Dr. Filardi hoped the threats were just talk, but he kept thinking back to May 2001, when an eco-terrorist group known as the Earth Liberation Front firebombed the Center for Urban Horticulture at the University of Washington, where Dr. Filardi was a graduate student. The bombing was aimed at the work of a professor they mistakenly believed was releasing genetically engineered poplar trees into the wild. (No one was hurt.)

Still, Dr. Filardi wanted to engage, if only to defend his field and the museum, which he had been visiting since his childhood. “I felt like a failed ambassador of the natural sciences,” he told me.

He wrote an essay for Audubon explaining the many steps he’d taken to ensure that the taking of a single kingfisher would not cause harm, including a survey of the population, which he estimated at 4,000 — a “robust number for a large island bird.” He highlighted the role the bird played in conservation efforts: After his findings were presented to tribal, local and national officials, they resolved to protect the area from being mined or logged.

His essay received over 900 comments, the most up-voted of which called him a murderer.

The mustached kingfisher was not gathered for public display, as a “trophy,” as many claimed. It resides in a carefully maintained part of the museum dedicated to research alongside nearly a million other ornithological specimens, none of which spawned death threats.

Some of the birds in the world’s museum and university collections were gathered before the word “scientist” was even coined. The naturalist Alfred Russel Wallace described them as the “individual letters” that “make up one of the volumes of our earth’s history.” Each scientific advance — the discovery of the nucleus, viruses, genes, DNA — has led to new ways of studying the same historic birds.

These collections have also directly contributed to policies that have helped wildlife. The pesticide DDT was ultimately banned after a comparison of museum egg specimens revealed that shells had grown thinner after it was introduced. A study of 120 years’ worth of seabird skins demonstrated rising levels of mercury in the ocean.

The collections almost certainly hold answers to questions that researchers haven’t yet thought to pose about the changes happening to our planet. And in this age of the Sixth Extinction, the collections are becoming even more vital.