A few things to consider when using poison as a control method for rodent infestations.

“If you put one gallon of petrol in a car it will of course work, however you won’t be able to drive 500 miles in it”

The same applies to rodent baiting, you need to ensure that you are putting down the correct amount of poison to gain control, suppress and then eradicate the population. To ensure that you are following a rodent baiting strategy tailored to your circumstance there are a few key considerations to make on which this article will seek to provide a brief overview;

Pre-treatment Population Numbers:

“Always assume there are more rodents than you expect”

As rodents are primarily nocturnal animals with their nests or burrows being hard to locate, determining the population numbers can prove rather difficult. But there are a few key signs to bear in mind when estimating rodent numbers.

1). Have you seen rodents during the day time?

As rodents a primarily nocturnal creatures seeing them during the day time is often an indicator of an established medium to large infestation.

2). Have you seen rodents moving across open spaces?

The eye sight of rodents is poor, as such they feel their way along using their whiskers. Seeing a rodent move across an open space can mean two things, either A). They are moving across the open space for a food source, such as bird feed left in the centre of the garden or B). Another rat/mouse was in their route of travel and they have sought an alternate run to avoid this rodent.

3). Have you found any dropping sites?

The brown rat will leave between 40-50 droppings per day, generally found in groups. The house mouse will leave between 70-150 droppings per day. Mice are largely incontinent so these can be widely spread. The number and frequency of droppings can be an indicator of population numbers.

4). How long have you noticed rodent activity?

Balance this against the breeding cycle information included below, assume that the rodent you have previously seen will be breeding and map out the maximum potential population level to give you an idea on the worst case scenario.

5). what commercial sites are in the near vicinity?

The availability of food sources is a key priority determining areas of rodent activity, if you property is near a commercial food products or distribution premises, a farm or area of waste disposal there is a high likely hood that rodent population levels will be high.

You first Aim: beating the breeding cycle

The Brown Rat ’Rattus  Norvegicus’ can breed throughout the year, producing up to five litters a year with each litter numbering up to 14, within five weeks they can reach sexual maturity and continue the breeding cycle.

In a 26 week cycle for one rat, in 10.4 weeks it could product a litter of 14, assuming half of all newborns are female, 7 of these would then reach sexual maturity within five weeks, in the 10.4 weeks following which they too would litter up to 98 young, alongside this the original rat will have had another litter of 14. Thus at the end of the 26 week cycle you would have 14 female rats ready to breed, 49 female rats beginning the 5 week run to sexual maturity, and the original female rat half way through the 10.4 week breeding period and 63 active male rats.

The house mouse ‘Mus Musculus’ can also breed throughout the year, producing up to eight litters, each litter can number up to 16 and within 12 weeks reach sexual maturity.

In a 26 week cycle for one mouse, in 6.5 weeks it would product its first littler of 16, assuming half of all newborns are female, 8 of these would then begin their 12 weeks of sexual maturing, the following 6.5 weeks they would have their first litters number a total of 128. The original mouse would also produce three more litters during the 26 week cycle. Thus at the end of the 26 week cycle, you could have 16 female mice starting the breeding cycle, 72 female mice beginning their 12 week sexual maturity cycle and 8 female mice with 6 weeks left until they can breed and 96 male mice.

The above examples display the maximum potential for breeding for the two rodent types, there are obviously factors affecting their reproduction, availability of food, shelter and mortality rates. However the above gives a good indication that if left unchecked what starts as a small rodent infestation can quickly grow in to an established, large, widespread and active problem. As such within the first two weeks you should aim to be killing more rats/mice than those reaching sexual maturity. By doing this you will start to supress the population. After you have accomplished this you will want to maintain the pressure with an aggressive baiting strategy, once the breeding cycle has been beaten the process is much like a boulder rolling down a hill, you need to keep the momentum until it reaches the bottom and you have reach eradication.