[Monica]

Males usually have brighter faces. It's harder to tell in mutations. Females usually have barring on tails, spots on flight feathers, and retain pearls. Males are usually known for singing a couple times throughout the day where-as females usually only chirp. Females may have a wider stance than males. Males may rub their bottoms on toys or perches, and may sing to their toys. Females will usually back up against an item.

Sometimes, the only sure way of sexing a tiel without knowing personality and mutations would be to have a dna sex done.