Appendices for: Heavy Metal and Essential Elements in Alaskan Red Squirrels Provide First Open Access Data Mining Implications with a One-Health outlook

Exceedingly high or low concentrations of essential elements and heavy metals can disrupt homeostasis and organismal health. While baseline elemental ranges are well established for domesticated species, they remain largely unknown for squirrels, particularly in remote regions such as Alaska (United States). North American red squirrels (Tamiasciurus hudsonicus) function as mesopredators interacting with diverse ecosystem components and thriving in semi-urbanized Anthropocene landscapes, making them suitable sentinel species. We collected 158 Interior Alaskan squirrels via citizen crowdsourcing, grouped them into 11 location-based composite liver samples, and analyzed 71 elements using ICP-MS. Most concentrations fell within reported Sciuridae ranges but ranked in the highest quartile for Mn, Cd, Hg, Ni, and Pb, often exceeding levels in experimentally exposed rodents. We modeled 21 health-relevant elements using TreeNet in Salford Predictive Modeler with 224 environmental predictors, generating ~656,000 pixel-level predictions per element. Hotspots near military sites raise contamination concerns and can guide future sampling.