Stable isotopes in cats’ whiskers tell us that domestic cats who hunt tend to leave prey uneaten

by Michael Broad · September 30, 2021

Stable isotopes in hair can reveal dietary protein sources. Scientists from the University of Exeter, UK, trimmed a whisker from each domestic cat participating in their study; once at the start and once at the end of the study. These domestic cats were allowed outside to hunt. They measured the stable isotope ratios in the whiskers. The results showed that about 96% of their diet came from commercially manufactured food provided by their owners. A mere 3-4% of their food came from consuming the animals that they had preyed upon.

Cat with mouse at door locked out as forbidden to bring prey animals in. Photo: u/sesame_cake on Reddit.com.

They concluded that even prolific domestic cat hunters don’t eat much of the prey that they catch. As I have not seen the study itself but I am reading off a report of it, I would suggest that, also, many domestic cats are either not that good at, or not that interested in, hunting when they are outside. My late female cat only caught one mouse all her long life (18 years) and she had no interest in eating it.

They also analysed different measures to stop domestic cats attacking prey including the colourful collar called the Birdsbesafe collar, meat-rich diets, providing food through an interactive puzzle feeder and regular play. They concluded that the Birdsbesafe collar worked and that they consumed fewer birds. I don’t have information about the other methods but presume that they were unsuccessful in stopping hunting.

It’s a known fact that domestic cats hunt instinctively. They do it whether they are hungry or not. It seems that if they aren’t hungry, they simply don’t eat the prey but the animal ends up attacked and killed nonetheless. It is a classic example of surplus killing to capture and store prey to eat later.

Dr. Martina Cecchetti, of the Environment and Sustainability Institute on Exeter’s Penryn Campus in Cornwall, said:

“When food from owners is available, our study shows that cats rely almost entirely on this for nutrition.”

This study probably doesn’t surprise most cat owners. It has always seemed to me that my current male cat hunts prey not for the food but because his DNA has programmed him to do it. He does eat his mice every time. And he mainly catches mice. He doesn’t eat pigeons although he has caught them. There are probably too difficult to eat because of all the feathers. He is well fed with commercial cat food.