Recently, I was invited to speak about Oahu’s fossilized bird bones to students enrolled in the Mālama ʻĀina Field School, which is a summer course coordinated by the Mālama Learning Center and offered by Nānākuli High & Intermediate Schools. I was very excited to share what I know with the students, especially since most people aren’t aware that Hawaii has fossilized bones!
On June 17th the field school students (grades 8-12) visited a very special site on Oahu’s southwest shore: the Kalaeloa Unit of the Pearl Harbor National Wildlife Refuge. This 37-acre land parcel was acquired by the US Fish & Wildlife Service (USFWS) in 2001 in order to recover and manage rare, native Hawaiian plant species that dominated this landscape thousands of years ago. The Kalaeloa site has the last remaining coastal dryland plant communities that were once widespread throughout the ‘Ewa Plain.
In addition to the rare plants, the Unit also contains limestone sinkholes that formed thousands of years ago as water eroded the raised coral reef. These sinkholes support a unique aquatic ecosystem centered around the rare ʻōpaeʻula shrimp. Unfortunately, many of the sinkholes have been filled in over the years by commercial, military and residential developers. While excavating the sinkholes in 2008 to restore suitable habitat for the native shrimp, USFWS staff made an incredible discovery: there are lots of ancient bird bones at the bottom of those sinkholes!
The exact age of the bones is unknown, but carbon dating from similar sites indicates that they’re likely between 1,000 and 8,000 years old. That might not seem very old compared to a dinosaur bone, which could be millions of years old. But wait… there’s a big advantage to finding “young” fossils! Remember that as skeletons lie buried in the ground, their organic compounds eventually get replaced with minerals, naturally turning the bone into stone. When this mineralization process is complete, you’re left with a stone replica of the original bone. Fossils from Kalaeloa haven’t been in the ground long enough to be completely mineralized. In other words, they still contain DNA!! This can be tested to determine what species the bones belonged to, and how those extinct species are related to birds that are still around today!
Once the importance of the sinkhole bones became apparent, USFWS started working with the Smithsonian Institution and Bishop Museum to properly clean, store, and identify them. And that’s when the really exciting part began… Based on the material found in the sinkholes and similar sites in the Islands, paleontologists were able to describe 35-40 new bird species that were previously unknown to science!
The fossilized bones discovered so far include those of an extinct hawk, long-legged owl, Hawaiian sea eagle, petrel, two species of crow, Hawaiian finches, Hawaiian honeyeaters, and the moa nalo (a turkey-sized, flightless goose-like duck that was the largest of the native Hawaiian birds). “These fossils of extinct birds give us a glimpse of an earlier time on Oahu when the lowlands teemed with native birds, insects, and plants,” says Helen James, a paleontologist who is both the curator of birds for the Smithsonian Institution and the world’s expert on Hawaii’s avian fossils.
As manager of Bishop Museum’s Vertebrate Zoology collection, it’s my privilege to care for the fossilized specimens from the Kalaeloa site, as well as from many other sites around Hawaii and the Pacific. This involves numbering the bones, ensuring they are housed safely in archival boxes, and managing their associated data and identifications in our database. Another part of my job is educating the public about these priceless specimens, and I’m grateful that the Mālama Learning Center and the managers of the Kalaeloa refuge site allowed me to share information about them with the field school students. It’s vital that the next generation recognize the importance of the Kalaeloa site and maintain its protected status. There are lots of fossils still in those sinkholes and more new species patiently waiting for their day in the sun!
Written by: Molly Hagemann, Vertebrate Zoology Collection Manager
Posted: 06 July 2016
All photos are courtesy of the Mālama Learning Center. Students signed photo releases as part of their participation in the field school.