Nature
PUBLISHED
If you’ve ever watched a small bird or insect flying around when it’s raining, you might’ve wondered how these creatures are able to navigate torrential downpours. New research published in the journal Royal Society Open Science investigated how it was possible for delicate animals to cope with such forces while flying by making a group of hummingbirds cross a waterfall.
The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.In the wild, hummingbirds aren’t known for diving in and out of such water features, but they’re a close relative to a variety of swift that nest behind them, making the treacherous journey in and out of the stream of falling water repeatedly throughout their lives. The researchers set up a feeder and a perch on opposite sides of a 54-liter flight chamber. Between the two was an artificial waterfall that used a small water jet and a pump to create a flow that was slightly stronger than the most torrential of downpours.
The species tasked with crossing the wall of water was four Anna’s hummingbirds (Calypte anna) who demonstrated an unexpected approach to coursing through the obstacle. Rather than tucking in their wings and shooting through like a bullet as biologist and lead author on the study Victor Ortega-Jimenez predicted, the majority of the birds actually shimmied through the waterfall sideways.
By making a sideways approach, the hummingbirds could part the falling water with one wing, slip through the gap, and use their second wing to separate the water once their leading wing was through to the other side. This left one wing free at all times to continue to generate thrust, keeping the bird moving forwards. One bird, however, did decide to take more of a face on approach, as can be seen at the end of the above video.
That they can survive the journey shows that such water cascades could represent a protective barrier for nesting birds whose chicks are often preyed on by parasites and raptors. Ortega-Jimenez and colleagues hope to further their understanding of how birds use waterfalls as a protective element in their habitat by monitoring swifts using drones to follow them into the waterfall. Fingers crossed the drones make it through to the other side.
[H/T: Science Magazine]
