Birds are among nature’s most accomplished flyers, and one of their most captivating abilities is the capacity to glide through the air without flapping their wings. This effortless, elegant motion is not merely a product of evolution—it is a sophisticated demonstration of aerodynamic physics in action [1].

A bird’s wing is shaped like an airfoil: curved on the top and flatter underneath. As the bird moves forward, air flows faster over the top surface and slower beneath it, creating a pressure difference. According to Bernoulli’s principle, this difference—lower pressure above and higher pressure below the wing—produces lift, allowing the bird to remain airborne without flapping [2]. Simultaneously, Newton’s Third Law reinforces lift: as the wings push air downward, the reaction force propels the bird upward [3].

To glide effectively, a bird must maintain a delicate balance between lift, weight, and drag. Since gliding birds do not generate thrust through flapping, they rely on their momentum or the natural energy of the atmosphere. One such energy source is thermals—rising columns of warm air that enable birds like eagles and vultures to gain altitude effortlessly [4]. Over oceans, large seabirds such as albatrosses utilize dynamic soaring, extracting energy from wind gradients at varying altitudes [5]. Ridge lift also assists gliders when wind is deflected upward by cliffs or hills [6].

Beyond harnessing atmospheric energy, birds minimise drag through wing extension, streamlined body posture, and smooth feather alignment. Species adapted for long gliding typically have long, broad wings that maximise lift while reducing air resistance [7].

Ultimately, the serene grace of birds gliding through the air embodies a harmonious convergence of evolutionary design and physical law. By mastering aerodynamic forces and harnessing environmental energy, birds can traverse vast distances with remarkable efficiency—a timeless natural marvel that continues to inspire the field of aeronautics [1,5].

References

1. Pennycuick, C. J. (2008). Modelling the Flying Bird. Elsevier.
2. Anderson, J. D. (2010). Fundamentals of Aerodynamics (5th ed.). McGraw-Hill Education.
3. Newton, I. (1687). Philosophiæ Naturalis Principia Mathematica.
4. Tucker, V. A. (1998). Gliding birds: The mechanics of soaring and thermal flight. Journal of Experimental Biology, 201(1), 1–15.
5. Weimerskirch, H., et al. (2000). Energy saving in flight formation. Nature, 405(6786), 295–297.
6. Pennycuick, C. J. (1972). Soaring behavior and the distribution of birds. Bird Study, 19(2), 151–169.
7. Norberg, U. M. (1990). Vertebrate Flight: Mechanics, Physiology, Morphology, Ecology and Evolution. Springer-Verlag.

Author: Dr. Emma Ziezie Mohd Tarmizi

            Physics Unit, ASPutra

Date of Input: 02/12/2025 | Updated: 02/12/2025 | emma