Carbon and nitrogen stable isotopic offsets between diet and hair/feces in captive orangutans

Estimating stable isotopic offset values is crucial for dietary reconstructions. Although research into stable isotope ecology of wild nonhuman primates is increasing overall, only a minority of studies involve laboratory experiments. This study is the first to report the carbon and nitrogen stable...

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Bibliographic Details
Published in:Primates 2021-11, Vol.62 (6), p.945-954
Main Authors: Tsutaya, Takumi, Ogawa, Nanako O., Nomura, Toshiya, Shimizu, Mika, Ohkouchi, Naohiko, Kuze, Noko
Format: Article
Language:English
Subjects:
Animal Ecology
Behavioral Sciences
Biomedical and Life Sciences
Carbon
Confidence intervals
Diet
Endangered species
Ethanol
Evolutionary Biology
Feces
Food
Hair
Isotope ratios
Life Sciences
Monkeys & apes
Monte Carlo simulation
Nitrogen
Nitrogen isotopes
Orangutans
Original Article
Pongo pygmaeus
Stable isotopes
Zoology
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Summary:Estimating stable isotopic offset values is crucial for dietary reconstructions. Although research into stable isotope ecology of wild nonhuman primates is increasing overall, only a minority of studies involve laboratory experiments. This study is the first to report the carbon and nitrogen stable isotopic offset values in hair and feces of orangutans. During an experiment lasting 1 week, the weight of each consumed food item was recorded for each of six captive Bornean orangutan ( Pongo pygmaeus ) individuals. The food, hair, and fecal samples were collected for a few days, and their stable carbon and nitrogen isotope ratios were measured using an elemental analyzer/isotope ratio mass spectrometer. Subsamples of feces were treated with ethanol during the preservation process. Monte Carlo analyses showed that the 95% confidence intervals (CIs) of the carbon and nitrogen offset values between hair and diet were +0.9‰ to +3.9‰ and +2.3‰ to +4.5‰, respectively. The 95% CIs of the carbon and nitrogen offset values between feces and diet were −3.7‰ to −0.9‰ and +0.3‰ to +2.7 ‰ , respectively. The effect of ethanol treatment on the stable isotope ratios of feces was unclear and inconclusive. The computed offset values of hair in captive orangutans are similar to those reported in other nonhuman primates, although those of feces showed greater interspecies variations. The offset values estimated in this study contribute to isotopic studies into the feeding ecology of free-ranging orangutans who are critically endangered in most wild settings.
ISSN:0032-8332
1610-7365
DOI:10.1007/s10329-021-00940-8