While hunting the Goodale Buck Hunt, I met several people who said that the mule deer in the Inyo National Forest were a distinct subspecies of mule deer, separate from the Rocky Mountain mule deer found further north along the Eastern slopes of the Sierra Nevada Mountains of California.
As I watched deer, it did appear to me that the deer were slightly smaller, on average, than the Rocky Mountain Mule Deer I’d been hunting in Modoc and Lassen Counties, but I didn’t give it a lot of thought until I’d killed my buck and returned home.
That’s when I remembered editing a piece for Mule Deer Magazine 1995. Dr. Valerius Geist was the author and he spoke of four or more distinct subspecies of mule deer in California. One of those is the Inyo mule deer, Odocoileus hemionus inyoensis. The other primary species being the Columbian black-tailed deer, the California mule deer, and Rocky Mountain mule deer.
Readings within recent issues of MDF magazine reminded me that another mule deer expert, Jim Heffelfinger, has studied and researched this topic. His views appear to be similar to Dr. Geist’s, but also divergent. A significant issue is whether the variations in mule deer characteristics within California deer are created by evolution or hybridization.
In their 1999 book, A Sportsman’s Guide to Improving Deer Habitat in California, Kenneth Mayer and Tomas Kucera, recognized six sub-species of deer in California. They expanded the listing to include the southern mule deer and the burro mule deer. Here’s what they said about the Inyo mule deer.
The Inyo mule deer occurs only in California, ranging east of the Sierra Nevada in Mono and Inyo counties. Like the Rocky Mountain subspecies, it is migratory, with low-elevation Great Basin winter ranges and higher-elevation summer ranges, often on the west slope of the Sierra Nevada. Although a bit smaller it closely resembles the Rocky Mountain mule deer. Most wildlife biologists believe the Inyo mule deer is simply a southern form of the Rocky Mountain mule deer.
Possibly the most heavily researched issue with regards to differences between blacktailed deer and mule deer has taken place along the western slopes of the Sierra Nevada mountains, primarily in the Shasta Cascade Region. Based upon conversations with Dr. Geist, it is clear to me that when he wrote the article in 1995 he considered the variations in the deer in that area were primarily related to evolution. He labeled the mule deer in the Shasta Cascade region as California mule deer.
Many sportsmen consider deer in that area to be either Columbian blacktail, mule deer or hybrids.
As I reread the article written by Dr. Geist, my take away was that he believed that the primary differences between the deer species living in different regions of California was primarily due to adaptation to differing habitats (evolution).
The fact that these various sub-species of deer live in adjacent habitats supports the concept of hybridization. It is logical that the sub-species variations would be blurred by cross breeding. Jim Heffelfinger’s recent articles in MDF magazine and also Fair Chase magazine, Fall 2005, discuss DNA sampling done for the Boone and Crockett Club. Addressing species boundaries has been an issue with record-keeping groups for years and the Boone and Crockett Club has made progress entering the arena of DNA sampling. Decisions about the species identity of an individual trophy can be made using DNA sampling technology instead of geographical location.
Since I’m not a scientist, I don’t want to go any deeper into the weeds, but I will say that my observations while hunting mule deer in the Owens Valley support the notion that the deer there are different from Rocky Mountain mule deer of Lassen and Modoc Counties in Northern California.
Here is a photo of a of an interesting illustration taken from the Winter 1995 issue of Mule Deer Magazine. In that article, Dr. Geist explains that a “cline” is a “…geographic line-up of forms that vary directionally in their characteristics… ” The sub-species of deer in the illustration fit that definition.