Living in Motion: How Birds Fly

Wednesday, February 17, 2021

I am surely not the only person who, when asked which superpower I most covet, answers "flying". Flying is only attainable for humans in aircraft but at one point or another, most of us have thought of how free it would feel to fly anywhere we want, it captures the human imagination. Perhaps that is part of why birds are so mesmerizing to us. They range in size drastically from hummingbirds to cranes, but they all possess this freedom and ability to fly and even migrate over thousands of kilometers, such an amazing feat that is impossible for a human being. This begs a bigger question, how do they do it? Why can't we just flap our arms and hope for the best? 

Mallards in flight. Photo by Shayna Hartley. 

Birds have many incredible adaptations that allow them to fly. Interestingly, flight style varies just about as drastically as bird species and size. We have birds that soar with their wings outstretched rarely beating their wings at all and we have hummingbirds who cannot rest their wings for even a second while in flight. We see woodpeckers swoop, crows fly in straight lines, and swallow species dart and weave. The one thing they all have in common is their ability to defy gravity and stay in the air. 

Of course, gravity pulls on birds too. So they have a number of adaptations to make them lighter, including: 

  • Hollow bones 
  • Feathers 
  • They do not carry their young (instead they develop in eggs outside of their body)
  • They eat high calories foods (i.e; seeds, fruits, and insects) to get as many calories from intake as possible. Quick metabolism gets rid of excess weight 
  • Birds don’t have bladders! They urinate as soon as they have to, ridding themselves of that weight too 

  • They do not have teeth or a nose, instead, they have a gizzard closer to their centre of gravity 

Great Egret taking flight. Photo by Heather Kerrison. 

All of these adaptations help birds to defy gravity, keeping them as light as possible. But how do they stay up once they are in flight? Again we see a huge amount of variation amongst species but let's take a look at the two main flying styles, soaring and flapping. 

Osprey in flight. Photo by Heather Kerrison. 

Soaring: When birds soar, they use air currents to hold them up. Thermal air currents, updrafts and wind help them to stay afloat. Adaptations vary amongst. Birds that soar thermals and updrafts tend to have very wide wings and tails like hawks and vultures. Species that use the wind such as gulls have long, narrow wings. 

Flapping: birds that flap have smaller wings than soaring birds, and therefore must move more rapidly to stay in the air. Most songbirds are flying around 11km/h to maintain height.  

This has just merely scratched the surface of all the amazing adaptations and variations amongst birds. Stay tuned for more information on how our feathered friends manage their lives in motion. 



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