[Vertebrate Pests] Rodent Whiskers and Control Strategies

You’ve seen it often enough. You install some glue traps for a rodent infestation, and when you check them later, some traps have rodents, some don’t. On the empty traps you often see evidence that a rodent was there, but failed to become captured. For example, we often find rodent hairs, patches of fur or embedded droppings in the trap. Or soil, cardboard, wall insulation or paper has been deliberately dropped or kicked onto the trap by the rodents themselves in their efforts to neutralize the trap’s dangerous sticky surface.

How are rodents capable of doing this? Are they “smart” enough, or specially equipped enough to help them to avoid getting captured in our glue traps? Well, at least with some rodents of a colony, the answer is yes. And new research out of MIT several weeks ago has revealed some amazing insights into this topic.

RODENT VIBRISSAE. As you probably know, rodents are equipped with specialized tactile hairs located around their bodies. The technical term for these hairs is “vibrissae.” In general, the vibrissae enable a rodent to sense and analyze the various types of surfaces and objects that exist around the rodent at a given place and time.

When the vibrissae occur on the body in groups as they do on rodents, they are referred to as “vibrissal apparatus.” Research has shown that different groups of vibrissal apparatus occur at different parts of the body, and each group provides for the rodent different tactile feedback functions.

For example, the vibrissae (often referred to as “whiskers”) located on the rodent’s snout enable them to feel and explore the areas immediately in front and to the sides of them. As a result, rodents can detect and avoid dangerous surfaces and elements. For example, away from our structural environments, rodents need tools to help them avoid naturally occurring dangerous surfaces such as mud and other substrates that may entrap them or slow them down, rendering them more vulnerable to prey. In the rodent’s world, differences of milliseconds in speed mean the difference between escape and life, or capture and death.

To gather such tactile information with the facial whiskers, rats and mice can sweep the facial vibrissae to the front and sides of their heads. But they can also focus a specific whisker on a particular surface to cue for travel orientation. This behavior is similar to how a blind person uses a touch stick to avoid stepping off of curbs or falling into holes, or uses their hands and arms as they move about inside their homes.

Meanwhile, the vibrissae located on the top of a rodent’s head perform a separate function. These vibrissae assist the rodent in locating harborage holes as well as triggering the digging of new burrow holes in areas the rodent detects there is cover or protection for the new burrow entrance. Moreover, in conjunction with other exploratory behaviors, the head vibrissae help the rodent decide whether or not it will be able to squeeze below a particular door, or through some other structural crevice.

NEW RESEARCH. New research out of the Massachusetts Institute of Technology (MIT) by Drs. Jason Ritt and Christopher Moore, published in the journal Neuron earlier this year sheds even more light on the function of rodent vibrissae. And their results are simply stunning.

Ritt and Moore have been able to capture millisecond frames of the highly complex rodent vibrissae movements using a super-high-speed video system developed by Dr. Ritt. In fact, the Ritt Video System captures rodent whisker movements at an unbelievable rate of 3,200 frames per second (fps) — about 100 times faster than the video systems we use at home. They also designed a highly sophisticated computer tracking system to analyze specific frames among the thousands of video data within just one second of data. You can appreciate how amazing this research breakthrough is if you have ever done any video editing. Now consider how much scientific editing time is required at 3,200 fps for just a five-minute video of say, a rat foraging along a city street. Wow!

So these researchers have been able to capture, record and then slow-mo analyze each movement of each rodent’s whiskers. Moore and Ritt refer to these movements as “micromotions.” The micromotions from each whisker are transmitted to the rodent’s brain for processing. “The whiskers of rodents,” Moore states, “are the Mercedes-Benz of high-performance sensory pathways. They are the key to a rat’s perceptions and behavior.” In short, he says, “rodents can detect things with their whiskers that humans cannot see.”

To view some of this research and get an appreciation of the utility of rodent vibrissae, go to www.livescience.com/php/video/player.php?video_id=080226-whiskers.

ON THE JOB. It’s our job as pest professionals to apply the results that new research offers up. (In fact, doing that is an inherent characteristic of a true professional.) A moment of your time watching the video should convince you that when you do a rodent job, it can be a costly mistake (i.e., callbacks, possible cancellation, etc.) to underestimate the capabilities of pest rodents. Anyone can catch the occasional or young rodent in a glue or snap trap. But as pest specialists, we are often hired to manage and eliminate rodent infestations. In the context of your everyday work, infestations are usually comprised of families and colonies of rodents existing within or around your client’s structures.

Our industry experience and field research has taught us that glue traps, compared to other traps and control methods, are not the most effective approach against rats. (Although if carefully and strategically installed based on a thorough inspection for high-activity areas, they can be an effective supplement to a diversified program.)

SUMMARY. We know, and the MIT research further supports, that adult rodents, and at the very least, adult breeding rodents, within established infestations are apt to be much more aware and better equipped than we could have ever imagined. Infestations are not likely to be defeated with mere yardstick service procedures, such as walking around the interior perimeter walls of buildings (e.g., basement warehouses, storerooms) and placing out glue traps every 15 or 25 feet. To be sure, such service can be delivered quickly and inexpensively, and it may look thorough to the average client. But such service doesn’t require a pest professional — only a service person.

A more professional program strategically selects those control devices and procedures that have the best chance of outsmarting these sophisticated mammals. To do this we must also identify points of entry, target potential nesting zones, and analyze the conditions that allowed the rodents to exist and thrive at a particular locale in the first place.

So watch the videos, read the research, and then ask yourself….are my rodent management programs sophisticated enough to match these animals? As Dr. Moore has stated, rodents’ whiskers are the “Mercedes-Benz of high-performance sensory pathways.” In the same way, pest management companies that keep abreast of scientific research from universities around the world and implement the results into their operations are the Mercedes-Benz of high-performance companies in our industry.

The author is president of RMC Consulting, Richmond, Ind.