Australia’s Night Parrots Can’t See In The Dark
By: 𝐆𝐫𝐫𝐥𝐒𝐜𝐢𝐞𝐧𝐭𝐢𝐬𝐭, Scientist
Tags: Evolution, Science, Ornithology, Ecology, Vision

A recent anatomical study of Australia’s nocturnal night parrot has revealed that it may not see very well in the dark. According to the study, the parrot’s vision is probably similar to that of day-active parrots. Thus, despite its nocturnal lifestyle, the night parrot’s inability to see in the dark could be contributing to its critically endangered status.

Night parrots went unseen for more than a century

The night parrot, Pezoporus occidentalis, is a small nocturnal parrot that can only be found in Australia’s immense arid interior. It is has cryptic greenish yellow plumage with yellow, brown, and black speckles throughout.

Night parrot (Pezoporus occidentalis) are small, elusive nocturnal parrots found only in Australia’s arid interior. (Credit: Rachel Murphy.)

Only 25 specimens had been collected between 1845 and 1875, when the night parrot suddenly disappeared. It went unseen for longer than a century all across its vast range, leading the Smithsonian Museum to recognize it as ‘the world’s most mysterious bird’. Some experts argued that the parrot could be extinct. A reward of $25,000 was offered for a night parrot, dead or alive.

Just when hope had almost completely evaporated that the elusive species’ might still be alive, two night parrot bodies were unexpectedly discovered, the first in 1990 (ref), and then a second in 2006 (ref). Finally, in 2013, several live individuals were photographed by camera traps in southwestern Queensland, which then led to the discovery of a small population of these birds. Having re-discovered the ‘holy grail’ of birds, much celebration ensued. Later, a few more populations of night parrots were found and soon, several studies — mostly observational — of these mysterious parrots began to appear in the scientific literature. The most recent of these studies reports that night parrots probably don’t see very well in the dark.

“Night Parrots must be able to find their way at night — to find food, avoid obstacles while flying, and escape predators”, said study author, evolutionary and developmental biologist, Vera Weisbecker, an associate professor at Flinders University’s College of Science and Engineering, in a statement.

There are only two nocturnal parrot species in the world, Australia’s night parrot and the distantly related Kākāpō in New Zealand. The night parrot is largely terrestrial — avoiding flight most of the time, but instead, sprinting madly between spinifex grass tussocks on the desert floor. However, unlike the flightless Kākāpō, the night parrot can actually fly — and often does so around dawn and dusk — in search of the grass seeds that it eats.

“We therefore expect their visual system to show adaptations for seeing in the dark, similar to other nocturnal birds — New Zealand’s Kakapo parrot and owls with enlarged eyes, for example”, Professor Weisbecker added. “However, we found that this wasn’t the case.”

Generally, nocturnal animals have more eye cells, called rods, that increase sensitivity to light. Many nocturnal animals also have unusually large eyes that allow them to capture every available photon of light. For example, owls are nocturnal birds that use their excellent night vision for hunting.

Night parrots are so rare that scientists had only one skull to study

Because night parrots are nocturnal, the researchers wanted to better understand this species’ visual abilities. However, the night parrot is so rare that every living bird is precious, so researchers could only examine dead specimens that had been collected throughout the past century and a half. The scientists found only one intact skull that was suitable for this study. This skull was part of the mummified body of a night parrot (Figure 1a) discovered in 1990 by ornithologist Walter Boles, a senior fellow at the Australian Museum.

“He spotted its mummified body by accident, lying by the side of the road after apparently being hit by a truck — it is amazing that its skull stayed intact!”

(L-R) Dr Karine Mardon, Dr Vera Weisbecker and Heather Janetzki getting ready to scan a night parrot specimen; An internal scan — or, endocast — of the inside of a night parrot’s head. (Credit: Steve Murphy / Charles Darwin University)

Study co-author, Karine Mardon, National Imaging Facility Fellow and Molecular Imaging Facility Manager at the University of Queensland’s Centre for Advanced Imaging, used computed tomography (CT) to scan this night parrot skull. These CT scans were used to produce a three-dimensional reconstruction (an endocast) of the night parrot’s brain so the research team could study the bird’s visual system (Figure 1b). Study co-author Aubrey Keirnan compared the 3D scans with those of its closest relatives, the ground parrots, as well as hundreds of other day-active parrot species (Figure 1c).