17-05-2025
Mystery over 'unusual' outbreak plaguing iconic Aussie animal
An iconic Aussie animal is at the centre of a mysterious outbreak that has left wildlife rescuers scrambling for answers. Over the past few months, dozens of black swans suffering from a photosensitivity illness have been rushed into care in Western Australia.
'This is significantly higher than usual — we typically see only a handful of cases per season. The cases tend to present during the summer months,' WA Wildlife veterinarian Dr Meg Rodgers told Yahoo News Australia this week.
So far the non-profit has tended to approximately 30 birds, however additional cases have been treated for the painful and potentially deadly condition at other wildlife organisations.
'Photosensitivity syndrome refers to a condition in which the skin becomes abnormally reactive to ultraviolet (UV) light,' Dr Rodgers said. 'In affected swans, this results in painful skin damage — including blistering, redness and sloughing of unfeathered areas such as the beak and occasionally the legs and feet.'
The symptoms are similar to a sunburn, Matt Watson, WA Seabird Rescue President, told Yahoo.
'It does also seem to have internal impacts too, potentially affecting the liver which slows down the swan's ability to metabolise the required nutrients from their food. If left untreated, it can also lead to secondary infections and dehydration.'
The exact cause of the illness, and the reason behind this year's high infection rate, remain unknown. Dr Rodgers said the condition 'may involve the ingestion or topical exposure to photodynamic compounds', which are 'activated by sunlight in unfeathered areas'.
The current outbreak could be linked to a range of environmental factors, including toxins, algae or other photoreactive compounds in the swans' habitat, she explained. Numerous sick birds have been rescued near the Swan River, but that hasn't helped experts narrow down the cause.
'There are a large number of swans along the Swan River, but these birds are highly mobile and often move between the River and surrounding wetlands, which complicates tracing the origin of exposure,' Dr Rodgers said.
'Ingestion of or contact with Moreton Bay figs has been suggested as a potential source of these compounds, though further research is required to substantiate this link.'
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The 'unusual' increase in cases has prompted renewed interest in the seasonal syndrome from researchers.
'While there have been previous investigations, the good survival rates of affected birds and their movement between locations make it challenging to isolate a definitive cause,' Dr Rodgers told Yahoo. 'Discussions are currently underway to facilitate future investigations.'
While the majority of the sick black swans have responded well to treatment and been released within six weeks, a handful have died. As the outbreak continues, locals are being urged to keep an eye out for affected birds and call WA Seabird Rescue for help.
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