We just use neon colored zip ties. Super cheap and easy to find. Also easy to see on the birds across the yard.
From baby to fully mature, we've only had to change them a couple times. When they're little, they will still stay on pretty well if you leave lots of growing room. Occasionally one will fall off, but hasn't happened to us but a couple times.
Oooo, good idea... (runs off to Atwoods)