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In case you are seeking an answer, consider that birds instinctively build nests but (most) don't put roofs on them although the process would be a logical cont
by tejtm 4y ago
In case you are seeking an answer, consider that birds instinctively build nests but (most) don't put roofs on them although the process would be a logical continuation of what they can already do.
Because what they have is good enough.
Without selective pressure, evolution just dithers around what already works.
There will be reasons they got to where they are, that they remain just indicates those reasons have not gone away.
- BlueTemplar 4y agoI'm not so certain that it's logical, considering how birds would tend to be away from the nest during the warm days in search for food, and back incubating the eggs during the cold of night, while a roof over a freestanding nest would require much more investment of materials and effort (especially for a species without hands !) ? And of course a lot of species of bird achieves this by nesting in (vertical) holes.
- hutzlibu 4y agoAlso the nest needs to be hidden and a roof would be much harder to spot. So building a roof, that does not draw attention and can resist strong winds would indeed be much harder. Also usually there is some sort of roof and protection by overlapping branches and their leaves.