Tracking food choice via feces – novel applications of FTIR

Studies on the foraging ecology of wildlife species are of fundamental interest as foraging of animals is closely linked to major ecological issues such as resource partitioning and population dynamics.Wildlife species in alpine ecosystems are potentially vulnerable to ongoing climate change, which is among others predicted to reduce both the availability and palatability of many plants. As particular plant parts and their quality might distinctly drive population dynamics of herbivore species, there is a need for methods that can assess both diet composition and quality at different spatial and temporal scales. FTIR is a well-established analytical technique to determine chemical and physio-chemical properties of a wide range of biomaterials. Analyses of feces with FTIR hold a clear advantage to DNA metabarcoding approaches by supporting the determination of specific parts of a plant or phytochemical composition. For this purpose, we will use samples of paired crop, gizzard and fecal droppings from individual wild birds to validate spectral correlations of undigested, mechanically digested and fully digested plant material that represents natural variation in the foraging ecology of grouse species. In addition, we will conduct feeding experiments with captive birds and fecal analyses to validate spectral correlations between undigested plant material and digested plant material. In parallel, we will apply traditional microscopic methods and use DNA metabarcoding to calibrate FTIR for qualitative analyses.