Tracking cats revisited: Placing terrestrial mammalian carnivores on δ2H and δ18O isoscapes.

Geoff Koehler,Keith A Hobson

doi:10.1371/journal.pone.0221876

Abstract

The relationship between hydrogen and oxygen stable isotopic compositions in environmental water and hair was investigated for both domestic cats (Felis catus) and dogs (Canis lupus familiaris). A strong, but different, covariance was measured between the hydrogen and oxygen stable isotopic compositions of local precipitation and hair keratin from both cats and dogs. These isotopic differences are most likely a result of the differences between the dietary and drinking water needs of cats compared to dogs. Moreover, the δ2H and δ18O values of hair from captive and wild felids and canids, such as cougars (Puma concolor), bobcats (Lynx rufus), and wolves (Canis lupus) are broadly consistent with these measurements. This evidence indicates that while the water budgets of terrestrial mammalian carnivores need to be considered in isotopic applications, it is clear that felids and canids may be placed on tissue–specific hydrogen and oxygen isotopic landscapes for ecological, provenance, or forensic studies.

Highlights

Global populations of terrestrial carnivores are increasingly threatened by habitat loss, reduction of prey, and direct hunting by humans for food, traditional curatives, predator control, and trophies [1, 2]
The numbers are shocking, with recent dramatic population and range declines being reported for most wild mammalian carnivores, including such charismatic and iconic species as lions (Panthera leo) [5, 6] and cheetahs (Acinonyx jubatus) [7]
This was the conclusion of Pietsch et al [20] who reported that because of these physiological effects, the hydrogen and oxygen stable isotopic compositions of cougar and bobcat (Lynx rufus) hair in museum specimens had little relationship to those of environmental water and so are not valuable for forensic tracking. Because their conclusion conflicts with other studies [21, 22] and because the use of isotopic methods to elucidate the provenance of carnivores is theoretically strong, we felt that a re-evaluation of the isotopic coupling between mammalian carnivores and environmental water was necessary but using modern unpreserved samples rather than museum specimens. To test this would require an inventory of hair or claw samples from a large number of wild mammalian carnivores from locations that have disparate stable isotopic compositions of environmental water

Summary

Introduction

Global populations of terrestrial carnivores are increasingly threatened by habitat loss, reduction of prey, and direct hunting by humans for food, traditional curatives, predator control, and trophies [1, 2]. This was the conclusion of Pietsch et al [20] who reported that because of these physiological effects, the hydrogen and oxygen stable isotopic compositions of cougar and bobcat (Lynx rufus) hair in museum specimens had little relationship to those of environmental water and so are not valuable for forensic tracking.

Results

Conclusion