Endemic to California’s arid Central Valley, endangered Blunt-nosed Leopard Lizards (Gambelia sila) have adapted to xeric conditions but like many desert lizards remain at-risk to extinction. Understanding how G. sila maintains water balance through cutaneous evaporative water loss (CEWL) and water intake from prey can help inform endangered reptile conservation strategies in warmer, drier environments. We hypothesized that seasonal changes in climate drive variation in prey water quantity and water loss across the skin, and thus hydration for insectivorous G. sila. To study the lizards’ osmoregulation, we measured CEWL and plasma osmolality of the same individuals throughout the field season. We also collected invertebrate specimens and quantified water content. We found great variability in lizard hydration during the field season. Meanwhile, prey species exhibit variable water content throughout the lizards’ active season, but their average water content remains consistent between wet and dry years. As the effects of climate change intensify, megadroughts may increase hydric pressure on G. sila and other sensitive species, so it will be important to identify which prey species contain the most water — making them integral to survival.