These attributes may explain their apparent population increase. Adapt well to a changing diet. They learn quickly how to exploit new foods, and thrive on oats, capeweed, dock and thistles. There is little competition for some of these seeds. Oats are especially useful to parrots to help them survive winter, because of their high oil and low gluten content.
Parrots also eat other oily seeds such as sunflower and canola.
High breeding success. Females start breeding when very young and can breed for many years. They lay about seven eggs per clutch, some females producing two clutches per year. After hatching out in October, the young birds grow rapidly, and are almost adult size when they leave the nest in November and early December. Mortality from hatching to fledging can be as low as 25 per cent.