Soil Ingestion by Mule Deer in Northcentral Colorado

Abstract

Soil ingestion rates calculated from titanium concentrations in feces from mule deer (Odocoileus hemionus) feeding in a grassland-shrub community in northcentral Colorado in g/day (mean +/- SD) were: spring, 29.6 +/- 20.1; summer, 7.7 +/- 10.2; fall, 8.8 +/- 6.5; and winter 18.3 +/- 10.8. Based on observations of feeding tame deer, intake in winter appeared to be primarily due to direct soil ingestion from pocket gopher (Thomomys talpoides) mounds, roads, and other areas of exposed soil. The greatest intake during spring was likely due to indirect consumption of soil adhering to ingested vegetation. Soils from locations where tame deer had consumed soil were analyzed for trace elements (Ca, Cu, Fe, Mg, Mn, P, K, Na, and Zn) and compared to areas where no soil intake was observed. No significant differences (alpha=0.05) in mean levels of these elements was detected between areas. Most likely, deer at Rocky Flats were not selecting soils based strictly on mineral content, but instead were consuming soil indiscriminately. Ingested soil may provide a source of trace elements as well as a mode of entry for environmental pollutants.