The rat who inhabited the sewers and basements of Victorian London was bigger, meaner, and generally better adapted to urban life than his predecessor. The brown rat, or Norway rat, arrived in England during the 18th century and quickly supplanted the native black rat; a smaller, arboreal species that was ill-equipped to stand up for itself. ”The large grey rats,” wrote naturalist Charles Fothergill in 1813, “having superior bodily powers…would easily conquer and destroy their black opponents wherever they could be found, and whenever they met to dispute the title of possession or of sovereignty.”
Not only did the brown rat usurp his English counterpart, Fothergill writes, but he was also a bloodthirsty tyrant in his conduct toward his own species, and an all-around bad family man:
The male rat has an insatiable thirst for the blood of his own offspring; the female, being aware of this passion, hides her young in such secret places as she supposes likely to escape notice or discovery, till her progeny are old enough to venture forth and stand upon their own energies; but, notwithstanding this precaution, the male rat frequently discovers them, and destroys as many as he can; nor is the defence of the mother any very effectual protection, since she herself sometimes falls a victim to her temerity and her maternal tenderness.
Besides this propensity to the destruction of their own offspring, when other food fails them, rats hunt down and prey upon each other with the most ferocious and desperate avidity, inasmuch as it not unfrequently happens, in a colony of these destructive animals, that a single male of more than ordinary powers, after having overcome and devoured all competitors with the exception of a few females, reigns the sole bloody and much-dreaded tyrant over a considerable territory, dwelling by himself in some solitary hole, and never appearing abroad without spreading terror and dismay even amongst the females whose embraces he seeks.
Fothergill supposed that it was only an innate propensity for cannibalism and infanticide that prevented the brown rat population from exploding out of control and rendering “the whole surface of the earth…a barren and hideous waste…against which man himself would contend in vain.”
Clearly, this is something of an exaggeration, drawn from accounts of rats living under distressed conditions; as the inhabitants of London, rodent and otherwise, often did. Under ordinary circumstances the brown rat prefers cereals and grains to the viscera of his offspring, though he is also an accomplished predator, known to feed upon frogs and salamanders, spiders and insects, fish, mollusks, and even poultry. Under extraordinary circumstances, however, he is known to go too far: