Which words are the signal words in the following script:

Well, the red squirrel is Britain's only native squirrel. It's graceful and athletic. Its Latin name, Sirus Vulgaris, comes from the Greek words describing a common type of animal which sits in the shadow of its own tail. At first I thought this description was funny and was kind of an exaggeration, but now I realize that this name suits them very well. Their fluffy tails under the sun normally cast a big shadow over themselves.

Which words are the signal words in the following script:

 You will be lucky to see a red squirrel in the areas where they still survive due to its timid nature and decreasing number in the wild. In the late 1800s, when gray squirrels and exotic species were first introduced into Britain, there were only about 20,000 red squirrels left, the majority of which lived in the north of England. The grays carry a disease called the squirrel pox virus, which could lead to the deaths of red squirrels. But their number had already declined before the disease spread there. The shrinking population actually corresponds to decreases in the number of nuts available.