In a worrying development, thousands of short-tailed shearwaters, also known as muttonbirds, have been washing up dead on beaches along Australia’s east coast. According to researchers, the cause and full extent of these unusual seabird “wrecks” remain uncertain, raising concerns about the health of marine ecosystems and the future of these remarkable migratory birds.
An Annual Migration Turns Tragic
Each year, around 20 million shearwaters undertake an incredible 15,000 km journey from the northern hemisphere to their breeding grounds in southern Australia. However, since late October, beachgoers have been making disturbing discoveries – the emaciated carcasses of countless shearwaters scattered along the shoreline.
The phenomenon first came to light on the beaches of south-east Queensland, but similar reports have since emerged from New South Wales and Victoria. The sight of these lifeless seabirds has left local communities and experts deeply concerned.
The Challenges of Quantifying Seabird Wrecks
Determining the precise number of birds affected and whether this constitutes a “normal” or “mass” mortality event is no simple task, explains Dr. Lauren Roman, a shearwater researcher at the University of Tasmania’s Institute for Marine and Antarctic Studies. While seabird wrecks are known to occur during the annual migration, the advent of smartphones and social media has heightened public awareness of these incidents.
There’s a perception that the mortality events are increasing, but it’s very hard to tell whether that’s actually the case, or just a function of increased awareness.
Dr. Lauren Roman, University of Tasmania
Roman points out that if a significant die-off were to occur hundreds of kilometers offshore, it would likely go unnoticed. Even a small fraction of the population perishing closer to the coast could result in hundreds of carcasses washing ashore.
An Evolutionary Puzzle
For Jennifer Lavers, a researcher at the Adrift Lab, the mass mortality of these long-lived seabirds raises troubling questions. Based on initial analysis of citizen science reports, Lavers estimates that hundreds or thousands of adult shearwaters have washed up dead or dying on beaches this year alone.
The mass mortality events were unusual for seabirds with long lifespans, and did not “make sense from an evolutionary perspective”.
Jennifer Lavers, Adrift Lab researcher
The emaciated condition of the washed-up birds suggests that food scarcity may be a contributing factor. However, the full picture remains elusive.
Echoes of a Previous Crisis
While the current reports pale in comparison to the catastrophic mass mortality event of 2013, which claimed the lives of millions of seabirds, they nonetheless raise red flags. The 2013 die-off was linked to an abnormal marine heatwave known as “the blob” in the North Pacific Ocean, underscoring the far-reaching impacts of oceanic disturbances on seabird populations.
The Importance of Breeding Adults
Dr. Eric Woehler, a veteran seabird researcher with over four decades of experience, emphasizes the gravity of losing adult shearwaters. As a species that typically only raises one chick per year and can live beyond 40 years, the death of breeding adults can have profound consequences for the overall population.
We believe that these birds, particularly, didn’t have enough food and basically started on their migration with insufficient body reserves.
Dr. Eric Woehler, seabird researcher
Vigilance Against Emerging Threats
While the highly pathogenic H5N1 avian influenza strain has not been detected in the affected shearwaters thus far, authorities remain vigilant. The potential introduction of this virus into Australia’s seabird populations could have devastating consequences.
Unraveling the Mystery
As researchers work diligently to untangle the complex web of factors contributing to these seabird wrecks, the public can play a vital role. Beachgoers are encouraged to report sightings of dead or distressed shearwaters to their local wildlife authorities, while taking care not to handle the birds directly.
In the face of these heartbreaking scenes, Dr. Lauren Roman offers a measured perspective:
If you find one or two dead ones, I wouldn’t worry too much about it, because that’s natural this time of year.
Dr. Lauren Roman, University of Tasmania
Yet, as the mystery of the shearwater deaths deepens, it becomes increasingly clear that the health of our oceans and the fate of these remarkable creatures are inextricably linked. Only through continued research, vigilance, and collective action can we hope to unravel this troubling enigma and safeguard the future of Australia’s magnificent seabirds.
