Integrating LIDAR-derived canopy structure into cerulean warbler habitat models

Researchers have suggested that the cerulean warbler (Setophaga cerulea), a declining species, settles on its breeding grounds in response to a particular canopy structure within mature deciduous forests. Conservation management strategies could be more effective if this association was further clarified; however, defining canopy structure from the ground can be laborious and subjective. We used light detection and ranging (LIDAR) data to create canopy height models that provide accurate objective data on the vertical and horizontal canopy structure throughout the extent of our study area in south-central Indiana's Morgan-Monroe and Yellowwood state forests. In addition, we used LIDAR data to construct digital terrain models to derive topographic metrics for our study area. We combined these data with data from ground-level surveys and created habitat models to determine which variables best predict cerulean warbler occurrence and density. Model subsets containing only LIDAR-derived variables performed better than model subsets containing variables derived only from ground-level surveys. The top occurrence model indicated that cerulean warblers defended areas that were associated with northeast facing slopes, lower elevations, gentler slopes, and greater hickory (Carya spp.) basal area (m(2)/ha). The top density models indicated that the high-use areas for cerulean warblers were associated with steeper slopes, lower total basal area (m(2)/ha), fewer large trees (53cm diameter at breast height), greater white oak (Quercus alba) basal area (m(2)/ha), and contained a homogeneous horizontal and vertical canopy structure. Conservation managers should consider silvicultural practices that promote old growth oak-hickory (Quercus spp.-Carya spp.) forests on mesic slopes. Furthermore, LIDAR can provide an objective and efficient method for collecting terrain and surface data at large scales, which can be used to define habitat and aid conservation efforts. (c) 2015 The Wildlife Society.