Oxygen isotope composition of North American bobcat (Lynx rufus) and puma (Puma concolor) bone phosphate: implications for provenance and climate reconstruction

Abstract

Feline carnivores are threatened by illegal wildlife trade. Tracing the provenance of unknown felid tissues via stable isotope analysis could provide important information in wildlife crime investigations. The oxygen isotope composition of mammalian skeletal phosphate (δ¹⁸O_p) is widely applied to trace the origin of animal remains and to reconstruct migratory patterns in palaeontological, archaeological, ecological and wildlife forensic applications. Teeth and bones of terrestrial mammals form at constant body temperature in isotope equilibrium with body water, which is predominantly controlled by ingested meteoric water (δ¹⁸O_w) that varies systematically with latitude, altitude and climate. Here we analysed δ¹⁸O_p of 106 North American puma and bobcat bones of known geographic origin to establish the first δ¹⁸O_p−δ¹⁸O_w regression for feline carnivores: δ¹⁸O_p = 0.40(±0.04) * δ¹⁸O_w + 20.10(±0.40) (R² = 0.46, n = 106). This was compared with those from their respective prey species (deer and rabbit), a canid carnivore (fox) and other placental mammals. Effects of species, sex and relative humidity on the feline δ¹⁸O_p−δ¹⁸O_w correlation were analysed and additional intra-individual tissue comparisons (hair δ¹⁸O_h vs. bone δ¹⁸O_p) were performed for some bobcat individuals. Bobcats and pumas exhibited only a moderate δ¹⁸O_p−δ¹⁸O_w correlation, which differed from canid carnivores and other placental mammals. However, feline δ¹⁸O_p values revealed a moderate relation with δ¹⁸O_w, which lacks for the δ¹⁸O_h of hair from the same bobcat individuals. This indicates a difference in oxygen isotope routing from body water to bioapatite and hair. Most herbivores and omnivores track δ¹⁸O_w in their bioapatite δ¹⁸O_p values much better, whereas δ¹⁸O_p and especially δ¹⁸O_h values of feline carnivores are less precise proxies for meteoric water δ¹⁸O_w values and thus for provenance determination in wildlife forensics and palaeoclimate reconstructions. Oxygen isotope fingerprinting of bobcat and puma is biased by factors related to their diet, behaviour and metabolism that need to be better understood.

Keywords:

• bone phosphate
• climate
• drinking water
• feline carnivore
• hair
• isotope ecology
• oxygen-18
• wildlife forensics

Acknowledgements

We thank Robert Fischer and Suzanne C. Peurach from the mammal collection at the Smithsonian Natural History Museum in Washington, DC, Eric A. Rickart from the Utah Museum of Natural History and Bryan T. Hamilton from the Great Basin National Park in Nevada for their assistance with the sample collection. We thank Keith Hobson and Matthew Kohn for discussions. M. Clauss and J. Hummel are kindly acknowledged for information about feline digestive physiology. Bernd Steinhilber, University of Tübingen, is acknowledged for running the TC/EA silver phosphate analyses. The animal symbols used for figures are courtesy of the Integration and Application Network (www.ian.umces.edu/symbols), University of Maryland Center for Environmental Science. Comments of Angela Lamb and an anonymous reviewer helped to improve the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Funding

This work was supported by the Emmy Noether Programm DFG grant TU 148/2-1 to TT. SP was funded by a PROMOS Academic Exchange Grant from the University of Bonn.

Supplemental data

Supplemental data (Appendices 1–4) for this article can be accessed at 10.1080/10256016.2015.1113957.