UNews - Aubrey Keirnan

��Ѹ��Դ��߿�Ƭ of Lethbridge PhD student leads international study of extinct Hawaiian bird

trevor.kenney — Tue, 03 Feb 2026 16:23:22 +0000

Islands are famous for producing some of the world’s strangest creatures, and a new study shows that evolution on islands can push birds into even more unexpected directions than previously recognized.

��Ѹ��Դ��߿�Ƭ of Lethbridge PhD student Sara Citron led an international team from Canada, the United States and Australia that discovered how an extinct Hawaiian ibis evolved unusually small eyes and a dramatically reduced visual system, traits seen only in a handful of bird species alive today.

ULethbridge PhD student Sara Citron led the international study.

The team made the discovery while examining the skull of Apteribis, a flightless ibis that once inhabited the Hawaiian Islands.

“Anyone who has spent time birdwatching or visiting a zoo is familiar with ibises. These are very distinct birds: they have exceptionally long, elegant beaks and many of them have striking colors that set them apart from other shorebirds,” says Citron. “Their elongated beaks are key to how they feed. By inserting the beak into mud, shallow water, or soft ground, they probe for subtle vibrations that reveal the presence of hidden prey, such as small invertebrates.”

Citron’s supervisor, Dr. Andrew Iwaniuk, explains that the team targeted the Hawaiian species because island evolution often produces bizarre anatomies.

“From the moment we looked at the skull, we could see that the orbits, the spaces where the eyes sit, were far smaller than they should have been,” says Iwaniuk.

The extinct Hawaiian Apteribis and its distinctive elongated beak and unusually small eyes.

In an international effort, the researchers examined skulls from 25 of the 28 living ibis species, using museum specimens from all over the world. With advanced imaging technology, they created 3D reconstructions of the birds’ brains and compared them with the fossil species.

“What we found was astonishing,” says Citron. “The eyes and all parts of the visual system that we can measure from the skull were dramatically reduced in Apteribis compared to its living relatives.”

Co‑author Aubrey Keirnan, a PhD student at Australia’s Flinders ��Ѹ��Դ��߿�Ƭ, says that such extreme reductions in vision are known only in a few birds, including the New Zealand kiwi and the world’s two nocturnal parrots, the critically endangered kākāpō and the elusive night parrot.

“What all of these species have in common is that they rely very little on sight and are active mainly at night,” says Keirnan.

The findings strongly suggest that Apteribis was also nocturnal, roaming the Hawaiian landscape under cover of darkness to feed and possibly breed, while resting during the heat of the day.

Dr. Vera Weisbecker from Flinders ��Ѹ��Դ��߿�Ƭ, explains that this then brings the question “why were they nocturnal?” The answer likely lies in Hawaii’s unique ecology.

“Hawaii is the most isolated archipelago on Earth and originally had no mammalian predators. Similar to the situation in New Zealand, large birds like ibises were safe on the ground and eventually lost the ability to fly,” she says. “Highly acute vision would not have been a particular advantage.”

However, Weisbecker adds that other factors must have existed to push Apteribis into the dark.

That missing piece may come from their prey. Helen James, Curator of Birds at the Smithsonian National Museum of Natural History in Washington, explains that the Hawaiian Islands were once home to an extraordinary diversity of snails and flightless crickets.

“Flightless crickets and snails are nocturnal and would have been more abundant then, exactly the kind of prey that could drive a bird like Apteribis to adopt night‑time foraging,” she says.

Why Apteribis became extinct remains a mystery, Citron explains.

“Possible causes of extinction are changes to the climate and vegetation on the Hawaiian Islands and the first arrival of humans. We may never know the true cause of the extinction of this wonderfully strange species.”

Iwaniuk emphasizes the broader implications of the discovery.

“The New Zealand Kiwi is often seen as a one‑of‑a‑kind oddity among modern birds, but this extinct ibis shows that similar forms evolved elsewhere,” he says. “It reminds us how much diversity has been lost, and how many ecological roles disappeared, before we ever had the chance to study them.”

��Ѹ��Դ��߿�Ƭ of Lethbridge-led international study finds harriers have evolved hunting technique similar to owls

trevor.kenney — Thu, 01 May 2025 14:58:34 +0000

Owls have long been considered unique in their famous ability to hear exactly where their prey is. However, a new study has shown that another, unrelated group of raptors – the harriers – are able to keep a much better ear out for their next meal than previously thought.

An international team of ��Ѹ��Դ��߿�Ƭ of Lethbridge and Flinders ��Ѹ��Դ��߿�Ƭ (Australia) researchers made the discovery when they found unexpectedly owl-like traits in the ear and brain of several harrier species, such as the Australian spotted harrier. Their study, The evolution of an “owl-like” auditory system in harriers: Anatomical evidence, is now available online in Journal of Anatomy.

A northern harrier seeks prey while flying over a field. PHOTO by Bob Bowhay, rdbimages.ca

“Owls have fine-tuned hearing abilities, allowing some species to locate prey in complete darkness. Until recently, it was assumed that all their hearing adaptations were unique to owls. However, our study shows that harriers have independently evolved several key adaptations for finding prey by sound,” says Sara Citron, a ULethbridge PhD student who led the study.

Citron’s supervisor, Dr. Andrew Iwaniuk, says the team focused on harriers — a group of hawks found in North America, Australia, NZ, Europe, and parts of Africa and Asia — because they show some unusual, owl-like hunting behaviours.

“Hawks tend to hunt primarily by sight. But unlike other hawks, harriers fly low over tall grass with their beak pointed to the ground. During this so-called “quartering flight”, they are not only looking for prey, they are also listening for it,” says Iwaniuk.

Co-author Aubrey Keirnan, a PhD student at Flinders ��Ѹ��Դ��߿�Ƭ who is co-supervised by Iwaniuk, says that simply by looking at the harrier, you can see similarities with owls.

A northern harrier in flight. PHOTO by Bob Bowhay, rdbimages.ca

“The Australian Spotted Harrier is a great example,” she says. “When you look at this species’ face, you can see a distinctive disc-shaped face, which may improve their prey localization just like owls.”

Citron adds that their find also matches older behavioural studies showing that harriers can locate sounds with similar accuracy to owls, but how they did this has previously remained a mystery.

Using specimens from wildlife rehabilitators and museums in Australia and Canada, the team examined the anatomy of the skull and brain of harriers and other, closely related hawk species such as the wedge-tailed eagle. They found that, like owls, harriers have enlarged ear openings and expanded two brain regions that are essential for calculating where a sound is coming from.

“These auditory nuclei are found in the brainstem and compare the time at which sounds arrive at the left or right ear. If a sound arrives at both ears at the same time, then the sound is coming from directly in front of an animal. If there is a delay, this indicates that the prey is more to the left or right,” says co-author Dr. Vera Weisbecker, an associate professor in evolutionary biology at Flinders ��Ѹ��Դ��߿�Ƭ. “By expanding these two brain regions, harriers can make such computations more accurately than other hawks, allowing them to locate where a potential rat, mouse or other rodent is hiding in the grass.”

“Harriers have therefore evolved an auditory system similar to owls, enabling them to target sounds as accurately as owls in a remarkable example of convergent evolution of both brain and behaviour in animals separated by over 60 million years,” adds Citron.

The team is careful to point out that the auditory system of many owls is far more sophisticated than that of harriers. This explains the ability of some owl species — like the barn owl — to hunt in complete darkness whereas hawks only hunt during the day.

“There are several other features that help owls with their keen hearing which we did not find in harriers,” says Citron. “For example, some owl species have asymmetric ears that allow them to locate sound with greater acuity, and these owls also have several other enlarged brain regions that were not enlarged in harriers.”

The team hopes their study results will encourage further research on bird anatomy to find out how a species perceives its surrounds.

“Anatomical studies like ours are a window into how a bird perceives the world around it, which can be extremely useful for bird conservation,” says Iwaniuk. “For example, harriers’ reliance on sound for prey location means that they are likely more sensitive to traffic and industrial noise. This could be contributing to the large decreases in Northern Harrier populations we have seen in Canada.”

UNews - Aubrey Keirnan

��Ѹ�����Դ���߿�Ƭ of Lethbridge PhD student leads international study of extinct Hawaiian bird

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