For a few months of the year, the Alaskan Arctic becomes flooded with birds. From shorebirds to waterfowl, these avians arrive in the spring to breed, nest, and raise their young, and to take advantage of the ample plants and prey (invertebrates and other animals) that thrive in Alaska’s short summers. They do it today, and they did it around 73 million years ago, too.
Documenting the earliest evidence ever discovered of birds breeding and nesting in the Arctic, a new study in Science describes a collection of avian fossils and fossil fragments from around 73 million years ago. The collection comprises dozens of bones and teeth from adult and baby birds, and it shows that avians similar to modern shorebirds and waterfowl reproduced in the Arctic in the Cretaceous period, when dinosaurs still dominated the Alaskan terrain.
“Birds have existed for 150 million years,” said Lauren Wilson, a study author and a student at Princeton University, who worked on the study while at the University of Alaska Fairbanks, according to a press release. “For half of the time they have existed, they have been nesting in the Arctic.”
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An Arctic Nursery
Millions of birds travel to the Arctic, and they’ve been traveling there for millions of years. (In fact, some 250 species of birds migrate to Alaska for the spring and summer breeding and nesting seasons today.) But up until now, the earliest traces of birds reproducing in the Arctic dated back to around 47 million years ago, following the disappearance of the non-avian dinosaurs from the Arctic terrain.
Now, the authors of the new study claim that birds and non-avian dinosaurs shared the Alaskan Arctic as far back as the Cretaceous period. Sifting bones and teeth from the sediment of Alaska’s Prince Creek Formation, the authors identified an assortment of Cretaceous fossils and fossil fragments, which resembled the remains of modern gulls, geese, ducks, and loons.
That the specimens belonged to adult and baby birds suggests that these species were breeding, nesting, and raising their young in Alaska, more than 20 million years earlier than previously thought.
“The Arctic is considered the nursery for modern birds,” said Pat Druckenmiller, another study author and a professor at the University of Alaska Fairbanks, according to a press release. “They have been doing this for 73 million years.”
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Finding Fossils, From Adult and Baby Birds
According to the authors, the bones and teeth of adult birds are often too fragile to survive in the fossil record, and those from baby birds are even more delicate.
“Finding bird bones from the Cretaceous is already a very rare thing,” Wilson said in the release. “To find baby bird bones is almost unheard of. That is why these fossils are significant.”
Though the majority of specimens that are taken from the Prince Creek Formation are large, the study authors opted to collect the smaller fossils and fossil fragments that most other studies miss. To do so, they inspected screened sediment with a microscope, which revealed their tiny finds.
“We put Alaska on the map for fossil birds,” Druckenmiller said in the release. “It wasn’t on anyone’s radar.”
Whether the find includes bones and teeth from the Neornithes — or the modern birds — is yet to be determined, though the authors stress that some of the fossils and fossil fragments feature skeletal and dental traits, such as fused leg bones and toothless jawbones, that are seen only in modern birds.
“If they are part of the modern bird group, they would be the oldest such fossils ever found,” Druckenmiller said in the release. “But it would take us finding a partial or full skeleton to say for sure.”
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Sam Walters is a journalist covering archaeology, paleontology, ecology, and evolution for Discover, along with an assortment of other topics. Before joining the Discover team as an assistant editor in 2022, Sam studied journalism at Northwestern University in Evanston, Illinois.
