I have two rosellas and was originally told they were both boys but over the past week they developed a strange ritual between them and one keeps getting on top of the other and shaking. The one on top is also feeding the other by mouth. are they mating?
hmmm, allofeeding is is definitely a behavior that can occur between any two birds especially if they have a bond together ... the mating behavior that you are experiencing, though, is usually reserved to a mating pair ... um, well, looks like it might be time for a DNA test. Don't know what might be going on other than possibly mating ...
Personally I would just give them a nest box and see what happens. The rosellas I have had would get pretty stressed out when being manhandled. If you get eggs you know you have at least one girl. Keep in mind that even with a true pair (male and female) the first clutch can be infertile. By the way, what type of rosellas are they? I ask because some rosellas are dimorphic (you can visually tell the sex like cockatiels).