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Assessing critical habitat: Evaluating the relative contribution of habitats to population persistence
Citation:
Heinrichs, J. A., D. J. Bender, D. L. Gummer, AND N. H. SCHUMAKER. Assessing critical habitat: Evaluating the relative contribution of habitats to population persistence. BIOLOGICAL CONSERVATION. Elsevier Science Ltd, New York, NY, 143:2229-2237, (2010).
Impact/Purpose:
A principal challenge of species conservation is to identify the specific habitats that are essential for long-term persistence or recovery of species at risk. However, many commonly used approaches to identifying important habitats do not provide direct insight into the contribution of those habitats to population persistence.
Description:
1. A principal challenge of species conservation is to identify the specific habitats that are essential for long-term persistence or recovery of species at risk. However, many commonly used approaches to identifying important habitats do not provide direct insight into the contribution of those habitats to population persistence. 2. To assess how habitats contribute to overall population viability and characterize their relative importance, a spatially-explicit population viability model was used to integrate a species occurrence model with habitat quality and demographic information to simulate the population dynamics of a case study species, the endangered Ord’s kangaroo rat Dipodomys ordii in Alberta, Canada. The long-term productivity (births-deaths) in each patch was simulated and iterative patch removal experiments were conducted to generate estimates of the relative contribution of habitat types to overall population viability. Both long-term productivity and the relative contribution of habitat types provided the basis for prioritizing habitats for conservation. 3. Our results indiciated that natural dune habitats are crucial for population viability, while disturbed/human-created habitats make a minor contribution to population persistence. The results also suggest that the habitats currently available to Ord’s kangaroo rats in Alberta are unlikely to support long-term persistence. 4. Our approach was useful at identifying habitat that did not contribute to population viability. In particular, a large proportion of habitat (39%) was comprised of sinks and their removal actually increased the estimated viability of the population. 5. Synthesis and Applications. The integration of population dynamics with habitat quality and occurence data can be insightful when assessing critical habitat, particularly in regions with variable habitat quality or for species that exhibit source-sink dynamics. Approaches that do not incorporate population dynamics may undermine conservation efforts by under- or over-estimating the value of habitat patches, erroneously protecting sink habitats or failing to prioritize key source habitats.
