Washington State Standard Study findings provide new details on a Caspian tern die-off near Port Townsend in 2023 and how the virus killed seals in the region, infecting their brains. More than half a colony of Caspian terns on a small island near Port Townsend died last year amid an outbreak of bird flu, underscoring the harsh effects the disease can have on wildlife.
Researchers say they directly counted 1,101 dead adult terns and 520 dead chicks and that at least 53-56% of the adult birds in a colony on Rat Island, in northern Puget Sound, were wiped out. After factoring in Caspian tern deaths in other parts of the region, the researchers estimated about 10-14% of the birds in the Pacific flyway were lost last year to bird flu.
The researchers also studied harbor seals that died from the virus on or around Rat Island during the same timeframe and found that the disease had attacked the animals differently than it did birds, causing severe inflammation in their brains.