“Between 2015 and 2016, cliff-rock crows on the west coast of North America, from California to Alaska, suffered severe famine and death,” according to a new study published in the journal Public Library of Science: Synthesis. The report said a strong El Nino caused a strong ocean heat wave during this period, causing the area to rise 3-6 degrees Celsius. A total of 62,000 cliff-headed crows were washed up on shore, but the total number of deaths is expected to reach 1 million, the study said.
Warmer waters increase the metabolism of predatory fish such as salmon, which eat more than ever before, while the small fish in the water are less likely to warm. Cliff crows that enjoy the same species as predatory fish lose the competition and starve to death.
Not only that, but famine has also affected the breeding of cliff sea crows, with no small cliff crows born in the breeding season in the three cliff sea otterhabitats in 2015, and 12 in 2016. In addition, seals, sea eagles and whales also died.
Researcher John Piatt says this is a warning to us about the huge impact of warming on marine ecology. In the context of global warming, it is unclear whether this group will be able to recover.