Very little is known about the behaviours of rodents in urban settings because people don’t want to live near them. As soon as a homeowner finds rats or mice on their property, they get rid of them. The problem with this routine is that it inhibits progress. What can we learn from rodents? Why do they break into our homes, and how do they behave? This information could be extremely useful for pest control professionals.
One of our technicians, Luigi Richardson, took it upon himself to study the rodents in his backyard – mice and voles specifically. What he found may come as a surprise to those dealing with rodent problems.
If you want to know more, you can read the study here.
The intentions of this study were as follows:
- To determine if small rodents share a preference for certain bait station styles (entry designs, bait placement, etc.).
- To determine if small rodents prefer certain feeding locations (alongside fences, foundations, brick faces, under cover, or out in the open).
- To determine if temperature influences rodent feeding.
- To determine if rodents remember bait stations or locations where they have previously fed and return to them, leaving droppings behind when there is no bait present.
- To determine if there is a correlation between rodent feeding and the number of droppings left inside a bait station.
In this study, the technician used 7 different bait stations, of which 3 different styles were selected:
- Previously used, patio-stone style station (a station that has previously been used with rodenticide, mounted on a heavy patio stone).
- New, patio stone style station (a station mounted on a heavy patio stone, never before used).
- New, ramp style station (a station with an internally weighted system, with a staircase or “ramp” to allow rodents to access the bait inside).
The stations were placed in 7 different locations around Luigi’s home. 2 stations were placed on the sides of his home, 4 were placed along the fence of his yard, and one was place in the middle of the yard, on the grass. See Figure 1 below for exact locations.
Following the first 6 weeks of the study, the stations were rotated in a clockwise manner, every 2 weeks, to observe the differences between station and location.
Every bait station contained a single block of non-toxic UV glowing bait, which was removed every week for weighing. Every week of feeding was followed by a week in which the bait stations were left empty. Droppings were also counted and collected at the end of every week.
The purpose of the UV glowing bait was to be able to see rodent trails and droppings more clearly, under a black light. The study took place between December 1, 2020, and lasted for 21 weeks, ending in April 2021.
A total of 709.78 grams of bait were consumed, and 1,949 droppings were found inside the bait stations. The highest levels of feeding occurred during week 12 (February 13 to 19), in all stations and locations combined. Week 10 (January 30 to February 5) yielded the highest number of droppings.
The most popular bait station style was the new, ramp style station, and the preferred location was area #7. The location with the highest number of droppings was location #4. Absolutely no feeding and no droppings were recorded in locations 1, 2, and 5. The rodents avoided the walls of the home and the middle of the yard. While location #7 was favoured, bait station design had no statistically significant impact on rodent feeding or droppings.
No correlation was found between temperature and rodent feeding levels. The rodents fed throughout the study and returned to the stations during “off-weeks” when there was no bait. The highest amount of feeding occurred in mid-February, going against the common belief that rodents are less active in winter.
A direct correlation was found between the number of droppings present and the amount of feeding that occurred. Pearson’s correlation (r) was calculated using Excel at 0.805, indicating that the number of droppings in each station was directly proportional to the amount of bait consumed.
So, what does this all mean? Here’s how the results of our study can be applied:
- Location matters
Bait stations work best in the yard, along the edges of the property. More emphasis should therefore be placed on treating for rodents out in the yard, along the fence, a few feet away from the home. Putting bait stations in the right spots will confirm the presence of rodents and ensure that they are being targeted.
While it must be investigated further, our findings go against the traditional placement of bait stations along the exterior walls of the home. It could be that rodents prefer to avoid human activity and feel safer along the outskirts of the yard.
2. Rodents eat year-round
Exterior rodent problems should be treated for year-round. If feeding decreases, don’t stop! Rodents are active all year long and they are always hungry. Indoor infestations can be solved, but those on the exterior can go on indefinitely. Rodent colonies may absolutely resurface when treatment stops. Neighbouring colonies may expand into the yard and surviving rodents can repopulate the area.
If there are rodents on your property, use caution and continue to replenish your bait stations throughout the changes in season. Continued treatment will keep the rodents at bay.
3. Feces can be used to identify feeding areas
When investigating rodent problems, technicians can use the droppings present to determine prominent feeding areas. Finding a part of the home that is covered in feces, for example, may indicate that there is a food source nearby, which should be replaced with bait.
This is due to the link between feeding and droppings. The droppings found inside the study’s bait stations were proportional to the amount of bait consumed. While it is obvious that rodents defecate more after eating more food, this suggests that the rodents felt comfortable enough to stay in the stations for extended periods. Prior studies have also shown that rodents use their droppings to signal that an area is safe. These findings may be useful for integrated pest management.
4. Rodent populations can be monitored
Pest control professionals can estimate rodent populations by monitoring bait station activity. Every month, they can record the amounts of bait being eaten, or the number of feces being left behind, and use these numbers to calculate a change in population. Here’s the formula:
Monthly Population Estimate =
(Total food consumption or droppings per month / Total food consumption or droppings during the year) x 100
This calculates a percentage of the year’s activity. By adding up the totals as the year progresses, we can get an idea of what’s going on every month and when the rodent population is at its highest. In our study, we found that the majority of bait consumption occurred in February.
Given that the rodents in the study continued to eat bait throughout the year, regardless of temperature, one can assume that a change in consumption reflects a change in population. The correlation between feces and consumption would also allow a technician to use feces instead of food.
The same logic can be applied in the shorter term, using this formula:
(Total food consumption or droppings this month / Total food consumption or droppings last month) – 1
By comparing the feeding or dropping levels in one period with the last, a technician can estimate a change in population. For example, if 200g of bait were consumed this month, while 250 were consumed last month, one can imagine that the rodent population decreased by 20% ([200/250] – 1 = – 0.2). These formulas can provide technicians with numerical evidence that their stations are working.
While this study answers some questions, it demonstrates the need for more research. Rodents do have preferences with regards to bait station location and they will come back for more, but more information is needed to understand the differences between rodent species and why more droppings were found in some stations than others. Continued research in a variety of different settings may further prove or disprove this study’s findings.
If you are currently facing a rodent problem on your property, reach out to the professionals at The Exterminators. Our technicians go the extra mile. We are a team of trained, licensed, and insured professionals dedicated to solving the toughest of pest-related issues. We work hard for your peace mind. So, leave the problem to us. Call The Exterminators for guaranteed rodent control.