South-west Endemics Part 4: Red-capped Parrot - The illegitimate child of inseparable parents?

The species name spurius, meaning illegitimate, might seem an incongruous name for a bird so elegant and beautiful - albeit slightly gaudy – as southwest WA’s endemic Red-capped Parrot Purpureicephalus spurius. The name stems from the fact that immatures are so plain as to hardly seem related to the extraordinarily vivid, though not often seen, bright adult male. The majority of birds observed lie between these extremes, with a partial or duller version of the male plumage, and one might be tempted to label these as females. However - perhaps obviously, given the extreme gender ratio this would imply - identifying the sex of adult birds is not so straightforward. In fact HANZAB [1] states that females are “very similar to male and often inseparable”.

An immature Red-capped Parrot, the 'illegitimate child' that gives the species its Latin name. It is thought to be impossible to sex immatures on plumage characteristics, but if this is an older immature (as suggested by the mauve breast), then it is probably a female, as males acquire a red cap more rapidly than females [2].