THE RELATIONSHIP BETWEEN DRINKING WATER AND THE HYDROGEN AND OXYGEN STABLE ISOTOPE VALUES OF TISSUES IN JAPANESE QUAIL (CORTUNIX JAPONICA)

Developing an understanding of how differences in the dietary ecology and physiology of different species can influence the incorporation of hydrogen and oxygen from resources into consumer tissues is an important factor to consider when designing, or interpreting data from, ecological studies using stable isotope analyses of these elements. Here, we present the results of an experiment designed to examine the relationship between the delta H-2 and delta O-18 of drinking water and the delta H-2 and delta O-18 values of body water, blood plasma, red blood cells, intestine, liver, muscle, and feathers of Japanese Quail (Cortunix japonica). Because Japanese Quail have high drinking-water requirements compared with many other bird species, we hypothesized that the relative contribution of drinking water to tissue delta H-2 and delta O-18 values would be higher than that of bird species with lower drinking-water requirements. Our results demonstrate that the contribution of drinking water to the delta H-2 and delta O-18 values of tissues is generally higher in Japanese Quail than in other birds with lower drinking-water rates. However, we failed to find significant relationships between drinking-water isotope values and tissue isotope values in many of the tissues that we examined. We suspect that this lack of significant relationships is the result of variation in tissue isotope values caused by differences in drinking-water consumption rates among individual birds. Given these results, we recommend that researchers use caution when interpreting data from ecological investigations using delta H-2 and delta O-18 analyses.