Thank you for joy

[busker]

The second half of the poem is beautiful and worthy of being a poem in itself. 
It's the repetition of 'in the morning' that seems off. 
'swallows in the morning' is essentially the same as 'birds in the morning' from the first half.
Just a thought,
Cheers

thanks, ambroisial - good point on the birds / swallows not achieving the desired effect. Will give it some thought.