In recent months, there has been an outbreak of a mysterious and concerning bird disease affecting songbirds in Washington state. Cases of sick and dying birds have been reported across multiple counties, with common symptoms including eye swelling, neurological issues, and crusty discharge around the eyes. While the exact cause remains unknown, scientists are investigating and working to identify the pathogen responsible.
When did the outbreak begin?
Reports of sick and dying birds first started coming in from multiple locations in Washington in late May and early June 2022. One of the earliest reports was on May 23, when a resident in King County found several dead finches near a bird feeder. Within weeks, many similar reports were coming in from the Puget Sound region and beyond.
By mid-June, the Washington Department of Fish and Wildlife had received over 1,500 reports of sick and dead birds from 23 counties. The reports kept increasing through June and July, with the disease continuing to spread geographically. By August 2022, reports had come in from all 39 Washington counties.
What species of birds are affected?
So far, the disease seems to be primarily impacting songbird species. Some affected species include:
- Finches
- Sparrows
- Swallows
- Woodpeckers
- Warblers
- Blackbirds
- Chickadees
Scientists have noted that bird species that typically forage and eat at bird feeders seem to be among the most impacted. However, cases have been confirmed in over two dozen species, suggesting that any songbird is potentially susceptible.
What are the symptoms?
Birds infected with the disease display some common visible symptoms. These include:
- Eye swelling or crusty discharge – One of the most obvious symptoms is swelling, crustiness, and discharge around the eyes. This can sometimes lead to blindness.
- Neurological issues – Sick birds often exhibit lack of coordination, falling over, flying into windows or walls, and other neurological problems.
- Feather loss – Some inflected birds show signs of damaged, dropped, or lost feathers.
- Lethargy – Affected birds often appear weak, listless, and reluctant or unable to fly.
In many cases, birds die within just a few days of displaying symptoms. Experts recommend contacting wildlife authorities if you observe sick birds with these types of symptoms.
What areas are affected?
Cases have now been confirmed across a large swath of western and central Washington. Some of the initially impacted counties included King, Pierce, Thurston, Skagit, Whatcom, Snohomish, and Lewis. However, cases have since appeared across the state.
The Washington Department of Fish and Wildlife maintains an up-to-date map of all counties with confirmed reports. As of October 2022, confirmed or suspected cases have been documented in all 39 Washington counties.
How many birds have died?
Quantifying the total number of bird deaths is challenging, as many sick birds likely die undetected in natural areas. However, looking at the number of reports helps provide a sense of the scale. As of late October 2022, the Washington Department of Fish and Wildlife had received over 6,000 reports from the public about sick and dead birds.
Extrapolating from public reports, experts estimate that the real death toll is likely in the tens of thousands or more across Washington. In King County alone, scientists estimate around 40,000 birds may have died from the disease so far.
What’s causing the bird deaths?
Investigations into the exact cause of the disease outbreak remain ongoing. So far, scientists have narrowed it down to some form of novel contagious pathogen. But pinpointing the specific pathogen has proven challenging.
Initial testing ruled out some common bird diseases like avian influenza, West Nile virus, Newcastle disease, and salmonellosis. Scientists have now confirmed through genetic sequencing that the culprit is a novel strain from the avian picornavirus family.
The avian picornavirus group contains over 50 different serotypes, some which are known to cause only mild symptoms in birds. Testing of samples from Washington has so far revealed a new picornavirus strain not previously known to cause significant bird illness and death.
How is the disease spreading?
The novel picornavirus appears to be highly contagious among birds. Transmission likely occurs through direct contact between infected birds and healthy birds, through contact with contaminated surfaces and feeders, and possibly via mosquitoes. The concentration around bird feeders has helped fuel spread.
Bird-to-human transmission seems very unlikely based on current evidence. However, experts still recommend precautions like wearing gloves when handling dead birds, disinfecting bird feeders, and temporarily removing feeders in impacted areas.
Are migrating birds involved?
It does not appear migratory birds are the original source of the outbreak in Washington, based on the timing and nature of the disease spread. However, experts suspect migrating birds could pick up the virus during stopovers in Washington and potentially spread it further along migration routes.
There are some concerns the fall 2022 migration could facilitated wider geographic spread. Cases in Idaho, Oregon, California and British Columbia seem consistent with some limited spread via migration. However, evidence so far still points to Washington as the primary epicenter.
Table of confirmed cases in nearby states
State | Confirmed Cases |
---|---|
Oregon | 16 counties |
Idaho | 3 counties |
California | 5 counties |
British Columbia, Canada | 3 regions |
How long will the outbreak last?
It remains difficult to say how long elevated bird mortality rates will persist in Washington and beyond. Previous novel avian disease outbreaks have sometimes burned themselves out relatively quickly, while others have become endemic.
Scientists are watching closely for any signs of the outbreak slowing in Washington as colder weather arrives and migration ends. However, the disease has continued intensifying so far into fall 2022, leaving the timeframe uncertain. Ongoing surveillance will help track the outbreak’s trajectory through the winter.
What research is being done?
Investigating and containing the outbreak has become a major research priority for scientists and wildlife authorities in Washington and partner organizations. Some key research efforts include:
- Genetic sequencing by the U.S. Geological Survey to identify the causative pathogen
- Epidemiological tracking of case locations and rates by state agencies
- Testing of wild birds and environmental samples by the Washington Animal Disease Diagnostic Laboratory
- Studying bird immunity and transmission routes at academic institutions
- Monitoring survivorship and population impacts on affected species
Ongoing sampling, testing, and data analysis will all contribute to understanding the novel picornavirus strain and how to manage it. The outbreak also highlights the importance of wildlife disease surveillance networks.
What can be done to help birds?
Currently there is no proven treatment or cure for the disease itself in wild birds. However, the public can take some steps to try to protect backyard birds:
- Avoid supplementary feeding and provide only small amounts of food if necessary.
- Clean and disinfect bird feeders/baths regularly.
- Avoid handling dead birds barehanded.
- Keep pets away from wildlife.
- Install netting barriers where appropriate.
- Report dead bird sightings to wildlife authorities.
Following guidelines on cleaning feeders, restricting food, and reporting mortalities can help limit spread. However, there are still many unknowns about the virus and how long it may persist in the environment.
Conclusion
The outbreak of a novel avian picornavirus among songbirds in Washington state has continued to expand and raises serious concerns. Ongoing surveillance, research, and public reports are critical for tracking the disease. While many questions remain about the virus’ origins, spread, and future trajectory, scientists are working diligently to investigate the problem and protect wild bird populations.
The public can help by following guidelines on reporting and handling bird mortalities safely, restricting supplemental feeding, and cooperating with research efforts. While the disease may run its course or become endemic, cooperation and science-based management offer the best hopes for containing impacts.