Rats

Rats are among the earliest and most consequential animals to occupy the cities after the Great Disaster. Left without people to limit their numbers, they find abundant food in shops and spread through the built-up area in a vast population surge. Their eventual decline is not a simple return to the old balance: scarcity and predation reshape their behavior, while their association with disease makes their expansion a direct source of fear for survivors. Their story gives animal populations their own arc in the aftermath, independent of human plans and only partly understood by the people who witness it.

First signs in an emptied town

When Ish drives through a small town after the catastrophe, his methodical circuit yields no human answer. He sees dogs, cats, hens, and a cow, but the large rat nosing around a doorway is a more telling sign of the changes underway: buildings and provisions remain, but the people who once controlled the town are gone. The animal is not yet part of a visible swarm. It is one detail in a landscape whose familiar human order has vanished.

As Ish begins establishing a life, he discovers that food supplies are already being altered by animals. Rats and mice have made a mess of food in stores; bread is unusable, and even some sealed crackers have been reached by weevils. Canned and glass-packed goods remain edible. When Ish finds functioning refrigeration and frozen food in a store, he closes the window carefully after taking supplies, hoping to keep rats out. The gesture reflects a temporary human advantage: preserved food can still be recovered, but only if access is controlled. In the abandoned city, even a shop window and its contents have become part of a contest over resources.

A new urban food chain

The animal population does not simply fill every part of the city in the same way. Ish observes small, active terriers and terrier-like mongrels concentrated near the waterfront, where rats had previously been numerous. The dogs scavenge food from shops, including crackers exposed after rats open their cartons, and appear to live largely by catching rats. Ish also concludes that the dogs have driven away or killed cats. The new arrangement is an improvised food chain: leftover human provisions support rodents and scavenging dogs, while dogs prey on rodents and displace another former urban predator.

The waterfront later continues to bear the signs of this animal occupation. Rats scurry, fight, breed, and nest on the piers, feeding at low tide on mussels and crabs. Their environment is no longer only the human-made supply network of shops and stored food. Coastal food sources also sustain them, illustrating how they can exploit both the remnants of the city and resources beyond it.

The population surge and the siege

After a period in which Ish has seen ants in overwhelming numbers, a new wave of rats engulfs the area. The animals look ordinary in size and condition, which makes their sheer abundance more disturbing: the danger comes not from any unusual individual rat but from the population as a whole. They occupy roughly the city and extend beyond its built-up area, farther than the earlier ant wave. Ish and Em encounter them as a pervasive presence, and the station wagon often crushes rats that dart across the road. What initially unsettles them becomes so frequent that they cease reacting each time.

Ish tries to understand the increase mathematically, using his father’s encyclopedia. Rats can produce a litter about once a month, averaging roughly ten young, and young females may begin breeding before two months of age. Under uninterrupted breeding, his rough calculation reaches about ten million rats in a month for the area he is considering. He recognizes that deaths and the number surviving to maturity matter, but the available numbers cannot contain the scale of the increase. With food seemingly unlimited, he sees no reason their population could not multiply several times over in a month. Before people disappeared, humans had been the city rats’ principal natural enemy, maintaining a constant effort to keep their numbers down. Now the remaining dogs and cats are too few to perform that role effectively.

The abundance becomes a domestic threat as well as a calculation. Ish and Em feel under siege and watch their doors closely, yet one rat gets into their kitchen from an unknown opening. Ish pursues it with a broom; when cornered, it leaps at the broom handle and leaves tooth marks in the wood before he kills it. The episode makes the scale of the crisis intimate: household boundaries offer no certainty of protection, and even a single rat can turn an ordinary room into a defensive space.

Scarcity, predation, and disease

The apparent plenty does not last. After several days, the rats look thinner, and Ish suspects the city’s enormous supplies are beginning to fail under the pressure of their expanding numbers. He also sees a terrier that appears to have died while fighting a group of rats. The sight leads him to imagine how a dog might be overwhelmed despite killing some of its attackers, and it changes his attention to Princess: he becomes more careful about protecting her. The dogs that had profited from the earlier abundance are vulnerable when the balance shifts and hungry rodents become more dangerous.

Ish’s concern also turns to disease. He knows that bubonic plague can spread among rats and that infected fleas can move from dead rats to living people. He does not establish that plague is present, but the possibility makes the human community’s exposure frightening: millions of rats, mass deaths, and flea transmission could create a further epidemic. This fear belongs to a broader post-disaster uncertainty about infectious disease. Earlier, a bacteriologist had described several possible origins for a new disease, including an animal reservoir, mutation, or a laboratory release, and noted that isolation had not seemed to protect individuals. That discussion does not identify rats as the source of the original catastrophe; Ish’s later fear concerns the distinct possibility of rat-associated plague.

As food becomes scarcer, Ish witnesses rats attacking and killing other rats. He sees a large rat pursue a smaller one, then a still larger animal join the attack; the larger rat drags away the smaller animal, while the first pursuer follows. He and Em increasingly see rats preying on one another, sometimes in groups, and conclude that the population is declining, though the animals may also be harder to see as they avoid open spaces. The change is both behavioral and ecological: the population that once seemed capable of endless expansion is now driven into competition by the limits of its food supply.

Disappearance and ecological aftermath

Day by day, the rats grow fewer until one morning they seem to have disappeared. Ish knows that some must remain, and he cannot be certain whether disease contributed to their decline. He believes cannibalism helped explain why so few bodies are left behind: the rats have, in effect, consumed one another and carried the population into another generation. He also recognizes that they must have removed many bodies of people who died in the original disaster, although he does not investigate the extent of this activity. Their impact thus includes both a visible invasion and an unobserved role in the disposal of the dead.

Rats recur as a measure of ecological upheaval even after their overwhelming wave has passed. In the fifth year, cattle have become numerous enough to be a nuisance, and the community remembers their abundance alongside earlier plagues of ants and rats. Later, rats and mice have chewed through cartons in a grocery store, leaving its floor covered with paper remnants and droppings; glass and tin have kept many bottles and cans intact, but even their labels have been damaged. The contrast with Ish’s early attempts to protect a store’s food is stark: scavenging continues over time, and human-made packaging outlasts the order and cleanliness for which it was designed. The rats’ rise, retreat, and continuing traces make them part of the book’s account of nature reorganizing the city—not as a backdrop to human survival, but as a force that changes what survival requires.