The record heat and unusually warm ocean water may have taken their toll on seabirds.
Common murres, for instance, did not normally stay at Lake Iliamna in Alaska. So when thousands of them – a species commonly favoring the sea as its winter habitat – were found dead at the Alaskan lake, biologists knew something was wrong.
“We’ve talked about unprecedented things about this die off. That’s another one,” warns research wildlife biologist John Piatt.
While there could be one or two “misguided” murres occasionally landing in fresh water, the recent discovery involved 6,000 to 8,000 birds, which the U.S. Geological Survey scientist dubbed quite mind-blowing.
This month, astounding numbers of these dead seabirds washed ashore on Alaska beaches, all looking starved. Post-December storms, about 8,000 were discovered at Whittier’s Prince William Sound community – the death toll now reaching 36,000, although most do not wash ashore.
There could be more dead out there, as relatively few beaches in Alaska, which has the most coastline in the U.S., had been surveyed.
The freshwater lake would not have been the first place to look, but local commercial fisherman Randy Alvarez, who has lived in Igiugig since 1983, alerted the authorities to the thousands of seabird carcasses back in mid-February.
Speculation has it that because the birds could not find any food in the Pacific Ocean, they fly to the lake to feed on salmon smolt. Another puzzling part is that the lake has not frozen in the past two winters.
In the summer, these common murres catch finger-length fish for their young and forage on krill, although their menu for the winter is far less known. They have such high metabolism that they can consume fat stored in their body, until reaching a critical phase of starvation in about three days.
If the birds cannot find anything to eat, the salmon probably won’t either, worried Alvarez.
Multiple federal agencies are trying to put the pieces together and determine which factors cause the die-offs, whether it’s lack of food, the weather, or some disease.
U.S. Fish and Wildlife Service biologist Robb Kaler told Live Science that while they know the murres are dying from hunger, the exact mechanism at play remains unclear. For instance, potential culprits are saxitoxin and domoic acid, but these toxins are difficult to tract in birds that have nothing in their gut – the likely case for most of the casualties.
Previous seabird die-off events have been linked to strong El Nino weather patterns. The most recent one, according to Kaler, could be tied to “The Blob,” one of the biggest oceanographic-atmospheric events where there’s water that goes above the usual temperature in the North Pacific.
“[W]e believe they are factors,” Kaler adds.
Seabirds behavior often serve as markers of how the marine ecosystem fares. While their die-offs do not necessarily signal an endangered status, scientists believe events like this indicate a bigger struggle among animals to deal with changing weather and natural circumstances.
Photo: Roy Lowe/USFWS | Flickr