Sci. Adv. 4, eaat2980 (2018)
Hovering is a tricky skill, but one that several species of birds and bats have perfected in order to consume nectar from flowers. The aerodynamics involved in supporting each animal’s body weight while it hovers have been hard to pin down but recently, a Stanford team combined a high-resolution aerodynamic force platform with a high-speed camera rig to capture and compare the details.
They looked at seventeen species of hummingbird and three bats found in Costa Rica. The hummingbirds generally were more efficient: they deployed quicker, more symmetrical wing beats than the bats. The birds also generated more force during their upstrokes, while bats, with their larger wings, supported their weight on the down stroke with slower beats. Regardless, each used similar amounts of energy relative to their body mass to hover.