GRAY SNUB-NOSED MONKEY

Rhinopithecus brelichi

Geographic Distribution and Habitat
The gray snub-nosed monkey is found in the Fanjingshan Nature Reserve in the Wuling Mountains in south-central China. There is also evidence that the species may be present in nearby forests. They live in mixed deciduous and evergreen mountain forests with heavy rainfall (79 in, or 200 cm, per year) and snowfall in the winter. They live at high altitudes (potentially over a mile high, or 1.6 km) in the summer and move to lower altitudes in the winter to avoid snow.

This monkey is primarily found in China’s Ghizhou province, which lends the species its other name, the Ghizhou snub-nosed monkey.

Gray snub-nosed monkey geographic range encircled in red. Map: IUCN, 2020

Size, Weight, and Lifespan
Gray snub-nosed monkeys are larger than most of their relatives. They stand at 25-29 in (64-73 cm) tall with a tail length of up to 38 in (97 cm). Males are almost twice as heavy as females, weighing in at about 33 lb (15 kg) on average compared to the average female weight of 17.6 lb (8 kg).

There is no recorded lifespan for this monkey, but one of their closest relatives, the golden snub-nosed monkey, can live to be over 23 years old in captivity.

Appearance
Gray snub-nosed monkeys can be immediately recognized by their pale blue face, full lips, large black eyes, and their namesake—a flat, upward-facing nose with large nostrils. Their fur is generally an uneven mix of gray, black, red, and brown. In addition to being bigger, males are also more brightly colored and have greater contrast than females. Males also have white nipples and genitals. Gray snub-nosed monkeys have a distinct white patch of fur on the nape of their neck.

Photo courtesy of Cyril C. Grueter, PhD and used with permission.

What Does It Mean?

Diurnal:
Active during daylight hours.

Harem:
A group of females guarded by a male, who prevents other males from mating with them; an animal group consisting of one or two males, a number of females, and their offspring. The dominant male drives off other males and maintains the unity of the group. If present, a second male is subservient to the dominant male.

Sacculated:
Having a series of different sections (e.g. langurs have sacculated stomachs, i.e. stomachs with three sections)

Scion:
Descendant.

Visit the Glossary for more definitions

Diet
Half of the gray snub-nosed monkey’s diet is made up of leaves with an even split between mature leaves and young leaves, although they prefer young leaves since they are less toxic. Another quarter of their diet is made up of fruits and seeds. The remaining portion of their diet consists of buds, flowers, and insect larvae. Diets change with the seasons. In the winter, the gray snub-nosed monkey is heavily dependent on the buds of Sprenger’s magnolia. In the spring, leaves make up around 93% of their diet. Like all leaf monkeys, snub-nosed monkeys have multi-chambered stomachs to aid in the digestion of plants.

Behavior and Lifestyle
Gray snub-nosed monkeys are diurnal and spend most of their lives in the trees, although they are not averse to moving on the ground.

Daily Life and Group Dynamics 
Gray snub-nosed monkeys live in groups of up to 10 individuals, which include a dominant male, a harem of females, and their offspring. These groups may combine with others to form temporary associations of up to 400 monkeys, which is over half the total population of the species.

Although groups can often be antagonistic toward each other on normal days, they become much friendlier when forming these supergroups. The babies in one group have been seen playing with babies from other groups with a single male watching over the group.

All-male groups consisting of 2 to 5 individuals usually live near family groups, waiting for an opportunity to take over a harem.

Fun Facts

The gray snub-nosed monkey was first described in 1903 and was thought to be extinct until the skull of one was found in 1962. The first living specimen was found by researchers in 1967.

Communication
There is no significant research related to the communication of the gray snub-nosed monkey, likely due to its rarity and remote location. Their closest relative whose communications are well studied is the golden snub-nosed monkey, who lives to the northwest of the gray snub-nosed monkey and separated from them around 2.42 million years ago. Even by evolution standards, two and a half million years can be a long time, and two scions of the same ancestor can differentiate quite a bit. However, we can make some safe assumptions regarding the gray snub-nosed monkey thanks to their golden cousin.

Due to their large nostrils, golden snub-nosed monkeys can vocalize ventriloquially, meaning they can vocalize without moving their mouth. Since gray snub-nosed monkeys have similar nostrils, they may be able to communicate the same way. Golden snub-nosed monkeys have a rich repertoire of vocalizations, numbering at least 18 individuals calls, which can be linked to the fact that they often gather in groups of several hundred monkeys. In such large groups, calls must be separate and distinct from one another to be understood by other members. Since gray snub-nosed monkeys also gather into similar-sized groups, they likely have a similar range of vocalizations.

Of course, the only complete conclusion one can make here is that more research is needed on the gray snub-nosed monkey.

Reproduction and Family
Mating in the wild occurs from September to October. Females avoid competition by staggering their mating periods, meaning that if one female in a group mates in early September, the other will hold off on mating for another week or so. Since groups are often in close proximity to other groups, mating outside of their group may occur, though it is rare. Babies are born between March and May. Females tend to give birth every two to three years.

Babies are carried around by their mothers in the first month of life. After that, they gradually grow more independent before being weaned off their mother’s milk between 12 and 20 months of age. All of the females in the group help raise the babies. Fathers may occasionally play with their offspring, but they do not take on much of a role in parenting outside of protection.

Males and females reach puberty after about 3 years, at which point the males will leave their natal group while females will usually stay. Although they have reached maturity, both males and females often wait at least two years before mating. It is unknown why males delay their mating opportunities, but for females, as is the case in most mammals, it is usually unhealthy to get pregnant immediately following puberty and it is best to wait until the rest of their body has fully matured.

Photo courtesy of Cyril C. Grueter, PhD and used with permission.

Ecological Role
With seeds and seed-bearing fruits making up 20–30% of their diet, gray snub-nosed monkeys are critical seed dispersers in their small habitat. Seeds that survive digestion are defecated far away from their parent tree. This creates a more diverse, and thus healthier, habitat, which benefits local plants, animals, and even humans.

Conservation Status and Threats
Gray snub-nosed monkeys are listed as Endangered by the International Union for Conservation of Nature (IUCN, 2015) due to their decreasing population and the continued degradation of quality habitats. Their population currently consists of no more than 700 individuals with an effective population size of 250-300 monkeys. The effective population size is the number of breeding individuals in a population, taking into account gender ratios, reproductive success, and the ability to raise offspring successfully. Scientists pay special attention to this number when dealing with small populations living in small areas.

The primary threats to the species include occasional illegal hunting for meat and use in traditional medicine, capture in snares intended for other animals, and habitat disturbance. The species is only known to occur in Fanjingshan National Nature Reserve. Tourism is a growing threat with roads and other modes of transport such as cable cars constructed to cater to the tourist needs.

Since the small population is vulnerable to inbreeding and has a limited distribution, this could mean low genetic variability to adapt to environmental and climate change. Since they only occur in one location, they are especially vulnerable to disease outbreaks and natural catastrophes.

Conservation Efforts
The Chinese government has said that measures taken to protect the local environment have had a noticeable effect on the gray snub-nosed monkey population, claiming that the population has more than doubled since 1979. This contradicts the IUCN claim that their numbers are declining. Both reports were released in 2008. Technically, both reports could be correct as the two assessments may have been made during different time periods. In other words, the population overall could have increased over a 30-year period, but it could have decreased over the last 10 years of that same period.

In the summer, gray snub-nosed monkeys have a diverse diet meaning that they can adapt to changes with relative ease. However, since monkeys in the winter depend heavily on Sprenger’s magnolia, it is vital to limit the harvesting of the plant, which local communities value for its use in traditional medicine (some communities have already stopped this practice). This flowering plant species is listed as vulnerable by the China Species Red List due to its decreasing and fragmented population, although the IUCN lacks the necessary information to verify this. More information on the ecosystem as a whole is needed to create an effective conservation plan.

The Fanjingshan Nature Reserve holds a captive breeding colony to help build a healthy population. There have also been discussions of relocating some monkeys to neighboring reserves so the species can become more diverse and less susceptible to disease, catastrophes, and other possible threats.

our gratitude

Many thanks to Cyril C. Grueter, PhD for providing and allowing us to use his stunning photos of the gray snub-nosed monkey.

To learn more about Dr. Grueter and his work, visit www.cyrilgrueter.net.

References:

  • Kolleck, Jakob, et al. “Genetic Diversity in Endangered Guizhou Snub-Nosed Monkeys (Rhinopithecus Brelichi): Contrasting Results from Microsatellite and Mitochondrial DNA Data.” PLoS ONE, vol. 8, no. 8, 29 Aug. 2013.
  • Xiang, Zuo-Fu, et al. “Current Status and Conservation of the Gray Snub-Nosed Monkey Rhinopithecus Brelichi (Colobinae) in Guizhou, China.” Biological Conservation, vol. 142, no. 3, 2009, pp. 469–476.
  • Xiang, Zuo-Fu, et al. “Diet and Feeding Behavior of Rhinopithecus Brelichi at Yangaoping, Guizhou.” American Journal of Primatology, vol. 74, no. 6, 2012, pp. 551–560.
  • https://www.arkive.org/grey-snub-nosed-monkey/rhinopithecus-brelichi/
  • http://www.iucnredlist.org/details/19595/0
  • http://www.iucnredlist.org/details/194009/0
  • https://www.upi.com/Endangered-China-monkeys-double-in-number/16191220724459/
  • https://www.nature.com/scitable/topicpage/genetic-drift-and-effective-population-size-772523
  • http://pin.primate.wisc.edu/factsheets/entry/golden_snub-nosed_monkey/taxon

Written by Eric Starr, August 2018. Population data updated Nov 2020.