Rodent Problem in Knysna and surrounds.

I was told that Brenton on Sea is particularly badly affected.  It was alarming to hear that one single household caught and dispose of 51 rodents in one week! The problem of rodent infestation is probably caused by the fire of 2017 when hundreds of snakes were killed. A single rat is capable of consuming up to 10% of its body weight in food each day. Assuming that the average rat weighs 250g, that’s 25g of food every day. These animals will migrate to an easy food source – households.  Droppings and urine can cause  diseases such as leptospirosis, toxoplasmosis and salmonella. It is even thought that rodents might contribute to the spread of foot-and-mouth disease.

Seeing a rat or mouse scurrying across your kitchen floor is never a welcome sight. But, before you shrug it off as a once-off occurrence, consider how many others may be hiding out in your roof or garage. Once they have established a nest in your residence, the reproduction rate of rodents is rapid and can quickly become unmanageable for the average homeowner. Do the (rodent) maths.  The infographic below shows just how one little mouse or rat, if left unchecked, can quickly turn into a full blown infestation. The breeding process begins soon after a male and female come into contact with one another. Depending on the type of rodent – brown rat, black rat, or house mouse – the gestation period can last anywhere between 18 and 22 days, with each litter bearing, on average, six to 12 pups. A single female can resume mating only a few days post-pregnancy and can produce up to 8 litters in a year, with separate litters being birthed within 25 days of each other. If you do the calculations, that roughly translates to about 56 offspring from one female in just a year.

Masters of Concealment: Rodents feed almost exclusively at night, remaining well concealed in dark, enclosed areas like crawlspaces, between walls, in roofs, under porches, or in boxed-in plumbing. They can also fit through surprisingly tiny holes, with smaller rats and mice being able to pass through a space as little as 2cm in diameter – making entry a cinch.

Adapt and Overcome: The only way to discourage rats and mice from taking residence on your property is either to prevent entry or by eliminating the conditions that make it a desirable place to set up shelter.

  • Seal holes inside and outside the home to keep rodents out. This may be as simple as plugging small holes with steel wool, or patching holes in inside or outside walls.
  • Remove potential rodent nesting sites from your property, including leaf piles and deep mulch.
  • Clean up food and water sources in and near your house.
    • Regularly empty the trash and ensure that all bins have a tight-fitted lid
    • Don’t leave pet food sitting out too long
    • Clean up spilled food right away and wash dishes and cooking utensils soon after use.

Essentially, once rodents have chosen your home as their nesting site, there’s a good chance that they’ll start breeding there. Before you know it, one will become many and, if left untreated, could cause big problems for you and your family, from property damage to health issues. Regular inspections in the areas of your home most prone to rodents can prevent a single mouse from turning into dozens of mice in just a few months’ time.

orange tabby staring at grey mouse

In many cases, leaving natural predators to sort out a rodent problem will seldom keep the rodents at an economic population level; they can often reproduce faster than predators can control them, unless predators are in sufficient numbers. There are two exceptions to this – cats and snakes. Not only do cats prey on rodents, their mere presence can act as a deterrent. Snakes are proactive in the control of rodents, eating young and old alike. If you do have snakes in your garden, relocate them to an empty plot, please do not kill them as they are a valuable asset to  control rats and mice.

Methods of control:

Traps and Ultrasonic devices: Mechanical control generally involves the use of spring traps, sticky pads (inhumane) and ultrasonic devices. However, although the latter are marketed as safe, reliable methods of rodent control, most of the scientific literature  says that ultrasonic devices do not work. Experiments have shown that rodents quickly become accustomed to repetitive sounds, a process called habituation. Over time, they realise that the ultrasound is not dangerous and simply ignore it.

Traps have been very successful in Brenton.  Cages can be obtained from Radical Raptors.  Caught rodents can be taken to Raptors or the reptile place near the Crags.

Rodenticides: One of the most common methods of rodent control is the use of rodenticides (poisons). But these can in turn poison domestic pets,  and wildlife such as birds and snakes that may eat the poisoned rodents. So PLEASE resort to alternative methods of control.

Drowning: Death by drowning is no doubt a terrifying way to die, and it takes several minutes to drown a rat. Yet death from rat poison is also cruel and a poisoned rat can take days to die – which is why the NSPCA itself is opposed to the use of poison, including against pests.

Working together

It is important that good management practices also be employed by surrounding neigbours or tenants. Although you may maintain a sanitised area, those around you may not, and there is a tendency for rats and mice to migrate between the two areas. It is therefore worthwhile to work with neighbours to synchronise when areas are being disinfected or cleaned in order to prevent rats or mice moving from one home to the next.