Failure to identify Scotland’s H5N1 swan highlights need for better data
UK Government officials have confirmed that the H5N1-positive swan discovered in Cellardyke, Scotland was a Whooper Swan Cygnus cygnus, not as previously thought a Mute Swan Cygnus olor.
In contrast to the mainly resident/sedentary Mutes Swan, Whooper Swans are migratory. The Icelandic breeding population winters in North-west Europe, including Britain and Ireland, the low countries and the Baltic.
H5N1 was confirmed in several Whooper Swans in the Baltic during February and March. “It seems plausible that the bird found in Scotland may have originated in this region and was attempting to migrate back to Iceland to breed, before becoming too sick to continue and alighting on the sea,” said Andre Farrer of the RSPB (BirdLife in the UK).
“However, it would be foolish at this stage, to dismiss the alternative theory that the swan was wintering in the UK, either in Fife or elsewhere, and contracted the virus locally from another species of waterfowl. For this reason the current restrictions should be kept in place and further surveillance of wild birds carried out”, he added.
It wouldn’t be acceptable to report that a mallard duck died of a virus yet reporting that a wild bird has died of H5N1 is often all the information that is released by public authorities —Dr Leon Bennun, BirdLife International’s Director of Policy
Initial identification in this instance had been hampered by the advanced state of decay of the carcass, and the species was only confirmed through DNA profiling. But according to Dr Leon Bennun, BirdLife International’s Director of Policy, studies of the aetiology of this disease world-wide have been held back by slack identification of the birds involved.
“It wouldn’t be acceptable to report that a mallard duck died of a virus yet reporting that a wild bird has died of H5N1 is often all the information that is released by public authorities”, Dr Bennun explained
“Better quality data collection, and reporting of both positive and negative avian influenza surveillance, are crucial to understanding general patterns in outbreaks, possible routes of transmission, and the potential impacts on migratory bird populations. This information can be used to focus contingency efforts, to predict future outbreaks, and to guide effective policy to reduce the economic and conservation impacts of avian influenza.”
BirdLife has prepared a document, Surveillance of wild birds, which provides guidance on appropriate sampling, data collection and reporting strategies to monitor avian influenza in wild bird populations.