Bumped into a rat in the wood the other day and was shocked by its size - it looked more like a small dog than a rodent!

It's funny how creatures' popularity rises and falls. In the east during ancient times the rat was welcomed as a protector and bringer of material prosperity.

It was an animal associated with aggression, wealth, charm, and order, yet also associated with death, war, the occult, pestilence, and atrocities. It is still one of the twelve animals in the Chinese Zodiac. Ancient Romans did not generally differentiate between rats and mice, instead referring to the former as Mus Maximus (big mouse) and the latter as Mus Minimus (little mouse).

There are two kinds of people - those that think rats are lovely and regularly keep them as pets and the others who think of rats as scaley tailed dirty little monsters who spread diseases and cause destruction where ever they are found.

Rats can and do carry diseases, more than 30 different diseases dangerous to humans, including Weil's disease, typhus, salmonella and bubonic plague. Black rats or ship rats are suspected to have had a role in the Black Death, an epidemic which killed at least 75 million people in Europe, the Middle East, and Asia in the mid-late 14th century.

There are two species of rat found in the UK, the brown rat and the black rat - the black rat is now very rare and only found in a few places. Brown rats, although originally native to east Asia and Japan, are now found all over Britain except for exposed mountain regions and some small offshore islands.

They arrived in Britain via the shipping traffic from foreign countries in the 18th Century, largely replacing the black rat. Along with house mice, they are considered to be the most widespread terrestrial mammal.

Another rodent we have had in the garden this week is the grey squirrel - another pest just as bad as the rat for different reasons.

They have been attacking our lawn - digging holes trying to find the caches of nuts that they buried last autumn.

They seem to have had a real good breeding year, I don't think I have ever seen as many in the woodlands.

This means that quite a few birds' nests will have fallen victim to the squirrels climbing abilities and taste for eggs.

To help bring further attention to the damage the grey squirrel inflicts on the bird population the British Trust for Ornithology has been commissioned to undertake a study on the effect of the grey squirrel on woodland bird populations.

The results of the first review phase of this study are due early next year.