They are not only constructed, thus request 'knowledge' of constructive processes. Note that this 'knowledge' is much more complex than what we know about tool-use, evidently more evolved knowledge too. There are also strong indications that psychologically great apes feel very 'homely' in their nests. In their spatial arrangements nests of temporary night camps are an indicator of social relations and show prototypes of human settlement. Various studies have clearly shown that learning is involved to a great extent.
Mothers teach their young how to build nests.
More important are the terrestrial groundnests. Note that the domain of terrestrial locomotion of the higher apes is in common with humans. In contrast to arboreal conditions of the tree-nest, the environmental conditions of the groundnest suggest a much wider choice of constructive materials. Thus, the groundnest is clearly an architectural prototype with a fundamental significance for pongid life. It outlines an evidently primary industry with fibroconstructive characteristics.