Tracking Cats: Using Stable Isotopes To Geographically Place Mammalian Carnivores

All African felids are considered either vulnerable to extinction or endangered on the IUCN (International Union for Conservation of Nature) Red List. These iconic and charismatic species face many anthropogenic threats which include predator control, loss of habitat or prey, and direct hunting for trophies or curatives. In addition, many species or their parts are also subject to the illegal wildlife trade. For such vulnerable or endangered species, the ability to link individuals to their geographic origin is an important tool for forensic or conservation purposes.

ADVERTISEMENT

One tool that researchers can use to assign organisms to their environment are the ratios of the stable isotopes of hydrogen and oxygen in tissues. Isotopes are variants of elements that vary in the number of neutrons and, thus, mass. The relative distributions of stable-hydrogen and oxygen isotopes do not decay, but instead vary globally in environmental waters. Because H and O in animals are derived to a great extent from water, researchers can measure the stable isotope distribution of these tissues to get an idea of where animals are from. For mammals, the most common tissue used is hair or claws because these tissues are easily sampled and, once formed, are relatively inert and resistant to decay.

Obligate carnivores, such as cats, only eat meat and drink very little water, so it was generally believed their unique physiology obscures any stable isotope patterns. Dogs, on the other hand, are facultative carnivores and, like omnivores such as humans, they readily drink water, and thus a good relationship between the relative hydrogen and oxygen isotope distributions in their hair and environmental water should exist. To test this hypothesis, we measured the hydrogen and oxygen stable isotope ratios in the fur of domestic cats (Felis catus) and dogs (Canis lupus familiaris) in urban animal shelters from different places in North America, and thus, from different environmental H and O stable isotope compositions of water.

We determined that not only did the stable isotope ratios of hydrogen and oxygen of dog fur vary predictably depending where the animals were from but, surprisingly, so did those of cats. The relationship between the isotopic compositions of fur and water in cats was different than that measured in dogs and is likely a result of the obligate carnivore physiology of felids and their water-conserving nature.

Fig 1. Figure 1. One of the cougars (Puma concolor) used in our study.

To be able to apply this to wild carnivores, we also measured samples of wild and captive big cats, such as cougars (Puma concolor – Fig. 1), lions (Panthera leo), tigers (Panthera tigris), and bobcats (Lynx rufus), and wild dogs, such as foxes (Vulpes vulpes), coyotes (Canis latrans), and wolves (Canis lupus). We found that the wild cats and dogs we examined followed the same H and O isotopic trends as their domestic cousins (Figure 2).

ADVERTISEMENT
Figure 2. Relationship between a) cat (F. catus) and b) dog (C. lupus familiaris) hair stable isotopes of hydrogen and oxygen. Also included are wild and captive bobcats, cougars, tigers, lions, coyotes, wolves, and foxes (L. rufus, P. concolor, P. tigris, P. leo, C. latrans, C. lupus, and V. vulpes).

These findings open up new avenues for conservation and forensic tracking of wild cats and dogs. This is important because many of the large mammalian carnivores are currently under threat worldwide and new methods are needed for geographic placement of these taxa and their parts.

These findings are described in the article entitled Tracking cats revisited: Placing terrestrial mammalian carnivores on 未2H and 未18O isoscapes, recently published in the journal PLOS One.

Comments

READ THIS NEXT

How Human Skeletons Are Illuminating Europe鈥檚 Islamic Past

Bioarchaeology, a field that combines the methods of archaeology and biological/physical anthropology, uses archaeological human skeletal remains to better understand […]

The Formal Charge Of NO3- (Nitrate)

Nitrate, chemical formula NO3, has a chemical charge of -1. Ion nitrates have a negative one formal charge. You may […]

An Isothermal Cloud Chamber To Test The Efficiency Of Seeding Agents

Published by Prabhat Kumar Department of Mathematics, MIT World Peace University, Pune, India These findings are described in the article […]

A New Approach For High-Performance K-Ion Batteries

The International Energy Outlook 2016 (IEO 2016) published by the U.S. Energy Information Administration shows that the world’s energy consumption […]

Modified Gloves Can Help To Reduce The Risk Of Hospital-acquired Infections

About two million hospital-acquired infections (HAIs) occur in the US every year, which leads to up to 100,000 annual deaths. […]

Precious Resource Basins: Facilitating Regional Transboundary Cooperation In The Eastern Nile Basin Beyond The River Flow

Cooperation among countries sharing a water basin is often difficult due to historic rivalries, conflict legacies, and the increased utilization […]

Vulnerability Of Antarctic Marine Ecosystem Engineers With Skeletal Magnesium Content In A Changing World

The oceans are being impacted by climate change from rising atmospheric CO2 levels and increasing pollution (e.g. petroleum hydrocarbons and […]

Science Trends is a popular source of science news and education around the world. We cover everything from solar power cell technology to climate change to cancer research. We help hundreds of thousands of people every month learn about the world we live in and the latest scientific breakthroughs. Want to know more?