Rat Pest Control – Trapping Rats

The first step in rat pest control is to understand your foe; simply putting down a rat killer or rat poison is unlikely to solve your problem. Rat pest control can be a very straightforward procedure as long as you fully understand the behavioural traits of the rats. We receive far too many emails from people who have used a rat killer poison only to discover that they subsequently end up with a rotting corpse under their floor boards. By reading the following we hope you will become a mini expert on rats. This section has been written for us by Ed Allen who is regarded as one of the worlds experts on rat pest control.

Introduction

The brown or common rat has been living in Britain since around the early 18th century having been brought in via shipping from Russia. The human population has increased considerably since those times and, not surprisingly, so has the rat population as it is one of the three "commensal" rodents in the UK. Commensal literally means living off the table of man and there is not a better example of an animal than a rat in showing us how to adapt to exploit the food we store and waste. When rats do come into contact with man our first instinct is to carry out rat pest control with little or no knowledge of what we are doing.

Common rats are never far from human habitation so if you have recently seen one in or near your property then it is likely to be living nearby and is searching for food. It won't be alone either. Rats seldom live alone unless a young male has decided to seek a new colony.

Species of Rats

In the UK we are reasonably fortunate in that we only have one species of rat, though it may be found in many different environments. This was not always the case. Years ago we also had the black or ship rat, which in fact had been in the UK previous to the arrival of the common rat. The ship rat probably originated in Southeast Asia and was thought not to have reached Western Europe until the Middle Ages, possibly returning with the Crusaders. However remains have been discovered in Roman deposits in York and London dating back to the 3rd and 4th centuries.

Although once the dominant rat species in this country, it is now rare and confined mainly to port areas in Tilbury, Liverpool and Avonmouth. It may be found very occasionally in some inland towns, especially those linked to ports by canals.

The brown rat The ship rat

The brown rat (Rattus norvegicus) typically is brownish-grey on the back and grey underneath. It is a muscular animal with small eyes and ears and a tail around the same length as its body. Despite its scientific name it did not originate in Norway, more likely specimens from Norway were used when the naming of species occurred.

The ship rat (Rattus rattus) is typically darker in colour and is a more slender animal with large ears and bright bulging eyes and a tail much longer then the body. It is more agile and in buildings is commonly found in the upper storeys or roof. You may remember from your history lessons that the plague was prevalent in Britain in the 1600s and it was the black rat that was responsible for the spread (with the help of the tropical rat flea of course).

Do not rely on colour though. There are always exceptions and there are some brown rats that can look black and some black rats that look much lighter.

Both species of rats are part of a larger group of mammals known as rodents of which there are over 2,700 different species throughout the world. In the UK there are 14 species which include voles, dormice, squirrels, and of course mice. The word rodent is derived from the Latin verb rodere which translates into English as to gnaw. Rodents do not just gnaw for the sake of doing it. They have to continually wear down their paired incisor teeth. Their incisor teeth have only one side covered with enamel and they continue to grow. This growth in rats can be 5 inches per annum, therefore the gnawing keeps these teeth at a reasonable length but because of the one-sided enamel covering also keeps them sharp.

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Why Pest Control For Rats?

You might think that rats living outdoors are unlikely to cause us problems and therefore could be left alone. This could not be further from the truth. Rats can cause us many serious problems.

The most serious problem is disease and the most serious disease is Weils Disease or Leptospirosis. This is a fatal disease transmitted by rats to humans (and other animals) via bacteria in the rats’ urine. The rats themselves are unaffected by the disease but if the bacteria manage to get into your bloodstream then the resulting infection can be fatal if not recognised. The worrying aspect is that if the rats urinate in a damp area (long grass, around or in a pond) then the bacteria can remain active for up to a month after. The way you can get the bacteria into your bloodstream is via cuts or even ingestion by not washing your hands properly. There has even been a case where the bacteria were transferred by drinking from a contaminated bottle of lager!

Rats can also transmit other diseases to humans including Salmonellosis, rat-bite fever, listeria, toxoplasmosis and toxacaria.

Rats can also cause significant problems by gnawing some quite solid and tough objects. Their teeth are very hard and slightly curved enabling them to exert a pressure of 7,000psi. This means they can chew through soft metals such as lead and aluminium as well as thick wood and even breeze blocks. If they get into buildings then electrical wiring can be damaged leading to fire risks.

The majority of people find the nearby presence of rats disgusting and even frightening and hearing them scurrying within a cavity wall or loft at night can cause a great deal of stress and anxiety. This stress and anxiety is often repeated when their rat pest control efforts have involved the use of rat killer or rat poison only to be left with the foul stench of a rotting rat carcass in a wall or ceiling cavity.

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Senses

Rats are mostly nocturnal and so their sight is generally poor and they are almost certainly colour-blind. Their senses of touch and smell are very well developed and they use these senses to recognise landmarks in their environment, to detect other members of their colony and to be alerted to danger. Their hearing is acute and they can detect ultrasonic noises. They are sensitive to any sudden noise which can lead to instant flight. They also communicate in ultrasounds.

Rats are Neophobic which means they are naturally wary of new objects. This may cause problems later on when you lay your traps for the first time. The traps will be new objects to the rats and so their instinct will be to ignore them for a time (maybe as long as one to two weeks). This is normal and you must not be despondent if you do not catch your rat immediately. With rat trapping, patience is the order of the day.

Activity and Behaviour

The movements of rats are mainly nocturnal and normal activity is at a minimum during daylight hours. The two peak periods of activity generally follow the onset of darkness and precede sunrise and coincide with the period of greatest food consumption. However, when food is scarce or when populations are dense and subject to little disturbance rodents may be seen during the daytime. Their feeding patterns and other activities can also change according to local circumstances and will be affected, for example, by shift work in factories.

In situations where food and harbourage are adequate, rats tend to have a restricted home range (area of normal movement) and follow regular routes. Their ranges tend to be smallest when they are living in areas such as food stores, where food and cover are generally abundant.

Rats tend to live close to their food source if possible so that extensive daily movements are unnecessary. However, regular journeys of more than one kilometre have been recorded on farmland when the rats usually kept to the shelter of hedgerows.

Generally, unlike rats that are wary of anything new, mice are inquisitive and investigate anything new in their area. We will use this fact later on when we set about trapping the animals.

Rat colonies typically develop from a pair or a single pregnant female. The animals within a colony will be able to recognise each other and behave socially with each other. The territory of a rodent colony is an area that is smaller than its home range and is defended by members of that colony. Any intruders into the territory are repelled vigorously and may even be killed. Defendable sites may be the only ones that can be used successfully for raising young and can be the limiting factor for population numbers in a particular area.

A dominance structure develops as population density increases. High-ranking individuals usually occupy favoured positions close to a food source. Low-ranking members of a colony may be allowed to feed only while dominants are inactive, for example, during daylight. Male rats will also compete to gain access to a receptive female - the stronger, more vigorous males copulating with the female.

This dominance may extend to trapping where sub-dominant animals may be reluctant to enter traps where a more dominant rat has previously entered.

Rats generally are poorer climbers than mice or even ship rats but are more cunning in the ways they gain access to buildings. They often use vegetation on or near buildings to enter buildings or even use a down pipe as a back rest to climb between the wall and the pipe.

Rat climbing up a wall using the drain pipe for support

They commonly enter under doors if the gap is 15mm or more.

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Feeding

Rats are omnivorous and can adapt to feed on a wide range of different foods. They can even be carnivores and commonly kill other small animals or nesting birds for food. In private gardens they are often attracted to bird tables and can be seen below them feeding off the scraps that the birds drop. If you feed birds, then do not put out too much food or rats can soon be attracted to your garden.

Another common source of food is that in compost heaps where a variety of household and garden waste can provide adequate nourishment for a colony of rats. Often they set up home within the compost heap or bin itself! The popularity of wooden decking outside houses is also ideal for rats as the area under the decking provide ideal harbourage and food dropping from outdoor meals through the gaps can also provide the nourishment.

On arable land, rats attack growing cereals and root crops and brassicas may also be eaten in the absence of more sustaining food. Weed seeds are also taken. Urban rats can obtain much food from garbage. Sometimes, unusual substances such as soap, glue, plaster and putty are eaten and this may be reflected in the colour of their droppings. Rats will eat around 25-25g of food per day. They also need a free water supply and, like us, need to drink daily. Needless to say, ponds, dripping taps, bird baths and water butts can all supply their requirements.

Breeding

Rats can breed even more efficiently than rabbits and sizeable infestations can develop very quickly from a single pair.

Conditions that suit a rapid population increase are even temperatures, surplus food with adequate water and undisturbed cover for rearing young and escaping from enemies. Under these optimum conditions rats may breed throughout the year. In less favourable habitats commensal rodent breeding takes place mainly in the summer and autumn.

Rats can breed at around 3 months old and rats on average can produce 6-8 litters per year of around 6-11 per litter. These are weaned at 1 month.

In the wild rats rarely live beyond a year though in captivity 2-3 years is not unusual.

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Detecting Rats

You may have seen a rat in the garden but are now unsure what to do. You need to carry out some detective work to establish where it is living, where it is feeding and the route it takes from getting from one area to another. This is important when we come to set the traps. Unfortunately all these areas may not be on your property as we know they do travel to find food.

If you have time quietly positioning yourself in a suitable position and watching at dusk or dawn may give you some information on the regular routine of the rats (they will have a routine).

The use of fluorescent tracking dust can be extremely useful in detecting rat activity. Apply small patches in suspect areas and then inspect the next day using a UV torch in the dark. The effect is remarkable if not somewhat alarming when you discover how active rats can be during the night. This can confirm entry points to outbuildings or the main house. If dry, you can use the tracking dust outdoors say by a hole in a fence where you suspect them to be coming into your property.

Rats will also leave droppings which can be seen in buildings or smear marks where they continually use the same entrances and exits.

Rat droppings Smear mark around door frame

Remember never handle rat droppings as they could contain disease organisms. Always wear disposable gloves and wash your hands thoroughly,
Clean surfaces with Professional Rodent Germ Clear Spray

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Trapping Rats

You have decided that your preferred method of rat pest control is to trap your rats rather than use rat killer poison. Poisoning can be an effective way of dealing with rat infestations but it does have its drawbacks particularly in domestic properties where the presence of children and pets can conflict with rat poisons. You also have no control over where the poisoned rat will eventually die and this can lead to unpleasant odour whilst an irretrievable rodent slowly decomposes. Trapping allows you to remove the animal well away from your property so you know it has gone.

Using the knowledge you gained during your rat detection exercise, you need to place your rat trap(s) in the areas where the rats were found to be moving. Ideally they should be placed between where they are living and where they are feeding along the routes they use. They are creatures of habits so will use the same routes every night. The more traps you can lay they more chance you will have of catching the animals. Again remember if the dominant male visits your one and only trap the other rats in his group will avoid it.

Remember Neophobia? You are placing new objects so the rats will avoid them to start with. It is recommended that you place the traps set in the open position at first and then ignore them for a few days or a week. This will allow the rats to get used to these "new objects" and even go in and out of them safely. Then set them to catch and do not move them if you are unsuccessful. An old object becomes a new one if you move it.

Enticing the rats into the traps can be assisted by the use of baits and rats are interested in anything tasty. Chocolate biscuits, fruit or even meat can all help to attract the rats in, though if you have found they have a particular fancy to a particular food (bird food?) then use that.

single rat trap multi rat trap

Check your traps regularly (at least once per day and preferably twice). If you are away for a weekend or a holiday, do not set the trap but leave it in position tied open so the animals get used to going in and out. This may increase your trapping success when you return.

Once you have caught a rat if you cannot bring yourself to kill it humanely you will need to take it up to a minimum of 2 miles away to ensure it will not return. Try to find a place where there is likely to be food and shelter e.g. a thick hedgerow would be good. Release it carefully so has not to harm it and to give it a fighting chance of survival.

Remember that as far as rat pest control goes it is illegal to drown a trapped rat or to treat it inhumanely. If you cannot deal with it humanely then release it.

What to do after?

Once you have managed to resolve your infestation there are a number of measures you can take to reduce the chances of further problems. The rats have exploited your property because they see it as a place that they feel safe and that provides them with their basic requirements. If it has gained access to buildings then identify the entry points. Typical ones are through airbricks, gaps under doors or in doorframes, through gaps in the eaves (they will climb up vegetation) or up the wall using a drain pipe as a back support and other defects including drains and sewers. These areas can be proofed to stop further entry. Airbricks can be fitted with framed mesh and the bottom of ill fitting doors can be proofed with bristle strips and the bottom of drain pipes can be covered with rat deterrent drain pipe guards.

Remember - rats have strong teeth so the materials you use to proof these areas must be strong enough to deter them.

Denying access to food can also help in reducing future infestations. Keeping bird and pet food in containers can help and do not over feed the wild birds. Examine your composting system to see if you can discourage future rat infestations and fit removable panels to decking so that the areas underneath can be examined.

In order to be successful rats need a place to live and breed which is safe from predators and has an ample food supply. If you can deny them access to any of these vital requirements you will go a long way to not having this problem again.

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