Walden and "Civil Disobedience"

"There is some of the same fitness in a man's building his own house that there is in a bird's building his own nest. Who knows but if men constructed their dwellings with their own hands, and provided food for themselves and families simply and honestly enough, the poetic faculty would be universally developed, as birds universally sing when they are so engaged? But alas! we do like cowbirds and cuckoos, which lay their eggs in nests which other birds have built, and cheer no traveller with their chattering and unmusical notes." p.36

(E) We, unlike those birds who's tones we admire, do not "build our own nests", which negates us from developing our own beautiful singing voices. Instead we do like the cowbirds and cuckoos, who's voices bring enjoyment to no one, and settle down in nests built by someone else.What do the birds who build their own nests learn that the rest of us who refuse to partake in this task don't?