Why do rats enter the newly installed bait trays or not?

The time it may take for rats to enter newly installed bait trays in their territory can vary significantly, from a day to weeks or even months, or they may also definitely never investigate this foreign object.

Whether it is early to late depends largely on the stability of the environment. For example, how long have food, water, and shelter been available unchanged over time? Have several generations of rodents been able to grow and thrive in such an environment?

If the environment has been beneficial to the colony and has allowed it to reproduce and raise its offspring successfully, rats may be reluctant to interact with suddenly appearing bait carriers or traps, especially adult females, responsible for breeding. This reluctant behavior is stronger towards unfamiliar objects (baits) than towards new foods.

A world of smells

The odors associated with individual rodents and with the colony in general can play an important role in feeding, social and reproductive behavior. These odors, which often contain pheromones, can also affect rodents’ responses to baits or traps. In studies carried out with  Rattus norvegicus , those bait trays installed in places with the highest level of activity in the colony, and therefore, where rat signals abound (excrement, urine, friction marks, etc.), received the highest amount.

Paths already made

Rattus norvegicus often follows trails left by other rats to find food. In part, this is because these roads are laden with the scent of the colony and family members.

Similarly, whether rats enter the bait rack and eat the bait inside it can be determined by the odors that rats that have been there previously have left in or around the bait rack. This is the same behavior that rodents follow when leaving odors associated with the entrances to their nests and shelters. Odors that may be present in  your stool, urine, and urogenital secretions.

Eat calmly

In general, rats prefer to feed in places in or near a hedge. If they discover a good meal in open, exposed areas, they will likely drag the food out to cover, or into an area they have successfully foraged in the past.

In severe infestations, rats have been observed to feed in groups of up to a dozen or more in the same location. When a large bait rack is installed in the right place, multiple members of a family will enter and feed at the same point.

Some scientists consider it important that adult rodents have space around them while they feed, to facilitate greater ingestion. Some adult rodents, for example, would consume more food if they can “sit” on their haunches and hold the food with their front legs while they eat. This could require about 20 centimeters or more of ceiling space in the bait rack for Rattus norvegicus .

Bobby Corrigan Recommendations 

After years of work dealing with meticulous and difficult-to-control rodents, Corrigan sets out in his article some recommendations, which can help increase the chances that rats and mice will quickly visit bait trays.

The first responds to the principle that “the success of the treatment depends on the accuracy of the previous inspection that we carry out.” Before installing any bait station, it is prudent, both from a service and a business point of view, to analyze the situation first.

Ask yourself questions such as: Where do rodents get their food and water? Where is their shelter? Environmental resources must also be taken into account, such as heat, hiding places (shadows, difficult access through narrow roads) or the tranquility of the environment, as well as the structural elements that these animals prefer, such as holes, nooks and channels.

Once the situation has been studied, the affected areas must be investigated to identify the areas with the highest rodent activity. This is possible by observing signs of active rodents, such as droppings, gnaw marks, hairs, or obvious footpaths where they usually roam. In the areas where these signs are more abundant and concentrated, and especially if they coincide with the environmental resources mentioned above, the chances of success of the bait trolley are much higher.

Another aspect to consider is to locate the bait trays directly next to, but not on top of, actively used trails. Just a few meters away can make the difference between the rats that circulate on the path access and feed on the bait rack or not. Once the baits begin to receive visitors, they should not move even slightly, or make changes to them for the duration of the control period.

To make rats overcome or reduce their aversion or concern to baits, it is important to place them in high activity areas and to pre-prime with familiar foods or to use attractive monitoring baits. Once the location and presence of the stations become familiar to the colony and the rats rapidly ingest the pre-priming food, the bait trays will begin to contain the colony “aroma”. At this time, the pre-bait feeds can be removed and replaced with the toxic bait. Non-toxic monitoring baits, if used, can be kept in place.

Another important point is to inspect for areas that provide hiding places for rodents, such as bushes, piles of garbage or dark corners. Once these locations are detected, inspect for signs of rat activity. If they exist, the place is good to place the bait rack.

Another expert recommendation is to collect fecal remains from the rats that are near the bait rack and place some excrement outside directly at both entrances of the bait rack and also inside it, just after the entrances, on the way to the bait. The same can be done, in situations where rats have nearby burrows in the ground, by collecting soil from the main entrance to their burrowing system and placing it on the ground in front of the two entrances to the bait rack.

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