011; 9(7): 377–382, doi:10.1890/110013.

Results published in the journal, Frontiers in Ecology and the Environment, were highlighted on the cover and chosen by Science Magazine for a ScienceDaily feature and an Editors’ Choice.

Contact: Dr. Kathy Martin, 604-940-4667, Wildlife Research Division