In the film, we see the ring shrink to Isildur's ring size when he hold it, and it remains that size when Dรฉagol finds it, after thousands of years without a carrier.
If you put it on a chicken, it is also gonna get really small, like chicken fingers small.
I'm not sure if this is a pro or con.
I would consider myself a Lord of the Rings fan, I've read the books maybe 3 times through and read The Silmarillion once.
I forgot the ring makes people invisible.