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Spatial synchrony of a threatened shorebird: Regional roles of climate, dispersal and management
- LUKE J. EBERHART-PHILLIPS, BRIAN R. HUDGENS, MARK A. COLWELL
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- Journal:
- Bird Conservation International / Volume 26 / Issue 1 / March 2016
- Published online by Cambridge University Press:
- 02 February 2015, pp. 119-135
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- Article
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Correlated climate patterns, dispersal, and similar management practices may synchronise dynamics of populations in close proximity, which tends to reduce metapopulation persistence. However, synchronising and desynchronising mechanisms can act at multiple spatial scales, which means that for wide-ranging species, patterns of spatial synchrony and their causes might vary across the species’ range. We examined the relationships of spatial autocorrelation in winter climate, dispersal distance and predator management to the spatio-temporal dynamics of the Western Snowy Plover Charadrius nivosus nivosus, a threatened shorebird that breeds along the Pacific coast of the United States. We investigated how signals and drivers of plover population growth dynamics vary among populations occupying northern, central, and southern regions of the species’ U.S. range. Across the metapopulation and specifically the core of the species’ range in the south, we found that plover populations within 132 km of each other exhibited detectable levels of synchrony, which fell within published estimates of dispersal distance. Furthermore, similar predator management among sites increased the degree to which nearby populations were synchronised. There was, however, no evidence of spatial synchrony in populations of the northern and central regions. Regional differences in synchrony were associated with different population drivers and structure; prolonged cold periods had the strongest influence on the growth of northern populations while predator management had the strongest influence on southern populations. Northern populations were also smaller than the south, which likely reduced our ability to detect spatial synchrony because of increased demographic stochasticity. Neither climatic nor management variables had a detectable influence on central populations. Although the primary objective of threatened and endangered species management is to increase populations to viable levels, we recommend that conservation biologists and land managers acknowledge region-specific processes when considering the long-term persistence of wide-ranging species and coordinate inter-agency efforts to manage neighbouring populations effectively.
22 - Assessing positive and negative ecological effects of corridors
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- By Nick M. Haddad, North Carolina State University, Brian Hudgens, Institute for Wildlife, California, Ellen I. Damschen, University of Wisconsin, Douglas J. Levey, University of Florida, John L. Orrock, University of Wisconsin, Joshua J. Tewksbury, University of Washington, WA, USA, Aimee J. Weldon, Potomac Conservancy, MD, USA
- Edited by Jianguo Liu, Michigan State University, Vanessa Hull, Michigan State University, Anita T. Morzillo, Oregon State University, John A. Wiens
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- Book:
- Sources, Sinks and Sustainability
- Published online:
- 05 July 2011
- Print publication:
- 30 June 2011, pp 475-504
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Summary
The most popular landscape-level strategy to conserve biodiversity is to link reserves with corridors. Despite much theoretical and empirical support for their benefits in creating or maintaining population sources, corridors may have negative effects and create sinks by altering the dynamics of competitors and natural enemies. In this chapter, we synthesize results from the largest and longest-running experiment to test the effects of corridors, the Savannah River Site Corridor Experiment, and assess their positive and negative ecological effects. In addition to reviewing previously published studies from this experiment, we present new findings about corridor effects on seed mass and number, bird-dispersed seed rain, and bird nest predation and density. Taken together, these empirical studies broadly affirm the positive effects of corridors, particularly on dispersal and diversity. Where there are negative impacts of corridors, the underlying processes are nearly always linked to edge effects, a side-effect of creating corridors. These negative edge effects have the potential to change source patches into sink patches. To further explore the balance of positive and negative corridor effects, we conducted a modeling study, and found that corridors can benefit populations despite edge effects, as long as the edge effects associated with corridors are not too large. Our synthesis serves to highlight areas for future research, particularly on the effects of corridors on population persistence and how corridor characteristics (e.g., width, length) and matrix permeability alter corridor efficacy. As long as efforts are taken to reduce the negative effects of edges, our findings generally support efforts to reconnect landscapes for biodiversity conservation.