Moose-elk Hybrids

Alces alces × Cervus elaphus

Mammalian Hybrids

EUGENE M. MCCARTHY, PHD GENETICS, ΦΒΚ

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An ostensible moose-elk hybrid. Note the elk-like antlers.

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Another view of the same animal

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A third view of the same animal

A diligent scholar is like a bee who takes honey from many different flowers and stores it in his hive.

—John Amos Comenius

Moose
Alces alces

Red Deer (Cervus elaphus), known also as an Elk or Wapiti in North America.

Moose (Alces alces) and elk (Cervus elaphus) come into potential breeding contact in both northern North America and northern Eurasia. And it does seem that moose-elk hybrids occasionally occur, given the existence of photos of obvious hybrids such as those shown above, and the fact that there are reports about such hybrids on record. Thus, a probable moose-elk hybrid, a male with mixed features, was shot in Montana in 1931. A communication appearing in vol. 20 (p. 95) of Science News Letter, and dated August 8, 1931, reads as follows:

The first known specimen of a cross between a moose and an elk was recently killed in the Deerlodge National Forest, in Bear Gulch [Jefferson Co., Montana]. The animal, known to United States forest rangers as ‘the elk with the funny horns,’ associated with elk and grazed like them, but had a body and horns that were half moose and half elk. He was first seen [in 1925] on the Boulder Creek District of the Deerlodge Forest when about three years old, judging from his appearance. When killed, the animal weighed 1100 pounds.” The presence of the animal in a C. elaphus^§ herd suggests its mother was an elk.^*

§ In the UK, Cervus elaphus is referred to by the common name red deer, whereas in North America the common names are elk or wapiti. These two deer have often been treated as separate species (Cervus canadensis in the New World and Cervus elaphus in the Old World), particularly since the publication of Pitra et al. (2004), but the two have often simply been lumped under the name Cervus elaphus. Hybrids of the two are fertile in both sexes (Flower 1929a, p. 317; Gray 1971, p. 152; Howard 1965; Lantz 1910; Rörig 1903; Seitz 1959a; von Knottnerus-Meyer 1904; Wodzicki 1950). Likewise, Alces alces has a different name in the UK, where it’s called elk, whereas in North America the common name used is moose.

* See also: California Fish and Game, 1931, vol. 17, p. 198 (Internet Citations: CALFG); Nature, 128, 676-677 (17 October 1931).

Hybrid variation or individual variation?

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An obvious moose-deer hybrid photographed near Red Feather Lakes, Colorado. The antlers of this animal are more similar to those of a mule deer (Odocoileus hemionus) than to those of an elk (Cervus elephas). Some authors use the term cervina to refer to such antlers. In Latin cervina means “of or pertaining to a deer or stag.”

It is well known that hybridization produces variation. Ongoing hybridization, especially when the hybrids themselves are capable of producing offspring, creates highly variable populations, typically made up of individuals that are intermediate in various ways between the two parental forms that originally crossed to produce them.

There is, however, a tendency among biologists to describe variation produced by hybridization as “individual variation.” Generally speaking, people who use this term leave hybridization out of account altogether, that is, they conceive of the population in question as pure (unaffected by hybridization) but variable. For example, in the present case Nygrén (2007) interpreted animals with moose-like bodies and deer-like antlers as pure moose with deer-like antlers. Indeed, she uses the term “cervina” to designate the sort of antlers seen on the moose in the slide show at the top of this page. In Latin cervina means “of or pertaining to a deer or stag.” So describing antlers as “cervina” amounts to a fancy way of saying they look like deer antlers.

Typical moose antlers are palmate. Palmate antlers are, at least in part, shaped like a hand, that is, there is a flat region like a palm, around the edges of which tines are attached like fingers. Fallow deer also have palmate antlers.

In her survey of what she called “A. alces” Nygren classified antlers into three categories palmate, cervina, and intermediate (between palmate and cervina). As she conceptualizes the population, it is composed of pure moose that somehow show a range of variation in their antlers from moose-like (palmate) to deer-like (cervina). So there is no discussion of possible hybridization. She summarizes her results as follows:

The cervina type had the smallest and the palmated the largest carcass weight, antler spread and tine numbers. The youngest age groups were predominantly of cervina type. At the prime age of 6.5–10.5 years, the prevalent types were intermediate and palmated. At an older age, the cervina type increased and the other types decreased. … The cervina type was most prevalent in the southern zone and the palmated type in the northern zone.

But how would anyone who did think in terms of hybridization interpret such results? Well, obviously, they would say that “moose” with cervina antlers are really moose-elk hybrids that tend more toward the elk end of the spectrum. They would go on to point out that the facts that such individuals tend to be smaller is consistent with such a hypothesis because elk are smaller than moose. And they would also point out that the higher frequency of cervina antlers toward the south is an independent fact that is also consistent with that notion because elk occur at lower latitudes, on average, than moose, so southern moose populations would be more affected by hybridization with elk than norther populations. As to the shift toward a higher frequency of cervina with age, anyone familiar with hybridization will know that, in many crosses, hybrids at a younger age more resemble one of their parents while coming to resemble the other at a later age. For example, hybrids between the polar bear and the brown bear are white at birth, but take on a yellowish-white or blue-brown coloration as they mature.

A key fact discriminating between the two hypotheses (individual variation vs. hybrid variation) in this case is Nygren’s finding that the frequency of cervina antlers increases toward the south. If the observed variation is due to hybridization this shift is expected because the chance of hybridizing with an elk increases toward the south as elk become more frequent. However, it is inconsistent the supposition the other alternative because in the absence of hybridization the expectation is for the variation to be spatially uniform, that is, cervina antlers would be just as likely to occur in all geographic regions, whether elk were present or not.

In connection with the present cross, Nygren's data is of interest because the high rates of cervina and intermediate antlers in so-called moose populations suggests that hybridization between moose and elk/red deer is extensive.

The Stag-moose

Stag-moose (Artist: Robert Bruce Horsfall)

In addition, an intermediate animal of this type is known from fossils and has been described as a species, the stag-moose (Cervalces scotti), pictured at right. According to Wikipedia, it

was a large, moose-like deer of North America during the Pleistocene epoch. It is the only known North American member of the genus Cervalces. It was slightly larger than the moose, with an elk-like head, long legs, and complex, palmate antlers. Cervalces scotti reached 2.5 m (8.2 ft) in height and a weight of 708.5 kg (1,562 lb). The species went extinct approximately 11,500 years ago, toward the end of the most recent ice age, as part of a mass extinction of large North American mammals. The first evidence of the stag-moose found in modern times was discovered at Big Bone Lick, Kentucky by William Clark, circa 1805. A more complete skeleton was found in 1885 by William Barryman Scott in New Jersey. Mummified remains have also been found. The stag-moose frequented wetlands in a range from southern Canada to Arkansas and from Iowa to New Jersey.

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A stag-moose skeleton in the Royal Ontario Museum (Image: Wikipedia, Staka)

The Illinois State Museum website states that “The stag-moose or elk (scientific name Cervalces scotti) is

an extinct deer slightly larger than the modern moose. Its name, stag-moose, refers to the fact that it looks much like a cross between an elk and a moose. If you had been around to see one alive, you might have thought it looked like a stilt-legged moose with the face of an elk and very complex palmate antlers.

Charles Hallock

In 1911, sportsman Charles Hallock claimed to have seen a specimen which apparently consisted only of a rack of antlers attached to a frontal bone. From his comments, it is not entirely clear whether the rack was of ancient origin or a modern specimen, but given that he says that he saw it in a region of northwestern Minnesota (Kittson County) where elk and moose regularly come together, it was probably the latter. At any rate, he is quoted in The Pittsburgh Press, (July 16, 1911, p. 5), as follows,

Similar crosses:

I have seen a great freak of natural product...which shows the horns of a moose and an elk, each perfectly developed on one frontal bone, but all one antler, half moose, half elk. What the animal was that wore these horns was like I was unable to ascertain. I should not suppose, though, that hybridity would manifest itself in the horns alone. Under the conditions of habitat, hybridity would not only be quite possible, but even natural.

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