Sounds made-up but it isn't. When one thinks about primates, one usually thinks about the jungle or rain forest, not snow, but this primate is very accustomed to it.
Macaca fuscata
The snow monkey—Macaca fuscata—is also known as the Japanese macaque (as creatively named in Japanese: Nihon zaru, "Japanese monkey"). Only native to Japan, they live within the latitudes of 41° 31'N and 30° 30'N (Cleveland, Ohio is at 41° 28'N and Jacksonville, Florida at 30° 22'N, for an idea of the range). The northern limit is the Shimokita peninsula of Honshu (which is why there are no native snow monkeys on the island of Hokkaido to the north) and the southern limit is Yakushima Island. No other primate (except the obvious) lives as far north as the snow monkey.
(I realize it is probably more "correct" to call them Japanese macaques but it doesn't sound as fun.)
Habitat
Snow monkeys live in forest areas, hilly highlands, and mountain regions. At the northern limit it can get as cold as -15°C (5°F)—between 1961 and 1990, the average winter temperature there was -2.5°C (27.5°F)—and snow can get one meter (3.2 feet) or more deep. To live in this kind of climate, they have made both biological and behavioral adaptations. In the winter, they grow a thick coat of fur to keep up their core temperature. Sleeping is done in trees where there is less chance of direct contact with ice and snow. Also, snow monkeys are known to "sun bathe" on the side of mountains, facing a southern exposure to soak up the heat of the sun and keep warm (another method of keeping warm will be mentioned below). There is also some seasonal migration.
Similar to the winter adaptation, they grow a much thinner coat in the summer, when the temperature can reach 23°C (73.4°F).
Vital statistics
The largest of the macaques, the snow monkey is considered a "medium-sized" monkey.
Details:
Longevity: 20-30 years in the wild (estimated; many die before twenty)
Length (head and body): 45-60 cm (17.1-23.6 inches)
Length (tail): 7.5-12.5 cm (3-5 inches)
Weight: 8-18 kg (17.6-39.6 pounds)
Snow monkeys exhibit sexual dimorphism, with females being somewhat smaller.
They have greyish to brownish fur and a distinctive red, partially hairless face (they do have some "whiskers" and a "beard"). They have opposable thumbs and are quite dexterous. Snow monkeys also have relatively complex communication, with over thirty vocalizations and numerous facial expressions and body gestures. They can move bipedally but mainly are quadrupedal animals.
Dinner
The snow monkey has a pretty diverse diet. They have been known to eat fruit, seeds, nuts, grasses and herbs, flowers, leaves, bark, roots, fungus, crabs and shellfish (ones near coastal waters have demonstrated fine swimming ability), insects, bird eggs, and crops like potatoes, corn/maize, and rice. It is their occasional raids on farmers' fields that sometimes get them clubbed to death or shot. Some 5000 are killed each year (10,000 in 1996, reportedly). Diet can vary due to location (shellfish near the coast, more fruit near the southern limits) and time of year (more bark and leaves during the cold months).
Barrels of monkeys
Snow monkeys live together in "troops" of anywhere from five to seventy (numbers of one hundred or more have been observed). They have a strong hierarchical structure with a general pattern of a central "core" group with less highly ranked individuals on the periphery. The central figure is the alpha male who gains the position through a combination of prior social rank (inherited, so to speak, from the rank of his mother) and physical strength. His main job is to lead and direct the troop. "Below" him (and not quite as close to the core of the group) are more central males who help keep order among the others. Additional males tend toward the periphery. (Information on social structure mostly came from www.geocities.com, any quotes are from there.)
There are four (social) methods by which a male may become the alpha. One is "succession" which is when a male gains the rank due to the "death or departure of the previous alpha male." When a troop is large and stable (particularly resource-wise), this is common. A second is when the ranking male loses his position to another male—usually the number two ranked male. Another comes when a larger troop separates into a smaller group ("fission"). Then the original alpha becomes the newer group's leader and a new one becomes alpha in the original or the alpha remains with the original group and the smaller group gets a new alpha for itself. An outside (of either troop) male may also join the new troop and become the alpha. Lastly, a male from outside the troop may show up who "aggressively takes over" as alpha. the last method seems more common in the southernmost monkeys, though succession is most common, overall.
Females also have a strong hierarchy that is even more stable than in males. There is usually a more dominant female, though even the lower ranked females stay near the core of the troop with the "children." Most important is the kinship relationship—the rank of one's mother being paramount. Since the strongest relationship in their social order is the mother-daughter bond, females rank more highly than males among infants (infants are socially ranked, as well).
Finally, of the infants, the youngest hold the highest rank. This is a beneficial structure, giving the most care and protection to those most in need of it.
A monkey in the oven
Snow monkeys reach sexual maturity between three and five years of age. Male strength and even social rank are not guarantees for reproductive success (in either sense of the word), as female mate selection is somewhat more important (possibly due to the already important social ranking involved with females). One aspect of the selection tends to be whether or not the female has mated with the potential male (snow monkeys being promiscuous). Males that they have not mated with are more often chosen. This leads to more diversity and less inbreeding among the troop. It also might lead to males leaving the troop when fewer and fewer mating opportunities exist (females tend to remain in the same troop most or all of their lives).
The peak month for births is May, following about 170 to 180 days gestation. There is usually only a single birth. The mother-infant bond is strong and mothers have been observed carrying deceased babies around for a period after the death—this is only if the infant died during the three month period during breast feeding, stillbirths and miscarriages are not part of the behavior. Mothers teach (especially the daughters) childrearing and daughters raised away from their mothers have been unable to care for their babies. Males also have a strong role in raising the infants.
By twenty days, the little snow monkeys are able to begin their first steps. Within a month, they can climb and the mother will carry them on her back instead of the infant clinging to the fur on her belly.
Acting like a monkey
Snow monkeys are quite intelligent and are fast learners. Even more, learned behavior gets passed on through the troop. Of course, this ability lead to the infamous "Hundredth Monkey Phenomenon."
In the 1950s, scientists were giving snow monkeys sweet potatoes that had been dropped in the sand. The monkeys liked the food but not the sand (unsurprisingly). One monkey (supposedly named Imo) discovered that by washing it in the water, it would become free of sand and then the tasty treat could be enjoyed. Other monkeys learned the trick and within about five years, almost all the monkeys on the island were washing their potatoes.
So far, so good. Then the "story" begins. The idea was that the learned behavior in the population could reach a critical mass ("one hundred" used as an example) after which the idea would be transferred to other monkeys elsewhere that couldn't have directly learned it from Imo. And it was true that they were able to find snow monkeys elsewhere demonstrating the behavior. A good story but, of course, that isn't an accurate representation of the facts.
To begin with (forgetting how unscientific this magical, collective unconscious, critical mass thing is), not all the monkeys on the island learned the behavior. It was also found that if a monkey grew to adulthood before learning to wash, it almost never learned—regardless of whether or not it took place after that "special" moment when the hundredth monkey learned unsandy potatoes were preferable and what to do about it.
And while instances of potato washing were noted in other troops elsewhere, there was no widespread mass behavior such as the "theory" suggested. In all likelihood, it was simply other clever snow monkeys who discovered what Imo did. It has even developed to the point where the monkeys hold the potatoes under the water longer so that the salt water can "season" them.
That all aside, it does show how the snow monkey can transmit learned behavior through the troop and shows the intelligence of the creatures. Other learned behavior has also been seen in snow monkeys. Perhaps most appropriately, the making snowballs. Not unlike children making a snowman, they take small handfuls of snow and roll them along to make them bigger. Begging for food in certain areas has also become common. They come over to people with food and raise their hand. Swimming is also a likely learned behavior passed on through generations.
Another interesting behavior (that was hinted at earlier and is finally being gotten around to) is the use of outdoor hot springs (rotenburo) to keep warm in the winter. Not a universal behavior, but another learned one. On the other hand, while this behavior might seem endearing (at least from a tourist point of view) it has become a nuisance. (I seem to recall in a news report during the 1998 Winter Olympics in Nagano that said it also made it easier for their bowel movements—I cannot substantiate this, though).
Though generally well-behaved and not very aggressive, snow monkeys have been known to attack people on occasion, biting them. It seems this is not universal behavior, either. Deforestation and human encroachment have brought them into more contact with people, increasing the possibility of negative "encounters." This also leads to more raiding of crops.
Save the monkey!
Numbers of snow monkeys were estimated (1990) at between 35,000 and 50,000 and declining and monkey has been listed as threatened or endangered in the past (Japanese scientists contested the data and numbers). It is clear that there is the potential for serious decline exists with loss of habitat, encounters with humans resulting in destruction of the animal because of attacks or because of raids, and use in medical experiments and research. Whether there is any immediate or short term danger is not clear.
Sources: www.geocities.com/Tokyo/Bay/9166/jmprof.htm, animaldiversity.ummz.umich.edu/accounts/macaca/m._fuscata.html, www.channel4000.com/partners/mnzoo/macaque.html