They are sexually dimorphic, meaning you are able to tell a male from a female visually. The Pacific, or Celestial, Parrotlets are the most beautiful of the pet parrotlet species. Less than five inches in length, they weigh approximately thirty grams. Both males and females have horn colored beaks and feet, with the blue eye streak in both, but more prominent in the males. The male's rump is a bright cobalt blue, a color displayed on the primary and secondary wing coverts, as well.
Pacifics seem to be the most agressive of the species.
Feisty birds, they have been known to launch attacks against much larger birds. There are several color mutations of the Pacific Parrotlet now available in America. The blue is beautiful, and far more colorful than can be shown on a web site. Other mutations are cobalt blue, yellow, fallow, lutino, albino, white, olive or dark factor green and blue-fallow. Green Rumps have sweet, gentle personalities and are a good choice for families with children.