I've been thinking more about the ways in which folk songs make use of birds, and it occurred to me that there is also simple observation of birds in some songs, which I guess if one assumes a pastoral or rural genesis for a lot of folk music is not surprising - it's simple reportage. An example is the Appalachian standard 'The Cuckoo' (aka The Coo-coo bird') which is a song I picked up from the singing of Clarence Ashley.
Here's a version I recorded with mandolin maestro Nic Zuppardi:
The first verse contains the lyrics 'the cuckoo she's a pretty bird, she warbles as she flies. She never will say cuckoo 'til the 4th day of July'. Which may be true in the US, but would very late for the British cuckoo which is normally returning to Africa by then.
The song seems to be of British origin, so presumably the Clarence Ashley lyrics are a variant as discussed on 'Mainly Norfolk'. In some versions of the song, the lyrics include a story which plays on the bird's association with cuckoldry (which word I've just realised the derivation of!) whereas in others it's simply a song about the cuckoo and its heralding of spring. As ever, there is a huge amount of slippage and borrowing of lyrics and verses between folk songs, as the song evolves and is adapted by each singer, making it impossible to identify an 'original' or pure version. But in this case, given the subject of the song, that seems quite apt!