Pattern does not equal process: What does patch occupancy really tell us about metapopulation dynamics?

Michael Clinchy, Daniel T. Haydon, Andrew T. Smith

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Patch occupancy surveys are commonly used to parameterize metapopulation models. If isolation predicts patch occupancy, this is generally attributed to a balance between distance-dependent recolonization and spatially independent extinctions. We investigated whether similar patterns could also be generated by a process of spatially correlated extinctions following a unique colonization event (analogous to nonequilibrium processes in island biogeography). We simulated effects of spatially correlated extinctions on patterns of patch occupancy among pikas (Ochotona princeps) at Bodie, California, using randomly located extinction disks to represent the likely effects of predation. Our simulations produced similar patterns to those cited as evidence of balanced metapopulation dynamics. Simulations using a variety of disk sizes and patch configurations confirmed that our results are potentially applicable to a broad range of species and sites. Analyses of the observed patterns of patch occupancy at Bodie revealed little evidence of rescue effects and strong evidence that most recolonizations are ephemeral in nature. Persistence will be overestimated if static or declining patterns of patch occupancy are mistakenly attributed to dynamically stable metapopulation processes. Consequently, simple patch occupancy surveys should not be considered as substitutes for detailed experimental tests of hypothesized population processes, particularly when conservation concerns are involved.

Original languageEnglish (US)
Pages (from-to)351-362
Number of pages12
JournalAmerican Naturalist
Issue number4
StatePublished - 2002
Externally publishedYes


  • Colonization
  • Dispersal
  • Extinction
  • Metapopulation
  • Pikas
  • Rescue effect

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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