Why are Brown Rats such a successful species?

An overview of the Brown Rat (Rattus Norvegieus) including characteristics, habitat, signs of an infestation and how to prevent brown rats becoming a pest issue. I will also be covering why Brown rats are such as successful species. 

Brown rats, also known as Norway rats (Rattus norvegicus), first arrived in the UK during the 18^th century, many sources suggest they were first recorded as early as 1720. It is believed brown rats first arrived in the UK on timber ships from the Baltic or Russia. Some 18^th century accounts incorrectly suggested that brown rats arrived from Norway, and this is why they were given the name Norway rat. Brown rats originated from Central Asia and China and they travelled through Europe via shipping routes before reaching the UK. Before Brown rats arrived, Black Rats (Rattus Rattus) were the only species of rat in the UK, however the Brown rats superior size and adaptability resulted in them quickly replacing black rats as the most common and widespread species. Black rats are now rare in the UK and are restricted to specific locations in port cities such as Bristol and London in dockland warehouses and coastal towns. It is estimated that the population of black rats in the UK is as low as 1300-1500 individuals.  

Where are Brown rats found? 

Brown rats can be found in almost any environment where they have access to a food and water supply. Their ability to dig extensive burrow systems allows them to create safe living areas in almost any environment. Their burrows are usually found within close proximity to food and water sources as this allows them to go out to forage whilst also being able to quickly retreat to the safety of their burrows if any threats arise. As well as living in burrows, brown rats can also live practically anywhere that provides them with cover and shelter such as in sheds, buildings, wall cavities, loft spaces, underneath stacked items such as wooden pallets etc. Another environment brown rats can thrive in is drains and sewer systems. It is well known that brown rats commonly reside within sewer systems which they used for shelter and as underground highways to travel around. Sewer and drains provide brown rats with everything they need to survive in the form of shelter and protection, water and food sources such as fat, waste food items and they will even feed on faecal matter within the drains. It is very common for brown rats to use drain systems to gain access into buildings if any drain faults are present within the drain system of a building. Rat Infestation York

What do Brown rats feed on?

Brown rats are opportunistic omnivores that can feed on almost anything including human or animal food items, cereals and grains, seeds, fruits, nuts, berries, vegetables, insects, meat, waste items and other animal carcasses. Brown rats do have a preference for high fat and high protein food sources. 

What are the characteristics of a Brown rat?

The Brown rat is a large rodent with grey or brown fur, a pointed muzzle, smallish bare ears, smallish dark eyes and a scaly tail which is always shorter than its body. They are generally a nocturnal species and are highly intelligent with an excellent sense of smell and hearing and a fantastic swimming ability. Brown rats live in social groups known as colonies which are dominated by larger males. Brown rats vary in size but body length is generally between 15-27cm, with a tail length of 10-24cm. The weight of a Brown rat ranges from 200-300g. pest control york  Rat infestation Selby

Brown rat underneath floorboards- picture taken with motion camera.

Neophobia

Brown rats have a behavioural condition known as neophobia which is one of their survival mechanisms to avoid danger. Neophobia is the is the fear, aversion or anxiety of anything new, unfamiliar or different. Rats avoid unfamiliar items such as new food sources, traps and bait stations, and brown rats are more naturally attuned to changes in their environment compared to other species. Neophobia in brown rats can make dealing with infestations both time consuming and challenging. Rat control york

https://video.wixstatic.com/video/29e660_027dad815d9c46399ba8730f23d4a990/360p/mp4/file.mp4

Motion camera video shows a brown rat displaying neophobia

Breeding

Brown rats are prolific breeders with females able to produces 5+ litters of young per year, with 3-12 young per litter, and they reach sexual maturity at around 3-4 months old. Brown rats experience postpartum oestrus which means they can breed within 18-24 hours after giving birth to a litter, which means they can become pregnant again more or less straight after giving birth, whilst also nursing newborn pups. The gestation period (the total time from conception to birth) of a Brown rat is only 21 days! rat catcher york

Lifespan

Brown rats have a short but fast paced lifespan. In the wild they typically live between 1 to 2 years, 18 months is generally considered the average lifespan of a wild rat. The lifespan of a wild rat generally is dependent on the environment. pest controller york

What are the signs of Brown rats?

• Sightings- Physical sightings of live rats 

• Droppings- Dark tapered droppings generally between 1-2cm in length.

• Urine- Stains and a strong, ammonia like odour produced by urine.

• Rat carcasses- Dead rats produce a sickly/deathly smell as they rot. Rat carcasses can result in a blowfly infestation and therefore blue bottle or green bottle fly issues may indicate a current rat infestation.

• Gnawing marks- On wood, pipes, wiring, lagging, plastic etc in a two-groove pattern indicating the large incisors.

• Footprints & Tail drags- Often visible in dusty environments or in soft or wet soil.

• Rat runs- Paths or trails that may be present over soil or through grass or vegetation in areas which are regularly frequented by rats.

• Smear marks- Dark greasy marks left on surfaces frequented by rats, smear marks are caused by contact with the oils and dirt in a rats fur.

• Burrows- Extensive holes in the ground which are tunnel systems dug by rats, burrows are often found in close proximity to buildings or nearby food and water sources.

• Nests- Brown rats create nests made from shredded up material.

• Noises- Scurrying, gnawing, scratching and squeaking noises, particularly at night is often a sign that Brown rats are present.

How do you prevent issues with Brown rats?

• Seal up ingress points leading into buildings such as holes in walls, gaps around pipework, vents with large gaps as well as installing brush strips or seals to the bottom of doors.

• Keep doors/roller shutters closed at all times when not in use.

Example of an ingress point exploited by rats- note the gnawed pieces of expanding foam.

• Remove food sources from the environment such as bird feeders, pet/animal feed or compost areas. Clean up spillages of food waste or animal feed. Keep any food items stored within sealed and secure containers so that it is inaccessible to rats.

• Remove water sources as rats require a reliable water source in order to survive.

• Manage waste well and do not leave loose bin bags outside.

• Ensure bin bags are contained within secure bins and make sure to replace any missing bin drainage bungs to prevent rats from gaining access into bins. Clean up any food residue from inside bins.

• Keep external areas well maintained. Keep grass and vegetation short to reduce cover and remove any clutter that might provide cover/structure.

• Repair drainage to prevent rats from gaining access to a property via the drains if the rat issue is linked to a drain fault. 

• Call a professional pest controller! If you are experiencing pest issues with Brown rats it is important to contact a professional pest control company for advice. DIY methods and products are often inhumane or unsuccessful at properly resolving issues.  

In conclusion, Brown rats are an exceptionally successful species due to their rapid prolific breeding, extreme dietary flexibility and high intelligence. They are very resilient and can easily adapt to a diverse range of human dominated environments. Their adaptability allows them to thrive in sewers, urban areas and farms where they utilise available resources in these environments in order to survive. They often live in close proximity to humans and take advantage of the food sources, waste and shelter we provide. Therefore, the brown rat’s ability to thrive is a direct result of their capability to exploit human environments and resources. Their natural survival instinct, known as neophobia, helps them avoid potential dangers and high intelligence helps them learn from past experiences, indicating strong cognition. pest controller selby

Example of an external rat box- these are utilised by pest controllers to safely control rats in outdoor areas.

If you are experiencing a rat infestation in Selby, York or any surrounding areas contact SLR pest management today.