This section is from the book "The Balance Of Nature And Modern Conditions Of Cultivation", by George Abbey. Also available from Amazon: The Balance Of Nature And Modern Conditions Of Cultivation.
Brown Rat (Mus decumanus), Fig. 13, belongs to the family Muridae or Mouse kind of the order Rodentia or gnawing animals. The lower incisors are narrow-pointed and smooth, two incisors, two pre-molars and four molar teeth exist in each jaw. Complete collar-bones exist, and the front limbs possess four toes and a rudimentary thumb, the hind legs having five toes. The tail is long, pointed and scaly and thinly haired.
Fig. 13. - The Brown Rat.
The brown rat is known by its brownish fur, and was first noticed in England in 1730. It is much larger than the Black Rat (Mus rattus), the British native species, supposed to have come into Europe about 1200. The males greatly outnumber the females. They commence breeding at four months of age, and from three to four broods of from eight to fourteen young each may be annually produced. Varieties of this species appear to exist, there being visible distinctions and differences between the barn and sewer rats. The habitats of the brown rat are cosmopolitan, in this country embracing hedgebanks, pond sides, corn and strawstacks, drains, barns, granaries, outhouses, warehouses, and dwellings. Its food consists of grain of all kinds, legumes, roots, vegetables, fruit - carrying it from stores, gnawing and spoiling great quantities, and the devastation committed in a house of ripe grapes is appalling. It also feeds on breadstuffs, fats, flesh - in fact, is a gourmand and scavenger. Its depredations upon poultry and pigeons are well known, also its feat in stealing eggs without breaking them.
Barking vines and other ligneous plants is not uncommon work of the brown rat, as well as the wholesale cutting off of ferns in ferneries and plants in plant houses, while its gnawing of woodwork and tunnelling under floors and walls attest its further despoliation.
The true English or Black Rat (Mus rattus) is smaller than the brown rat, and possesses a blackish-grey fur. Although the black rat has been exterminated by the increase of the brown species, some observers incline to the belief that the scarcity of the former has arisen from the stronger males of the brown rat mating with the black females, and thus producing a brown progeny.