They differ however in a number of characteristics , including the presence of a gall bladder , some other anatomical details and their lack of the Dyck texture feather composition which causes the bright blues and greens seen in true parrots .
They differ however in a number of characteristics , including the presence of a gallbladder , some other anatomical details and their lack of the structures in the feathers which cause the bright blues and greens seen in true parrots .