Pallas’s Long-tongued Bat and Hummingbirds

Most of us have seen hummingbirds hover over flowers or at our backyard feeders. Studies of hummingbirds show that they have a powerful downstroke and a recovery upstroke that twists part of their wing almost backward. The twist supplies about a fourth of the energy required to keep the bird in the air. The rest of the lifting energy comes from the downstroke. Because the hummingbirds have such a small mass, it doesn’t take a lot to keep them airborne. There is a bat known as Pallas’s long-tongued bat (Glossophaga soricina). It also sips nectar like the hummingbirds, but the bat is much larger.

Aerospace engineer and biologist David Lentink wanted to see how a more massive animal can accomplish hovering. His Ph.D. student Rivers Ingersol built a flight chamber with special sensors to study the hovering of hummingbirds and bats. He took it to Costa Rica and measured the hovering of 17 species of hummingbirds and three bats, including Pallas’s long-tongued bats.

Ingersol discovered that the upstroke of the nectar-sipping bats’ wings generated a little more energy than the upstroke of other bat wings. But the majority of the lift was generated by the powerful and deeply-angled downstroke. The result is that the bat’s very large wings provide the same hovering power per gram of body weight as the hummers wings. The authors of the study conclude that “supersizing can have its own kind of high-tech design elegance.”

Building a bigger wing that can withstand the stress of rapid beating to allow hovering is an engineering challenge. Proverbs 8 discusses the role of wisdom in all that God has created. Pallas’s long-tongued bat is a wonderful display of that wisdom.
–John N. Clayton © 2018
Source: Science News November 10, 2018, page 4, or CLICK HERE. Original report in Science Advances CLICK HERE.