Are Elk and Red Deer the Same Species? What DNA Shows

Why people thought they were one species

The elk and the European red deer clearly belong together. Both are large, reddish-brown deer of the genus Cervus, both live in herds, the stags or bulls grow big branching antlers and call loudly in fall, and both shed their antlers every spring. Early English settlers in North America even called elk “red deer”.

Because the two can mate and produce fertile young, many biologists followed the traditional idea that animals able to interbreed belong to one species. Elk were therefore listed as subspecies of red deer, with names such as Cervus elaphus canadensis and C. e. nelsoni. Hunting books, zoos and even some major reference works used this system into the 2000s.

What the DNA shows

In the late 1990s and early 2000s, researchers compared mitochondrial DNA, genetic material passed down through the female line, from deer across Europe, Asia and North America. A large 2004 study by Ludt and colleagues, published in Molecular Phylogenetics and Evolution, sampled hundreds of red deer and wapiti from many populations. It found two clearly separate main groups:

• a western group: the red deer of Europe, North Africa and southwest Asia
• an eastern group: the wapiti of Siberia, Mongolia, China and North America

The two groups had been evolving apart for a long time. In fact, the DNA suggested that elk are more closely related to some Asian deer, such as sika deer and Thorold’s (white-lipped) deer, than they are to the red deer of Europe. That pattern does not fit the idea that elk are just a type of red deer.

Based on this evidence, the IUCN and most mammal checklists now treat the elk as its own species, Cervus canadensis, while the red deer remains Cervus elaphus. Both are listed as Least Concern on the IUCN Red List. The deer of Central Asia, such as the Kashmir stag or hangul, are still debated and are sometimes placed in a third species, Cervus hanglu.

Key differences between elk and red deer

The difference in voice is one of the easiest to notice. A bull elk’s bugle rises into a high whistle; see why do elk bugle? A red deer stag’s roar is deep and throaty, closer to a cow’s bellow; see when is the red deer rut?

Size also differs, though there is overlap. Western European red deer are clearly smaller than most elk, but stags from the Carpathian Mountains and the Caspian red deer or maral of the Caucasus can be large enough to rival elk.

Hybrids in New Zealand and on deer farms

The fact that the two species can interbreed has real consequences. In 1905, a small group of wapiti from North America was released in Fiordland National Park on New Zealand’s South Island. Red deer, introduced to New Zealand from Britain in the 1800s, later spread into the same area. The two interbred freely, and today almost no pure wapiti remain in Fiordland. Most of the animals there are hybrids.

On deer farms in New Zealand, Europe and North America, red deer and elk are sometimes crossbred on purpose to produce larger animals. Wildlife agencies in North America generally try to prevent escaped red deer or hybrids from mixing with wild elk, to keep native herds genetically pure.

Hybridization does not mean the two are one species. Many closely related animals, such as some ducks, big cats and wolves and coyotes, can produce fertile hybrids in some situations but still remain separate species in the wild.

The name problem: elk, wapiti and moose

The naming adds a final twist. In Britain and much of Europe, elk means the moose, Alces alces, a much larger deer with flat, palm-shaped antlers. In North America, elk means Cervus canadensis. The name wapiti, from a Shawnee and Cree word for “white rump”, is often used by scientists to avoid confusion. So a European who says “elk” and an American who says “elk” are usually talking about different animals, and neither is talking about the red deer.