I've always been fascinated by the differences in pelage coloration and patterns of white-tailed deer, including genetic mutations that cause other color abnormalities such as melanism, albinism, and another interesting pelage pattern - piebaldism.
Piebald, which simply means, "of different colors; spotted or patched or blotched, especially with black and white," is not common, but routinely shows up in populations of deer. Think of a pinto horse and you pretty much have an example of what piebald is.
That said, while the genes responsible for the piebald phenotype is a dominant genetic trait in the pinto breed of horse, it is a recessive gene in the white-tailed deer. Hence, the occurrence of piebald deer in free-ranging, wild white-tailed deer is very low.
What a piebald deer is not, is an albino. True albinism is the total lack of pigmentation, which results in white hair and pink skin and eyes, whereas melanism is the opposite of albinism in which the animal is entirely black. A piebald deer, on the other hand, is a deer with white hair, often occurring in spots or blotches throughout the animal's body. Sometimes a piebald deer can be over 90 percent white with very little brown. Such a deer, though indeed appearing every bit an albino, is not "part albino," it's just a variation of piebald.
I've been fortunate to observe a couple of piebald deer in the wild - one near Warren, Minn., and the other not far from La Salle Lake State Recreation Area near Becida, Minn. But I've also observed countless other pelage and color pattern differences in deer that don't fall into any of the aforementioned genetic color mutations. In these cases, I'm referring to patterns or markings that are different and perhaps otherwise thought of as atypical.
For example, I've observed white-tailed deer with large, white "bibs" on their necks and throats, which is typical for the species. Yet, oddly, some populations of whitetails have no bibs at all. I've also observed deer with white "socks" on the lower portions of their legs, perhaps a form of piebaldism, whereas most deer have little to no white on their legs. And I've also seen deer in the fall and winter with reddish colored coats instead of the standard overall gray coloration during these times of year.
It is thought that the occurrence of piebald deer in a population increases when populations become too high. For example, at the USGS Patuxent Wildlife Research Center (a wildlife refuge and research facility in Maryland) a number of piebald deer have been observed and studied in the refuge. A student who studied the refuge's deer herd in 1998 documented twin piebald fawns born to a normal colored doe.
Other observations included piebald siblings with normal colored siblings, in addition to normal colored fawns born to piebald does. What's more, piebald deer, no matter the amount of white in their pelage, were not ostracized by other, normal colored deer. Piebald deer, as well as any other abnormally colored deer, behave as any white-tailed deer would behave - piebald or not - under normal circumstances.
A short time ago a news story was published in several newspapers and on the Internet about a hunter in Wisconsin that killed a white-tailed buck that the headline called an "albino." The deer was mostly white, it even had pinkish colored ears and nose, yet the forehead of the animal was completely brown-gray in color, as would be expected. In this case, though the media called the deer an albino, the buck wasn't a true albino because pigment was not entirely lacking otherwise brown hair wouldn't be possible. As such, the condition of this particular deer would correctly be called "leucism," which is "... a condition of partial loss of pigmentation that results in white, pale, or patchy coloration of the skin."
The appearance of oddly colored deer is one of those rare occurrences in nature that's exciting and interesting to observe. Genetics and genetic defects are the reasons why such atypical pelage patterns and color abnormalities occur.
These oddities are merely rare variations in pelage coloration occasionally exhibited in white-tailed deer and in some other animals. Indeed, by spending time to look more closely at species that seem to always look alike, one is bound to notice differences great and small, as we get out and enjoy the great outdoors.