The spectacled bear ( Tremarctos ornatus ), also known as the Andean bear, is the only bear species native to South America. It is also the largest carnivore of the Tropical Andes. The spectacled bear is the last remaining short-faced bear (subfamily Tremarctinae).
Physical Characteristics
Spectacled bears are mid-sized animals. Adult weight ranges from 34 to 175 kg and body length from 88 to 206 cm. Males are usually one third larger than females. They have short but strong legs. The dense coat is black to brown in colour, although some individuals with a reddish tinge have been identified. Their fur is blackish in color, though bears may vary from jet black to dark brown and even to a reddish hue.
Facial patterns of white to yellowish marks that usually occur around the eyes are characteristic of the species and are the reason it is often known as the spectacled bear. These markings often extend down their chest, giving each bear a unique appearance and helping scientists identify individuals. These marks may extend under the chin and across the throat onto the chest, are known to be highly variable, may change in shape and colour with age, and in some individuals may be absent altogether. The markings also give them their scientific name: Tremarctos ornatus, or decorated bear.
As a characteristic of the subfamily Tremarctinae, or short-faced bear, Andean bears have massive skulls compared to other omnivore bear species and their snout is relatively short compared to that of other bear species. They have strong jaw muscles for crushing and grinding tough fibrous food such as bromeliads, palms, and bamboo.
Distribution and Habitat
Spectacled bears are mostly restricted to certain areas of northern and western South America. Endemic to the Tropical Andes, the Andean bear inhabits the mountain regions of Venezuela, Colombia, Ecuador, Peru, and Bolivia. The presence of the species in Argentina has been considered possible, but evidence is inconclusive and controversial. In terms of extent, the area occupied is about 4,600 km by 200-650 km.
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Before spectacled bear populations became fragmented during the last 500 years, the species had a reputation for being adaptable, as it is found in a wide variety of habitats and altitudes throughout its range, including cloud forests, high-altitude grasslands (páramo), dry forests and scrub deserts. They are also found in paramo, scrub forest and grasslands. A single spectacled bear population on the border of Peru and Ecuador inhabited as great a range of habitat types as the world's brown bears ( Ursus arctos ) now occupy. The best habitats for spectacled bears are humid to very humid montane forests. These cloud forests typically occupy a 500 to 1,000 m (1,600 to 3,300 ft) elevational band between 1,000 and 2,700 m (3,300 and 8,900 ft) depending on latitude. Generally, the wetter these forests are the more food species there are that can support bears. Occasionally, they may reach altitudes as low as 250 m (820 ft), but are not typically found below 1,900 m (6,200 ft) in the foothills.
Behavior and Lifestyle
Spectacled bears are diurnal, and unlike other bear species they do not hibernate. In Andean cloud forests, they may be active both during the day and night, but in the Peruvian desert are reported to bed down under vegetative cover during the day.
Spectacled bears are one of four extant bear species that are habitually arboreal, alongside the American black bear ( Ursus americanus ) and Asian black bear ( U. thibetanus ), and the sun bear ( Helarctos malayanus ). Their continued survival alongside humans has depended mostly on their ability to climb even the tallest trees of the Andes. They usually retreat from the presence of humans, often by climbing trees. Once up a tree, they may often build a platform, perhaps to aid in concealment, as well as to rest and store food on. Tree nests are built to serve multiple behavioural purposes and are used for feeding on fruit or carcasses and for resting or guarding feeding sites.
Although spectacled bears are solitary and tend to isolate themselves from one another to avoid competition, they are not territorial. Generally solitary, this species can occasionally be seen feeding in small groups where food is plentiful. Extensive home range overlap has been found, especially between females and males. Males are reported to have an average home range of 23 km2 (8.9 sq mi) during the wet season and 27 km2 (10 sq mi) during the dry season. Females have an average home range of 10 km2 (3.9 sq mi) in the wet season and 7 km2 (2.7 sq mi) in the dry season. When encountered by humans or other spectacled bears, they will react in a docile but cautious manner, unless the intruder is seen as a threat or a mother's cubs are endangered. Mothers are protective of their young and have attacked poachers.
Very little is known regarding communication behaviour, but field observations indicate that this species scent-marks trees, which could represent a means of communication among adult bears, whereas auditory calls occur mainly between mother and cub. Olfaction is the dominant form of communication for spectacled bears.
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Diet and Feeding Habits
Although the Andean bear is omnivorous, vegetative matter forms the majority of its diet. Spectacled bears are more herbivorous than most other bears; normally about 5 to 7% of their diets is meat. The most common foods for these bears include cactus, bromeliads (especially Puya ssp., Tillandsia ssp. and Guzmania ssp.) palm nuts, bamboo hearts, frailejon ( Espeletia spp.), orchid bulbs, fallen fruit on the forest floor, unopened palm leaves, and moss. They will also peel back tree bark to eat the nutritious second layer. The bears feed year round on these fibrous plant species; however, they depend on fruits and other more nutritional food items such as bark from trees, rodents, birds, and insects to obtain the necessary nutrients to survive. They also occasionally prey on livestock. Much of this vegetation is very tough to open or digest for most animals, and the bear is one of the few species in its range to exploit these food sources.
The spectacled bear has the largest zygomatic mandibular muscles relative to its body size and the shortest muzzle of any living bear, slightly surpassing the relative size of the giant panda's ( Ailuropoda melanoleuca ) morphology here. The musculature and tooth characteristics are designed to support the stresses of grinding and crushing vegetation.
On occasion an active predator, the spectacled bear has several hunting techniques- principally, the bear surprises or overpowers its prey, mounts its back, and consumes the immobilised animal while still alive, pinning the prey with its weight, large paws and long claws. Alternatively, the bear pursues the prey into rough terrain, hillsides, or precipices, provoking its fall and/or death. Animal prey is usually quite small, but these bears can prey on adult deer, llama ( Lama glama ) and domestic cattle ( Bos taurus ) and horses ( Equus caballus ). Animal prey has included rabbits, mice, other rodents, birds at the nest (especially ground-nesting birds like tinamous or lapwings ( Vanellus ssp.), arthropods, and carrion.
They are occasionally accused of killing livestock, especially cattle, and raiding corn fields. Allegedly, some bears become habituated to eating cattle, but the bears are actually more likely to eat cattle as carrion; farmers may mistakenly assume the spectacled bear killed them. Spectacled bears may gather in small groups to feed in corn fields.
Reproduction
Most of the information available about the reproduction of this species has been through observation of captive animals. In captivity, mating is concentrated in between February and September, according to the latitude, and, in the wild, it has been seen how mating may occur at almost any time of the year, but activity normally peaks in April and June, at the beginning of the wet season and corresponding with the peak of fruit-ripening. The mating pair are together for one to two weeks, during which they will copulate multiple times for 12-45 minutes at a time. As in other bear species, the length of gestation is highly variable and difficult to calculate because of delayed implantation. Births occur about 6 weeks prior to the fruit-ripening period, with litter size possibly correlated to female body condition and habitat quality.
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In the wild, births usually occur in the dry season, between December and February. However, in captivity, it occurs all year within the species' distribution. The gestation period is 5.5 to 8.5 months. From one to three cubs may be born, with four being rare and two being the average. Per ex situ observations, females give birth in a den and remain there from 3 to 4 months.
The cubs are born with their eyes closed and weigh about 300 to 330 g (11 to 12 oz) each. Births usually occur in a small den and the female waits until the cubs can see and walk before she leaves with them. Maternal care may last up to 2 years. The cubs often stay with their mother for 1 year after birth. Spectacled bear cubs stay with their mother for up to a year after birth. Like other newborn bear cubs, Andean bear cubs are helpless and totally dependent on their mothers.
Predators of spectacled bear cubs may include pumas ( Puma concolor ), jaguars ( Panthera onca ), and adult male bears.
Conservation Status
The Andean bear is classified as Vulnerable on the IUCN Red List. According to the IUCN Red List, the total population size of Spectacled bears is around 2,500-10,000 mature individuals. There are estimated populations of the species in the following areas: Venezuela - 1,100-1,600 bears; Colombia - 3,000-6,000 bears; Ecuador - 1,200-2,000 bears; Peru - around 5,000 bears; Bolivia - around 3,000 bears.
Based on the current state of the Andean bear’s habitat, the fact that many threats causing reduction and degradation of Andean bear ecosystems are ongoing, and projected patterns of biodiversity shift caused by climate change, it is likely that the species will remain in the Vulnerable criteria through the year 2030. Patches large enough to sustain viable Andean bear populations have been reduced nearly 30% within the past 20 years.
Spectacled bears are threatened due to poaching and habitat loss. Habitat loss, degradation, and fragmentation are the main threats for Andean bear populations. Perhaps the most epidemic problem for the species is extensive logging and farming, which has led to habitat loss for the largely tree-dependent bears. As little as 5% of the original habitat in the Andean cloud forest remains. Agricultural expansion prompted by agrarian reforms and farming practices (such as monocultures, slash and burn, shifting cultivation, and extensive highland grazing) have considerably reduced Andean bear habitats. Shortage of natural food sources might push bears to feed on crops or livestock, increasing the conflict that usually results in poaching of individuals.
Poaching, including the pet trade, is also a significant threat for the species. The impact of this threat, however, remains to be estimated accurately. Poaching might have several reasons: trophy hunting, pet trade, religious or magical beliefs, natural products trade, and conflicts with humans. Crop raiding and feeding on livestock are main drivers of poaching. Andean Bears are often suspected of attacking cattle and raiding crops, and are killed for retaliation or in order to avoid further damages. It has been argued that attacks to cattle attributed to Andean bear are partly due to other predators. Religious or magical beliefs might be motivations for killing Andean bears, especially in places where bears are related to myths of disappearing women or children, or where bear parts are related to traditional medicine or superstitions. Their gall bladders appear to be valued in traditional Chinese medicine and can fetch a high price on the international market.
Andean bears are now protected by international trade laws, but they are still illegally hunted for their meat, fat, and body parts, or sometimes in retaliation or to protect livestock. Conservation scientists estimate that fewer than 10,000 Andean bears may remain in their native habitats, and their populations continue to decrease. Mining operations, oil exploitation, farming, and climate change all continue to impact their native habitat.
Conservation Efforts
National governments, NGOs and rural communities have made different commitments to conservation of this species along its distribution. Conservation actions in Venezuela date back to the early 1990s, and have been based mostly on environmental education at several levels and the establishment of protected areas.
To evaluate the protected status of the Andean bears researchers evaluated the percentage of their habitats included in national and protected areas in 1998. This evaluation showed that only 18.5% of the bear range was located in 58 protected areas, highlighting that many of them were small, especially those in the northern Andes. Protect high-quality habitats while maintaining connectivity between their different elevational zones. In reality, it is not possible to manage all the undisturbed habitat the bears need in the long term. Integrate hydrological criteria at a landscape scale will benefit bears and other biotic communities that associate with aquatic environments, including humans.
Andean bears possess great mythological and ritual importance for native peoples who share their range. They are a flagship species given their charismatic nature, so they can act as an umbrella for the protection of Andean biodiversity. They are a keystone species, as they play a major role in maintaining the dynamics of the cloud forest ecosystem they live in.