I guess you’d call it survival of the fittest.
The strong bird survived and the weak one didn’t.
The weaker bird was caught by something and was left on the grass, as demonstrated in the picture.
The stronger bird is still scurrying around the garden. It had taken up residence in the drain that runs around the house but managed to leave the drain, perhaps using the plank of wood I left in the drain in order to climb out.
It looks healthy and strong, even though it’s still incapable of flying.
I didn’t leave any food for it to eat because as far as I could discover, swiftlets eat insects and I don’t have any insects in the fridge or the pantry. I do, however, have a compost pile and a number of fruit trees in the garden which attract insects, plus I live opposite a reasonably large fruit farm.
There are many adult swiftlets near my house, and a nest under my house, so I assume one of them must be the mother and maybe she is feeding the remaining juvenile bird.
I had constructed a temporary birds nest and hung it in one of the mango trees in my garden. I placed the birds in that nest, but they got out.
I think I’ll leave the nest there for the time being, it might attract some bird life and give them somewhere to rest.