A Behind-the-Scenes Look at the Wolves Stalking the Collections

Published March 4, 2025

The stunning images and candid videos featured in Wolves: Photography by Ronan Donovan contrast the lives of wolves living near humans in Yellowstone and wolves living far removed from humanity in the Canadian Arctic.

We’ll look at what separates wolves from the rest of the pack through the lens of some of more than 100,000 specimens of skins, skulls, skeletons, tanned hides, and fluid-preserved specimens in NHM’s Mammalogy Collections with Dr. Kayce Bell, Curator of Mammalogy at NHM.
 

The photographs from Wolves: Photography by Ronan Donovan capture the private lives of two different wolf packs, while specimens in collections like NHM's let scientists dig deep into the history of wolves across time and space.   

Ronan Donovan

“Specimens like these are invaluable for research. They capture changes in organisms over time and across space,” says Bell, “and offer presence records to let us know when and where animals like wolves were through history, helping us understand complex relationships that have changed so much as humans have dramatically altered the landscape.”

Ice Packs

Wolves did not get their start in North America (unlike the coyote), but came over from Eurasia during the Pleistocene, a series of cooling events commonly called the Ice Age (really, the Ice Ages), initially into the Arctic at least 500,000 years ago, and finally into the middle of the continent around 100,000 years ago. Like coyotes, wolves were one of the few large predators to survive the mass extinction event at the end of the Pleistocene that claimed dire wolves and saber-toothed cats, only to be targeted for destruction by successive American governments. While coyotes proved to be basically unkillable furry terminators, the U.S. nearly succeeded in exterminating wolves in the contiguous United States—they’d been wiped out everywhere in the U.S. except the Isle Royale National Park and part of Minnesota by the time they were first protected under law in the 1960s. Bringing back wolves to control elk populations in Yellowstone was already being discussed at the time, but it wasn’t until 1995 that wolves were returned to Yellowstone, following decades of careful study and lawsuits. Efforts to bring back wild populations have largely succeeded with roughly 7,500 individuals roaming the United States outside of Alaska.

“Collections are really valuable when we think about things like reintroductions (bringing back wild animals to regions they inhabited before human intervention), because they show us where animals like wolves lived, offer clues to their diets and lifestyles, and all that makes it easier to understand the best ways to reintroduce them and the likely effects,” says Bell.

Like all collection specimens, the date and location of its collection are recorded on a tag. Recent efforts to digitize this kind of information has opened new doors to potential science, letting researchers aggregate data from across museums and other institutions. 

Tyler Hayden

Gray Wolves of Many Colors

The stunning photographs featured in the Wolves exhibition track the lives of gray wolves (Canis lupus). A quick peek at the photos, and you’re probably noticing that these “gray” wolves come in a variety of colors: brown, white, black, and gray. The colors come from their outer coats, longer hairs that repel moisture. Their downy undercoats are light gray. Genetic studies have shown that black wolves, like those found around Yellowstone, are unique to the populations in North America, the result of interbreeding with human’s domesticated dogs about 7,000 years ago.

An animal's fur can be analyzed for isotopes that reveal key information, like diet. This pelt was seized by law enforcement and donated to the Museum.

Tyler Hayden

Big, Not Bad

One of the things that separates wolves from coyotes and (most) domesticated dogs is size. Although their size can vary by population, wolves are bigger, reflecting their place as apex predators. Broader muzzles and deeper jaws stocked with enlarged canines and incisors all help wolves take down bigger prey. That bigger size needs to be nourished, ideally with big, hooved herbivores, and if that sounds like a cow, you can see why ranchers frequently have issues with reintroducing the predators.

The oldest terrestrial mammal specimen in the Mammalogy Collection happens to be this wolf skull. The size and shape of its teeth and muzzle speak to its status as a predator of large animals.

Tyler Hayden

When the ideal prey is less available, wolves can shift their diets widely to a ridiculously long list of smaller mammals, black bears, and even birds, depending on their location. This wide-ranging diet likely helped them survive the Ice Age and also helped make them one of Earth’s most successful carnivores.

Wolves primarily howl to communicate across distances, as depicted in this diorama from NHM’s North American Mammal Hall.

Paws

Wolves are the most widely distributed species of large carnivores on the planet, with populations across North America, Europe, and Asia. Their larger paw size points to one of their key advantages in spreading so far and wide: directional dispersal. Packs are usually mostly families, with only the alpha pair breeding. Young adult wolves eventually break away from the pack to start their own, trekking more than 800 km in a single direction—a single wolf famously made it all the way to Southern California from Oregon. Their large paws and blunted claws also support their hunting style of running down prey as a pack (as opposed to grappling big cats that sink in their retractable claws).

A wolf paw print in the snow is nearly as big as an adult human hand while a coyote paw print is larger than a quarter, reflecting their stark size difference.

Wolf at the Doggy Door

One of the most notable aspects of wolves is how quickly humans have shaped them into dogs. Domesticated dogs—from giant mastiffs to itty-bitty chihuahuas—are all a single subspecies of wolf: Canis lupus familiaris. While the story of domestication is still being unraveled, researchers think that dogs began to split from wolves around 27,000–40,000 years ago. The incredible differences in body size, skull shape, and behavior over such a short period of time highlight how much populations can change. 

Side-by-side, the skulls of a wolf (far left) a coyote (middle) and three different breeds of dogs (right)—an Irish setter, Mexican hairless, and  Griffon Bruxellois (front right)—highlight the size differences between these animals, all the same genus—Canis—as well as the incredible effect that selective breeding by humans has had on the ancestors of wolves. 

Tyler Hayden

“The changes in anatomy from wolves to dogs show how quickly species can change under the right pressure,” says Bell. “If dogs have been shaped so drastically by selection, breeders are looking to get specific traits like smaller size, for example. It’s like watching a fast-forward of evolution in action. The incredible pressures of natural selection become easier for people to imagine.”