Tips and Filed Identification- age and sex guide to mountain goats
Look for as many of the following features as possible when choosing a mountain goat. These characteristic help determine sex:
Identifying a male adult mountain goat in the field can be a difficult task. The following information concerning physical and behavioral traits of male, female and juvenile mountain goats is designed to assist the hunter and wildlife watcher in determining the sex and relative age of individual mountain goats in the field. In most states and provinces which support mountain goats, past declines in populations have signaled the need for a better understanding of the species and development of management strategies specifically suited to mountain goats. Mountain goats become susceptible to over harvest if inordinate hunting pressure occurs on local herds, if road access penetrates mountain goat habitat or if adult females comprise the majority of harvest from an area. The hunter can do a great deal to alleviate these problems by selectively harvesting adult males.
The mountain goat (Oreamnos arnericanus) is the only genus and species of its kind in the world. Its closest relatives are the chamois of Europe and the goral and serow of Asia. The domestic goat is not closely related to the mountain goat.
Mountain goats occur only in northwestern North America. In Montana, they are native west of the Continental Divide and have been introduced into several mountain ranges east of the Divide. Although goats do not typically venture far from cliffs and broken terrain, which provide escape cover from predators, they do use dense timber and creek bottoms for security and thermal cover against extreme heat, cold and wind. Within their range, mountain goats may be found at any elevation or exposure at any time of year. Some goats move down in winter to steep cliffs with good snow shedding properties while others move up to windswept ridges to feed on exposed forage.
At birth, kids stand about 13 inches (34cm) at the shoulder and weigh 5 to 7 pounds (3kg). Yearlings may average about 45 pounds (20kg) and 2-year-olds about 55 pounds (25kg). Mountain goats continue to grow through their fourth year achieving average weights of 125 to 155 pounds (57 to 71 kg) for females and 135 to 180 pounds (61 to 82kg) for males.
The breeding season occurs from mid November through early December. Females do not breed until 2.5 years. After a gestation period of 6 months, kids are born in late May or early June. Kids closely follow their mothers for the first year, relying upon them to expose winter forage in deep snow conditions. Adult females rank highest in the social order. By association, kids also assume the superior status of their mothers who vigorously defend them until the kids are 1 year old. Yearlings drop to the bottom of the peck order and are forced to forage last in areas pawed out by other goats. Kid and yearling survival may be less than 50 percent depending upon the severity of the winter. Mountain goats have one of the highest natural mortality rates among big game animals due to the dangerous terrain and hostile climate in which they live. If a goat survives the juvenile years, longevity is normally 10 to 13 years.
Juvenile mountain goats learn a number of lessons from adult females, among them:
So in addition to maintaining the herd through offspring production, adult females are reservoirs of tradition and knowledge. Loss of an adult female from the population therefore, constitutes more than simply the loss of a single mountain goat.
Female-juvenile (nursery) groups may range in size from 2 to well over a dozen mountain goats in native populations on and west of the Continental Divide. In some introduced populations east of the Divide, groups of up to 50 goats sometimes can be observed. Large groups generally occur during early summer when goats congregate on prime feeding grounds or on mineral licks.
As the summer progresses and the vegetation dries out, group size diminishes. Although juveniles are normally found in the company of adult females, a goat of any age or sex may be alone, so careful scrutiny is required to determine its status.
By the age of 2, males begin to disassociate themselves from nursery groups. Adult males generally lead solitary existences. Outside of the mating season they tend to associate primarily with other males. Females normally inhabit the most desirable cliffs which are also often more visible and accessible than areas frequented by males. From late October to mid-December, males seek out females, so both sexes can be found together at this time of year.
Probably the best feature in identifying a mountain goat's sex is urination posture. The male stretches forward with the front legs while keeping the hind legs stationary.
The female stands in place, sometimes moving the hind legs apart, then squats to situate her rump closer to the ground. At close range, when goats are still in summer pelage, the genitalia may be observed. By autumn, however, the winter coat generally obscures the scrotum, but the black vulval patch of the female is visible when the tail is raised, regardless of coat length.
Composed of a fine, thick under-layer of very soft fur and an outer, longer layer of guard hairs, the white coat of the mountain goat is one of the most beautiful in North America. (Among hoofed mammals, only the Dall Sheep shares the distinction of a pure white cape.) This coat is shed annually in the summer, but by November it has nearly reached maximum length. Average maximum length of guard hairs on portions of the body is 6 to 8 inches (15 to 20 cm). Males tend to have more pronounced development of the beard and pantaloons and longer hair over the top of the shoulders than do females.
By late October, the mountain goat's beard becomes a reliable but subtle indicator of age. The adult's full beard extends the full length of the face and may reach 6 to 7 inches (15.5 to 18 cm) in length, while younger animals have progressively shorter, thinner beards. The full beard of the adult gives the face a wider appearance. In comparison, a yearling's beard seems to be confined to the chin and is less than 4 inches (10 cm) in length.
Males characteristically dig rutting pits as the breeding season approaches. Pawing the ground until a depression is created, the male will urinate in the pit then lay in the moist dirt often throwing loosened soil backward with the front feet, over the flanks. This process results in a soiled coat, particularly around the knees and flanks. Females occasionally will indulge in similar behavior, so a dirty coat is not a foolproof indication of a goat's sex. A taxidermist can transform a soiled coat into a beautiful white cape, so hunters should not be discouraged by the dingy color of a goat's pelage in the field.
Body size differences between male and female goats 3 years of age and younger cannot be reliable distinguished in the field. In animals 4 years of age and older, males are usually larger than females, standing 3 to 6 inches (7.5 to 15 cm) higher at the shoulder and slightly longer in body length.
Muscular development of the males' shoulders and the depth of the chest is greater than that of females. Subtle facial features may include a more angular appearance in males, although 1 and 2-year-olds retain a blocky appearance due to the shorter snout typical of juveniles.
Males and females both have shiny, black horns which grow from a bony core. Mountain goats do not shed their horns. An increment of growth is added to the horn annually. During the first year of life, the horns continue to grow throughout the winter so a distinct ring is not created, although a ridge or indentation in the horn often occurs. The majority of horn growth occurs during the first 2.5 years. The age of a goat may be determined by counting the annual growth rings which are formed each winter except the first year. For example, the horns of a 5- year-old goat harvested in the fall will show 4 visible rings.
The male's horns curve back in a greater, more uniform arc. The female's horns tend to curve more toward the tip although this feature is variable. Average horn lengths for adult males range from 8 to 10 inches (20.3 to 25.4 cm), and adult females from 7.5 to 10 inches (19.0 to 25.4 cm) depending on the area of the state from which they are taken. Although the length of a male's horns may not exceed those of a female, the circumference of the horn at the base is greater. A careful observer will notice that there is less space between the horns of males then females. Basal horn circumference for males ranges from 4.3 to 5.8 inches (1.7 to 2.3 cm) while in females circumference is from 3.5 to 5.0 inches (8.9 to 12.7 cm).
Length of the horn in relation to the ear is one field indicator of age. From the age of 1 year the ears are at least 4 inches (10.2 cm) long, reaching 5.5 inches (14.0 cm) in some adult males. In yearlings, the horns are equal or less then the length of the ear. In 2-year-olds the horns exceed the ear length by 1 to 2 inches, or up to half again the length of the ear. The horn to ear length ratio in adults is variable, but the horns are at least half again as long as the ears, and they may achieve double the length of the ears. If the horn appears to be full-length, but the nose seems short, the animal is probably a 2 or 3 year old, and other body characteristics should be checked.
Sketches courtesy of Douglas H. Chadwick. (1983). A Beast the Color of Winter-The Mountain Goat Observed.