Simplify the following text for a Grade 8 native English-speaking person.
Original: Generally it is only about 1 % or less of all monarchs , but has maintained populations as high as 10 % on Oahu in Hawaii , possibly due to selective predation .
Simplified: The white form makes up about 1 % or less of all Monarchs except for on Oahu , Hawaii where it has kept populations as high as 10 % .