For as long as humans and rats have co-existed, humans have tried to exterminate rats, and rats have repeatedly learned to thwart these attempts. Dr. Gerhard J. Gries, a professor in the department of biological sciences at SFU, wants this stand-off with rats to come to an end.
Rats provide a difficult challenge for population control: as a result of interacting with humans for thousands of years, they have developed a healthy dose of fear and apprehension when presented with new objects, called “neophobia.”
Therefore, even with the promise of food, it can be difficult to entice rats into entering traps. As a result, we depend on traps such as poison boxes that are efficient at killing but result in the poisoning of animals that consume rats, including domestic cats and dogs.
The Gries Lab studies the communication systems of animals. “[W]e want to understand how animals, including rodents in this case, communicate and once we understand their language we can talk back and manipulate them to our advantage,” explained Dr. Gries.
Therefore, in order to bypass the rats’ neophobia, the Gries Lab has developed a trap that uses a three-pronged approach to exploit rat senses and communication strategies. The first property of the trap is food bait: the team has developed bait that is laced with odorants so that no matter the rat’s craving — be it nuts, meat, or cheese — it will be emitted from the trap. The food bait is important because its manipulation is necessary to trigger the snap mechanism that results in almost instantaneous death for the rat.
The second tool used to attract rats is the promise of a mate. Male rats mark their territory using urine. This urine contains sex-attractants that lure females and deter males. The Gries Lab isolated these molecules, and by including them in the trap capture 10 times the number of females; however, males will be deterred by their presence, therefore these traps are used only to target females.
Lastly, Dr. Gries and his collaborators created a device that synthetically produces the sounds of rat pups. When mother rats leave their pups alone, they often get cold and express their discomfort by producing short ultrasonic bursts. These were recorded and an algorithm was developed that generates bursts that differ in pitch, intensity, and duration, with intermittent silence between the emissions. Therefore, it is very difficult for the rat to realize that the sounds are artificial.
The next stage in trap development is to make it a multi-killing trap so that it does not have to be serviced after every catch. The team is also looking for a sex-attractant produced by female rats, so that a similar trap can be developed to target males.
As Dr. Gries said, “We have tried to get rid of [rats] for a long, long time.” With his lab’s development of the rat trap, we may be at a new frontier in population management: “It smells like rat, it sounds like rat, it must mean someone is there and it is safe to enter.”