Captive birds are likelier to be less fertile. A variety of hypotheses to explain the phenomenon have been proposed - Low (1995) suggests that this is because amazon parrots have shorter breeding seasons, while Hagen (1994) suggests that this is because male and female parrots may not be ready for breeding at the same times.
CApTive BiRDs arE likEliEr To be LesS feRtilE. A varIety oF HypOtHesEs tO explAIn tHE pheNomenOn have Been prOposeD - loW (1995) suggEStS ThAt this is becAuse amaZon pArroTS HAve sHorter brEedIng sEasoNS, whilE Hagen (1994) sugGEsts tHat ThiS is BEcause MAlE and femAlE parRots mAY Not Be REAdy fOr brEEding aT the saME tiMes.