Spatial and Temporal Variation in Triglyceride Concentration in the Blood of Nestling Blue Tits Cyanistes Caeruleus
Plasma biochemistry values are useful tools for ecophysiological research of birds and other vertebrates. They provide data on the physiological and nutritional state of individuals in various life stages. We predicted that blood triglyceride levels correlate with nutritional state of birds and that this trait is temporally variable. Therefore, we studied the effects of year and distinct habitat type (urban parkland vs woodland) on triglyceride concentration in the blood of nestling Blue Tits Cyanistes caeruleus. We ascertained both seasonal and inter-habitat variation within the trait. Specifically, (1) nestlings from trophic rich forest site were characterised with significantly higher mean triglyceride levels, and (2) mean triglyceride content was significantly higher in one out of three breeding seasons. These results suggest that the studied trait may be used as a robust indicator of habitat trophic abundance and quality.