Swans, ducks and fish have been dying in droves at a popular Irish wildlife sanctuary, reports ProMed Mail (which keeps tabs on mass animal deaths as a means to provide an alert for possible human health threats). Officials in Cork, where the sanctuary called the Lough—is located, have not announced a cause, but observers and experts are positing everything from a foreign virus to lead poisoning. 

“Some swans I have seen are in a terrible state,” local resident Annie Hoey told the Irish Times. Symptoms seem to suggest that something is attacking the birds’ central nervous system.

The Cork City Council’s chief veterinary officer told the Irish Examiner that avian flu isn’t to blame for the birds’ deaths. Others are noting that the bird and fish deaths might have different causes.

One possibility, which could explain all the deaths, would be an outbreak of botulism, noted the Examiner. Samples have been sent to Scotland to test for the toxin, but a local veterinarian Joe Kean told the Times that if the culprit does turn out to be botulism, “you could clean out the water, but the reality is that the botulism will always be there…there is little we can do but continue to provide support treatment.”

At least 50 swans had died in the area as of earlier this week. Many report that the die-off has been going on for about a month.

Image of a mute swan courtesy of Wikimedia Commons/Mindaugas Urbonas