Woodpeckers and Snag Dynamics

Standing dead trees, or snags, are a critical component of western coniferous forests as numerous wildlife species rely upon them for survival and reproduction. Despite their ecological value, snag-creation processes have been disrupted by wildfire suppression and pest reduction. This has led to sharp reductions of many snag-dependent species, especially the so-called secondary cavity nesters (species dependent upon cavities but unable to create them). WCS is engaged in research on the interdependent factors contributing to the supply of snags and nest cavities in order to better inform forest management policy and practice.

The Human Aspect
Woodpeckers are central to the creation of snag cavities, and thus the management and conservation of wildlife in western coniferous forests. However, most woodpecker species cannot excavate nests in sound wood and require decomposition of wood by fungal organisms prior to nest creation.

Threats
The suppression of fire, insects, pathogens, and large-scale salvage logging may be detrimental to wildlife.  Fire, insects, and pathogens interfere with processes that are integral to snag production, and thus the survival of snag-dependent animals.

 WCS Activities
Because snags are critical habitat components for many different wildlife species, and are often overlooked in management activities, WCS initiated an effort to examine woodpecker and snag ecology in 1998 as part of a long-term project.  The effort is aimed at understanding the integrated roles of tree mortality agents, bark and wood boring beetles, wood decaying fungi, and woodpeckers in the creation of nest cavities in coniferous forests.  Our focus is on three main projects: (a) the overall study of snag decay of ponderosa pine, (b) evaluating the role of foraging woodpeckers in the decay of ponderosa pine, and (c) charting the decay patterns and woodpecker foraging use of both ponderosa pine and white fir following prescribed fires.  We have been conducting this research at two different sites in central Oregon and northeastern California.

Important Next Steps
• Determine the role of foraging woodpeckers in snag decomposition.
• Continue long-term monitoring of snags in order to chart critical
  temporal patterns (timing of cavity generation, timing of snag
  fall/breakage, secondary wildlife use).
• Determine the role of fire severity on subsequent wildlife use and decomposition.
• Provide land managers with information regarding optimal snag
  management practices.

Forests, Fires and Wildlife Related Publications