A wide variety of animals can fly (more than just birds, butterflies, bees, or bats), and among those flyers, a select few can perform aerial acrobatics, like hovering — suspended in space, defying gravity in the process.
A few of those hovering specialists passed through the backyard this summer, and I attempted to capture their effort one wingbeat at a time. And this is by no means easy when the subject a) darts from one hovering location to another in a millisecond (the hummingbird and the dragonfly) and b) is so small it’s difficult to focus on it (the dragonfly and the hoverfly). The video clips below illustrate the difficulty.
A Ruby-throated Hummingbird in a sea of red Cardinal flower, delicately moving from blossom to blossom while beating its wings 80 times a sec. I could stop the wing motion of this bird with the camera shutter speed at 1/2000 of a second.
Hummers move their wings in a figure-eight pattern, rather like the sculling motion of the hands of water ballet performers make to keep them static in a column of water. Forward and backward movement of the wings cancel horizontal movement, and the lift provided by the figure-eight motion keeps them suspended vertically.
A stocky bee mimic, the drone fly (Eristalis tenax) took up territorial residence outside my backdoor, hovering near the peonies in May. One of the most widely distributed species in the world, drone flies maintain small territories near flower beds to attract females, occasionally darting out to chase off intruders.
Freezing the drone fly wing beat in time required the fastest shutter speed on my camera dial (1/8000 of a sec). Two tiny wings propel the fly forward, backward, or keep it motionless in space, moving faster than the eye can see them — sort of like a helicopter rotor.
Dragonflies hover with two sets of wings, i.e., four moving blades swooping independently through the air. Normally, dragonflies dart along the shores of ponds and streams, moving quickly from spot to spot, but occasionally they pause in their patrol efforts to hover over particular spots they are defending or to advertise their presence to females.
The 4-spotted Skimmer hovered almost motionless in space in front of me as I tried to focus on its abdomen. Although the wings look synchronized in this view, front and back pairs move independently, as illustrated in the video below. The wingbeats flutter in a blur to the human eye, but they beat at a much slower rate than those of hummingbirds or drone flies, and I was able to capture static shots at 1/1000 of a second.
It’s a most impressive feat of flying that is demonstrated by these animals, and one that has been copied by human engineers seeking to copy vertical take-offs and hovering efficiency in aircraft.