Curlew Sandpiper
Credit: Photographer Ryan Barnaby
Why Australia’s Shorebirds Are Evolving in Real-Time
By Sarah Hard
While politicians debate climate policy, Australia’s wildlife is engaged in a silent, desperate race against the heat – and new research shows that some populations are literally evolving their body shape to survive.
A major study from Deakin University, led by Dr. Sara Ryding, has found that specific populations of Australian migratory shorebirds are exhibiting a dramatic form of “shapeshifting,” developing longer wings relative to their body size over the past four decades. But the findings carry an alarming distinction: this rapid evolutionary change is only happening in the birds that migrate to the scorching tropical north, and not among their counterparts in the milder, temperate south.
A Biological Radiator
The change observed is rooted in a fundamental biological principle known as Allen’s Rule, which predicts that animals in warmer climates will have larger appendages (like ears, limbs, or wings) to better dissipate heat. Dr. Ryding explained that this increase in relative wing length is a notable adaptation.
“Our study shows that wing length relative to body size is increasing, meaning the birds are changing their body shape slightly,” Dr. Ryding said. “We believe that these changes could enable greater heat loss, as the underside of bird wings are highly vascularised with lots of blood vessels, meaning birds can direct warm blood to these sites and lose heat to the environment.”
In simple terms, a larger wing surface acts like a bigger radiator for the bird’s body.
However, the primary function of a wing is still flight, which makes the finding even more compelling. “Of course, the biggest function of wings is flight – but we do not see evidence that flight patterns (like migration distance, or distance between foraging sites) has impacted changes in wing length,” Dr. Ryding noted. This suggests the change is directly linked to the overwhelming pressure of environmental temperature.
The Geographic Tipping Point
The most significant takeaway for Australian conservation is the dramatic contrast between the north and south. The study of 11 species – including the Curlew Sandpiper, which showed the most opposing trends – found that only tropical populations exhibited this shapeshifting trend.
Dr. Ryding highlighted why this finding shifts the focus of climate change research: “So far, much emphasis has been put on birds in temperate climates… However, there is a great deal of difference in coping with 2 or more degrees warming in environments that are 25-ish degrees, compared to coping with just 1 degree of warming in environments that average 35 degrees.”
She explains that even a smaller amount of warming in an already hot environment may be more impactful because it pushes animals closer to their upper thermal limits.
“Our results highlight that the baseline environment is also an important predictor, to integrate with the amount of climatic warming a region has experienced, when considering climate change responses,” Dr. Ryding stated. The research effectively reveals Australia’s tropical north as a biological tipping point for climate adaptation.
Evolution vs. Adjustment
The researchers went a step further, specifically testing whether the wing length increase was a short-term response driven by temperatures during a bird’s development (developmental plasticity). Their analysis of juvenile birds revealed no such link, leading to a strong conclusion.
“This could indicate that the changes are evolutionary in nature (especially given that for some aspects of morphology, populations of the same species showed different responses),” Dr. Ryding confirmed.
While the magnitude of the shape-shifting is modest so far, the research proves that while conservation and political debates continue, nature is already scrambling to adapt.
“What we do know is that while politicians argue about whether climate change is real and whether we should do anything about it, the birds on our beautiful planet are experiencing it and are indeed showing signs of change.”
The long-term consequence for species that fail to adapt remains difficult to predict, especially since shorebirds face multiple threats, including critical habitat loss along coastlines. But this groundbreaking Australian research provides a critical, real-time measure of climate pressure that no one can afford to ignore.
Author Bio:
Sarah Hard is a conservation writer and photographer based in Australia. She focuses on telling the unique stories of Australian wildlife and aims to inspire environmental awareness through her articles and photography.
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