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

Area of Science:

• Ecology
• Population Biology
• Conservation Science

Background:

• Patch occupancy surveys are standard for metapopulation models.
• Isolation is often linked to colonization-extinction balance.
• Alternative explanations for occupancy patterns require investigation.

Purpose of the Study:

• To test if spatially correlated extinctions can mimic balanced metapopulation dynamics.
• To evaluate the reliability of patch occupancy surveys for inferring population processes.
• To inform conservation strategies for species with ephemeral recolonization.

Main Methods:

• Simulated spatially correlated extinctions using 'extinction disks' in a metapopulation model.
• Applied simulations to pika (Ochotona princeps) occupancy data from Bodie, California.
• Analyzed observed occupancy patterns for evidence of rescue effects and ephemeral recolonization.

Main Results:

• Simulations of correlated extinctions produced patterns similar to those attributed to balanced metapopulation dynamics.
• Varying disk sizes and patch configurations yielded consistent simulation outcomes.
• Bodie pika data showed limited rescue effects and predominantly ephemeral recolonizations.

Conclusions:

• Static or declining occupancy patterns may be misidentified as stable metapopulation processes.
• Overestimation of persistence is likely if correlated extinctions are not considered.
• Patch occupancy surveys alone are insufficient for robust conservation decision-making.