Statistical sensitivity for detection of spatial and temporal patterns in rodent population densities

A long-term monitoring program begun 1 year after the epidemic of hantaviru s pulmonary syndrome in the U.S. Southwest tracked rodent density changes t hrough time and among sites and related these changes to hantavirus infecti on rates in various small-mammal reservoir species and human disease outbre aks. We assessed the statistical sensitivity of the program's field design and tested for potential biases in population estimates due to unintended d eaths of rodents. Analyzing data from two sites in New Mexico from 1994 to 1998, we found that for many species of Peromyscus, Reithrodontomys, Neotom a, Dipodomys, and Perognathus, the monitoring program detected species-spec ific spatial and temporal differences in rodent densities; trap-related dea ths did not significantly affect long-term population estimates. The progra m also detected a short-term increase in rodent densities in the winter of 1997-98, demonstrating its usefulness in identifying conditions conducive t o increased risk for human disease.