PARENT SESSION
Contributed Oral Session 7: Disturbance Ecology: Fire; Litter; Animal response
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 518 A, Level 5, Palais des congrès de Montréal

Life in a charred landscape: The role of scale and salvage logging in nest site selection by cavity-nesting birds.

Saab, Victoria^{*,1, 2}, Russell, Robin^{1, 2}, ¹ USDA Forest Service, Rocky Mountain Research Station, Bozeman, MT, USA² Montana State University, Bozeman, MT, USA

ABSTRACT- Wildfires and subsequent postfire salvage logging have become increasingly prevalent in western North America. Recently burned forests provide critical breeding habitat for many cavity-nesting birds, yet little is known about their nest site selection in relation to postfire salvage logging. We studied nest site selection by cavity nesters over a 10-year period after fire (1994-2003) on two burns in western Idaho, USA. The 1992 Foothills Burn (89,000 ha) was created by a mixed-severity wildfire that was partially logged, whereas the 1994 Star Gulch Fire (12,000 ha) was an unlogged, low-to-moderate severity burn. Our goal was to determine which spatial scale and habitat descriptors had the greatest influence on nest site selection and whether that influence differed by temporal scale. Data were collected on three spatial scales (microscale, macroscale, and landscape) at nest and random (non-nest) locations. Microscale data (local vegetation characteristics) were field collected, whereas data for macroscale (patch size) and landscape (surrounding crown closures and burn severity) were derived from satellite imagery. We monitored nests of six species (Melanerpes lewis, Picoides arcticus, Colaptes auratus, Picoides villosus, Sialia currocoides, S. mexicana) and found 1,408 nests that were used to model nest site selection. We tested a set of models with logistic regression to determine the scale and habitat descriptors that best distinguished between nest and random locations during two postfire periods: 1-4 years postfire; and 5-11 years postfire. Overall, microscale was the most important spatial scale in predicting nest occurrence, while burn location was secondarily important. Within the microscale, snag densities, tree diameters, and tree decay class best distinguished between nest and random locations. Even within unlogged areas, birds were selecting nest locations with higher snag densities than at random locations. The most plausible models differed between the two postfire periods for three species (Melanerpes lewis, Colaptes auratus, S. mexicana ), and macroscale was important for these species in at least one postfire period. Our results are being used to develop design criteria for postfire salvage logging that will conserve breeding habitat for cavity-nesting birds.

Key words: wildfire, salvage-logging, cavity-nesting birds, scale