My new ducklings

[Quackers n milk]

I just bought some new ducklings when should I zip tie tag them

 

[Bills vs Beaks]

Cute
When they are grown is best. Doing it now will be hard as you will have to cut them several times off as they grow to avoid the tag cutting into the leg as it grows

 

[TLWR]

Little ones grow so fast the first couple of months. If you do a ziptie on them, you will need to change them every few days or just keep them rather loose to get a bit more time before needing to change them.