We present and compare demographic data for cerulean warblers (Dendroica cerulea) from 5 study sites across the range of the species from 1992 to 2006. We conducted field studies to collect data on daily nest survival, nest success, and young fledged per successful nest, and we used data to estimate fecundity. Daily nest survival, nest success, young fledged, and fecundity varied widely across the cerulean range and among years. Study sites in agriculture‐dominated landscapes (Mississippi Alluvial Valley, IN, and MI, USA) had negative growth rates in all years monitored because measured values of nest success and young produced per successful nest were incapable of offsetting apparent mortality. Ontario (Canada) and Tennessee (USA) populations had greater nest success and fecundity but still appeared to be incapable of producing stable populations (λ = 1) under field‐measured and assumed conditions. We had survival data only for one site (Ontario); thus, additional survival data are greatly needed to enable more reliable estimates of population growth. Conservation strategies for cerulean warblers in agriculture‐dominated landscapes (e.g., Mississippi Alluvial Valley, IN, and MI) may require major landscape‐level habitat reconfiguration to change agriculture‐dominated landscapes to forest‐dominated landscapes to increase fecundity. Conservation strategies in predominantly forested landscapes in the core of the range (e.g., TN) require a focus on minimizing habitat loss and developing management prescriptions capable of improving fecundity. In both cases, based on sensitivity and elasticity analyses, efforts to improve survival during the nonbreeding season would have the greatest positive effect on population growth. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):646–653; 2008)
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 highuse areas for cerulean warblers were associated with steeper slopes, lower total basal area (m 2 /ha), fewer large trees (!53 cm 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. Ó 2015 The Wildlife Society.
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