22. Jun, 2021

Rats and Compost bins

I have updated the Carry-on Composting  page on rats. http://www.carryoncomposting.com/416920198)

This is the equivalent of 12 A4 pages and gives an overview  as well as specific actions to help deal with the rat problem. 

Rats are commensal rodents the numbers of which are influenced by our activities, buildings, and the landscape we have created. The type, style age and size of our houses and gardens and what we do in them will also impact on the number of rats. Some activities such as keeping chicken, feeding the wild birds, and composting using an open heap may be beneficial to the rats while others such as keeping cats or terriers may discourage them.

Although many gardeners and composters will only see rats infrequently, if at all, a study conducted in central New York reported that pests, including rats, were the third most common obstacle to home composting (Tompkins County Compost Study. Prepared by: Cornell Cooperative Extension’s Compost Education Program 2001). Undoubtedly opening a bin to find a rat sitting on the composting looking at you can be a disconcerting even if it only happens once.  While rats may visit, or nest in, a compost bin if they are already present in the area composting does not generally attract the rats in the first place. 

When rats are feeding, sheltering, or nesting in a compost bin burrows 30-40mm in diameter can often be seen under the bin or holes are visible chewed into the side of the bin. Rats are attracted to compost bins and heaps as a source of food, shelter and as a warm dry place to nest. The compost bin will be particularly attractive during the winter as it can provide warmth and a good supply of food with kitchen scraps being regularly added to the top while the material in the lower part of the bin is relatively undisturbed.  Rats need to gnaw hard surfaces to keep their teeth under control as they grow throughout their lifetime so many wooden and some plastic bins will offer little obstacle if the rats smell the decomposing food inside the bin.

The signs of their presence in the rest of the garden are also relatively easy to detect.

The Norway rat creates burrows and makes “rat runs” along building foundations, garden fences and walls. They will also burrow beneath chicken houses, woodpiles, manure, and compost heaps. Nests in compost heaps or bins may be lined with shredded paper, other dry material from the heap or material brought into the bin. The contents of the compost bin make a good restaurant for brown rats as their preferred diet includes cereal grains, nuts, and fruits, meat, and fish.

The Black rat seldom digs burrows preferring to nest in locations off the ground in dense vegetation, shrubs, trees, vines etc. They also eat a range of foods that might be found in the compost bin. There preferred diet consisting of fruits, nuts, berries, slugs, and snails. 

The information on the website includes:

 Signs of Rat Infestation,  Reducing the risk of rat infestation,  Weil’s disease,  Location of the bin, Material being composted and rat infestation, Regular Human Interventions, Rats and Compost bin design, The Bin Contents, Rat Shelter and nesting in the compost bin, Rat Infested bins, Making the garden less rat friendly,  

Other suggestions and rat poison advice, Selected Sources, and further reading.