impacted isn't really all that common it is just when they eat something that is too large or too long and it won't pass through the crop, it all depends upon the birds some are more prone to the problems than others.
Peafowl Image Database
BYC Recognition Awards - Educator, Friend, Spirit, & Greeter
Suggestions for a First Aid Kit - Preliminary
Oxytetracycline and Tetracycline Powder Doses
How to Provide Emergency and Supportive Care
Poop Tests - Veterinary Parasitology Laboratory
It isn't that common so no worries have fun with your girls.