The monk parakeets that now call Brooklyn home are believed to have escaped from New York’s JFK Airport in the 1960s. Initially bound for pet stores, they famously found their way to various places throughout the borough, including Brooklyn College. They currently nest in the tall light posts and around the school’s athletic fields.

Monkey Island began as a place to send monkeys that were terrorizing the town of Homosassa, Florida. A group of former research monkeys retired to a wildlife park where they began stealing from and harassing visitors. A local developer decided to exile the monkeys to an island on the Homosassa River, where they live peacefully on their own.

Kostroma Moose Farm is a Soviet-era institution that primarily exists to produce moose milk. The farm was established in the 1940s, as moose proved to be as easily milked as cows. The current farm opened in 1963 with just two moose calves, and has housed over 800 moose during its existence.

Normally, the yellow-red rat snake is a forest-dwelling snake that hunts small animals on the ground. But in the Cave of the Hanging Snakes in Mexico, these creatures occupy holes in the ceilings and walls of the cave, which they spring out of to catch flying bats. The dangling snakes have become a tourist attraction in recent years.

A nematode worm species known as Halicephalobus mephisto is the deepest-living animal ever found. The worm was discovered living 2.2 miles beneath the Earth’s surface, depths that were previously only known to be occupied by microbes. The worm was discovered in the caverns of a South African gold mine.

Palau’s Jellyfish Lake is so named for the strikingly beautiful golden jellyfish that migrate across its waters daily. The creatures have evolved in isolation and don’t sting, allowing humans to swim among them. The lake saw its population dwindle from 30 million in 2005 to nearly none in 2016, but the population has since rebounded to over a million.

The endangered Salt Creek tiger beetle is one of the rarest insects in the world, as it’s only known to reside in Lancaster and Saunders counties in the state of Nebraska. The beetles are native to dwindling wetlands habitats that have largely been lost to the development of the city of Lincoln, and they live in the remaining saline mud flats.

In 1921, the yellow-rumped leaf-eared mouse was discovered living at over 22,000 feet above sea level on the summit of Volcán Llullaillaco in Chile. No mammal has ever been discovered living at a higher altitude. The mouse also holds another notable distinction — it has the broadest altitude distribution of any mammal, with some living as low as sea level.

Located west of Berlin, Pfaueninsel was once known as “Rabbit Island” because of a 17th century-era rabbit farm. Years later, the island was turned into a habitat for exotic animals. Though many of those animals were transferred to the Berlin Zoo in the 1940s, many of the peacocks remained and can still be found wandering the island.

Once called home by the bear-loving Rosenberg family, Český Krumlov Castle has housed bears since the 1500s. Bears started living in the castle’s moat around 1707, and though the originals died, new ones have been gifted by fellow aristocrats. There are four bears currently living in the moat, and a festival is held in their honor each year on Christmas Eve.

Ōkunoshima is a Japanese island also known as “Rabbit Island” for the hundreds of rabbits that roam its landscapes. Though there’s debate over whether the rabbits were former lab animals or just released in conjunction with a new park built on the island, the population has only grown over the years due to a lack of natural predators.

The Dublin Zoo saw an uncontrollable rise in their wallaby population throughout the 1980s. The solution? Relocating their wallabies to Lambay Island, a nearby body of land that’s located 10,000 miles from the wallabies’ native Australia. The creatures continue to thrive on the island, and their population has continued to grow in size since they were first introduced.

Pelicans were introduced to London’s St. James’s Park in 1664 as a gift from the Russian ambassador. Centuries later, more than 40 pelicans have called the park home. The pelicans live mere steps away from London landmarks like Big Ben, are extremely social, and will sometimes sit on benches next to visitors.

The rough bark and craggy branches of the Argania tree may not make it visually appealing, but it provides a comforting place for hordes of goats in Tamri, Morocco. The goats ascend the precarious branches to feast on the tree’s fruit. In turn, the goats provide farmers with nutrient-rich excrement that is pressed to create Argan oil.

Located in downtown San Francisco, Telegraph Hill welcomed its first parrot residents around 1990, when an escaped pair of birds nested on site. The flock grew as other birds escaped from around the city, and by 2005, the parrot population on Telegraph Hill had grown to over 200. These wild parrots can now be seen flying throughout San Francisco.

The Galapagos penguin differs from most penguins that prefer cold weather environments, as it’s the species of penguin living closest to the equator. The Galapagos Islands are full of other unique bird species, including Darwin’s finches, which are 13 distinct species descended from one common ancestor that are endemic to the Galapagos.

Siberia’s Lake Baikal is both the oldest and deepest lake in the world, but it is also known for its unique animal residents. Nearly 80% of the lake’s plant and animal species can’t be found elsewhere, including the Baikal seal. This creature is one of the world’s smallest seals and the only seal species to live exclusively in a freshwater habitat.

Officially known as Big Major Cay but also referred to as Pig Beach, this Bahamian island contains a population of 20 to 25 swimming pigs. Big Momma is the largest and oldest pig on the island, which is a popular day trip from nearby Nassau. It is unclear how the pigs came to live on the island — one theory is that the pigs were brought to the beach by people displeased with their odor.

When engineers remodeled Austin's Congress Avenue Bridge in 1980, they didn't know that the crevices they added were perfect bat roosts — that is, until bats started showing up by the thousands. The Congress Avenue Bridge is now home to some 1.5 million bats. On summer nights, hundreds of people gather at the bridge to watch them emerge.

Lemurs, the world’s oldest living primates, are endemic to the African island nation of Madagascar. There are over 100 species of lemurs, which are believed to have originated from an ancestor that arrived on the island around 70 million years ago. Around 90% of Madagascar’s total flora and fauna is unique to the country and can be found nowhere else in the world.