Why Can't Some Birds Fly?

You might have many birds which can't fly. Have you ever wondered why can't they fly? So, in this session, we'll be finding answers to this question. So, without any delay, let's get started...

Well, there are many flightless birds from Australia to Africa to Antarctica. They include some species of duck and all species of penguins, secretive swamp dwellers, speedy ostriches, giant emus, and tiny kiwis. Though all the ancestors of modern birds could fly many bird species have independently lost their flight.

A question might be arising to mind, what is the use of flight for birds? Well, the flight can have many benefits, especially for escaping from predators,  hunting, traveling long distances, and migrating. But, the flight also has a high cost. It consumes a high amount of energy and limits body size and weight. So, we can say that a bird that doesn't fly conserves energy, so it may be able to survive in a scarce conditions or with less-nutrient rich food sources than one that flies.

When a bird species doesn't face pressure to fly, it can stop flying for a few generations. Then, over thousands or millions of years, the birds' bodies adopt the new behavior. Their bones which were once hollow become dense. Their sturdy feathers turn to fluff. Their wings shrink, and in some cases disappear entirely. The keel-like protrusion on their sternums, where the flight muscles are attached, shrinks or disappears. And finally, they are unable to fly. Well, there is an exception too: The penguins, who repurpose their fight muscles and keels for swimming.  

Most often flightlessness evolves after a bird species fly to an island where there are no predators. As long as these predators' free circumstances last, the birds develop, but they are vulnerable to changes in their environment. For instance, human settlers bring dogs, cats, and rodents to the island. These animals prey on flightless birds and can drive them to extinction. So, this is the reason why there are so few flightless birds now, most of them were extinct by predators. 

Unlike most small flightless bird species that came and gone quickly, the giants have been flightless for millions of years. Their ancestors appeared around the same time as the first mammals, and they were probably able to survive because they were constantly evolving and growing at the same time. Most birds like emus and ostriches ballooned in size, weighing hundreds of pounds their wings can lift. Their legs grew thick, their feet sturdy, and they developed thigh muscles that turned them into runners. 

Though the flightless birds don't use their wings to fly they use them for other purposes. They can tuck their young ones' heads to give warmth, flash for coolness, and shelter eggs with their wings. 

I hope you have got something new to learn from this session. That's all for this session.  Share it with your friends and family members. Thank you for reading.