Last updated on October 21st, 2023 at 10:27 pm
Panic on board, you have just met a long and thin little snout and a pair of bright eyes that are watching you from inside your compost! A rat! Yes, you saw it right, and contrary to what you might think, it’s not very surprising. It’s not very worrying either! However, this presence may well disturb you, so how can you avoid rodents in green waste? Don’t worry, there are many methods, and there is no need to use toxic products to get rid of these rats in your compost!
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Rats and compost
Two species of rats are commonly found: the brown rat, or surmulot, in all environments, and the black rat, which is more common in the countryside today. They both have different preferences, especially in terms of habitat: the black rat likes dry, elevated places, while the Norway rat prefers wet areas and lives at ground level. It is the brown rat, the overmulot, that is found in composters.
Why does compost attract rats? Well, rodents, whether they are rats, mice, field mice or others, are very numerous in our environment but most of the time we don’t see them, simply because they are afraid, even if the opposite is often just as true, and they are very discreet! Rats are omnivorous, their presence will be conditioned by what you put in your pile because they come to look for food, but it is also the soft heat which reigns there which attracts them. Fall is the time when they seek shelter for the winter, and a compost heap can be an ideal refuge, combining both food and shelter. However, they will prefer dry piles, which will be much more attractive than a moist, frequently mixed pile.
However, the presence of 1 or 2 rats in the silo is not in itself detrimental. They contribute to the aeration and mixing of the pile thanks to their galleries and their movements, their galleries also facilitate the movement and the work of the decomposers, and they accelerate the decomposition process of the hardest waste.
Moreover, the rat is an animal that adapts to the conditions that are offered to it, especially in terms of reproduction. This means that there will not be more rats in your composter than it can feed and shelter. No fear of seeing them proliferate. And even less so if you put in place some of the precautions listed below! Unless the compost is too close to the house or they scare you, why not let them live in peace?
Note that rats can be frightening because they are known to carry diseases such as plague and leptospirosis. However, the plague was transmitted by the flea of the black rat, and this one was chased out of the cities by the brown rat, which thus contributed to make the plague disappear in Europe. As for leptospirosis, there are less than 1000 cases in metropolitan France per year… And it is also transmitted by farm animals and domestic animals. It is the urine of carrier animals that transmits it, via a wound, and the contagion is often made during bathing in fresh water or in a professional context (sewage workers, veterinarians, public works agents, fishermen, fish farmers…).
In prevention
You can nevertheless avoid the presence of rats in the silo thanks to some precautions and good gestures, quite simply!
Avoid throwing all your leftover meals on the compost heap. Meat and fish in particular will inevitably attract them, as will pasta and cooked rice, cheese, ready-made meals, bread (these are not products that are usually put in the compost), and fruit and vegetable peelings. You will prefer to bury them in the pile, they will decompose faster and their smell will be less detectable. To learn more, read our tips on how to make a successful compost.
Install a rat screen in the silo. Choose a fine mesh and place it around and under the pile. A perforated metal plate is also suitable.
Why underneath? Simply because rats live a lot underground, where they dig galleries that allow them to safely access food. A closed compost bin, such as a wooden or plastic silo, is not enough to prevent their intrusion, the ventilation slots allow them to pass through and they are quite capable of gnawing even on plastic.
Installing the composter on concrete slabs can be a good idea to prevent rodents from climbing up through their underground galleries.
Aerate your pile regularly. This gesture is essential for a good decomposition of the waste and also to disturb the rodents that may have settled there. Follow our tip to aerate your compost pile.
Moisten the pile, first of all because it helps with decomposition, but also because the rats will not like to see their house flooded and always wet, it is not very comfortable!
The proximity of the hen house, or rather the food for the hens, which is often made up of meal scraps and grains, is a major attraction for rats. It is advisable to keep the compost away from the coop. Read our article on chicken predators to learn more.
If you have a cat, don’t hesitate to let it roam freely in the garden, as it may discourage rodents from moving in.
You can eventually throw the used cat litter in the compost, provided that the litter itself is biodegradable. However, this compost can only be used in vegetable beds if the composting is done in a silo, because the temperature rises sufficiently to destroy the parasites, bacteria and/or drugs found in our pets’ stools. However, there is no problem using this compost in flower beds.
How to get rid of these rodents?
You have a rat in the compost, what to do to really get rid of it?
Of course, poisoning is not a recommended method, for several reasons: not only rats will be poisoned, but also hedgehogs, your cat or your neighbor’s cat if it hunts a poisoned rat, and birds. Moreover, you risk contaminating your compost with a particularly toxic product. If the problem is really important, it is better to call a specialized company.
The best method is the gentle one: get a trap with a trap door and put some seeds in it. The trap will catch the little beast without hurting it, and then you will just have to take it away from your home, in the middle of nowhere. But be aware that rats are very intelligent animals, it is likely that the ploy will not work for long.
Other visitors?
Rats and other rodents are not the only small animals that find refuge or food in our composts. We can also find orvets, which are not snakes but tailless lizards that feed on slugs, caterpillars and other invertebrates, or hedgehogs, or even shrews. And just like rodents, they are very useful to the gardener!
Note: shrews are more “dangerous” for the compost than rats, because they feed on worms and other larvae of cetoins that are very useful for the work of decomposition of waste.
Like spiders, rats are the object of a very common phobia, or, to a lesser degree, a strong repulsion. However, they know how to make themselves useful in our piles of organic matter and can be considered as harmless, as long as they don’t cross the limits! If you need to chase them away without violence, there are many ways to do so, and everyone can do it. Or you can consider that they are part of your environment, accept them as such and let them work for you!