Smithsonian Science » Feather Identification Lab

Fossil feathers from a Hawaiian cave help reveal lineage of extinct, flightless ibis

John Barrat — Mon, 21 Nov 2011 14:44:02 +0000

A remarkable first occurred recently at the Smithsonian’s National Museum of Natural History when ornithologists Carla Dove and Storrs Olson used 700- to 1,100-year-old feathers from a long extinct species of Hawaiian ibis to help determine the bird’s place in the ibis family tree. So fragile that some parts disintegrated as they were being mounted on microscope slides, the feathers are the only known plumage of any of the prehistorically extinct birds that once inhabited the Hawaiian Islands.

Discovered with a nearly complete skeleton, the feathers retained enough microscopic structure to allow the scientists to confirm the classification of the bird, known by its scientific name Apteribis sp, as a close relative of the American white ibis and scarlet ibis. DNA analysis confirmed this classification.

Image left: Skull (top) and (below) detail of feathers adhering to the cranium of Apteribis sp. from Lanai, Hawaii Islands (Photo courtesy Carla Dove)

Remarkably, the feathers also retained enough pigmentation to allow Dove and Olson to determine the bird had been brown-black to ivory-beige/light brown in color. Before now, any reconstruction of the appearance of a prehistorically extinct Hawaiian bird had been only speculation.

Image right: This scanning electron photomicrograph shows the prongs on the downy barbules of an Apteribis sp. feather. (Photo courtesy Carla Dove)

Apteribis sp. is one of only two species of ibises, both now extinct, known to be flightless. Its skeleton differs so much from its mainland ancestors that the bird’s relationship to other ibises could only be determined through the study of its feathers and DNA analysis, Olson says.

The find is highly unusual because “feathers do not preserve well and often decay before a bird is fossilized,” Dove says. “These weren’t fossil imprints in a rock, but feathers and bones we could actually pick up.”

Exceptional geologic circumstances led to the preservation of the feathers inside a lava cave on the Hawaiian Island of Lanai. The floor of the cave was partially covered in a deep layer of flaky gypsum crystals, which, for hundreds of years absorbed humidity in the cave and created an arid environment ideal for preservation of the feathers. The crystals were shaken off of the walls and ceiling of the lava tube by seismic tremors.

Image right: American white ibis (Photo by Terry Foote at en.wikipedia); below, scarlet ibis (Photo by Hans Hillewaert). Both of these birds are closely related to the extinct Apteribis sp., which did not fly.

From a taxonomic standpoint feathers are significant because the shape of microscopic barbs on specific areas of a feather have distinct features that taxonomists can use to determine what bird group it belongs to, Dove says.

“The barbs are unique only on the downy, fluffy part at the base of the feather, not at the tip,” Dove says. “These microstructures are similar among orders of birds—pigeons, ducks, songbirds, for example.

Using the extensive collections in the Division of Birds at the National Museum of Natural History, Dove compared the microscopic structures of the ancient feathers (which she describes as “short barbules with these long prongs,”) to those of modern day birds.

Her analysis confirmed that Apteribis sp. is most closely related the New World ibises of the genus Eudocimus, the American white ibis (Eudocimus albus) and scarlet ibis (Eudocimus buber). Apteribis sp. was first described from fossils found on the Hawaiian Islands of Molokai and Maui. It is one of dozens of bird species known to have gone extinct following the arrival of humans on the Hawaiian Islands.

“Fossil Feathers from the Hawaiian Flightless Ibis (Apteribis SP.): Plumage Coloration and Systematics of a Prehistorically Extinct Bird,” by Carla Dove and Storrs Olson appeared in the September 2011 issue of the Journal of Paleontology.

Invasive Burmese pythons are taking a toll on Florida’s native birds

John Barrat — Fri, 11 Mar 2011 13:46:45 +0000

The Everglades National Park in Florida is home to hundreds of species of native wildlife. It has also become the well-established home of the non-native Burmese python—known to be a predator of native species. Now scientists, for the first time, have conducted a detailed analysis of the avian component of the python’s diet and the negative impact the snakes may have on Florida’s native birds, including some endangered species.

Image right: Great blue heron.

The Burmese python (Python molurus bivittatus), native to Southeast Asia, was first recorded in the Everglades in 1979—thought to be escaped or discarded pets. Their numbers have since grown, with an estimated breeding population in Florida in the tens of thousands. As researchers investigate the impact of this snake in the Everglades, scientists from the Smithsonian Institution, South Florida Natural Resources Center and the University of Florida examined the snake’s predation of the area’s birds. They found that birds, including endangered species, accounted for 25 percent of the python’s diet in the Everglades.

Image left: A Burmese python eats a great blue heron in Florida.

“These invasive Burmese pythons are particularly hazardous to native bird populations in North America because the birds didn’t evolve with this large reptile as a predator,” said Carla Dove, ornithologist at the Smithsonian’s Feather Identification Lab in the National Museum of Natural History. “Conversely, the python is able to thrive here partly because it has no natural predator to keep its numbers in check.”

Image right: The remains of an American coot recovered from the intestinal tract of a Burmese python captured in Florida.

The scientists collected 343 Burmese pythons in Everglades National Park as part of their study between 2003 and 2008. Eighty-five of these snakes had bird remains in their intestinal tract. From these remains the team identified 25 species of birds by comparing feathers and bone fragments with specimens in the Smithsonian’s collection. The results reflected a wide variety of species, from the 5-inch-long house wren to the 4-foot-long great blue heron. Four of the species identified (snowy egret, little blue heron, white ibis and limpkin) are listed as “species of special concern” by the Florida Fish and Wildlife Conservation Commission. The team also identified the remains of a wood stork, which is a federally endangered species.

Image left: Researchers implant a radio transmitter in a 16-foot, 155-pound female Burmese python (Python molurus) at the South Florida Research Center, Everglades National Park. Radio-tracking builds understanding of where pythons spend their time and therefore where they can be controlled in practice. Photo courtesy of Lori Oberhofer, National Park Service. (Credit: U.S. Geological Survey)

“These pythons can also inhabit a wide variety of habitats, so their impact is not restricted to just the native species within the Everglades,” Dove said. “The python’s high reproductive rate, longevity, ability to consume large prey and consumption of bird species are causes for serious conservation and control measures.”

The team’s findings are published in the scientific journal BioOne, March 2011.–Johnny Gibbons

Turkey’s trip to table: Domesticating North America’s largest fowl

John Barrat — Mon, 22 Nov 2010 20:21:26 +0000

The turkey has become synonymous with Thanksgiving in the United States. But people were raising and eating these large ground-dwelling birds long before the creation of the holiday. But when exactly where turkeys first domesticated? And where? Bruce Smith, senior archeologist at the Smithsonian’s National Museum of Natural History has the answers.

“The first evidence we have that turkeys were kept and bred by humans comes from Tehuacan in Mexico about 2000 years ago” Smith says. “By around A.D. 500 turkeys were also being raised by Native Americas in the Southwest United States, based on early evidence recovered from cave sites such as Tseahatso in Arizona’s Canyon del Muerto and the Tularosa Cave in New Mexico.”

Image right: Turkey pens at the site of Casas Grandes, Chihuahua. (Courtesy Amerind Foundation, Inc., Dragoon, Az. Photo by Tommy Carroll)

Natalie Munro, a former postdoctoral fellow in the Natural History Museum’s Program in Human Ecology and Archaeobiology, and now a professor at the University of Connecticut has recently summarized the different archaeological clues that scientists look for when trying to answer such a question. Such evidence includes the existence of eggshells, gizzard stones, healed broken bones, the remains of turkeys outside their natural range, and evidence that turkeys consumed food raised by humans, such as corn and beans. “The most convincing evidence for domestication is turkey droppings and the presence of enclosures that served as pens,” Smith says.

Image left: The remains of a headless turkey excavated at the site of Casas Grandes, Chihuahua. Turkeys were apparently frequently sacrificed as part of dedication ceremonies for buildings and plazas at the site. (Courtesy Amerind Foundation, Inc. Photo by Alfred Cohn)

Morphological studies of turkeys recovered from Southwest prehistoric sites have classified most as belonging to the local Southwest subspecies, Merriam’s wild turkey (Meleagris gallopavo merriami).

Unlike today, the original reason for raising turkeys may not have been for food. Archaeological evidence has revealed that the original motivation for domesticating turkeys was for their feathers. The turkey’s symbolic role in historic Southwest societies is extensively documented and there are frequent references to the use of turkey feathers in ritual contexts as components of costumes, ritual regalia, prayer sticks, and isolated feather bundles.

By examining clues such as cut marks, fragmented bones, burning, and disposal of bones in trash middens, scientists have determined that raising turkeys domestically for food became widespread across the Southwest after A.D. 900. It took another 900 years, however, for the turkey to find its way to the Thanksgiving dinner table as a holiday staple.–Johnny Gibbons

Meet Our Scientist: Forensic ornithologist Carla Dove explains bird-strike science

John Barrat — Thu, 07 Oct 2010 15:55:11 +0000

Scientists Determine Geese Involved in Hudson River Plane Crash Were Migratory

John Barrat — Fri, 10 Jul 2009 15:06:43 +0000

Scientists at the Smithsonian Institution examined the feather remains from the Jan. 15, 2009, US Airways Flight 1549 bird strike to determine not only the species, but also that the Canada geese involved were from a migratory, rather than resident, population. This knowledge is essential for wildlife professionals to develop policies and techniques that will reduce the risk of future collisions. The team’s findings were published in the journal “Frontiers in Ecology and the Environment” in June.

Photo: A crane lifts US Airways Flight 1549 from the Hudson River in lower Manhattan on Jan. 17, 2009. Two days earlier it had crash-landed in the river after colliding with a flock of geese.

The US Airways plane took off from New York’s LaGuardia Airport, colliding with a flock of geese approximately 2,900 feet above the ground, extensively damaging both engines five miles from the airport. The pilot conducted an emergency landing in the Hudson River, and all 155 people on board survived with only a few serious injuries. Investigators at the National Transportation Safety Board later sent feathers and tissue extracted from the plane’s engines to the Smithsonian in Washington, D.C., for analysis.

Researchers in the Feather Identification Laboratory at the Smithsonian’s National Museum of Natural History used molecular genetic techniques and feather samples from museum collections, as well as a technique developed for rapid species identification with small genetic samples called DNA barcoding, to determine that the birds involved were Canada geese (Branta canadensis). This is one of the largest species of birds in North America. The birds involved are estimated to have weighed about 8 pounds each.

Photo: An investigator from the National Transportation Saftey Board removes bird remains from one of the jet engines of US Airways Flight 1549. The remains, analyzed by Smithsonain scientists, were determined to be from migratory Canada geese from the Labrador region. (Photos courtesy NTSB)

The next step for the scientists was to find out if these geese were migratory or non-migratory (resident) birds. “Determining whether these birds were migratory or not was critical to our research and will help inform future methods of reducing bird strikes,” says Peter Marra, research scientist at the Smithsonian’s Migratory Bird Center located at the National Zoological Park, and lead author of the project’s paper. “Resident birds near airports may be managed by population reduction, habitat modification, harassment or removal, but migratory populations require more elaborate techniques in order to monitor bird movements.”

The team took their research to a molecular level at the Smithsonian’s Museum Conservation Institute labs in Suitland, Md., where experts examined stable-hydrogen isotopes from the feathers to confirm whether the geese were from resident or migratory populations. Stable-hydrogen isotope values in feathers can serve as geographic markers since they reflect the types of vegetation in the bird’s diet at the time it grew new feathers after molting. Using a mass spectrometer, which measures the masses and relative concentrations of atoms and molecules at high precision, Museum Conservation Institute scientists compared the bird-strike feather samples with samples from migratory Canada geese and from resident geese close to LaGuardia Airport. Their analysis revealed that the isotope values of the geese involved in the crash of Flight 1549 were most similar to migratory Canada geese from the Labrador region and significantly different from feathers collected from Canada geese living in the New York City region.

“Knowing the frequency and timing of collisions is important,” Marra says. “Otherwise we are missing valuable information that could reveal patterns of frequency, location and the species involved.”

Smithsonian Scientists Determine Geese in Hudson River Plane Crash Were Migratory

admin — Tue, 09 Jun 2009 15:34:03 +0000