Rat Burrows

A scientist named Calhoun (1963) studied rats' behaviour closely in a semi-natural enclosed environment. He then discovered that most Norway rats would dig burrows and live in there the rest of the time. These underground burrows would comprise networks of tunnels each leading to specific compartments serving different purpose while other would lead through exits from the underground. Usually, the networks are complexly interconnected.

Burrows don't say the same for too long. Eventually they change through the constant activities of rats inside their burrow system. The activities by rats inside the tunnel would require the burrows to renovate according to the immediate needs of the rats in order to fully satiate the needs of their existence. Accessibility and convenience are among the primary factors to be considered in justifying the changes that take place inside the burrows. When burrows grow, they get deformed beyond repair as new tunnels and passages are created by their inhabitants. There will be certain areas and sections that will be left unattended and eventually cave in the future. However, the burrows would take a new face as an accommodation to the rats' present needs. We could even say that the structural system of the burrows has got something to do with the social relationship of rats that inhabit there. If ever comes a time that the social structure and relationship of rats would break down, the burrow will eventually fall into disarray and becomes irreparable.

Parts of the burrow

1. The entrance of a burrow is usually placed or located in areas that are sheltered or sloped. Can often be found sealed with grasses or piles of dirt.

2. The tunnels' median diameter would range from a width of 8.3 – 9 cm allowing only one rat to pass at a time. The straight tunnel segments which also serve as the rats' super highway, have a larger median diameter length of 29-30 cm. At the end of that length, the tunnel would either separate into two smaller passages or bend and ends with a cavity or a dead end.

3. The cavity are small sized areas and may differ from 18.3 x 22.1 cm, making it possible to accommodate a group of 6-7 rats at a time. This is where communal nesting would often take place especially in low density rat colony population. The smallest chamber areas could only accommodate 3-4 rats at a time and the largest on the other hand would reach as much 11 rats in a space. There are different usages to any chambers. They could either be:

a. Nesting area - would practically be consisting of a bedding and litter area for rats and its younglings to rest.

b. Resource cache - where food would be stored for future consumption.

4. The nest would most often be composed of shredded materials like grass or garbage and sometimes dirt. This area of the burrow would serve as the rats resting place. There are three different kinds of nest:

a. Pad - The simplest form of a rat nest and usually made of few trash objects like flat bond paper or leaves. This would elevate one rat from the floor.

b. Cup shaped nests - It is basically a larger sized nest taking a cup-like shape. It is usually consists of more shredded materials like paper or leaves, intermeshed to come up with a wall for the cup. The surfaces are then usually flat.

c. Hooded nest - One could practically say that this is the largest of all the nest types. They can be so high that they would virtually form a ceiling for the nest. The hollow spherical shape of the nest would become the dwelling place for rats, especially mother rats which happens to be the ones usually responsible for such nesting structures. However, such nests are quite rare.