Hi Leticia,
I framed this question as 'What herbs can interfere with estrogen?', on the assumption that if we can reduce reproductive hormone activity in the parrot, the egg laying will cease.
One approach is a plant called Xia Ku Cao (Self-Heal; Prunella). It has outright estrogen antagonizing effects, but is quite bitter. I guess if it could be given in a fruit paste or something, perhaps that might work
The second approach is to administer phytoestrogens, which are weaker plant-derived estrogens that can competitively inhibit the action of more potent bodily estrogen. A good formula studied for that effect is Si Wu Tang (Four Materials Combination). You could always use the two approaches together, I suppose, and hedge your bets!
Steve