PARENT SESSION
Contributed Oral Session 48: Landscape Ecology: Animal Dynamics
Tuesday, August 9, 8:00 AM - 11:30 AM, Meeting Room 520 B, Level 5, Palais des congrès de Montréal
Forest structure and avian habitat: Scale dependencies in occurrence prediction.
Manaras, Katherine*,1, Keeton, William1, Donovan, Therese1, Mitchell, Brian1, 1 Rubenstein School of Environment and Natural Resources, Burlington, VT, USA
ABSTRACT- Avian species are known to select habitat based on both landscape pattern and site-specific vegetation. The former is often judged to be less predictive of avian community composition, while the importance of the later has been stressed extensively in recent studies. We hypothesize that specific-specific avian habitat relationships at the scale of individual forest stands have not been accurately assessed in previous research due to a mismatch of spatial scale between forest sampling and bird sampling (point count radius). We explore the role of stand level forest structure and spatial scale of forest sampling in models of avian occurrence in northern hardwood-conifer forests in Vermont. Seven forest birds, black-throated blue warbler (Dendroica caerulescens), black-throated green warbler (Dendroica virens), ovenbird (Seiurus aurocapillus), winter wren (Troglodytes troglodytes), wood thrush (Hylocicla mustelina), and yellow-bellied sapsucker (Sphyapicus varius), were used as indicators of biodiversity and ecosystem function because of their reliance on different components of stand level structure for reproduction and foraging. We used Program MARK to estimate probabilities of occurrence from point counts at 20 sites, and characterized the forest structure at these sites at three spatial extents (0.1, 3.14 and 12.5 ha) using forest inventory plots and detailed canopy measurements. Analyses using information-theoretic model selection criteria in Program MARK suggest that weight of evidence is greatest for habitat models using forest stand structure at the 12.5 ha scale. This scale is similar to the territory size of focal species and our point count area. Additionally, we were able to identify specific habitat features and variables that are related to the probability of occurrence of our focal species. These results are of interest to land managers who seek to maintain or enhance habitat for species of concern. We recommend that researchers consider the biology of their study organisms and the scale at which population size, occurrence or relative abundance is estimated when making decisions about scale of forest sampling for habitat modeling.
Key words: forest structure, avian habitat selection, microhabitat models, spatial scale