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Special cranial adaptations, including an asymmetrical “wonky” skull and enlarged ears, may give the critically endangered, ground-dwelling nocturnal parrot the edge it needs to navigate the Australian outback in the dark – even with limited eyesight and a large “bluffing” head.
Flinders University paleontologists used a historic nocturnal parrot specimen from London’s Natural History Museum to study its anatomy using high-resolution CT scans after struggling to identify its fossil remains.
“In our work, we typically study the anatomy of extinct animals, but we also use our skills to investigate living species – in this case one of the endangered bird species prioritized by the Australian government for recovery over the next decade,” says Flinders University researcher Elen Shute, who published the latest study of the cryptic nocturnal bird in EMU—Austral Ornithology.
“We hope that conservationists can make the most of the next 10 years to learn as much as possible about the biology and behavior of nocturnal parrots and determine how many there are, in how many places they survive, and what we need to do to put their populations on the upward trajectory.”
The new study sheds light on the life of the small, nocturnal and highly elusive nocturnal parrot, which was only first photographed in 2013, after eight decades of outback expeditions without finding a surviving population.
New insights from a 160-year-old specimen
Flinders University researchers examined the museum specimen used by the eminent British ornithologist John Gould to officially describe the nocturnal parrot in scientific literature in 1861. Carefully preserved for over 160 years, the British specimen gave the South Australian team new information about the species.
3D image of a night parrot skull and brain size. Credit: Flinders University
“The use of non-destructive CT imaging is paramount in studies of such rare material,” says co-author Alice Clement, of Flinders University’s Paleontology Laboratory.
“Using CT scans, we were able to digitally peel away the preserved feather and skin layers to reveal the skeleton underneath without damaging the specimen. Additionally, digital models of the nocturnal parrot’s bones are now available for researchers around the world to examine without the need to capture new animals. .
The large size of the outer ear region is also notable, the researchers found.
“We were impressed by how far one of the nocturnal parrot’s ears protrudes to the side, as well as the size of the outer ear region,” says co-lead author Gavin Prideaux, professor of paleontology at Flinders.
“Taking up about a third of the length of its head, its enlarged ear chambers can act as amplifiers, which would in turn increase the volume of sound transferred to the inner ears.
The advanced scan revealed another evolutionary glimpse into how this clever little bird manages to survive with limited night vision – its advanced audio abilities likely to compensate for small eyes and optic nerves.
“Examination of the skull showed how the enlarged ear cavities appear to limit the nocturnal parrot’s maximum eye size, but they are able to fly up to 30 kilometers at night to feed before returning to roost at sunrise.”
“By measuring the scleral ring – a ring of bone that sits inside the eyeball – and comparing it to those of other birds, we found that a nocturnal parrot’s cornea is about as small as possible while still allowing for visually guided nocturnal flight. A millimeter or two smaller, and they would truly fly blind,” says Shute.
“This is probably why ornithologist John Gould described the nocturnal parrot as having an oversized or ‘bluffing’ head in relation to its body – evolution has cram as much as it could into its skull.”
Flinders University researchers call for more investigation into the particular sensory powers of this intriguing Australian bird, which lives in remote arid pockets of the country and is one of only two strictly nocturnal parrots in the world, along with the New Zealand Kakapo.
Its diurnal relatives are the eastern ground parrot and western ground parrot, which are ground-dwelling species in Australia’s subcoastal habitats.
Thanks to Flinders University for providing this news.
