Think Like a Rodent

Features - Focus On Rodent Control

During PCT’s recent Rodent Virtual Conference, Urban Rodentologist Bobby Corrigan said that observing and understanding rodent behavior is the best way to perform rodent control services.

March 12, 2020

Rodent: Envato; ©Rahul |

At PCT’s recent Rodent Virtual Conference, Bobby Corrigan, a consultant and expert in urban rodent control, gave a presentation on his best rodent control practices. Corrigan began by presenting listeners with a simple point: In order to make effective rodent control decisions, pest management professionals need to be able to think like the rodents they deal with every day.


NOTICING RODENT BEHAVIORS. Corrigan stated that there has been an increase in urban rodents on a global scale, and therefore an increase in the rodent control business as well. In the wake of this increase, PCOs need to do everything they can to provide the best rodent control service to their customers, starting with understanding the fundamentals of rodent biology.


“Make no mistake about it, it is biology first and business second,” said Corrigan. “We’re dealing with live animals. All of our pests — cockroaches, bed bugs and so forth — they’re complex animals.”

Working in New York City, Corrigan sees his fair share of rat and mice activity. Whether it is down in the subway or in between alleyways on the street, Corrigan uses his knowledge of rodent behavior to locate where they are hiding and the best places to place baits and traps.

“There’s a whole world of these guys down there. It could be rats. It could be mice. It could be roof rats,” he said. “It’s their world, but we have to go looking for them. We have to be observant, and we have to consider what are their needs and where are they going to be? And where do they like to run with their food sources?”

From noticing the amount of litter on the street to the patterns of urine decorating the sidewalk, there are obvious signs of rodent activity that can be useful for setting up a control plan if one knows where to look.

“If we think like rats and mice — and by the way, of course, they do think — we’re going to be better at our jobs. Our customers are going to be happy with us. We’re going to reduce callbacks. We’re going to be safe to the environment. We’re going to be humane,” Corrigan said. “All of those things are possible. But we have to do this by engaging with the rodents first.”

THE BIG THREE. Corrigan focused on the behaviors of the three primary rodents that PCOs are likely to encounter: the house mouse, the brown rat (Norway rat) and the black rat (roof rat). Thinking like these rodents when on the job, Corrigan has developed tips on how to provide the best control services for each rodent pest.

House Mouse. Corrigan, citing good science, says the house mouse is one of the most common rodents in the world and is the second most successful mammal on earth.

“Biologically speaking, many people think they’re just animals that act by instinct,” Corrigan said. “That’s completely not true. These animals think, they plan. They learn from mistakes. They’re incredibly adaptive to many different situations.”

It was recognizing the intelligent mind of the house mouse that led to Corrigan always asking the same first question when working a mouse control job. “When I go looking for mice inside schools and office buildings and restaurants and houses, the first question that comes to my mind is, ‘Where is the warmth in this building?’”

Throughout his years of experience in the field, Corrigan learned that house mice love warmth, and their intelligent survival instincts mean they often seek a warm place to live and reproduce before they begin the hunt for food.

So instead of looking for mouse droppings or small, tight places first, PCOs should think like a mouse and search for the warm place an infestation of mice are likely to inhabit first in order to find and control the mice quickly and effectively.

Norway Rat/Brown Rat. Next, Corrigan explained the rodent control techniques that should be used when thinking like the brown rat, also known as the Norway rat.

Thinking like a brown rat means studying their biological behaviors and knowing that they love to burrow into the ground and they need lots of food to survive.

In addition to food and burrowing, it is also important to understand the movement behaviors of these rodents to predict where they could be travelling. “These days, we know that in urban environments they’ll go anywhere from 90 to 450 feet easily. No problem. They’ll even disperse and come back,” Corrigan said.

Combined with understanding the biological behavior of both significant amounts of food a night and their burrowing nature, Corrigan said PCOs attempting to control brown rat infestations should begin by searching for areas that contain easily accessible food nearby. “In areas of abundant rats in landscapes, notice how there is no more vegetation growing there, no more bushes,” Corrigan said when showing a picture of a patch of land that had been devastated by an infestation of brown rats. “All the vegetation has been destroyed by the burrowing activities of the rats.”

It is spaces like these, discovered by analyzing the behavior of brown rats, where PCOs should be implementing their control measures to control a brown rat infestation.

Humans have recreated the perfect jungle treetop habitat for roof rats with modern-day commercial ceilings. See the similarities?
Top: Bobby Corrigan; Bottom: © Stéphane Bidouze | AdobeStock

Roof Rat/Black Rat. Corrigan then reviewed the roof rat, commonly known as the black rat. When studying the behavior of this particular species, Corrigan pays attention to the black rat’s tendency to stay away from the ground, whether that means carving out a place in the tops of trees or on someone’s roof. “They’re originally from Southeast Asia, where they lived in jungles and the treetops and in the shadows below those treetop canopies,” he said. “Shadows are the key to great roof rat work.”

He said humans have recreated the perfect jungle treetop habitat for roof rats with modern-day commercial ceilings. They are warm, shadowy, and have pipes and wiring that are perfect for climbing, so the necessary control for roof rats in these places can be difficult.

Thinking like a roof rat that loves to hide in shadowed, elevated areas, Corrigan said a rodent control technician searching for roof rats should first ask, “Where are the shadows?”

“If there are roof rats in an area, they are using those shadows to hide or traveling to them. So by understanding their origins, we understand how to think like them and have a greater role in control,” he said.

Locating these lofty, shadowed areas can lead to quicker discovery of a roof rat infestation. And by understanding roof rat behavior, technicians also will know the best places to position traps and baits, which minimizes wasted resources and time.

BEHAVIOR-BASED CONTROL. Corrigan stressed it is important to realize that thinking like a rodent does not mean just simply putting out equipment every 15 to 25 feet for mice and every 25 to 100 feet for rats. “Anybody can do that,” he said. “Our job as pest professionals is to be those observational biologists and realize there’s a lot going down as to where the rodents use certain spots in our buildings. Those sites are our responsibility for finding and installing equipment. Otherwise, we’re just laying down equipment and hoping for the best.”

One of the most important parts of using an observation and behavior-based approach to rodent control is conducting a proper inspection first in order to determine which spots the rodents are going to encounter the traps, rodenticides and other control measures. PCOs need to analyze rodent behavior,so they can use specific equipment based on the rodents’ movements as opposed to simply spacing out traps and baits and waiting for rodents to find it. “It’s our job to go to them, not for them to come to us,” Corrigan said. “So our equipment is only as good as where we put it.”

Customers want to know that their money and time is being used effectively, and it is the rodent control technician who provides service based on the biological behaviors of rodents that is going to have the right answers for their clients.

The author is a New York City-based writer.