Five Points Small Mammal Blood Plasma Isotopic Values for Carbon, Nitrogen and Hydrogen

There has been little comprehensive research undertaken to quantify
resource use by small mammal communities in a nutrient limited, highly
stochastic ecosystem. The most abundant small mammals in this
ecosystem are Heteromyids, food-caching granivores, and Cricetids,
omnivores that must utilize on board fat stores as energy reserves.
Heteromyid populations co-vary with primary production whereas the
cricetids can forage at multiple trophic levels reducing their
dependence on primary productivity. Using isotopic values for Carbon,
delta13C (a ratio of 13C to 12C), of primary producers consistent
within a photosynthetic pathway, C3 = -26.6 +/- 1.8Permille and C4, =
-14.4 +/- 0.8Permille we can track mouse dietary assimilation of
forage by plant functional type. Nitrogen isotopic values 15N (a
ratio of 15N to 14N) fluctuate constantly, reflecting the landscape of
primary production. Therefore, tracking nitrogen values in small
mammal plasma provides a landscape level tool for studying diet by
trophic level and nutritional value.