In our local bush in Australia, there are two types of birds: those that walk, such as magpies, and those that hop, such as kookaburras. Is one of these groups more advanced than the other?
Pauline Provini, Interdisciplinary Research Centre, Paris, France
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Why certain bird species walk while others hop is a question that scientists have tried to elucidate for decades. There are three main hypotheses, yet there are always exceptions among the huge diversity of bird species on Earth.
The first is linked to their phylogeny or place on the family tree. Bird species inherit their walking or jumping characteristics from their ancestors. This explains why closely related species are more likely to share the same types of locomotion. But this isn’t always the case. Similarly, ostriches and penguins both walk, even though they aren’t closely related.
Size could be a factor too. Larger birds tend to walk rather than hop, as jumping uses more energy, especially for bigger birds. However, toucans hop even though they are much bigger than pigeons, which walk.
The third hypothesis relates to the arboreal way of life: in trees, it is easier to jump from branch to branch than to walk. A I conducted on 1000 species of birds showed that those living in trees are more likely to hop than those that live on the ground. However, parrots walk, yet are mostly found in trees.
“Is a hummingbird, which can hover in the air, a more advanced flyer than an albatross, which can soar for months on end?”
As you can see, there is no clear explanation, and a combination of factors probably explains why some birds hop while others walk.
Linda Phillips, Narrogin, Western Australia
I live in the countryside of south-western Australia and often see crows and parrots standing in the road. I decided to conduct some research by observing their behaviour while out driving. Note: no birds were harmed in the course of this research.
Parrots mostly hopped, whereas crows seemed to prefer walking. I found that, as my car approaches, crows are clearly aware of it and make judgements as to whether it is on a collision course. If a crow realises it cannot walk out of the way in time, it changes to hopping. This is faster, although it takes more energy – try hopping for any distance and you will understand. When my car drives relatively close to a parrot, it reverts to flight immediately. A crow uses the intermediate stage of hopping because it takes more effort for it to get airborne.
As to why crows like to stroll around on open roads… well, I did ask, but got no answer!
Herman D’Hondt, Sydney, Australia
The problem with this question lies in one word: advanced. Evolution isn’t progressive. It doesn’t lead to more advanced organisms. It leads to creatures that are better at the job they are doing. Is a hummingbird, which can hover in the air, a more advanced flyer than an albatross, which can soar for months on end? All we can say is that they need different skills for their survival, and that evolution gave them those skills.
Evolution can go “backwards” as well as “forwards”, too. That is why animals have evolved eyes – and it is why cave fishes lost them. All living things are equally evolved, equally “advanced”, whether it be a virus or a human. They are all the outcome of nearly 4 billion years of blind evolution.
Martin Jenkins, London, UK
Organisms aren’t more or less “advanced”. They are simply better or worse adapted to their environment. A bird hops or walks because it has found this to be the best means of locomotion on the ground. Neither is superior, or more advanced, than the other.
While Australian magpies may walk, the European magpies that I see most days prefer to hop. So both hopping and walking work. In evolutionary terms, that is all that matters.
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