If Ostriches Can’t Fly, How Did Their Ancestors Manage To Cross The Seas?

It has long been believed that birds fly as it helps them escape predators, find food, and migrate according to the changing seasons. However, there are a few other species of birds that have evolved to stay on the ground, developing strong legs or specialised bodies in the process. For instance, large birds like ostriches and aquatic birds like penguins can live without flying. The long legs of ostriches are built for speed, making them the fastest birds on our planet. However, scientists are now wondering how the ancestors of these huge birds reached the faraway lands of Africa, Australia, New Zealand, and South America by crossing vast oceans, despite their inability to fly.

Researchers once believed that ostrich ancestors were separated when the Gondwana split more than 150 million years ago. However, genetic studies suggest a different story. As reported by Earth.com, Klara Widrig, an expert in the field, said, “The evolutionary splits between paleognath species happened long after the continents had already separated." She and her team then decided to analyse the matter in depth. For this, the team of scientists and expert researchers studied a well-preserved fossil breastbone of one of the oldest relatives of today’s flightless birds.

The analysis proved that these ancient birds were probably able to fly across long distances, much like modern pigeons or parrots. Once these birds reached a landmass, they eventually grew larger in size and lost their flying ability. These findings were revealed in a recent study titled, "Quantitative analysis of stem-palaeognath flight capabilities sheds light on ratite dispersal and flight loss." It was published in the Royal Society’s Biology Letters. Ostriches, emus, and a few other birds are part of a group called Paleognathae, which also includes tinamous and other ground-dwelling species. This group once included the now-extinct species, too, like moas from New Zealand and elephant birds from Madagascar.

As reported by Smithsonian Magazine, Helen James, a zoologist and one of the co-authors of the study, spoke about the findings and said, “I am amazed that the surviving lineages of this ancient group of flying birds are all either completely unable to fly or capable of flying only short distances. The ability of these poorly dispersing species to survive and persist is now the big mystery.” Widrig provided a simple explanation for the reason behind modern ostriches and emus eventually giving up the skies.

She said, “Birds tend to evolve flightlessness when two important conditions are met: they have to be able to obtain all their food on the ground, and there cannot be any predators to threaten them." The absence of predators likely happened after the dinosaurs disappeared millions of years ago. The lead author said, “With all the major predators gone, ground-feeding birds would have been free to become flightless, which would have saved them a lot of energy." Over the years, some birds, like ostriches, developed speed to survive, while others, like cassowaries, began using their strong legs and deadly kicks as defence.