Today I had occasion to wax eloquent about a cow. Those who know me may find this novel for, although I have during several different periods of my life been responsible for the care, management, milking and even midwifery of various groups of bovines, I generally make no bones about my feelings for and about cows. I typify this by stating I am glad they make up two of the major food groups.
That is not to say I am incapable of appreciating an occasional great animal. I actually got to see probably the most important Holstein bull in history, Round Oak Rag Apple, in the late 1970s. He was already aging and died not too long after I saw him, but he was an impressive beast.
The cow I talked up today, I referred to as currently being “Argyle’s most prominent citizen.” Her name is Lu and, with a little help from Anthony Liddle, she just won first place in the 150,000 class at the World Dairy Expo in Madison, Wisconsin. Think about that for a minute. Lu was not only the best cow, she was the best cow in a group of cows that had already in their lifetime produced more than 150,000 pounds of milk.
Not being a dairyman by inclination, I must admit I was most impressed not by her straightness from chine to loin or udder attachment or even the classic set of her thurls, but rather by her color. Lu is not the picture-book black-and-white cow. Her dark spots are outlined with a rich blue roan border. I found this quite amazing because back when I was milking cows and they were trying to kill me, there was a superstition about so-called “blue” cows. Any bit of roan, either red or blue, was considered to be bad luck even stronger than mirror-breaking, and such calves were immediately sent to the auction to end up as beef.
Probably the best cow I ever milked was an almost pure white, registered Holstein named PV Jennie. I convinced the owner to get her bred, at great expense, to a top end bull, and waited with great anticipation for the calf. I helped her deliver a large, healthy heifer calf and I was horrified to find, when I came in after school to do the milking the next afternoon, the owner had sent it off to auction because, like Lu, its black patches were strongly outlined with a roan border. Probably just as well. Had it turned out to be a great cow, I might have been heartened by the success, stayed in dairying, and wound up killed by a cow.
Humans have always been particularly concerned with animal pelage that is not “normal.” Sometimes it is treated as special and even sacred, other times, like blue cows, it is considered unlucky, weird or even dangerous. It is surprising how consistent this has been in groups throughout the ages all around the world. The appearance of an unusually colored animal seems to engender one of two responses — to venerate it or to immediately kill it or sometimes both. In many cases, there are mirroring legends surrounding both black and white specimens.
The reason for the pervasiveness of these cultural beliefs is a trait that a large number of animal species, as well as many birds, seem to share. This involves the color range within the population. If you look back over the “Sightings” columns, you will find many examples of this in everything from squirrels to hawks to rabbits to goldfinches. I have touched upon the science behind it but, from the number of questions lately, apparently not enough for a number of readers. So ...
The typical pattern is for the vast majority of the individuals to conform to a “normal” but with an occasional large variation either to a light/white or a dark/black phase. The white variant is referred to as leucistic (from the Greek ‘luekos” meaning white.) Dark phases are known as melanistic.
The first important distinction, and great confusion, revolves around the concept of an albino. In a leucistic animal, the body is capable of producing color and does so in the skin, but the hair, feathers, scales or whatever are actually colored white. An albino animal lacks the gene necessary to produce any melanin at all. Such animals will have a definite pink cast to their skin and particularly their eyes.
Easily damaged by ultraviolet rays of the sun, most albinos do not survive long. Albinism seems to occur at a particular rate in most species, typically around one out of every 20 to 30 thousand. This is also true for humans although there are some variations. Within some African groups, for example, it is a frequent as one in five thousand while some northern groups may find it in no more than one out of 40 thousand births.
The same sort of variation may be seen in the leucistic to melanistic range. In Europe, red foxes almost never produce a dark kit. When Europeans came to this continent, and saw the melanistic color phases, which are almost as common as normal reds in some areas and can occur in the same litters, they named it a “cross fox” thinking it was a hybrid of red and gray foxes. There are also leucistic red foxes but these so-called “ghost foxes” seem to have poor survival and are only common in captive populations.
Color extremes seem to be more prevalent and persistent in predator species than in prey. In this area, for example, we quite often see both white and dark redtail hawks. Cottontail rabbits also produce light and dark phases. However, less that one in 10 rabbits survive their first six months and any hindrance, like a color that contrasts with the surroundings, lowers even these terrible odds for the individual.
At times, one end of the spectrum may be favored over a “normal” color. The gray squirrel is typically a light agouti color. Agouti means each hair has bands of darker and lighter colors. This is a great adaptation because every movement causes a ripple of color and provides a confusing picture to a pursuing predator.
However, from the end of the last glacier until 1900, one of the most dominant mast-producing trees in North America was the American Chestnut. These trees had a very dark bark which favored the melanistic squirrels and well over 70 percent of the population was black. When the Chestnuts rapidly disappeared due to a blight, the next most common nut-producing tree was the beech. Against its bright gray bark, the black squirrels were very visible and natural selection moved the population to what we now consider “normal.”
There is the quick overview of coloration. Now I think I will go have a hamburger and glass of milk.