Quantifying a dynamic risk landscape: heterogeneous predator activity and implications for prey persistence

Area of Science:

• Ecology
• Predator-Prey Dynamics
• Spatial Ecology

Background:

• Spatial heterogeneity in predation risk can mitigate negative impacts on prey populations.
• Generalist predators, like white-footed mice, create spatially heterogeneous risk landscapes.
• The scale and persistence of these risk refugia influence prey survival strategies.

Purpose of the Study:

• To quantify the magnitude, spatial scale, and temporal persistence of predation risk heterogeneity.
• To assess the risk posed by white-footed mice (Peromyscus leucopus) to prey like gypsy moths and songbirds.
• To understand how prey might utilize spatial refugia to avoid predation.

Main Methods:

• Track plates were used to measure white-footed mouse activity at over 170 trees across three forest plots.
• Data were collected during summers from 2003 to 2005 in upstate New York.
• Statistical analyses included beta-binomial distribution, disattenuated autocorrelation, and exponential variograms to assess risk variation, temporal persistence, and spatial scale.

Main Results:

• Mouse abundance and overall track activity were lower in 2005, but heterogeneity (coefficient of variation) increased.
• Mouse track activity showed positive temporal autocorrelation between months and years in 2003-2004, but weaker autocorrelation in 2005.
• Positive spatial autocorrelation of track activity was observed over distances ranging from approximately 30 to over 1000 meters.

Conclusions:

• White-footed mouse activity, and thus predation risk, varies significantly in space and time.
• These spatial and temporal scales of risk variation appear linked to mouse population dynamics.
• Prey species may benefit from utilizing identified refugia by returning to or remaining within them to avoid predation.