Mass Short-tailed Shearwater die-off in Alaska

Unusually high numbers of seabird fatalities have been reported from Alaska for the fifth year running.

Federal wildlife officials confirmed last week that the deaths of thousands of birds was due to starvation, as warm sea surface temperatures continued off the state's coasts.

Thousands of Short-tailed Shearwaters were reported dead and washing onto beaches in the Bristol Bay region starting in late June, the National Park Service (NPS) said in a statement on 9 September. Deaths of the long-distance migrants, which breed on offshore islands around southern Australia and New Zealand, extended to the Chukchi Sea off north-west Alaska as the summer progressed.

A Short-tailed Shearwater found dead near Shishmaref, north-west Alaska, in August 2017 (Ken Stenek / Coastal Observation and Seabird Survey Team).

"Initial results indicate starvation as the cause of death for most locations," said the agency, which is working with the US Fish and Wildlife Service to monitor the deaths.

The agency added: "Puffins, murres [guillemots] and auklets are also being reported, but in much lower numbers than shearwaters."

Seabird die-offs have been known to occur in Alaska, but large numbers of different varieties of seabirds have been found every year since 2015, with starvation blamed. The die-offs have come as the temprature of Alaskan waters continues at a level warmer than normal, NPS explained, potentially impacting sea life on which the birds depend for food.

In south-east Alaska, the agencies blamed a "localized die-off" of breeding Arctic Terns in June on exposure to saxitoxin, a biotoxin associated with paralytic shellfish poisoning. The agency explained: "Analyses of tissue samples for harmful algal bloom toxins are ongoing and results will be shared as they become available. To date there has been no evidence of disease."