Urban rats, mutant rats or myths

rat groupIt sounds like a Halloween movie that Hammer House of Horror might have envisaged or the latest x-box game – ‘giant, mutant super rats’ ready to invade the UK!

Despite recent reports, the majority of rats found in the UK are approximately 25 cm long (excluding their tails) and weigh in the region of 250 g. Pests are a symptom of their environment – whilst rats are an obvious problem they are present in certain areas because of specific issues, for example fly-tipping or drainage defects.

Giant rats

Rats are focused on finding food and shelter and once they have discovered a reliable supply of food and favourable conditions to live, they will stay and continue to prosper and grow to a decent size. Rats living in urban areas have almost unlimited access to food from rubbish bins and discarded left-overs from cafes, restaurants and takeaways to foraging in garden compost bins and our kitchen cupboards if they manage to get in.

Access to the high carbohydrate, sugars and fats in our urban waste offers rodents a high energy, good quality food source that can give them a longer lifespan. They also tend to grow more rapidly on such a diet (as such junk food can cause obesity in people) also rats continue to gain weight as they age, allowing them to reach a higher body mass.

Where rats in rural areas live near farms and access animal feed units, they are able to feed on the proteins designed for bulking up animals for slaughter, which will have the same effect on the intruding rodents of increasing their size.

To help control rodents we need to do the basics, and not give them the ideal conditions in which to thrive.  Things like ensuring food waste is properly and securely sealed and disposed of can make a big difference, as can proofing (to stop them entering) in cutting rodents access to food.

Mutant rats

Over recent years, the British Pest Control Association (BPCA) and its members have seen examples of some rodents developing a resistance to traditional anticoagulant baits, particularly to the over the counter DIY baits for home use. Stronger rodenticides can be more effective, but are subject to strict legislation and can only be handled by professional, qualified pest controllers.

-rat-in-rubbish-binA rodent’s resistance to bait can be seen as similar to that of antibiotic resistance, where continuous use of weaker baits or under baiting can lead to an accumulated resistance to certain baits in some groups of rodents. Resistance is based around a selection of genetic mutations in a few rodents that develops into a reduced sensitivity to bait due to their genetics.  Compounding this issue is the fact that where a rodent population (who are susceptible to baits) are treated and die, if the access to their food source remains then potentially bait resistant rodents may move in to take advantage.

Proactive prevention is always a better option than having to get rid of rats. Proofing your property and taking a few precautions can help reduce the risks of an infestation. Rats and mice are constantly seeking new sources of food, so eliminating this access is vital.

  • Ensure rubbish is securely stored in sturdy bins with tight fitting lids and do not leave bird or pet food out overnight.
  • Keeping gardens, garages and sheds clean and tidy will reduce opportunities for rodents to nest and shelter.
  • Check your property for entry points, around plumbing and pipes, unscreened vents or gaps in eaves, under doors and roof edges, seal or screen these as necessary.

Rats can grow to a decent size if given the right conditions and some, due to genetics and accumulated resistance may not be as susceptible to baits as others. None of this however makes them indestructible, super rats!

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