Buzz
Up until 2007, rural areas were more populated than urban centers. However, since then, there has been a shift, with human populations increasingly clustered in cities, leading to rapid urban expansion. Interestingly, certain animal species have lived in similar close-knit environments for centuries, driven by similar needs for resources, defense, and social interaction.
While these animal “cities” lack trained architects and urban planners, many of them are surprisingly sophisticated. Some have evolved over generations, while others skillfully adapt to their surroundings. In fact, the populations of some animal cities outnumber even the largest human settlements. Below are ten of the most remarkable animal cities, in no particular order.
10. Eel City
Eel City is aptly named for the slippery inhabitants it hosts. What’s curious, however, is that it is the only known place like it. Located about 2,000 feet (609 meters) beneath the South Pacific Ocean near the summit of a newly-formed volcano called Nafanua, just off the coast of American Samoa, this unique ‘city’ was discovered by scientists in 2005. While studying the volcano, they were astonished to witness hundreds, possibly thousands, of eels weaving in and out of its crevices.
Some scientists, experienced in exploring hydrothermal vents beneath the ocean, claimed that they had never encountered anything like the eel city. While small eels are commonly seen in deep-sea environments, the sighting of such a large congregation of them was unprecedented. What's more intriguing is that eels do not typically feed on microbial mats, the only potential food source visible around the volcano.
9. Octlantis
A colony of just 15 octopuses might not sound like much of a city, but when those octopuses are typically solitary and known for their reclusive nature, it becomes quite an extraordinary discovery. The researchers who found this Australian site dubbed it Octlantis, which should not be confused with Octopolis, another octopus community they discovered a few years earlier. While the octopuses of Octlantis no longer lived in isolation, they still exhibited antisocial behaviors, often engaging in fights and even evicting each other from their hiding spots.
Though 15 may seem like a crowd, the octopuses still maintained a certain level of privacy. The scientists also observed the creatures mating and communicating. The reasons behind their collaboration remain unclear. It could have been for mutual defense, showcasing the octopuses’ impressive intelligence, or simply because the area offered abundant food but limited shelter.
8. Underground Ant City
In 2012, scientists unearthed an elaborate and mysteriously deserted underground city. At its peak, this city was home to millions of inhabitants, all under the rule of a queen. Each citizen had a specific role, ranging from soldiers to sanitation workers. The city left behind a sprawling network of tunnels, highways, waste disposal areas, and gardens. Anyone eager to witness this ancient marvel will need to travel to Brazil, though access may not be easy. Why is that?
Because the city was not constructed by humans, but by tiny leaf-cutter ants. For creatures of their size, their achievement is comparable to the scale of the Great Wall of China. Spanning an area of 500 square feet (46.5 square meters) and descending 26 feet (7.9 meters) beneath the ground, it is a monumental feat. While their colonies are typically much smaller, the ants likely didn’t find the project too strenuous, as they are incredibly strong and can carry up to 50 times their own weight.
7. Ancient Termite Megalopolis
As remarkable as the Great Wall-like city built by ants may be, it is eclipsed by the work of another small insect species. Termites are believed to have started constructing their 200 million mound megacity around 4,000 years ago in northeastern Brazil. Despite its age, the site is still in use and continues to be developed. The intricate tunnel systems beneath the massive, hill-like mounds—some reaching heights of 10 feet (3 meters)—cover an area as large as Great Britain. The volume of soil displaced by these tiny creatures is equivalent to that of approximately 4,000 Great Pyramids of Giza.
Surprisingly, the termite city is not easily visible from the ground due to its location in a semi-arid forest. However, it can be detected from space. The forest itself is why the termites went to the effort of digging their tunnel system; they feed on decaying leaves, and the tunnels allow them to safely emerge when it’s time to forage for food.
6. The Valley of Giants
Imagine stepping into a vast, dark cave deep within a forest, its walls marked by massive grooves that could only have been carved by the claws of a giant creature. Not for the faint-hearted, these caves, discovered and explored by paleontologists in Minas Gerais, Brazil, were once home to enormous animals that went extinct approximately 10,000 years ago. These caves are actually ancient animal burrows, likely made by massive ground sloths and armadillos from the prehistoric era.
Some species of ground sloths could grow as tall as 20 feet (6 meters) when standing, and the massive burrows—reaching up to 131 feet (40 meters) in depth and 13 feet (4 meters) in height—suggest that they were dug by a colony of animals rather than a single creature. This theory is supported by small, smooth indentations found in the walls of the last chamber of each burrow, which may have served as resting spots for individual animals.
5. Aerial Cities
The ‘Sociable Weaver’ is not a member of a knitting group but a fascinating bird species found in South Africa and Namibia. True to the saying, ‘birds of a feather flock together,’ these birds create enormous nests that resemble large thatched roofs in the treetops, where they live in huge colonies. A single nest can contain up to 95 chambers, each one serving as a home for a family of Sociable Weavers.
The first person to document these birds in the late 18th century described their nests as an 'aerial city.' He even came across a nest so large that he speculated it could house between 800 and 1,000 birds. These birds are incredibly sociable, allowing other species such as the pygmy falcon to take refuge in their nests for shelter and breeding.
4. King Penguin City
St. Andrew’s Bay, located on the frozen island of South Georgia near Antarctica, is home to one of the world’s largest penguin colonies. About 400,000 king penguins congregate there, a remarkable number considering that just a century ago, whalers nearly wiped out the local wildlife, forcing them to abandon the island. Even more impressive is that the adult penguins, who leave for up to five months to find food, can still navigate the crowded beach to reunite with their young.
While this penguin 'city' lacks shelters or tunnels, its structure is surprisingly well-organized despite the absence of a clear leader. Molting penguins group together, while the playful chicks gather in their own areas as their parents are away. Penguins who need to bathe naturally gather around the bay’s pools, and long, sparse columns lead to the sea, resembling highways.
3. The Polar Bear Capital of the World
Some courageous species have chosen to inhabit human cities, not by their own design but by necessity. These are not only abandoned cities, but bustling metropolises where humans and animals coexist. While rats, foxes, and pigeons are commonly seen living alongside city residents worldwide, in Churchill, Canada, both locals and tourists share their space with the largest land carnivore on Earth—the polar bear—for a few months each year.
During the winter months, as the polar bears make their way to Hudson Bay to hunt seals, hundreds of them converge near Churchill. This transforms the area into the 'Polar Bear Capital of the World.' Efforts are made to deter the bears and guide them around the town, though it’s not uncommon for some to sneak through. Fortunately, most polar bears tend to retreat when they encounter humans, and fatal incidents are rare.
2. Monkey City
A characteristic shared by many animal cities is their distance from human populations. However, abandoned structures often serve as new homes for animal colonies, and many of these spaces don’t remain uninhabited for long. For example, the ancient ruins of Polonnaruwa in Sri Lanka, which date back centuries, now house around 4,000 macaques. Interestingly, the monkeys at this site were the subjects of a major study conducted by the Smithsonian Institute from 1968 to 2008.
Each macaque residing in these ruins was given a name, some of which were inspired by famous personalities and local leaders. The monkeys gained some fame as well, appearing in documentaries like Animal Planet’s Dark Days in Monkey City. Other major networks, such as Discovery Channel and the BBC, also featured the monkeys in their own productions.
1. Prairie Dog Town
Some might argue that the groups of black-tailed prairie dogs are technically called "towns" rather than "cities," but the largest known prairie dog town once had a population that outnumbered any human town. This immense colony was found in Texas in the early 1900s and stretched over an area of 250 by 100 miles (402 by 161 kilometers), with a staggering 400 million prairie dogs.
This meant that approximately half of the prairie dogs in Texas at that time lived in that one massive town. However, due to human development and settlement, this 25,000-square-mile (64,750-square-kilometer) town has been divided, leading to a dramatic decline in prairie dog numbers by more than 99%. Despite this, the population has now stabilized at around eight million.
