Can larger animals travel faster? A new study challenges this notion and reveals why medium-sized animals tend to have the fastest sustained speeds.

A recent study, led by Alexander Dyer from the German Centre for Integrative Biodiversity Research (iDiv) and the Friedrich Schiller University Jena, Germany, has revealed that the ability of animals to effectively shed excess heat generated by their muscles is the key factor that limits their traveling speed, regardless of whether they are flying, running, or swimming.

The findings, published today in the open-access journal PLOS Biology, have important implications for the survival of animals, as their ability to travel plays a critical role in finding food and mates, migrating, and expanding into new territories.

The study highlights that the challenges for animals are even greater in today’s human-dominated world, where habitats are increasingly fragmented, and resources such as food and water are limited due to climate change.

Thus, the ability to regulate body temperature becomes a critical factor in determining an animal’s survival and success.

In their study, Alexander Dyer and his colleagues created a model that examined the relationship between animal size and traveling speed. The researchers analyzed data from 532 species to understand how animal size affects their ability to move quickly. Surprisingly, the study found that medium-sized animals tend to have the fastest sustained speeds, despite the belief that larger animals with longer wings, legs, or tails should be faster.

The study’s authors suggest that the reason behind this finding is due to larger animals generating more heat when they move, and thus, they require more time to dissipate this heat to avoid overheating. This slower speed allows them to regulate their body temperature effectively, ensuring their survival. The researchers concluded that an animal’s traveling speed can be explained by considering how efficiently it uses energy and sheds heat.

These findings shed light on the complex relationship between body size, energy use, and heat regulation in animals, and their importance in determining the speed at which animals can travel.

The findings of “the new study provides a way to understand animal movement capacities across species and can be used to estimate any animal’s traveling speed based on its size,” remarks Dyer.

The study’s approach has practical applications, such as predicting an animal’s ability to move between habitats that are fragmented due to human development. Even if the biological details of the animal are not fully understood, this method can still be useful in making predictions.

“We anticipate that large animals are potentially more susceptible to the effects of habitat fragmentation in a warming climate than previously thought,” adds last author Dr. Myriam Hirt, “and therefore more prone to extinction. But this needs further investigation.”

Image Credit: Ulrich Brose (CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/)