I have used colored zip ties. Now I buy leg bands. The birds grow so fast I just order the adult size of what ever breed I want to band. I have read of some one using nail polish on the birds toenails.
Guideline Chart for Bird Leg Band Sizes
Band Size, Physical size, Fits
2 1/8" Canaries, day old Quail
3 5/32" Parakeet, 1-4 week old Quail, Doves, Cockatiels, Guinea keets
4 1/4" Baby Chicken, Coturnix Quail, small Pigeon, adult Bobwhite Quail
5 5/16" Pheasant hen, Tumblers, medium Pigeon, Homers, Wood Duck
6 3/8" Pheasant cocks, month old Chickens, large Pigeons, Chukar Partridge
7 7/16" Ringneck Pheasants, Mallards, Wild Ducks, Bantams, Feather Leg and Runt Pigeons
9 9/16" Wild Ducks, Pheasants, Leghorn hens, Ancona, Silkie, Gamebirds
10 5/8" Wild Turkey, Minorcas, Cross breeds, adult Guineas
11 11/16" Rock hens, Wyandottes, Rhode Island Red hens, Leghorn cocks, medium Ducks: Runners, Swedish, Harlequin
12 3/4" Wild Geese, Rocks, Turkey hens, Geese, Jersey Giants, Orpingtons, larger Ducks: Pekins, Rouens, Muscovy
14 7/8" Canada Geese, Turkeys, Honkers, Jersey Giant Cocks