Abstract:
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Diet to tissue discrimination factors for the blood and feathers of the monk parakeet (Myiopsitta monachus)
and the ring–necked parakeet (Psittacula krameri). Stable isotope analyses (SIAs) have been widely used in
recent years to infer the diet of many species. This isotopic approach requires using diet to tissue discrimination
factors (DTDFs) for each prey type and predator tissue, i.e., to determine the difference between the isotopic
composition of the predator tissues and the different prey that conform its diet. Information on DTDF values
in Psittaciformes is scarce. The aim of this study was to assess DTDF values for the carbon and nitrogen
isotopes of the monk parakeet (Myiopsitta monachus) and the ring–necked parakeet (Psittacula krameri), two
invasive alien species of concern. We fed captive birds of the two parakeet species on a single–species diet
based on sunflower seeds to establish the DTDFs for the blood and feathers. In the monk parakeet (N = 9)
DTDFs were Δδ13C 2.14‰ ± 0.90 and Δδ15N 3.21‰ ± 0.75 for the blood, and Δδ13C 3.97‰ ± 0.90 and Δδ15N
3.67‰ ± 0.74 for the feathers. In the ring–necked parakeet (N = 9), the DTDFs were Δδ13C (‰) 2.58 ± 0.90
and Δδ15N (‰) 2.35 ± 0.78 for the blood, and Δδ13C 3.64‰ ± 0.98 and Δδ15N 4.10‰ ± 1.84 for the feathers.
DTDF values for the ring–necked parakeet blood were significantly higher than those for the monk parakeet
blood. No difference was found between the two species in the DTDF for feathers. Our findings provide the
first values of DTDFs for blood and feathers in these parakeets, factors that are key to infer the diet of these
species based on SIA.
Key words: Stable isotopes, Parrots, Captive birds, Control diet, Invasive species |