Originally Posted by junebuggena
That only works on birds that are old enough to begin developing those male specific feathers. That's usually not until about 10 weeks or older.
Feather sexing in older birds depends on sex related feathers...roosters have different coloring, spiky saddle feathers...wings generally don't come into play unless the particular breed has red barring on the wings.
Feather sexing, as I think is being referred to, must be done on very young chicks (1 to 3 days of age) and only works when one parent is rapid feathering and the other slow feathering. The female chicks will have longer primaries than secondaries (coverts) while the males will have equal length primaries and secondaries (coverts) showing slower feathering.
That type of feather sexing cannot be done in older birds reliably. By then, you will be relying on secondary sexual feathers and the fact that roosters often, but not always, feather slower than pullets, but that is very dependent upon breed and bird and thus can't be relied upon across the board.