Strange as it may seem, I have only ever witnessed this twice - condensation on a bird's breath... Oh my, talk about beautiful!
Image of adult & juvenile Tui - Buller's A History of Birds of New Zealand, 1888
I was topping up the birds' coconut chalice this morning when the tuis came down to the nearest low branch to watch what I was doing (as they do; they're incurably inquisitive) and to offer me their twangy encouragements.
And then I saw it - a tiny, airborne estuary; a vapour drawing; the tuis' song momentarily visible in air. I could almost reach out and touch the clacks and trills, the rattling flourishes and chest-filling tributaries.
It was not unlike watching steam escape from a teapot's spout; birdsong on the boil, a micro-storm brewing in the fork of the old macrocarpa.