Simplify the following text for a Grade 7 native English-speaking person.
Original: The nominate subspecies of this parakeet is 29 cm long on average , with a 48 cm wingspan , and weighs 100 g. Females tend to be 10-20 % smaller but can only be reliably sexed by DNA blood or feather testing .
Simplified: The parakeet is on average 29 cm long , with a 48 cm wingspan , and weighs 100 g. Females tend to be 10-20 % smaller , but it is hard to tell the sexes apart , unless they test the feather or blood DNA .