Airborne hippos? Giant water dwellers fly briefly at full speed: Study

We all know hippos as giant, grumpy water dwellers. But a new study reveals a surprising secret about how they move on land.

To shed light on landlubber behavior, Professor John Hutchinson of the Royal Veterinary College (RVC) has studied how hippopotamuses (hippos) walk and run.

Researchers determined that hippos “almost exclusively trot” – even at slow speeds. This is unusual for large animals, who typically have a wider range of gaits. But the surprises didn’t stop there. The study found that the fastest hippos actually become airborne at their full trot.

Hutchinson said, “We’re thrilled to provide the first study purely focused on revealing how hippos walk and run. We were pleasantly surprised to see how hippos get airborne when they move quickly – it’s really impressive!”

Fastest hippos take to the air

From the lumbering walk of an elephant to the graceful gallop of a horse, each species has its distinct style of moving around on land. But not much was known about the hippos’ movement pattern on land.

Previous research offered conflicting views on the hippopotamus movement on land. Some studies suggested a standard four-legged walk, similar to elephants, while others proposed a trotting gait with diagonal legs moving together.

Moreover, no prior research explored whether hippos become airborne at high speeds, a common occurrence in many mammals but rare for such large animals.

The Hutchinson-led team decided to look into it by gathering video footage from the Flamingo Land Resort in Yorkshire. The videos captured two hippos as they go about their day in their paddock.

In addition to the footage, the researchers searched online for hippo movement videos. This expanded their dataset to include 169 locomotion cycles from 32 different hippos.

Interestingly, they found that hippos primarily trot, even at slow speeds of walking or running quickly.

“This is unusual for land animals, which tend to have a wider repertoire of gaits – for example, rhinoceroses can use a standard quadrupedal walk, trotting and galloping as they increase speed; much like a horse,” the researchers explained in the press release.

The most unexpected finding is that fastest hippos take to the air for a surprising amount of time — 15% of their stride cycle, or more than 0.3 seconds. This flying action has never been observed in hippos previously. This entire-body lift movement is highly surprising as these water-loving giants reach a weight of over 2,000 kilograms.

Diverse locomotion patterns

Before this study, understanding hippo locomotion remained elusive. As per Hutchinson, this is due to their aquatic lifestyle, minimal presence in trained zoo environments, and of course, their inherent danger.

The unique locomotion of hippos expands our understanding of how giant land animals move. As per the press release, the findings reveal a surprising diversity in their movement patterns, challenging previous assumptions.

Kieran Holliday, Science and Conservation Officer at Flamingo Land Resort, said, “This research will improve scientific understanding of how the size of large animals influences their movement on land, support the reconstruction of the evolutionary biomechanics of hippo lineages, and help veterinarians diagnose or monitor hippos that have problems moving or are experiences lameness.”

The study has been reported in the journal PeerJ.