Assam macaque (Macaca assamensis)
The Assam Macaque (Macaca assamensis) is a Macaque of
the Old World monkey family native to South and Southeast Asia. Since 2008, the
species is listed as Near Threatened by IUCN, as it is experiencing significant
declines due to hunting, habitat degradation and fragmentation.
The Assam Macaque has a yellowish-grey to dark brown pelage. The facial skin is dark brownish to purplish. The head has a dark fringe of hair on the cheeks directed backwards to the ears. The hair on the crown is parted in the middle. The shoulders, head and arms tend to be paler than the hindquarters, which are greyish. The tail is well-haired and short. Head-to-body-length measures 51 to 73.5 cm (20 to 28.9 in), and the tail is 15 to 30 cm (5.9 to 12 in) long. Adult weight is 5 to 10 kg (11 to 22 lb).
Distribution and habitat
The Macaca assamensis population is endemic to Nepal and likely in some way distinct from the two recognized subspecies, which occupy adjacent areas to the southeast and east of the range of M. assamensis. There is a gap in north-eastern India between the two main population pockets, specifically between central Bhutan and the south side of the Brahmaputra River; the east bank of its upper course marks the division between the two recognized subspecies
The Eastern Assamese Macaque, M. a. assamensis, occurs in Bhutan, Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, and Tripura in north-eastern India, into Northern Myanmar, southeast through the Myanmar-Thailand border ranges as far as Chongkrong, to the upper Mekong in Tibet, into the provinces of Guangxi, Guizhou, Tibet and Yunnan in South-Western China, in Thateng in Northern Laos, and Hoi Xuan in Northern Vietnam; The Western Assamese Macaque, M. a. pelops, is found from central Nepal through Uttar Pradesh, Sikkim, Assam and Northernmost West Bengal in Northern India, into central Bhutan and the Sundarbans in Bangladesh. During surveys carried out in 1976, 1978, and 1984 in Nepal, Assam macaques were found to be patchily distributed along rivers in tropical and subtropical forests at altitudes from 200 to 1,800 metres (660 to 5,900 ft). They are apparently absent from areas west of the Kaligandaki River. In India, they live in tropical and subtropical semi evergreen forests, dry deciduous and montane forests, from the sea level to altitudes of 4,000 metres (13,000 ft).They usually inhabit hill areas above 1,000 m (3,300 ft), but in the wetter east they may occur even in the lowlands, and frequent areas that only marginally reach this altitude. In Laos and Vietnam, they prefer high altitudes, usually above 500 m (1,600 ft). In forests on limestone karst, they occur in much lower elevations.
There is little information available on the global
population, but it is thought to be relatively high. There is decline in the
wild populations in certain countries, but not throughout the distribution. It
is probably the most common Macaque species in Lao PDR, where it is widespread
through hill and mountain forest ranges, though no population estimate is
available (Duckworth et al. 1999; R. Timmins pers. comm.). In Nepal the taxon is
also restricted to less than 300 mature individuals, distributed in eight
subpopulations, with no subpopulation having more than 50 mature individuals.
There is no information on population estimates from
Thailand (R. Boonratana pers.
comm.). In Northern Myanmar it is a very common species, but information from
the eastern part of the country is not available (S. Htun pers. comm.). Due to
hunting pressure, macaques in Vietnam are scarce. However, there is no precise
information for this species on population and status (R. Timmins pers. comm.).
The subspecies M. a. assamensis is relatively widespread in its extent of occurrence (Molur et al. 2003). In Namdapha National Park, Arunachal Pradesh, India, the population was found to have a group density of 1.11/km2, and an average group size of 13.93 individuals (Chetry et al. 2003). This species is the most abundant monkey in the mountains of Arunachal Pradesh (Choudhury 2001). In China, there are estimated to be over 3,000 individuals (Zhang et al. 2002).
The subspecies M. a. pelops is only found in adjacent populations in India, Bhutan, and adjacent China. There are likely less than 1,000 individuals remaining (Zhang et al. 2002).
A subpopulation of M. assamensis is endemic to Nepal and relegated to a single population there, and is considered as a possible new subspecies (M. Chalise pers. comm.). However, further taxonomic clarification is needed.
Population Trend: Decreasing
Ecology and behaviour
Assam Macaques are diurnal, and at times both arboreal and terrestrial. They are omnivorous and feed on fruits, leaves, invertebrates and cereals. It prefers dense forest (Choudhury 2001), and does not usually occur in secondary forest. It is found in tropical and subtropical semi-evergreen forests, dry deciduous and montane forest (Srivistava and Mohnot 2001; R. Boonratana pers. comm.). Particular habitats and niches vary some depending on the subspecies. This species is found from the floodplains to the high mountains, up to 2,800 m, and sometimes 3,000 m in the summer (Choudhury 2001), and perhaps up to 4,000 m (Srivastava and Mohnot 2001; Zhang et al. 2002). It is generally an upland species, and usually associated with hill areas above 1,000 m. In the wetter east the species may also frequent areas that do not or only marginally reach 1,000 m and may occur even in the lowlands. In Lao PDR and Vietnam the species is predominantly associated with high altitudes, usually above 500 m. In forests on limestone karst the species occurs in much lower elevations (R. Timmins pers. comm.). The generation of this species is 10-12 years (Molur et al. 2003)
The gestation period lasts for 165 days. Assemese Macaque give
birth to single offspring which weighs around 400 g at birth. Gestation length
was on average 164.2 d (range: 158–170, n=10), and females had their
first infant at an age of 5 yr (n=4). Interbirth intervals were
bimodally distributed, with females giving birth on average every 13.9 or 23.2
mo. Shorter interbirth intervals were linked to early parturition within the
birth season. Most females displayed subcaudal sexual swellings which, however,
did not reliably indicate female reproductive status or fertility. Overall,
results fall within the range of findings reported for other macaque species.
These results thus add to the growing body of information available for wild
macaques, facilitating comparative studies for a better understanding of
interspecific differences in social and reproductive patterns. Macaques provide
ideal conditions for comparative studies concerning the linkage between life
histories and reproductive strategies. All Macaque species share basic patterns
of social organization: They all live in MultiMate, multifamily groups and they
mate promiscuously, males disperse, whereas females are philopatric (Thierry
2007). On the other hand, they vary in social
and reproductive traits, e.g., the degree of seasonality, with births occurring
year-round or being restricted to a few months; social structure, dominance
relationships; mating patterns; and the development of sexual signals, e.g.,
sexual swellings, sex skin coloration, copulation calls, all of which may
influence the reproductive strategies of both sexes (Dixon
1998; van Noordwijk and van Schaik.Timing of
reproduction was strictly seasonal (births: April–July, 86% in April–June, 4 yr,
n=29; conceptions: October–February, 65% in December–January, 2 yr,
n=17). Females showed no cyclic ovarian activity outside the mating season
and conceived in their first or second cycle (mean: 1.2 cycles to conception,
n=13). Gestation length was on average 164.2 d (range: 158–170, n=10),
and females had their first infant at an age of 5 yr (n=4). Interbirth
intervals were bimodally distributed, with females giving birth on average every
13.9 or 23.2 mo. Shorter interbirth intervals were linked to early parturition
within the birth season. Most females displayed subcaudal sexual swellings
which, however, did not reliably indicate female reproductive status or
fertility. Overall, our results fall within the range of findings reported for
other macaque species. These results thus add to the growing body of information
available for wild macaques, facilitating comparative studies for a better
understanding of interspecific differences in social and reproductive patterns.
The threats to this species' habitat include selective logging
and various forms of anthropogenic development and activities, alien invasive,
and hunting and trapping for sport, “medicine,” food, and the pet trade.
Additionally, hybridization with adjacent species poses a threat to some
populations (Molur et al. 2003). Although it has a wide distribution, the
species is considered to be threatened in most parts of its range. Habitat
destruction is the primary cause of the decline.
Habitat destruction poses the greatest risk to this species in North-Eastern India (Srivistava and Mohnot 2001). However, it has been hunted in the Himalayan regions of North Bengal, Sikkim, and Arunachal Pradesh, where it frequently invades crops (Srivistava and Mohnot 2001). Locals use skulls as an “evil eye” in front of houses in North-Eastern India (Das pers. comm.). There has been extensive habitat loss over the last 15 years in several states of North-Eastern India (from 30-60%), with major impacts on M. a. assamensis.
The Nepal population of Macaca assamensis is threatened due to its restricted distribution of less than 2,200 km2 extent of occurrence and 914 km2 area of occupancy and continuing decline in area, extent and quality of habitat, the number of locations and in the number of mature individuals—the latter two conditions being inferred from threats to habitat and population from degradation and hunting, respectively. Given its restricted extent of occurrence, threats on its population and habitat, and small numbers in fragmented patches, the Nepal population of this macaque is categorized as Endangered.
In Thailand habitat loss is the primary threat, hunting for food less so (R. Boonratana pers. comm.). It is protected only in temples.
In Eastern Myanmar habitat loss is the primary threat, but hunting is presumed to occur. They are hunted to make footwear, and the skins are taken to Tibet as it is more profitable than taking it to Yunnan province of China. In Northern Myanmar, hunting and habitat loss due to conversion are the major threats. There is more than 30% decline in forest cover over the last 30-35 years. The combination of habitat loss and hunting heavily impacts the subpopulations, and the threats are likely to continue in the next three decades if the demand for this continues in Tibet (S. Htun pers. comm.).
In Lao PDR and Vietnam the primary threat is hunting for food and for bones to make balm and/or glue. The bones are not used within Lao PDR, but sold to Vietnamese and traders within Lao PDR. The balm is used for pain relief and other speculative “medicinal” purposes. The trade also goes into China (R. Boonratana pers. comm.). This species has declined in Vietnam and Lao PDR in the last 30-35 years by more than 30%, and is expected to continue to decline in the future.
In Tibet the habitat is good, but there is some hunting, and no detailed data exists for M. a. pelops from that region of China (Z. Zhou et al. pers. comm.). For M. a. assamensis, hunting is a major threat. Logging has ceased, but was a major threat for the last 30 years. Conversion to pastures is still ongoing, but not a significant threat. There are extensive habitats still left for this subspecies and the taxon is relatively safe.
This species is listed in Appendix II of CITES (Chetry et al.
2003). It is legally protected in all countries of occurrence. For the
populations that reside in India, the species is listed under Schedule II, part
I of the Indian Wildlife (Protection) Act (amended up to 2002) (Chetry et al.
2003). In Bangladesh it is listed as Schedule III in the Bangladesh Wildlife
(Preservation) (Amendment) Act, 1974. In Myanmar it is legally protected
according to the 1994 Wildlife Protection Law. In
Thailand the species is protected by the Wildlife
Protection Act, 1960.
The species has been recorded from at least 41 protected areas in north-eastern India, and maybe four others (Choudhury 2001), and may also be found in the following protected areas: Nam Ha National Biodiversity Conservation Area (Lao PDR); Langtang National Park, Makalu Barun National Park (Nepal); Doi Suthep-Pui National Park, Huay Kha Khaeng Wildlife Sanctuary, Phu Khieo Wildlife Sanctuary (Thailand); Pu Mat National Park (Vietnam).