Linking environmental indicators to blood, feather and claw δ18O in the Saffron Finch (Sicalis flaveola) in the central Brazilian savannas
2022
Costa, Fábio José Viana | Hobson, Keith A. | Wunder, Michael B. | Nardoto, Gabriela Bielefeld
Understanding linkages between biotic and abiotic processes operating in highly seasonal environments such as the Savannas in the Neotropics is tremendously challenging but has been aided considerably through biogeochemical markers. Stable isotope ratios have been widely used as spatial and temporal integrative markers, signaling environmental information. Our objective in this study was to examine the relationship of tissue δ¹⁸O and environmental factors and among multiple tissues in Saffron Finches, since this species is primary resident and abundant in the region. We conducted this study in a private farm in the central Brazilian savannas. We sampled 194 individuals in seven field samplings between January 2017 and March 2018. We collected whole blood, feathers and claws and analyzed them for δ¹⁸O in both the yellow (YEL) and dull (DULL) plumage categories. We built different sets of environmental variables as predictors of blood δ¹⁸O. Median blood δ¹⁸O varied widely throughout the year (13.4–18.8 ‰), differing in most pairwise comparison of months. Primary and tail feathers for both categories showed narrower isotopic median ranges compared to blood. Claw δ¹⁸O showed smaller isotopic ratio variation than the other tissues. Our results showed that δ¹⁸O values in avian blood are related to local climatic variables and reflect changes through time. The amount of precipitation, humidity and temperature were the most important environmental predictors. Therefore, the use of δ¹⁸O in different avian tissues could be used as a proxy to infer different environmental and ecological aspects related to the Saffron Finch.
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