What these 250,000 dead birds can tell us

David Peet, retired physician and volunteer, was removing the innards of a dead sharp-shinned hawk that had been brought recently to the Academy of Natural Sciences of Drexel University in Philadelphia, where one-quarter million perished birds are stored.

An eyeball that poked from the hawk’s stomach seemed to stare unnervingly back at Peet as he sliced. Feathers were still tangled in the hawk’s talons.

Nate Rice, collections manager of the ornithology department at the academy, observed that the shredded plumage was from a robin, whose eye remained undigested when the hawk died, probably after striking a building or vehicle in the city.

“The stomachs go to our biogeochemistry lab,” Rice said. “They will screen for PFAS and use the tissues and stomachs to track those chemicals in wild populations. They’re already finding microplastics in all kinds of birds now.”

PFAS are environmentally persistent manmade chemicals that have posed a growing concern about their possible impact on human health. Their impact on animals has not been widely studied.

The hawk was just one of the many birds that die annually in Philadelphia and are brought to the Department of Ornithology at the Academy to be processed for research. They are stored in a row of metal cabinets 100 feet long, 30 feet deep, and 8½ feet high.

It’s the second largest university-based collection in the world next to Harvard and one of the top museum-based collections of preserved birds of any kind in the world, according to Jason Weckstein, the department’s associate curator.

The collection includes an extinct auk’s skull from the 1700s, Weckstein said. Trays in the cabinet contain thousands of birds, like vaults of a mausoleum.

Each bird has its own story, Weckstein said. The oldest specimens date to around when the academy was founded in 1812. The collection includes birds killed in the first known mass death by building strike in Philadelphia in the 1890s when City Hall was electrified. The newfangled electric lights lured birds to their deaths over a once dark city.

“We have thousands of species of birds in this collection,” Weckstein said. “This is a library of biodiversity. People think, oh it’s a museum with a bunch of dead stuff. But dead stuff tells us about life.”

Scientists use data from the collection to research specific species or trends.

Tens of million of birds pass through the city during spring and fall migrations, and many are killed when they fly into buildings, attracted by lights and reflective glass. The most notorious mass bird death in recent city history took place Oct. 2, 2020, when 500 birds were found dead in a 3½-block radius of Center City after being forced lower by bad weather and confused by bright lights. It’s estimated 1,500 or more birds likely died throughout the city in one night.

The death toll prompted the Lights Out Philly initiative to get some of Philadelphia’s most iconic skyscrapers — Comcast Technology Center, Cira Centre, and Liberty Place — as well as other buildings to turn off, or dim, their lights at night. The program runs April 1 to May 31 and Aug. 15 to Nov. 15 as buildings darken midnight to 6 a.m.

Many dead birds end up at the academy. There Weckstein and his team examine and catalog 2,000 deceased avians annually collected from the city and elsewhere.

» READ MORE: ‘The right thing to do’: How a darkened Philly skyline has helped save birds

The birds are stored in freezers until they can be examined. They are weighed and measured. Their vitals, flesh, eyes and other tissue are removed. Data such as what they’ve eaten, illnesses, or parasites are logged. Skins are sewn shut, and the bodies are dried without preservatives before being stored according to each bird’s taxonomy.

The sex, eye color, age, weight, amount of fat, stomach contents, and other vitals of each bird are recorded, along with the date it was found. Researchers comb through data held by the Department of Ornithology for trends in diseases, weights, food sources, parasites — even plumage.

Outside the processing room, Weckstein turned a crank and separated two cabinets. He pulled open a drawer and pulled out a five-inch long male blackpoll warbler.

“Each bird tells a little bit of a different story,” Weckstein said. “They’re all unique individuals.”

The warbler in his hand had engorged on caterpillars in Central America sometime in early April 2000. It took flight over the Yucatán Peninsula, headed north across the Gulf of Mexico, then toward the Northeast in a 2,000-mile journey that burned marathons of calories.

Still slightly fattened, the adult warbler was using stars and the earth’s magnetic field to navigate as it passed over Philadelphia on May 3, 2000, and crashed into a building at Temple University. Its epic migration in search of abundant food ended the same as tens of thousands that die in the city each spring.

Genomic sequencing and DNA testing, both unavailable in decades past, have opened whole new doors of research, Weckstein said.

“The reality is we find all kinds of new things with DNA. For example, traditionally hawks and falcons were kept together in the collections because they were thought to be closely related,” Weckstein said. “We now know that falcons are not closely related to hawks. It’s independent evolution of a raptorial way of making a living. Falcons are closely related to parrots and songbirds. Hawks are in a totally different part of the family tree.”

He added with a smile: “But of course we can’t move them around in here. If we had to reshuffle this place, it would make us insane.”

The academy gets its collection from a variety of sources, such as scientists, academics and volunteers. For example, Audubon volunteer, Stephen Maciejewski roams blocks of Center City each morning collecting birds killed in building strikes. The birds go in the collection.

Just before Weckstein’s crew started their workday Monday, Maria Pacheco, an assistant professor of biology at Temple, brought in a yellow and olive-green plumaged Kentucky warbler she found dead at the university. Weckstein said Philly is close to the bird’s usual outer range and so it was unusual to find one.

“Oh my God, it’s gorgeous,” Weckstein said.