The little bird is who went - here is my so far but I'll ask Mom:

-Away went the little bird to the idegen country
-What they (s/he) wrote back was, would I go there too

-I will not go there, to the idegen country
-(Until I have to wear?) black clothes here {until I am widowed?)

-Noon is darkening, afternoon is going to/becoming somewhere/thing
-As the evening progresses I get sadder and sadder

-Show (Get) yourself back here, little bird, my little (?) is empty
-Because I (was the one who) fed you white buns

-I don't (?), I don't (?) eat white buns
-I only (?), I only (?) wake up (on?) nice morning(s?)

-Wake up on a good morning, drink some dew
-Drink some dew, eat some wheat heads
-Drink some dew, wake up (on a) good morning.

nice song!