It’s the size of Ireland and home to a whopping 400 million individuals – making it one of the most densely populated places on Earth

Earth is full of incredible wildlife spectacles, with thousands of animals gathering in one place – often putting on an awe-inspiring display.

But if you want to find out the largest colony of mammals, you’ll have to turn to the history books.

According to the Guinness World Records, zoologist and ecologist C H Merriam discovered a prairie dog town that spanned 6.5 million hectares in West Texas, USA, in 1901.

This made it almost the size of the Republic of Ireland, with estimates suggesting that the colony supported over 400 million prairie dogs.

The black-tailed prairie dog is known for its loud and complex alarm calls and large colonies – also known as ‘towns’.

Their towns are made up of interconnected burrows and mounds, which provides them with protection from predators such as coyotes, eagles and snakes, and are often described as ecosystem engineers.

This article by Sophie Ellis was first published by Discover Wildlife on 5 August 2026. Lead Image: Getty.

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