Excavated bones of Hawaiian petrels – birds that spend the majority of their lives foraging the Pacific – show substantial change in the birds' eating habits.
Hawaiian petrels are now listed as endangered in the United States, but they are said to have darkened the skies of Hawaii for thousands of years. The birds' surprisingly well-preserved fossil record doubles as a time capsule for scientists studying fish populations of the past.
The gray-and-white, tube-nosed seabirds spend most of their lives searching for food in the open waters of the Pacific, but they come ashore to breed in burrows and caves. If they happen die at these on-land locations, the petrels' bones are preserved for a long time.
Researchers with the Smithsonian Institute have amassed a collection of more than 17,000 ancient Hawaiian petrel bones, dating back to 4,000 years ago. By comparing the bone chemistry of these specimens to that of modern samples, scientists can see how the species' diet has changed — and by extension, how fish availability in the open seas has been transformed over the years.
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