Degree Name

BS in Biological Sciences


Biological Sciences Department


Francis Villablanca


Long-term biodiversity surveys are a useful tool for assessing the impacts of stochastic events on wildlife and their communities. A recent stochastic event to affect the state of California is the historic 2013-2015 drought. This drought, described as a one-in-one-thousand year event, brought precipitation to a historic low; the statewide rainfall reaching 34% below average (Swain et al. 2014). While humans are feeling the impact of this water shortage, the effects on native ecosystems and wildlife populations are poorly documented. Baseline small mammal biodiversity data collected in 2011, before the drought, allows us the opportunity to study the impacts of the drought on populations of small mammals, which are important indicators of ecosystem health. In this study, we compare small mammal abundance and diversity in chaparral, oak woodland, and riparian habitats measured before and during the drought. Here we show that there was an overall reduction in small mammal abundance and in species diversity during the drought. Not all habitat types were affected equally. The abundance of small mammals in oak woodland habitats was the most negatively affected by the drought. Abundance in chaparral habitats was least impacted by the drought, and evidence suggests that chaparral was the preferred habitat type during drought-stress conditions. While most species of small mammals declined in abundance, a few did increase, likely due to increased niche availability. These results shed light on the dramatic effects that a major drought can have on natural ecosystems, and the varied responses by different species in different habitat types. As the frequency and intensity of stochastic events increase due to climate change, it is important to understand the effects they may have on natural systems in order to better prepare and manage for them.