1. Stable isotopes analysis (SIA) of carbon and nitrogen provides valuable information about trophic interactions and animal feeding habits.
2. We used near-infrared reflectance spectroscopy (NIRS) and support vector machines (SVM) to develop a model for screening isotopic ratios of carbon and nitrogen (δ13C and δ15N) in samples from living animals. We applied this method on dried blood samples from birds previously analysed for δ13C and δ15N to test whether NIRS can be applied to accurately predict isotopic ratios.
3. Our results show a prediction accuracy of NIRS (R2>0.65, RMSEP<0.28) for both δ13C and δ15N, representing a 12% of the measurement range in this study.
4. Our study suggests that NIRS can provide a time- and cost-efficient method to evaluate stable isotope ratios of carbon and nitrogen when substantial differences in δ13C or δ15N are expected, such as when discriminating among different trophic levels in diet.

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