Identification

The brown rat is a large rodent whose fur is generally brown but may also shade to grey or even black, sometimes with slightly paler fur on the undersides. It has no fur on its tail and its ears stand out prominently.

Size

Body length ranges from 20-28cm (8-11in), and the tail can reach up to 23cm (9in) in length.

Distribution

Widely spread throughout Britain, in both urban and rural locations near human habitation.

Status

Brown rats are widespread; already one of our most numerous mammals, and their numbers may be increasing. They have no legal protection.

Habitat preference

Rats are highly adaptable. While some live along hedgerows or watercourses, others have moved into human habitats. They like grain and so are found near farms, as well as in warehouses and sewers.

Where to find them in the garden

Rats will often move into gardens; compost heaps, garden sheds and outbuildings may be used as nest sites.

Role in the garden

Brown rats have a varied diet, including grain, seeds and invertebrates. They will also eat cooked foods (including meat). In gardens they have been known to climb up onto bird feeders, or take food left out for cats or hedgehogs. They are especially likely to be attracted to bird feeding areas if these are not kept clean, or if there is insufficient food for them to find elsewhere. They also like compost heaps both for their food and their warmth. However, a compost bin will not attract them unless they are already present in your locality. Rats can be discouraged by reducing available food supplies: regular sweeping up under the bird table and not putting food scraps in the compost bin. When building a compost bin, laying a fine wire mesh underneath stops rats burrowing in from underneath.

How to exclude rats from your compost bin

If you are concerned about rats coming to your compost bin, follow these guidelines from Gloucestershire Wildlife Trust:

  • Keep the compost contained, and line your bin with chicken wire with gaps of less than 0.6cm (1/4in) (a rat’s skeleton collapses allowing them to squeeze through tiny holes)
  • Disturb the compost by turning it. This helps the heap rot quicker, and makes the heap less suitable for rats as they don't like disturbance.
  • Do not add meat, dairy, nuts or cooked food. Cooked food would smell more attractive to a rat and is likely to have a higher fat, protein and carbohydrate content, making it better rat food than vegetation.
  • Keep bird feeding areas clean and the food confined to bird tables and feeders.
  • If you live near fields, grain stores, farms or streams then you are more likely to have rats present. Place the bin away from linear routeways like streams and hedges and move the bin if it appears to be in a popular rat run.