6 Four species of penguins can be found on Macquarie Island, an Australian Antarctic Territory in Tasmania. The island houses an estimated 4 million penguins in all and only a dozen humans. 

Macquarie Island is an isolated island in Tasmania’s Australian Antarctic Territory. The island is teeming with seabirds who have made the island their home. Penguins, petrels, and albatrosses are the primary breeding species.

But the most widely distributed birds on the island are the penguins. There are four species of penguins on the island. The royal penguin is endemic to the island and it is their only home. They have a population of 850,000. The other penguin species include king penguins with a population of 100,000, Gentoo penguins, and southern rockhopper penguins. All in all, the Antarctica Government has estimated the number of penguins on the island to be around 4 million.

Nearly 100 years ago, these penguins were exposed to cruelty when they were used to produce oil for lamps. This made the population of 3 million penguins reduce down to just 4,000. In 1919, this practice was banned. In over 80 years, the penguins were able to recover their population. Moreover, there’s an ongoing program that eradicates predators from that island in case they are seen to harm the penguins. (1, 2, 3)

7 While approximately 6,000 seals populate the island of Duiker in South Africa, there are no people on the island. Also known as “Seal Island,” this one-acre landmass is made mostly of rocks and is home to several wildlife species including African penguins.

Duiker Island in South Africa is home to one of the largest colonies of Cape fur seals. These adorable creatures have made the rocky island there home. There are around 6,000 seals that live on the island and can be seen sunning themselves lying on the rocks.

Regular ferries and boats take visitors to get a glimpse of the seals. The island has come to be lovingly referred to as “Seal Island.” During the birthing season around April, adorable little seals can be seen huddled close up to their mothers or learning to swim in the waters. (1, 2)

8 The Brazilian island, Ilha da Queimada Grande, has one snake per meter of its area. The snakes present there are golden lancehead snakes which are one of the most poisonous and deadly snakes in the world.

Ilha da Queimada Grande is an island filled with poisonous vipers. The island is located off the Brazilian coast in the Atlantic Ocean. The island is home to a critically endangered venomous species of snakes, Bothrops insularis or the golden lancehead pit viper.

Decades ago, the island was connected to the mainland via a land strip. But with rising sea levels, the connecting land mass went under the water and the island was completely disconnected from the mainland. As a result, the snakes were stranded on the island. With the pressure of survival of the fittest, the snakes quickly adapted to their new environment. They multiplied aggressively rendering the island dangerous for human visits.

Today, the island is closed for the public as a protective measure for humans as well as the snakes. Only a few researchers and the Brazilian Navy are allowed on the island. (source)

9 Ōkunoshima Island in Japan once used to be a chemical-weapons-manufacturing site, a very top-secret facility during World War II. Now, it’s covered in bunnies and has been given the name of “Rabbit Island.” While some suspect that the bunnies are descendants of the factory test subjects, the official account says that schoolchildren introduced them to the island in 1971.

Also known as Usaga Jima, which translates to “Rabbit Island” in English, this Japanese island is a paradise for bunny lovers. During World War II, the island was a chemical-weapons research and manufacturing site. The island was kept a secret during the war, and it didn’t appear on any Japanese maps. The story is quite different today. Tourists flock to the island to get a glimpse of the hundreds of rabbits who have made the island their home.

How the rabbits ended on the island is still a mystery. Some believe they might have been test-subjects during the war, and after the war, workers may have released the remaining rabbits. But according to Ellis Krauss, a Japanese politics professor, not one test-subject survived after the war. He believes that the rabbits are descendants of eight rabbits introduced to the island in 1971 by school children.

With no natural predators like cats and dogs on the island, the rabbits bred aggressively, and today there are around 1,000 bunnies roaming around the island. (1, 2)

10 Tiny Christmas Island in Australia is home to around 30 million crabs. Once a year, millions of adult crabs travel from the forests on the land to the seashore so they can reproduce, and the sight is mind-blowing. 

Christmas Island was once home to an estimated 43.7 million adult crabs or about 0.09 to 0.57 adult red crabs per meter square. But in recent years, the introduction of a very specific ant, the yellow crazy ant, has reduced the crab population to around 30 million. For most of the year, the crabs can be found lying in the forests. But once a year something wonderful happens. Millions of crabs come out from the forests and go towards the ocean for the breeding season.

The migration happens between October and December. Crabs from across the island make their way towards the ocean. The male crabs first reach the shores and dig burrows. The females then reach the shores and the mating takes place in or near the dug burrows. After the mating process, the males return to the forests while the females stay in the burrow for about two weeks to lay their eggs. Once the incubation period is over, the females leave their eggs in the ocean, mostly during the high tide of the last quarter of the moon.

The females return to the forest while the larvae spend three to four weeks in the ocean. They then return to the land as juvenile crabs. (source)