5. The Yearling. — During the first five months of his life, the calf changes its coat completely, and becomes in appearance a totally different animal. By the time he is six months old he has taken on all the colors which distinguish him in after life, excepting that upon his forequarters. The hair on the head has started out to attain the luxuriant length and density which is so conspicuous in the adult, and its general color is a rich dark brown, shading to black under the chin and throat. The fringe under the neck is long, straight, and black, and the under parts, the back of the fore-arm, the outside of thigh, and the tail-tuft are all black.
The color of the shoulder, the side, and upper part of the hind quarter is a peculiar smoky brown ("broccoli brown" of Ridgway), having in connection with the darker browns of the other parts a peculiar faded appearance, quite as if it were due to the bleaching power of the sun. On the fore quarters there is none of the bright straw color so characteristic of the adult animal. Along the top of the neck and shoulders, however, this color has at last begun to show faintly. The hair on the body is quite luxuriant, both in length and density, in both respects quite equaling, if not even surpassing, that of the finest adults. For example, the hair on the side of the mounted yearling in the Museum group has a length of 2 to 24 inches, while that on the same region of the adult bull, whose pelage is particularly fine, is recorded as being 2 inches only.
The horn is a straight, conical spike from 4 to 6 inches long, according to age, and perfectly black. The legs are proportionally longer and larger in the joints than those of the full-grown animal. The countenance of the yearling is quite interesting. The sleepy, helpless, innocent expression of the very young calf has given place to a wide awake, mischievous look, and he seems ready to break away and run at a second's notice.
The measurements of the yearling in the Museum group are as follows:
Bison Americanus. (Male yearling, taken Oct. 31, 1886. Montana.)
(No. 15694, National Museum collection.)
| Feet. | Inches. | |||
| Height at shoulders | 3 | 4 | ||
| Length, head and body to insertion of tail | 5 | |||
| Depth of chest | 1 | 11 | ||
| Depth of flank | 1 | 1 | ||
| Girth behind fore leg | 4 | 3 | ||
| From base of horns around end of nose | 2 | 112 | ||
| Length of tail vertebræ | 10 | |||
6. The Spike Bull.-In bunters' parlance, the male buffalo between the "yearling" age and four years is called a "spike" bull, in recognition of the fact that up to the latter period the horn is a spike, either perfectly straight, or with a curve near its base, and a straight point the
