OH RATS!

Recently there have been scare stories in the press saying that Covid-19 lockdowns plus cold weather are going to produce an explosion in rat populations in homes.

Where to begin? Well, for starters, the story appears to emanate from pest control companies who have a vested interest in selling their services. As well as rats, these companies typically tout the control of, and I quote from adverts: mice, rabbits, fleas, cockroaches, bed bugs, ants, wasps, bees (yes, bees – they mean honeybees – if you have a bee problem, call a beekeeper!) and flies. These terms include many different species (there are over seven thousand different species of flies in Britain, for example, virtually all highly beneficial to proper ecosystem function) and these companies often seem to ignore the fact that many pesticide control methods are responsible for introducing highly toxic substances into our environment at a time of crisis in the natural world. There is a truly shocking lack of biological and ecological knowledge as well as recognition of the importance of biodiversity and the attacks we humans are making upon it at grave risk to our own very survival.

For the purposes of this note, though, I will just focus on rats. The species they are talking about is the common rat Rattus norvegicus, which is found everywhere in Britain except parts of the Scottish Highlands, especially in association with human settlements. They are fossorial (living in burrows, often extensive networks), commonly in sloping ground and ditch banks or under large stones, tree roots, etc. but they also happily colonise rubbish tips, sewers and human premises. Being rodents, they gnaw, and they will chew through wood, plastic and even softer metals to get at food which, as they are omnivores, can be just about anything with a starch or protein content including cereals and seeds, bones, meat, fish and even candles and soap! 

I do not mean to belittle the adverse interactions there are between rats and people, but we should be mindful of scaremongering. As with many animals, humans being no exception, rats do carry parasites and pathogens that potentially infect humans; these include various ticks and fleas, salmonella, cryptosporidiosis, toxoplasmosis, tuberculosis and leptospirosis. The latter of these zoonoses, also known as Weil’s disease, is perhaps the most important to humans, especially to those who may come into contact with soil or water contaminated by rats’ (and other mammals’) urine. There are only about sixty cases a year recorded on average in Britain, though.

We should not forget that rats, especially young ones, are an important food source for predators such as foxes, weasels, stoats, owls, and other birds of prey. Cats will catch young rats but probably not larger adults, and cats are a serious problem for our wild birds, so need to be kept inside or fitted with an alarm bell anyway. 

The population of common rats in Britain numbers many millions. They breed very quickly in favourable conditions and are an ecologically r-selected (“boom or bust”) species. Changes in land-use or human activity can be either catastrophic or a boon to rats. The onset of winter certainly drives them to seek food in human dwellings, and always has, though urban rat populations fluctuate less than rural ones which react to harvests. Whether Covid-19 will have a significant additional effect is moot but obviously it is sensible to ensure properties closed for any length of time are not inviting to them (no accessible food storage, no gaps in walls, roofs, windows or doors, solid drain covers, etc.).

So should you be worried that hordes of hunger-crazed rats will invade your house in the winter as the press stories seem to suggest? No, I don’t think so, but don’t encourage them. Remember that rats are opportunistic omnivorous scavengers, so make sure you do not store food that is accessible to them, and any food waste you store outside is in an inaccessible, sealed bin. 

Prevention is far better than cure: putting poison down carries serious risks for pets and, children, general wildlife and the environment, and rats rapidly develop resistance. Traps are unlikely to control more than a few and rats are very wary of new objects in their range. I have not found sonic or spray repellents to be effective but you can try them. If you prevent rats from feeding and therefore reduce the habitat’s carrying capacity, they will disappear or at least become rare. Dispose of waste food properly and campaign against fly-tipping and councils that allow litter bins to overflow or don’t have rat-proof fastenings.

Betts do not use poisons to kill any animals. Knowledgeable habitat management and minimising opportunities for excessive rat colony establishment is preferred. If you need specific ecology-based advice, please contact us, but do not be provoked into a state of panic by inaccurate press scare stories. Rather, please focus on eliminating any opportunities for rats to feed on your property and practise scrupulous personal hygiene and attention to cuts or scratches so that pathogens cannot enter, especially if you are in contact with soil or aquatic habitats. 

© Betts Ecology