• Wang, Guiming
  Department of Wildlife and Fisheries, Mississippi State University - Mississippi State, Mississippi
  
• Wolff, Jerry O.
  Department of Biology, St. Cloud State University - St. Cloud, Minnesota
  
• Vessey, Stephen H.
  Department of Biological Sciences, Bowling Green State University - Bowling Green, Ohio
  
• Slade, Norman A.
  Department of Ecology and Evolutionary Biology and Museum of Natural History/ Biodiversity Research Center, University of Kansas - Lawrence, Kansas
  
• Witham, Jack W.
  Holt Research Forest, University of Maine - Arrowsic, Maine
  
• Elias, Susan P.
  Holt Research Forest, University of Maine - Arrowsic, Maine
  
• Merritt, Joseph F.
  Illinois Natural History Survey - Champaign, Illinois
  
• Hunter Jr., Malcolm L.
  Department of Wildlife Ecology, University of Maine - Orono, MaineG
  

Temporal variation in population size is regulated by both exogenous forces and density-dependent feedbacks. Furthermore, accumulating evidence indicates that temporal and spatial variation in climate and resources can modify the strength of density dependence in animal populations. We analyzed six long-term time series estimates of Peromyscus leucopus (white-footed mouse) abundance from Kansas, Ohio, Pennsylvania, Virginia, Vermont, and Maine, USA, using the Kalman filter. Model-averaged estimates of the strength of delayed density dependence increased from west to east and from south to north. The strength of direct and delayed density dependence was positively related to the annual number of days with minimum temperature below -17.8°C. Annual population growth rates of P. leucopus at the Maine site were positively related to acorn abundance and P. leucopus populations tracked the changes in red-oak acorn abundance. The populations of P. leucopus living in northern latitudes might be more dependent on northern red oak (Quercus rubra) acorns for winter food than P. leucopus in southern latitudes. Furthermore, northern red oak trees mast every 4–5 years. Thus, longer, colder winters in northerly latitudes might result in stronger delayed density dependence in mouse populations with a shortage of winter food. Mice might simply track the acorn fluctuations in a delayed autocorrelated manner; however, delayed density dependence remained in our models for the Maine mouse populations after accounting for acorns, suggesting additional sources for delayed density dependence. Our results suggest that, in seed-eating Peromyscus, cyclicity may be regulated, in part, from low to high trophic levels.