You are here:
How big and how close? Habitat patch size and spacing to conserve a threatened species
Citation:
Marcot, B. G., M. G. Raphael, N. H. SCHUMAKER, AND B. Gelleher. How big and how close? Habitat patch size and spacing to conserve a threatened species. NATURAL RESOURCE MODELING. Wiley InterScience, Silver Spring, MD, 26(2):194-214, (2013).
Impact/Purpose:
We present results of a spatially-explicit, individual-based stochastic dispersal model (HexSim) to evaluate effects of size and spacing of patches of habitat of Northern Spotted Owls (NSO; Strix occidentalis caurina) in Pacific Northwest, USA, to help advise USDI Fish and Wildlife Service’s current NSO recovery planning efforts.
Description:
We present results of a spatially-explicit, individual-based stochastic dispersal model (HexSim) to evaluate effects of size and spacing of patches of habitat of Northern Spotted Owls (NSO; Strix occidentalis caurina) in Pacific Northwest, USA, to help advise USDI Fish and Wildlife Service’s current NSO recovery planning efforts. We modeled 31 artificial landscape scenarios representing combinations of NSO habitat cluster size (ranging 4-49 NSO pairs per cluster) and edge-to-edge cluster spacing (ranging 7-101 km), and an all-habitat landscape. Each scenario was run using empirical estimates on NSO dispersal dynamics and distances, and under known NSO stage class-specific demographic vital rates (representing current population declines) and under adjusted adult survival rates (to achieve an initially stationary population). Results suggested that long-term (100-yr) occupancy rates of habitat are significantly higher with habitat clusters supporting ≥25 NSO pairs and ≤15 km spacing, and with overall landscapes of ≥35-40% habitat. Although habitat provision is key to NSO recovery, no habitat configuration provided for long-term population persistence when coupled with currently observed vital rates. Model results also suggested a key role of floaters (unpaired, non-territorial, dispersing owls) in recolonizing vacant habitat, and that the floaters segment of the population becomes increasingly depleted with greater rates of population decline. Our results generally compared well to a similar, previous NSO model. We suggest additional areas of modeling research on this and other threatened species.