Small Mammals Along Elevational Gradients & Ground-Dwelling Arthropods Along Red Squirrel Midden Residency Gradients, Pinaleño Mountains, Arizona

Ecosystem stability is important for threatened biomes such as the Madrean Archipelago that harbor endemic species of conservation concern. Small mammals play key ecological roles that influence ecosystem function (e.g. homeostasis, or how ecosystem structure remains constant in response to disturbances), yet knowledge of their distributions and interactions is lacking in the region. In my first study, I documented richness and abundance patterns of small mammals along an elevation gradient in the Pinaleño Mountains, the most prominent mountain range of the Madrean Archipelago. I found that species richness peaked in the semi-desert grassland and mixed conifer life zones, but the life zone with the greatest abundance varied seasonally. The study provides insight into factors influencing elevational distributions and serves as a baseline to incorporate monitoring of small mammals as indicators of environmental change. My second study investigated how endangered Mt. Graham red squirrel (Tamiasciurus fremonti grahamensis) middens (cone scale piles where squirrels larderhoard food) influenced the community of ground-dwelling arthropods across a gradient of residency history. I found that middens that had longer squirrel residencies (squirrels residing at and maintaining the midden for longer time periods) were associated with more arthropods compared to lower residency middens. However, the diversity of ground-dwelling arthropods relative to squirrel residency history depended on the diversity metric used. Monitoring of arthropod communities within middens can provide a novel method to assess temporal changes in squirrel food-caching strategies and evaluate forest management actions that may influence midden conditions. Collectively, studying small mammal interactions across diverse gradients can identify new ways of seeing and responding to disturbances that the region may experience in the future.