Starlinography?

https://www.tomshardware.com/pc-components/storage/yes-you-can-store-data-on-a-bird-enthusiast-converts-png-to-bird-shaped-waveform-teaches-young-starling-to-recall-file-at-up-to-2mb-s

Taking this proof-of-concept to a ridiculous destination, imagine taking a very simple secret message, converting it to sound, and tasking a starling to smuggle it out somewhere. (This seems very impractical compared to an amateurishly knitted scarf with a code in the seemingly random purl stitches.)