The crimson rosella was formally described in 1788 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[3] This Latin name had been used in 1605 by the Flemish botanist Carolus Clusius in his book Exoticorum libri decem for the hawk-headed parrot,[4][5] however this predates the start of Linnean taxonomy.

[2] The crimson rosella had been described and named by John Latham in 1781 as the "Beautiful Lory", from a specimen in the collection of Sir Joseph Banks,[6] and then as the "Pennantian Parrot" in 1787[7] in honour of Thomas Pennant.

[10] Most authors used Latham's combination Platycercus pennantii until 1891, when Italian zoologist Tommaso Salvadori established that P. elegans had priority, leading to its universal adoption thereafter.

[11][12] Edward Pierson Ramsay described the subspecies nigrescens in 1888, noting its darker crimson plumage, black back and nape, and smaller size yet larger bill.

The yellow rosella, also known by a variety of alternate common names including Murrumbidgee lowry, murray rosella, swamp lowry and yellow-rumped parakeet,[19] was described as Platycercus flaveolus by John Gould, who gave it the last common name mentioned.

The main distinction between these is size: nigrescens is the smallest of the three and melanoptera is the largest; both are slightly darker than the nominate race.

Both of these still interbreed with the Adelaide rosella where its range crosses theirs, and it exhibits variation in its plumage from dark orange-red in the south of its distribution to a pale orange-yellow in the north.

They will also live in human-affected areas such as farmlands, pastures, fire-breaks, parks, reserves, gardens, and golf-courses.

Outside of the breeding season, crimson rosellas tend to congregate in pairs or small groups and feeding parties.

[25] Crimson rosellas forage in trees, bushes, and on the ground for the fruit, seeds, nectar, berries, and nuts of a wide variety of plants, including members of the Myrtaceae, Asteraceae, and Rosaceae families.

[26] Their diet often puts them at odds with farmers whose fruit and grain harvests can be damaged by the birds, which has resulted in large numbers of rosellas being shot in the past.

[27] Rosellas will also eat many insects and their larvae, including termites, aphids, beetles, weevils, caterpillars, moths, and water boatmen.

[28] Nesting sites are hollows greater than 1 metre (3.3 feet) deep in tree trunks, limbs, and stumps.

Once the site is selected, the pair will prepare it by lining it with wood debris made from the hollow itself by gnawing and shredding it with their beaks.

The nominate bird is mainly red, and a few colour mutations exist, such as the blue, yellow, white, and cinnamon, in aviculture.

Predators of crimson rosellas include the peregrine falcon, grey goshawk and powerful owl,[30] as well as feral cats and foxes.

A new study has shown that hybrid birds were more likely to fight off diseases than were pure breeds; an example of the biological phenomenon of heterosis, in which a crossbreed is stronger than its two purebred ancestors.

Scientists from the Centre for Integrative Ecology at Deakin University in Geelong, Victoria, studied the infection patterns of beak and feather diseases in crimson rosellas across southern Australia.

This included several hybrid populations in northeastern Victoria and southern New South Wales, located in between the range of the two parent subspecies.