Is a bird cage a solid?

Answer 1

All birds nests are a solid state of matter (not liquid, gas or plasma), constructed predominantly from solids (leaves, twigs, bark, etc) however, depending on the species of bird, the nest itself can be quite fragile and/or full of holes, so would not be considered "solid".

Answer 2

Yes, most bird cages are pretty solid and keep the birds from escaping. Go with a metal bird cage or a solid wooden to be on the safe side.