Female lovebirds Vs male lovebirds

The more common lovebirds such as peach faced and masked are not sexually dimorphic which means you can not tell what sex the lovebirds are by looking at them and the only way to tell is by DNA sexing them. Because telling which sex a lovebird is so difficult you often do not know what sex your lovebird is when you buy it unless you get a DNA test done before you buy it. 

When your lovebird or reaches maturity which is around one years of age it may show some signs of wether it is male or female such as ripping up paper and stuffing it into it's feathers (female) or regrugitating for its owners (male).
The things an un-sexed lovebird can is not a reliable way of telling if it is a male or female which is unfortunate.