• Question: Why do some birds fly and some don't?

    Asked by FabGuy5000 (Wilfred from Broadoak) to Theo, Philip, Kerry, Ali, Alex on 12 Nov 2014.
    • Photo: Philip Ratcliffe

      Philip Ratcliffe answered on 12 Nov 2014:

      Why do some people do anything that others don’t – because they can and the others can’t (but not always). Don’t forget that at the beginning of evolution no animal could fly and then some learnt … and some didn’t.
      Maybe what’s confusing is the use of the word “bird” – at least when you’re younger you associate the idea of a bird with flight, but if you’d been brought up with ostriches or emus it would’ve been different.
      Notice that you could’ve asked: ” Why do some birds swim and some don’t?”, but you didn’t.

    • Photo: Alison Thomson

      Alison Thomson answered on 13 Nov 2014:

      Philip is right! It’s also to do with how heavy the bird is, and how big it’s wings are. The next time you see a feather have a look at the bony bit of it – it’s really light! That’s because there’s no point in having super heavy bones – that would be more weight to carry around.
      And each bit of the feather is joined to the next bit with little ‘hooks’, kind of like velcro.
      Get a piece of paper and try to ‘flap’ it. Now cut loads and loads and loads of holes in the paper and try to flap it again – it’s easier this time isn’t it? That’s because there’s less resistance – the air is passing right through the holes.
      That’s how the wings work – there are no holes, so there’s more resistance against the air, which makes it easier for the bird to fly.
      As long as the bird is light enough and has big enough wings, it will be able to fly. Penguins and ostriches are really big with tiny wings – that’s why they can’t fly – they can’t create enough resistance with their wings to get off the ground.

      Great question!

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