Tracing Deuterium through the food web and into Birds and Mammals along an elevational gradient in the Southern Rocky Mountains

Animals incorporate local δ2H values from available water and dietary sources during tissue synthesis, which can provide evidence of elevational movements if multiple tissues with different turnover times are examined. Here we test the applicability of using δ2H as an indicator of altitudinal movements by examining multiple tissues (δ2Hbw (body water), δ2Hfeather, δ2Hfur, and δ2Hclaw) in birds and mammals in the Sangre de Cristo Mountains. Additionally, we measured δ2Hsw (stem water) and insect δ2Hbw and δ2Hwb (whole body) values to assess changes with elevation. We sampled 15 species of birds and two small mammal species along with potential food sources (three plant families and four insect groups) over an ~1200 m elevational gradient. δ2Hsw and δ2Hbw of plants, birds, and mammals decreased with increasing elevation. δ2Hfur, δ2Hfeather, δ2Hclaw, and δ2Hbw of insects did not show any discernable pattern with increasing elevation. Only one animal species, the least chipmunk (Tamias minimus), showed significant decreases in δ2H values with increasing elevation. Additionally, δ2H feather differed based on foraging guild. Other contributing factors such as diet, physiology, ecology, and within site variation may all contribute wide variation in values observed at a specific elevation. Given the amount of variability in each tissue type sampled in this study, we conclude that the use of δ2H for elevational movements will require careful selection of species, tissues, and extensive validation efforts to ensure accuracy of using this technique. Local variability in δ2H among species and tissues needs to be understood in detail before elevational movements can be assessed.BiologyMastersUniversity of New Mexico. Biology Dept.Wolf, BlairWitt, ChristopherNewsome, Set