In that scenario, climate change, pollution, accidental catching with hunting tools, and the purchase of microplastics were not enough. Seabirds face another deadly threat: bird flu. H5N1, a highly pathogenic avian influenza, has caused thousands of deaths in the northern hemisphere over the past two years. It has spread southward rapidly and has been detected in areas that had never seen it before. Recent outbreaks have predominantly affected seabirds, an unusual pattern until now.
Spain is not new to this serious problem. Since last October 1, there have been 128 observed cases of avian influenza in wild birds, with 15 cases in the last two months. The disease has affected species such as the black-headed gull, the tern, the gull-billed tern, the peregrine falcon, the little tern, the pagen, and the yellow-legged gull.
The incidence of avian influenza in susceptible species is of particular concern, including the Sandwich tern and the Black-billed Shrimp, whose mortality has been reported in the Albufera de Valencia natural park.
In response, SEO/BirdLife emphasizes the need to improve the conservation status of seabirds to boost their resilience against such events and to encourage citizen participation through citizen science programs like ICAO, which can provide valuable information on the disease impact.
Worldwide distribution of avian influenza with zoonotic potential has been observed since 1 October 2022, according to assessments from FAO.
Avian influenza began as an issue for poultry and started appearing in wild species in Europe at the start of this century, spreading along migratory routes. Since then, sporadic mass mortality events among mainly aquatic birds have been noted. In 2021, the highly pathogenic H5N1 strain spread to seabirds, creating an unprecedented situation that continues today.
Devastating effect
The disease knows no borders. The bird flu virus has been detected in about 400 different bird species across much of the world. The colonial behavior of species such as gannets and terns during the breeding season creates ideal conditions for rapid virus spread, according to the NGO. These colonies host a large portion of the world population of some species, so the global population impact is severe.
Some data collected so far underline the critical situation:
– Atlantic booby. At least 75 percent of existing colonies are affected, with a total mortality rate of around 60 percent. More than 11,000 casualties are estimated in Scotland, where main nesting grounds are located. In Bass Rock, the world’s largest gannet colony, occupied area declined by 71 percent and breeding success fell by 66 percent.
– Pay big. At least 2,700 carcasses have been counted, with a 70 percent reduction in occupied areas in the British Isles, home to about 8,900 breeding pairs worldwide, and an estimated global mortality rate around 7 percent. Reproductive success in affected colonies during 2021 and 2022 was nearly zero. Many of the dead birds were over 20 years old.
– Sandwich Tern.
– Snowflake Tern. During the 2022 epidemic, 20,531 dead adults were counted in northwestern European colonies in just two months, corresponding to a 74 percent mortality rate of the nesting population.
– Breed Pelican. In 2022, the disease killed around 60 percent of the world’s largest colony at Lake Prespa in Greece and affected other eastern European colonies. It is estimated that about 40 percent of the European population and 10 percent of the global population could be lost.
– Laughing gull. An estimated 10,000 deaths among black-headed gulls have been recorded in the United Kingdom, with hundreds of additional cases across several continental European countries.
Spain cannot shake off the virus
These figures may still be underestimated due to difficulties in retrieving carcasses and because not all colonies have completed long-term population estimates for year-to-year comparisons, according to SEO/BirdLife. The populations will take decades to recover if recovery is possible. Seabirds are long-lived with slow maturation and few chicks; the survival of adults is crucial for species continuity, adds a technician from the NGO’s Maritime Program.
Spain operates a National Avian Influenza Surveillance Program for early detection. Between 1 July 2022 and 7 June 2023, seven outbreaks in domestic birds, one in captive birds, and 117 outbreaks in wild birds were detected across various autonomous communities including Andalusia, Catalonia, Galicia, the Basque Country, Aragon, Castilla y Leon, Castilla la Mancha, Cantabria, Extremadura, Madrid, La Rioja, Asturias, Murcia, and the Valencian Community.
Valencia’s Albufera lagoon and the Ebro delta are especially scrutinized due to their importance for both marine and waterfowl populations. The NGO notes that a substantial number of carcasses in these areas likely indicate flu involvement, but exact numbers remain uncertain. The Catalonia climate action department has confirmed a bird flu outbreak in the Ebro delta, and the national reference laboratory identified positive results for the H5N1 strain in July in several Sandwich tern specimens from the Fangar peninsula.
What to do with a sick or dead bird
In light of the situation, surveillance and biosecurity measures in poultry farms are strengthened to minimize contact with wild birds. Monitoring of seabird colonies has intensified to gauge disease incidence. The NGO stresses that extreme measures and appropriate management actions are necessary to prevent contamination of highly sensitive species.
Although human transmission remains rare and often mild, handling and disposal of sick or dead birds should be performed by trained personnel with proper protective equipment to reduce zoonosis risk.
What to do if a sick or dead bird is found:
– Do not pick up or touch the birds that are dead or diseased.
– Keep pets away from dead or sick birds.
– Do not lure birds with water sports or feed them.
– Do not touch feathers from wild birds or surfaces contaminated with droppings.
– If poultry or other birds are present, wash hands and clean and disinfect footwear before handling birds.
Call 112 or contact Fauna Rescue Center and follow the indicated instructions. Environmental agents will respond to retrieve the animal or its carcass.
– Submit observation data to contribute to improved understanding of seabird mortality through the ICAO app available for Android and iOS.
Latest FAO report on bird flu covers developments and policies as of 2023.