Wednesday, September 13, 2017

The search for humane rodent control, or, what to do with excess cat fur


rat, humane pest control, rodents, predator scent, rodent control
I recently found this black rat living in a neglected corner of our garden.
What if it were possible to deter unwanted rats and mice using just a scent? Not only would this reduce the deaths of rodents, it may also save the lives of native rats and mice, and reduce the number of accidental poisonings of dogs, cats and other animals with rodenticides.

Miguel Bedoya-Perez is a postdoctoral research associate in behavioural and chemical ecology. In a collaborative project between the School of Psychology and the School of Life and Environmental Sciences, at the University of Sydney, he is exploring the chemical, biological and evolutionary aspect of anti-predator behaviour in introduced and native rodents, in response to predator odours, working under the direction of Professor Iain McGregor.

Dr Bedoya-Perez took some time out of his day to answer our questions.

What’s your day job?

I am postdoctoral research associate in behavioural and chemical ecology at the University of Sydney. My current research focuses in the anti-predator behaviour rodents show when presented with the smell of predators, in particular cats.

What is the aim of your project?

The aim of this project is to isolate, identify and potentially synthesize the molecule, or molecules, in cats’ smell that scare rats, as a non-lethal alternative to poisoned baits for the management of rodents.

Why is there a need for more humane pest control?

Several species of rodents are a recognised world-wide as pests that destroy crops, spread disease and cause enormous damage to infrastructure. It is estimated that 280 million undernourished people worldwide could significantly benefit by reducing the losses in harvest due to rodents. However, these species are also known to develop resistance to many first, second and third generation poisons, making the development of alternative methods of control crucial. In Australia, as well as in other parts of the world, pest rodents can either share their habitat with other native species, or be themselves native species with population explosions caused by particular environmental conditions. Poisons and traps are not target specific, and have the potential to impact these other, sometimes vulnerable, populations. By tapping in the intrinsic fear rodents show for predators, we have the potential to develop a method of control that would be specific for rodents and at the same time non-lethal, reducing the impacts in other species. But also, because this response is evolutionarily stable, shown by laboratory rats that have been bred in captivity for generations and have never being in contact with any predators, there is little chance of development of resistance.

In a nutshell, how do scientists capture and reproduce a smell?

The process of capturing and reproducing the smell is somewhat complicated. But it basically involves acquiring sources of the smell, like fur, or collars, and using chemical procedures to obtain an extract, something no different to getting powdered instant coffee from brewed coffee beans. This extract can then be separated into its individual chemical components and screened to determine which of those components are responsible for inducing the fear response in rats. Once the individual chemical or chemicals are identified, chemists can, depending on the nature of the molecules, replicate the molecule in the lab.

What is the outcome of the research?

The method to use the smell will depend largely on the nature of the chemical and the management target. We need to first understand how stable the molecule is, its shelf life and the best ways for application. A stable long-lived molecule could potentially be added to materials, like the plastic covering of electrical cables or paint use in grain silos. But if the molecule is less stable and short lived, a regularly applied spray or diffuser may prove to be more effective.

What is the most interesting thing you’ve learned about cat fur so far?

I would say, probably the level temporal and individual variability of the fear-inducing odour in cats. Not all cats are scary, and this has nothing to do with breed, sex, age or even environment. We have cats that live in the same house, and are fed the same food, and one cat’s scent is scary while the other’s is not. We also found that some cats are not scary some times of the year, but scary at other times. We have a more questions than answers on why this could be, but we think this may be due to the seasonal shedding of coats from winter to summer, and also the process of domestication of cats.

How can people help with your project?

We are very thankful of all the help that we have received so far from vet clinics, pet groomers and cat owners giving us fur. 

The best way you can help is, if you have a cat, brush it regularly and keep as much fur in as possible in a plastic bag and post it to me within two weeks of collecting it. We are always looking for fur. If you want to offer extra help, add details to the fur sample (cat age, sex, breed, is it desexed or not, is it an indoor or outdoor cat, date of collection, etc.) try to collect all the fur per sample within a day or two, and finally, the more samples we get from the same cat several times over the year, the better.


Thanks Dr Bedoya-Perez for your time. You can follow Dr Bedoya-Perez on twitter @MA_BEDOYAPEREZ, or to donate cat fur, contact him via email at Miguel.bedoyaperez[AT]sydney.edu.au

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