Carbon and nitrogen isotopes in tissues can be used to understand plants consumed by various taxa, but can they provide additional information about consumers? Values of δ13C and δ15N were assessed from tissue of free-ranging elk (Cervus elaphus) occupying disparate habitats of mixed prairie-oak savannah that contained C3 agricultural crops in a C4-dominated landscape and in key plants consumed by elk. Muscle and hoof samples were collected from female and male elk in two subpopulations (forested land and grassland) from private land and one subpopulation from the Wichita Mountains Wildlife Refuge (refuge) in 2001-2006. Previous research identified differences between mean muscle δ13C and δ15N and mean hoof δ13C and δ15N indicating that isotopes differed between tissues of varying metabolic activity. Mean δ13C in hoof of elk on forested land and grassland were lower than hoof δ13C from elk in the refuge indicating greater long-term consumption of C3 plants by elk on forested land and grassland subpopulations. The δ15N in hoof was greater for elk outside the refuge than that for elk in the refuge. Interaction of sex and subpopulation only occurred for hoof δ15N suggesting that factors such as tissue type, sex, and habitat need to be considered to understand free-ranging ecology of generalist herbivores using stable isotopes. Availability of C3 agricultural crops high in percent nitrogen on a nearly annual basis in a C4-dominated landscape was likely driving differences in tissue δ13C and δ15N among subpopulations of free-ranging elk. An increase in tissue δ15N resulted from an increase in the consumption of higher δ15N in forage for sexes and subpopulations of a free-ranging ungulate in North America but δ15N should be further evaluated as an index of nutrition for subpopulations of generalist herbivores.
All Science Journal Classification (ASJC) codes
- Environmental Chemistry
- Environmental Science(all)
- Inorganic Chemistry