Avian Influenza

What is Bird Flu?

Bird flu or Avian Influenza (AI) is a common virus affecting captive and wild birds. As with influenza in humans, many different strains of the virus exist, and new strains regularly evolve over time. Strains vary significantly in their infectiousness and pathogenicity (the ability to cause disease and mortality). The most dominant strain in the UK currently is the highly pathogenic H5N1. 

How is the current outbreak different?

Previous outbreaks of AI in UK wild birds tended to be minimal and affect wintering waterfowl. These subsided as wintering flocks dispersed for their breeding grounds in spring. Last winter, a strain of H5N1 led to large mortalities in geese, particularly in Scotland and the disease subsequently spread to breeding seabird colonies. Such colonies are globally important and have experienced unprecedented mortality, placing additional pressure on species already under threat. Despite this, cases of mortality in waders are rare. 

How have conservation and government wildlife agencies responded? 

In the UK, ringing activities are licenced through the British Trust for Ornithology (BTO). The BTO is part of a discussion group made up of ornithologists from NGO’s and Statutory Nature Country Bodies and experts in virology and disease from DEFRA and the Animal and Plant Health Agency. This group meets regularly to share information, assess available data on AI incidence and discuss the implications for monitoring birds. Currently, restrictions have been placed on ringing seabirds and working at seabird colonies in Scotland, Northern Ireland, the Republic of Ireland and Wales but not England. No restrictions have been placed on monitoring or ringing activities with other species outside of seabird colonies due to a lack of evidence of AI cases and the high value of continuing to collect demographic data.

Why is monitoring and ringing important? 

Bird ringing is an invaluable tool for monitoring population change as it provides crucial parts of the population puzzle – survival and productivity, as well as allows us to monitor the health of birds. The unique metal rings fitted by ringers allow a bird to be identified when it is recaptured or found dead and using this information statistical analysis can tell us “How many do we know are still alive?” and much more. The data we gather through ringing continues to contribute valuable scientific data and help conservation efforts for birds using the Wash (read more about WWRGs contribution here). Ringing and other data are used to track population trends, identify emerging threats, and target conservation actions. Such data are especially important for understanding the impact of the current AI outbreak, so suspending vital monitoring is not without cost and must be assessed in light of current evidence. 

How does ringing affect the AI risk to birds?

There is the potential for ringing to facilitate the transmission of the disease between individual birds through contact with infected secretions or faecal matter. The BTO, with guidance from other relevant organisations, has established a list of biosecurity protocols to minimise this risk whilst still allowing the collection of valuable monitoring data. 

How does this affect WWRG research and fieldwork?

Currently, no restriction has been placed on ringing non-seabirds outside of seabird colonies in the UK. However, WWRG have chosen to make our own assessment and adopt a precautionary approach, balancing the value of continuing over 60 years of monitoring with the risk to the birds we are studying. Importantly, there is little evidence of mass mortality from H5N1 in waders. Also, WWRG benefits from having a host of ornithologists among our members, many of whom have already been involved in assessing the impact of AI for their professional work. Our adopted measures include using DEFRA-approved disinfectants to sanitise equipment before and after visiting a site, avoiding contact with domestic birds, and avoiding sites where there is evidence of active AI infections. In addition, WWRG are seeking to contribute additional data to inform our understanding of the AI outbreak by recording observations of dead or sick birds whilst conducting our fieldwork and reporting these to the relevant agencies. Furthermore, WWRG are partnering with academic researchers who are collecting samples from captured birds to test for avian pathogens, including AI. This project will provide monitoring of infection levels in the population as a whole, beyond observations of sick or dead birds. WWRG policy to continue with our research activities will be assessed regularly, and we will follow any restrictions imposed by the BTO or Government agencies. 

Can AI be transmitted to humans? 

Very few strains of AI have made the jump to also affect humans. Although H5N1 can affect humans, the UK Health Security Agency (UKHSA) has said that AI is primarily a disease of birds, and the risk to the general public is very low. H5N1 does not spread easily from birds to humans, or from human to human, but those who have prolonged close contact with birds are at higher risk. There is no risk from enjoying watching the waders on the Wash. As WWRG volunteers work closely with birds during our activities, we have had to consider this risk alongside guidance from the British Trust for Ornithology and adjust our working procedures to minimise risk. This includes many of the measures we adopted during the height of the Covid-19 outbreak, including regular hand sanitising. If you are concerned about exposure to AI and your health, please consult guidance from GOV.UK available at the link below.

Useful links for further information

Natural England – HPAI position statement (August 2022)

BTO HPAI position statement including reference to surveys (July 2022)

APHA Report on weekly findings of highly pathogenic avian influenza (bird flu) in wild birds in Great Britain (regularly updated)

GOV.UK Guidance – Avian Influenza (regularly updated)

GOV.UK Report – Highly pathogenic avian influenza (HPAI) in the UK and Europe (June 2022)