Sun bears

Sun Bear – Helarctos malayanus

Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Ursidae
Genus: Helarctos
Species: Helarctos malayanus

The Malayan Sun bear is also known as the Honey Bear, or Beruang Madu in Malaysia and Indonesia. It has neglected from much scientific study, and is the least known and understood of the eight species within the family Ursidae. The bears’ closest living relatives are the walrus, sea lions and seals. Different species within the family are adapted to many different habitats, and are found in many areas of the world from the arctic to the tropics. Bears found in the northern hemisphere hibernate through winter months, and therefore their behavioural patterns are very much seasonal.

The sun bear, Helarctos malayanus, inhabits more tropical climates; therefore their behaviour is not influenced by seasonal changes. Sun bears are found in tropical rainforests, and their distribution depends on the availability of lowland forest habitats and also human and cattle populations’ infringement on their range. They are found throughout South East Asia, from north east India, to China, to Sumatra and Borneo. Though it was once true that sun bears occupied most areas in this range, their populations are now sporadic and fragmented, and the decreasing frequency of sightings of them in many countries in South East Asia has led to assumptions of their extinction from much of their original range.

There are two subspecies of Helarctos within the southern part of the bears’ range; Helarctos malayanus malayanus found through most South East Asian areas with the exception of Borneo; Helarctos malayanus euryspilus is the subspecies found on this island. The species were separated taxonomically due to a difference in size, the Bornean specimen being smaller, significantly enough for Pocock (1941) to consider it a separate species.

There are two distinct types of rainforest that the sun bears inhabit within their range. On Sumatra, Borneo and Peninsular Malaysia the forests are aseasonal; temperature and rainfall remains at a more or less continual level throughout the year. These tropical evergreen forests include a wide diversity of forest types including lowland dipterocarp, peat swamp, fresh water swamp and lower montane forest, and the sun bear utilises all these areas. These bears also show successful inhabitation of secondary forests, areas of regrowth and fringe forests bordered by plantations or human habitations.

In mainland South East Asia, the forests experience very distinct wet and dry seasons, with three to seven months of each year having average rainfall of less than 100mm. Forest types found in these areas are semi-evergreen, mixed deciduous and montane evergreen forest. In these seasonal forests, sun bear habitat overlaps that of the Asiatic black bear (Ursus thibetanum). Sun bears have reportedly been seen in mangrove forests, though it seems this depends on the mangrove’s proximity to other forest areas and is not a primary habitat of choice for the sun bear. A study by Augeri (2005) of the biogeography of the sun bear in Sumatra and Borneo found the bears to be in undisturbed forest in 92.7% of all recorded observations. As disturbance of an area increased, so evidence of bear activity significantly decreased.

Helarctos malayanus is the smallest of all the bears, which is thought to be an adaptation to its arboreal lifestyle. It stands approximately 1.2 metres, and this small stature has led some to call it the ‘dog bear’. It is thought that pressures of predation encouraged the evolution of the small size of the bear; swiftly being able to climb tall trees provides an effective escape from potential danger. It has a small tail, five centimeters long, and usually weighs less than 65kgs. Slight sexual dimorphism is shown in the species, with males being larger than the female, usually weighing 10-20kgs more. However, this difference may not be so pronounced in the Bornean subspecies. This is a much less distinct difference than in other bear species. Colouration is the same in both males and females; fur is very dark, generally black in colour, and this colouration is uniform over the body, except on the chest and the muzzle. The chest displays a pale, orange-yellow marking in the shape of a horseshoe, earning the sun bear its name, though the marking can be absent in some individuals. The fur around the muzzle and the eyes is also this colour, or can also be grey or silver. The fur is short and sleek, in contrast to other bears, which is probably an adaptation to the tropical climate of the countries it inhabits. The paws of the bear are large with naked soles, and the legs are slightly bowed. They turn inward, giving it a ‘pigeon toed’ walk when on the ground, but giving the bear excellent climbing skills. The claws are long, sickle-shaped and lightweight, which aid in both climbing and feeding.

The cranium of the sun bear is the feature that distinguishes is most from other bear species; the length of the skull is only slightly larger than its width. Skull sizes between Bornean and South East Asian specimens were found to be significantly different, with Sumatran skulls being longer. Sexual dimorphism is shown in skull size, but not always to a significant level. The jaw is relatively short, causing a crowding of the premolars within the jaw space. The sun bear also has large canine teeth, with these teeth in males being significantly larger than those in females. The tongue of Helarctos malayanus is very long – about 20-25cms in length – and pale in colour. The bear is able to roll the sides of the tongue upwards, forming a cylindrical shape. This could be an adaptation for insect eating, particularly ants and termites. The ears of the sun bear are short, basically immobile and lacking cartilaginous ridges. Captive studies show these bears to rely on smell to detect food rather than sight, but following knowledge of other well studied bear species, we can assume that the eye sight is very good.

Helarctos malayanus is an omnivore with a widely varied diet including lizards, birds, small mammals, fruits, eggs, termites and other insects, coconuts, plants and bees’ nests. It is able to crack open nuts with its powerful jaws. Food habits of wild sun bears have not been greatly studied; Wong et al (2002) found through observation of wild Sun bear and analyses of scat samples that invertebrates made up an important proportion of the bears’ diet, and sun bears were observed breaking open decayed wood in search of termites, though remains of beetles were most commonly found in scat. The mobile lips of the sun bear and the near-naked snout are further adaptations to its insectivory. Figs were the second most important food items within the diet, and trees of Ficus spp. were one of two types of trees most frequently climbed. Acorn-producing Lithocarpus spp. were the other trees most frequented by the bears, indicating that these may be important foods. There is debate as to which foods are of highest importance to the sun bear, and it seems that their diets are variable depending on what is available in their habitat.

The trees within the habitat of the sun bear are not regular fruiters. Diperocarpacae dominate most areas, and these have a unique reproduction pattern causing them to fruit every 2-10 years. These periods of mass fruiting, followed by times of relative scarcity of fruits, have led frugivores to develop strategies to deals with both overabundance, and a lack, of preferred fruits. In some studies, the Sun bear has been found to be, in the main, frugivorous, and during periods of mass fruiting it will dedicate almost 100% of its feeding time to fruits, on occasion remaining in one fruiting tree until the crop has diminished. Figs provide an effective fall-back fruit, as Ficus spp. flower consistently year round. Fredriksson et al (2006) noted that the bears mainly fed on fruits that had fallen to the floor, only climbing for fruits on 24.5% of feeding events. As well as supplementing their diet with a wide variety of substance, sun bears are also able to put on and store fat during times of plenty to help see them through periods of shortage. It is thought their small size also evolved as an adaptation to the lack of continual food abundance within their habitat. Many older specimens of Helarctos malayanus have damaged teeth, and this is thought to occur from time spent stripping bark off of trees and breaking open the wood, often in search of honey. The sun bear is also very fond of palm hearts, which are vegetables contained within the inner core of certain palm trees. Removal of palm hearts will often kill the tree of origin, therefore the bears’ partiality to these makes them a pest to farmers of these crops. The sun bear has recently been recognised as a pest in many agricultural plantations in Sabah and Sarawak.

Unfortunately, many bears do die in the wild due to starvation. Wong et al (2005) suggest this to be a regulatory factor on the population density of primary consumers, such as Sun bear. The habitat of the sun bear is lacking in large predators that would serve to control populations. During times of low fruit production, the forest can not support high levels of frugivores, and many animals may die as a consequence. This is turn reduces numbers, so when fruiting occurs some seeds are able to escape predation and survive to germination. Sun bears do play an important ecological role in seed dispersal, though McConkey (1999) was not able to draw conclusions as to the effectiveness of this. Seed survival in some sun bear defecation was found to be nil, whereas in other cases it was as high as 55%. Factors influencing the success were the species consumed, the number of seeds ingested and the deposition site.

The sun bear, similar to all other bears, is a solitary animal. They may roam in similar areas when fruiting is booming, but do not interact socially. This isolation in the wild is thought to be a consequence of food availability – all the bear species are among the largest mammals in their various habitats, therefore moving around in groups would provide a huge challenge in terms of finding adequate amounts of food, particularly given seasonality of the habitats throughout their range. When housed in captivity, we see that in fact all the bear species are incredibly social animals, and it is considered in their best interest to house them with conspecifics so they may socialise (with the exceptions of the males of some species). When the competition for food is removed, the social side of the bear is able to thrive.

Sun bears are inoffensive and timid; even a mother with cubs will avoid humans if possible rather than display aggression. Helarctos malayanus is thought be nocturnal in East Kalimantan, diurnal in other areas of habitation, but activity patterns may adapt according to human infractions on their habitat. Griffiths and van Schaik (1993) found sun bears to be 100% nocturnal at a sight heavily travelled by humans. Daily movement of bears studied by Wong (2002) averaged 1.45±0.24km, and this was influenced by food availability. The bears were thought to have an average home range size of 14.8±6.1km². It is thought that due to the opportunistic feeding habits of the species, the home range is liable to change in accordance with resource abundance. These specimens of Helarctos malayanus studied by Wong (2002) were found to be diurnal, with just a couple of the individual males being active at night, and then only for short periods.

Sun bear do have a repertoire of sounds; they may make grunting and snuffling noises while searching for insects, produces hoarse grunts and load roars, and also occasionally give short barks, often emitted when the bear is alarmed. The sounds they produce, as well as their general habits and food consumed, are very similar to those of the Asiatic black bear. Locations for bedding sites vary from fallen hollow logs, found by Wong (2002) to be most frequent, to standing trees with cavities and cavities underneath fallen logs or tree roots. Occasionally sun bears will rest on tree branches high above the ground, sometimes forming makeshift nests by pulling in smaller branches and leaves from the surrounding area to make a platform able to support their weight with ease, other times simply lying down and balancing on a branch. Sun bears have been observed to spend most of its day on this kind of look out platform, usually situated some two to seven metres off of the ground. There are questions as to whether this nest constructing behaviour is a common occurrence amongst the sun bear.

As the sun bear does not hibernate, they are able to produce cubs year round, and this behaviour separates the sun bear from other bear species, who show distinct seasonality in their breeding. In captive animals, sexual maturity is reached at around 3.5 years of age, though first conception is recorded at 6.5 years. Gestation period seems to average at around 100 days, and mothers will give birth to one or two cubs. Cubs are born blind and deaf, and though eyes open at around 25 days, they remain blind until the age of 50 days. The cubs will stay with the mother until they are very nearly fully grown at two to three years old, and will sometimes still be suckling from the mother at 18 months old. Young cubs have been observed sucking on their paws, or paws of their siblings. It is thought that as this produces the same sound as when suckling from the mother, it could be a comfort behaviour for the young. It is not known whether these reproductive facts differ greatly for animals born and raised in the wild, as to date only captive Helarctos malayanus have been studied.

The sun bear is not at danger from many natural predators. It is known to be eaten on occasion by tigers and large reticulated pythons, and perhaps sometimes will be hunted by the leopard and clouded leopard. Their greatest threat comes from man, from many angles.

Helarctos malayanus has just recently been classified by IUCN as ‘vulnerable’; up until November 2007 the species was listed as ‘data deficient’ as so little is known with regards to the biology and ecology of the species. There are still no valid population estimates anywhere within their range, though numerous threats to the animal are such that the species is thought to be under threat, despite the lack of official figures. It is estimated that their numbers have declined by 30% in the past 30 years, and will continue to decline at this rate. It has been listed on CITES Appendix I since 1979, but its status here is weakly enforced and trade in the animal, both as a whole and various parts of the body, continues to be increasingly profitable.

Loss of habitat is a great threat to the sun bear and the threat of this differs throughout their range. Forests come under threat due to many reasons; clearing of entire areas for plantation development, unsustainable logging practises, illegal logging, taking place both within and outside of protected areas and also forest fires. In Peninsular Malaysia, Sumatra and Borneo, the loss of habitat is a significant threat as rainforest is being converted into cash crop plantations, such as oil palm, at rate of thousands of km² per year. Bears are able to adapt to partially logged areas of forest, but only should there be primary forest close in locality. They are also able to feed from crops harvested by people, though their presence in such plantation is regarded as ‘crop pest’ and many sun bears are shot and killed in order to eliminate this disturbance to the crop. Fires also diminish the habitat quality for the sun bears, and fires become more extensive during El Niño related droughts. These droughts have also disrupted fruiting patters, noticeable on Borneo, and this taken in hand with a decrease in habitat quality and therefore a lack of viable alternative habitat for the sun bear to utilise, has in the past led to starvation of many bears. Logging is also a problem due to the vast numbers of fig trees being lost, which provide the staple of the bears’ diet during times of scarcity of other resources.

Illegal poaching of bears is also a great threat to their population, and this occurs across their range of distribution. It was estimated by local hunters in Thailand that poaching of sun bears for commercial use depleted numbers of the wild population by 50% in 20 years. In Myanmar, Laos, Cambodia and Vietnam Sun bears are desired for the gall bladder and bile. These are used frequently in Chinese medicine. Bear bile contains ursodeoxycholic acid (UDCA), which is thought to have many beneficial properties including reducing fever, improving eye sight, protecting the liver, breaking down gall stones, improving virility and also produce an anti inflammatory effect. The bile is highly sought after, and this demand has led to the creation of bear bile farms, where bears are kept in small cages and effectively ‘milked’ for their bile. However, demand is such that people are able to make a profit from the gall bladders of wild bears. Though the farms do breed the bears they have in captivity, they will also regularly restock with individuals from the wild. Families will also sometimes capture a bear in order to have ‘stock’ there in case of unexpected serious injury or illness. As well as the bile, the gall bladder itself is desired and also thought to be a remedy for internal injuries and other serious illness.

There is also demand for other bear parts. Their paws are a delicacy, and bear paw soup was found served in two hotels in Medan, within areas of predominantly Chinese population. These dishes sold for US$222.20 per portion. Food containing the bear’s paw is thought to increase or strengthen a man’s virility. The pelts, teeth and claws of the Sun bear are traded simply for decorative purposes.

Many people long to keep a sun bear as a pet. As cubs, they are cute and attractive, and therefore a highly appealing cuddly pet. They generally have an inoffensive nature, and are small enough in size to have good pet potential. However, adult sun bears do not make ideal pets, and when owners realise this they often appeal for zoos to take them. At present, zoos in most countries are fully, if not over, stocked with sun bears, so are unable to take on ex-pets. If just released, these bears have little, if any, chance of survival in the wild. To obtain a cub from the wild, the mother bear is shot, killed, and liberated of any valuable body parts. Poachers are then able to take the cub with ease. Local villages do often have a fear of the sun bear, so if any are identified in surrounding areas, villagers will kill them simply to remove them from the area.

 

 


 References

Augeri, DM (2005) On the biogeographic ecology of the Malayan Sunbear PhD Dissertation University of Cambridge, Cambridge, UK

  • Obtained from Denver Zoo website 

Wong, ST, Servheen, C and Ambu, L (2002) Food habits of Malayan Sun bears in lowland tropical forests of Borneo Ursus, Volume 13

Fredriksson, GM (2005) Predation on sun bears by reticulated python in East Kalimantan, Indonesian Borneo The Raffles Bulletin of Zoology Volume 53

Fredriksson, GM, Wich, SA and Trisno (2006) Frugivory in sun bears (Helarctos malayanus) is linked to El Niño-related fluctuations in fruiting phenology, East Kalimantan, Indonesia Biological Journal of the Linnean Society, Volume 89

Meijaard, E (2004) Craniometric differences among Malayan sun bears (Ursus malayanus); evolutionary and taxonomic implications The Raffles Bulletin of Zoology Volume 52

McConkey, K and Galetti, M (1999) Seed dispersal by the sun bear Helarctos malayanus in Central Borneo Journal of Tropical Ecology Volume 15

Kurniawan, D and Nersahid, R (2002) Bear Markets: Indonesia. A summary f the finding of ‘The illegal trade in bear products, bear parts and live Malayan sun bears in Indonesia’ Published by Animal Conservation for Life via WSPA

Fredriksson, G (1998) Monitoring the adaptation process of reintroduced sun bears (Ursus (Helarctos) malayan us euryspilus), East Kalimantan, Indonesia

Fitzgerald, CS and Krausman, PR (2002) Helarctos malayanus Mammalian Species, Number 696 published by the American Society of Mammalogists

Wong, ST, Servheen, C and Ambu, L (2004) Home range, movement and activity patterns, and bedding sites of Malayan sun bears Helarctos malayanus in the Rainforest of Borneo Biological Conservation Volume 119

Wong, ST, Servheen, C, Ambu, L and Norhayati, A (2005) Impacts of fruit production cycles on Malayan sun bears and vbearded pigs in lowland tropical forest of Sabah, Malaysian Borneo Journal of Tropical Ecology Volume 21