Results of elemental analyses of desert tortoise (Gopherus agassizii) burrow spoil and undisturbed surficial soils in California, 2023

Bighorn sheep (Ovis canadensis) were frequently photographed by wildlife cameras when they visited desert tortoise (Gopherus agassizii) burrows in the eastern San Bernardino Mountains near Palm Springs, California, USA (Mesa Windfarm). A previous study suggested that sheep may have been utilizing the excavated spoil material from burrows as a mineral lick. We aimed to test this possibility by collecting soil samples from the tortoise burrow spoil piles and undisturbed surface soil less than a meter away at two different desert tortoise study sites with bighorn sheep, the second site (Deep Canyon) in the Santa Rosa Mountains near Palm Desert, California. Both study sites are located in the Sonoran Desert ecosystem of Riverside County, CA. Concentrations of major cations (sodium, magnesium, aluminum, potassium, calcium, iron, and strontium) and other elements (beryllium, vanadium, chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, molybdenum, silver, cadmium, tin, antimony, barium, thallium, lead, bismuth, thorium, uranium) were quantified in the soil samples using inductively coupled plasma-mass spectrometry following microwave-assisted digestion to solubilize the fraction of elements that could become biologically or environmentally available to bighorn sheep following geophagy.