Small mammal responses to environmental change: integrating past and present dynamics

Forecasting the response of species and communities to environmental change is a priority for multiple disciplines in the natural sciences. In looking toward the future, much can be learned from examining faunal response under past episodes of environmental change. Typically, retrospective approaches are limited to one spatial and temporal scale. Here, we illustrate how integrating across spatiotemporal scales can provide powerful insights into faunal response, and can inform conservation and management. To do this we compare paleontological and neontological studies on the small mammal fauna of the Great Basin. Small mammal species and their assemblages have long been recognized as indicators of ecological change and ecosystem health. We use fossil data from two long-term owl roosts to reconstruct patterns of richness and the apportioning of abundance among functional groups across multiple episodes of warming during the Holocene (last 10,000 years). We then use these findings as a climate-only baseline against which to compare changes in richness and abundance in 2 independent mountain ranges over the past century. While the past century has been marked by climate warming, the modern day Great Basin landscape also has been subject to intense human land-use practices and the introduction of nonnative plant species. Our contrast highlights that for Great Basin small mammals, modern-day land-use practices are modifying climate-based expectations.