Amateur Hoppers

When you think of a hopping animal, your mind probably ~jumps~ to a kangaroo, or a rabbit, or a frog. And with good reason — these animals all exhibit specializations in their bodies that make them great jumpers, like extra long legs and huge leg muscles. There are also plenty of lesser-known animals that are master hoppers: the springbok and klipspringer, antelope species native to Africa, can jump over two meters off the ground, and kangaroo rats (not actually closely related to kangaroos) are teeny tiny rodents that can jump just as high!

But what about the many animals that aren’t jumping pros? Plenty of animals can jump, even though it’s a really hard thing to do — including you — and tons of them even do it every single day. So how do they pull it off?

Let’s ~Jump~ Right In

To get at this question, Dr. Peter Bishop and colleagues from across Europe and the United States decided to study a run-of-the-mill bird with a very fancy name — the elegant-crested tinamou — and see how it manages to jump. The only issue is… birds really don’t like to jump on command. So instead of wrangling live birds, Bishop and colleagues turned to creating a sophisticated 3-D musculoskeletal computer model of a tinamou. By using a lot (a LOT) of complicated math, the researchers were able to get their digital bird to jump! (…eventually.) The results of this work were published recently in Integrative Organismal Biology.

Once the researchers had a successful jumping bird simulation in hand, they were able to dive into the details of how their virtual tinamous got themselves off the ground. Notably, Bishop and colleagues discovered a consistent “countermovement” before the bird lifts off — in other words, the bird crouches down super low before jumping up. The researchers suggest that this movement might help birds’ leg muscles work better, and also lay out some basic physics for why it could be more universally helpful in jumping. Think about when you want to take a huge leap — you probably crouch down first, too!

Leaping Ahead

This new research helps us understand how tinamous get off the ground — but it sets up a lot of interesting future research questions, too. How universal is the use of a countermovement across bird species? How about across the animal kingdom? How might jumping performance differ in birds with different limb segment (thigh, shank, foot) proportions? Could extinct dinosaurs (the ancestors of modern birds) jump, too? How well?

Thanks to the jumping simulation framework created by Bishop and colleagues, we might have answers to these questions very soon! In the meantime, keep checking out iobopen.wordpress.com for the latest in cool, organism-centered biology.

By Armita R. Manafzadeh

Armita R. Manafzadeh is a PhD candidate studying the dynamic arthrology of the archosaur hindlimb at Brown University. Her interests include functional morphology, vertebrate paleontology, and biomechanics.