This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Birds may not always take the flight path that physics suggests is the perfect landing, at the safest and lowest possible speed, using the least energy, according to new research. Most birds flap their wings as they come in to land, despite powered flight requiring more energy than gliding.
Now, researchers at The University of Manchester have used mathematical modeling to help explain why. The study, published in Proceedings of the Royal Society A Mathematical Physical and Engineering Science, found that a bird flying without flapping its wings could, in theory, reach zero speed just as it touches down. However, the maneuver would require much higher approach speeds and considerably more space than birds typically use when landing.
For a pigeon-sized bird, the model showed that reaching zero speed would require it to begin at more than twice its typical cruising speed, travel around 60 meters (197 feet) horizontally and climb around 20 meters (66 feet). The findings suggest that achieving the lowest possible touchdown speed may not always be practical. Birds may use flapping not simply to slow down, but to do so within the limited space available in a real landing environment.
The research also provides new insight into why some birds swoop when landing on a perch, and how the physical demands of landing may have helped shape bird evolution. Ben Parslew, lecturer in aerospace engineering at The University of Manchester, said, "Birds might make landing look effortless but coming to a safe stop presents a fundamental physical challenge. Landing isn't as simple as just slowing down.
The slower a bird flies, the less aerodynamic control it has, so it has to find a way of reducing its speed while still being able to maneuver safely. How birds do this and manage these competing demands is still not well understood. "We used mathematical modeling to calculate how a bird flying without flapping could minimize its speed at touchdown while maintaining the control needed to complete the maneuver.
"In doing so, we've been able to gain insights into the swooping approaches seen in some perching birds, such as birds of prey, and more broadly, understand how physical demands of landing may have helped shape their evolution." The modeling also provides new insight into the swooping behaviors observed in some birds when landing on perches. Previous research on Harris's hawks found that the birds learned to swoop down below their target landing spot before gliding upward toward a perch. It was proposed that the maneuver helped them minimize the distance they traveled after their wings stalled, when aerodynamic control is reduced.
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