The bird at the center of the worst single-species die-off in modern history has yet to recover, scientists say

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A marine heat wave killed about half of Alaska’s murres, the study found, marking the largest single species extinction event in recent history. The catastrophic losses point to broader changes in the marine environment as a result of warming ocean temperatures that are rapidly and severely rebuilding ecosystems and suppressing the animals’ ability to reproduce, a new study says.

From late 2014 to 2016, the Northeast Pacific heat wave known as the “Blob” swept through marine ecosystems from California to the Gulf of Alaska.

The event is believed to be the largest and longest-lasting marine heat wave known, with temperatures An increase of 2.5 to 3 degrees Celsius (4.5 to 5.4 degrees Fahrenheit) above normal.

Common murre or urria murre, Known for its distinctive black and white plumage, which resembles the tuxedo appearance of a penguin. These predators play a key role in regulating the flow of energy within marine food webs in the Northern Hemisphere.

Although murres have suffered fewer deaths in the past due to environmental and human factors, they often recover quickly when favorable conditions return. However, the scale and speed of deaths during this heat wave particularly shocked Drummond and her team.

Researchers determined the scale of this catastrophic population loss by tracking extreme population declines in 13 colonies in the Gulf of Alaska and Bering Sea that were monitored over time. By the end of the 2016 heat wave, Drummond and her team had counted more than 62,000 common seabird carcasses, which represented only a fraction of the losses because most dead seabirds never appeared on land.

From there, biologists monitored the rate at which common murres died and reproduced and found no signs of the colony returning to its previous size.

“The only reason we have this data and were able to detect this (event) is because we have these long-term data sets and long-term monitoring,” said Drummond, a wildlife biologist at the Alaska Marine National Wildlife Refuge. “(Monitoring) is the only way we can continue to keep an eye on what happens in the future.”

Extinct species face challenges

Research shows that as temperatures rise in Alaska, the murres’ food supply decreases, and the number of Pacific cod, one of their main prey, dropped by about 80% between 2013 and 2017. Researchers estimate that about 4 million murres died in Alaska between 2014 and 2016 as this important food source collapsed.

“New York City has about 8 million people, so it’s like losing half of its population … in one winter,” Drummond said.

Before the 2014 heat wave began, Alaska’s murre population accounted for 25 percent of the world’s seabird population.

However, when the seven years before the heat wave (2008 to 2014) were compared with the seven years after the heat wave (2016 to 2022), the study found that 13 habitats spread between the Gulf of Alaska and the Bering Sea had The murre population has declined between 52% and 78%.

Drummond and her colleagues continued to monitor the murres after the 2016-2022 heat wave ended, but found no signs of recovery.

While further research is needed to fully understand why murres have not rebounded, Drummond’s team believes the changes are driven by changes in marine ecosystems, particularly those related to food availability.

Breeding challenges and difficulty relocating may also be responsible for the species’ lack of recovery, said Dr. Falk Huetman, associate professor of wildlife ecology at the University of Alaska Fairbanks, who was not involved in the study.

Unlike some other species, seabirds such as seabirds take longer to reproduce, making the process slower, Huetman said.

Additionally, Huetman noted that murres are closely tied to the habitats they live in, and when they are forced to relocate, it may be more difficult to adapt to new conditions.

Survive in a changing environment

While temperatures continue to rise in areas like Alaska, tropical or subtropical waters are moving to different areas, creating conditions for entirely new ecosystems, Huetman said.

With these environmental changes, animals either adapt or are unable to survive in the new climate.

Gulls aren’t the only species in Alaskan waters experiencing significant changes. Huetman noted that the tufted auk is a sensitive seabird that has been seen migrating north due to harsh conditions in the southern North Pacific, including California, Japan and Russia, but is struggling to adapt to its new home. Other species, including king salmon, whales and crabs, are also struggling to find their own habitat, he said.

Drummond said that while the heat wave affected many species, other groups were not significantly affected.

Half of the data collected from organisms such as phytoplankton and even endothermic apex predators showed “neutral” responses to heat waves. Research shows that 20 percent of apex predators even respond positively to unusually high temperature exposure.

Warm-blooded animals, including birds and mammals, have a stable internal body temperature regardless of the ambient temperature.

“This gives us an idea of ​​which species may be more likely to adapt to such future water temperature warming events and which species will not,” Drummond said.

While rising temperatures are the main factor affecting animals like sea turtles, other factors may also be causing changes in marine life.

“From an ecological perspective… microplastics, ocean acidification, sea level rise and long-term oil spills… are other factors that are causing huge deaths,” Huetman said.

However, there are limited studies tracking the long-term effects of climate events on marine life, so scientists are still unsure how these animals will continue to be affected in the future.

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