Spectacled bear
| Spectacled bear | ||||||||||||
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Spectacled Bear ( Tremarctos ornatus ) |
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| Tremarctos | ||||||||||||
| Gervais , 1855 | ||||||||||||
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| Tremarctos ornatus | ||||||||||||
| ( F. Cuvier , 1825) |
The spectacled bear or Andean bear ( Tremarctos ornatus ) is a species of predator from the bear family (Ursidae). It lives as the only bear in South America and systematically occupies a special position as it is the only surviving representative of the short-snouted bears (Tremarctinae). An adult male reaches a length of 190 centimeters and a weight of 130 to 175 kilograms; Females are considerably smaller, about two thirds the length of the males and weigh only around 60 to 80 kilograms. Its common name comes from the striking light color of the face, otherwise its fur is black.
Spectacled bears are endemic to the tropical Andes and upstream mountain ranges in Colombia , western Venezuela , Ecuador , Peru and Bolivia . They are omnivores , but feed mainly on plant material, especially the shoots and fruits of bromeliads and cactus plants . More rarely they prey on rodents , insects , snails and birds as well as larger mammals such as deer or unguarded domestic cattle . The bears live solitary and only form pairs during the mating season. The females give birth to their young alone and look after them for up to two years.
The spectacled bear is classified as endangered (vulnerable) by the International Union for Conservation of Nature and Natural Resources (IUCN). Its population is estimated at around 24,000 to 25,000 and is falling sharply due to the continuing loss of habitat. The extinction of the species has already been predicted on the basis of projections for the expansion of human activity in the bear habitat.
features
general characteristics
The spectacled bear is a medium-sized representative of the bears. A fully grown male animal reaches a head-torso length of 130 to 190 centimeters, a shoulder height of 70 to 90 centimeters and a weight of 130 to 175 kilograms; in exceptional cases up to 200 kilograms are possible. Females are considerably smaller and reach about 2/3 the length of the males, they weigh only around 60 to 80 kilograms. The tail is very short in both sexes with less than 10 centimeters.
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The fur of the spectacled bear is predominantly black or dark brown to red-brown in color, it is long and rough. Yellowish to creamy white bandages extend from the forehead to the cheeks and from there to the throat. In addition, a white stripe runs from the neck and forehead over the bridge of the nose. As a result, the eyes are surrounded by white drawings that resemble glasses and have given the bear its scientific name ornatus and its common German and English names ; In the English-speaking world, the bear is accordingly known as the "Spectacled Bear". These patterns are different for each animal; in some individuals they can be completely absent, others have an almost completely white snout. Compared to other bear species, they have a relatively short snout.
In their physique they show the typical bear characteristics: The trunk is stocky and strong, the tail is only a short stub. The feet each end in five clawed toes, like the other members of his family, the spectacled bear is a sole walker . The claws of the spectacled bear are short. The feet between the toes and balls of the feet are hairy and between the fingers and heels of the hand hairless. The front legs are extended as an adaptation to the sometimes arboreal way of life, i.e. climbing and living on trees.
Features of the skull and skeleton
The massive skull is characteristic of the fossil and recent species of the subfamily Tremarctinae. It is compact and rounded, and with an average length of 20.15 centimeters, it is the shortest of all recent bear species. The skull of the males is 23.1 to 26.3 centimeters in length larger than that of the females with 19.7 to 21.0 centimeters in length; it also has a well-developed crest along the lambda suture ( Sutura lambdoidea ), which females lack. The snout is very short compared to other bears. The lower jaw has a clear pit in front of the insertion of the masseter muscle , which can only be found in this form in the Tremarctinae. The zygomaticomandibularis muscle is very long, and other features of the masticatory muscles and the corresponding cranial attachments differ from those of other bear species, which are mainly seen as an adaptation to the vegetable-dominated and strongly fibrous food. The tympanic bulla is flatter than other bears, has an irregular surface and a relatively small tympanic cavity .
| 3 | · | 1 | · | 4th | · | 2 | = 42 |
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The set of teeth corresponds to the typical bear bite with three incisors , one canine , four premolars and two molars in the upper jaw as well as the same number of teeth and an additional molar in the lower jaw. The jaw is comparatively stiff and the molar areas are enlarged. In contrast to the typical bear bite, the third premolar teeth are enlarged and have blunt crowns as well as three tooth cavities and three roots. In this way, the chewing surface is enlarged, so that larger amounts of plant-based food can be chewed. The relatively small canine teeth are blade-shaped and correspond to those of the American black bear ( Ursus americanus ) and the Asiatic sun bear ( Helarctos malayanus ). The spectacled bear can also use them to tear down and eat animals.
The number of ribs is an important skeletal characteristic : unlike all other recent bears, the spectacled bear has 14 pairs of ribs instead of the usual 13 pairs. The articular cartilage of the humerus has an additional window, which is also found in the giant panda ( Ailuropoda melanolueca ) and is probably related to the lengthening of the upper arm and the enlargement of the joint. Both species also have what is known as a “false thumb” in the shape of a sesame bone on the hand, which is much larger in the giant panda. With the spectacled bear this cannot be used for grasping, but it is probably used together with the fingers to align and manipulate the plant food.
The penis bone corresponds in shape and size to that of the American black bear. It is fairly straight, curved upwards at the base and has an enlarged, thick and blunt tip.
Genetic traits
The spectacled bear has a genome of 2n = 52 chromosomes with 15 metacentric and 10 acrocentric pairs of autosomes and the two sex chromosomes . The X chromosome is large and metacentric, while the acrocentric Y chromosome is the smallest of all chromosomes.
distribution and habitat
Distribution area
Spectacled bears are the only recent bear representatives in South America. They live endemically in the tropical Andes and upstream mountain ranges in Colombia , western Venezuela , Ecuador , Peru and Bolivia . The northern border of the distribution area is formed by the Sierra de Perijá , Macizo de El Tamá and the Cordillera de Mérida in Venezuela. From there the area extends over Colombia, the eastern and western ranges of the Andes in Ecuador, the Andean regions and the desert areas of the coast of Peru to the eastern foothills of the Andes in Bolivia. The area stretches over 4,600 kilometers in length, but is only 200 to 650 kilometers wide. Historically, the distribution extended over other areas of the Andes.
There are also said to have been individual sightings in the El Darien region in Panama and northern Argentina , but this has not been scientifically confirmed and is questioned.
The height distribution of the species ranges from 200 to 4750 meters, with the deepest distribution areas in western Peru. In all countries, the most common sightings come from altitudes over 1000 meters. The preferred habitat of the spectacled bears are moist forests at an altitude of 1900 to 2350 meters; but they are also found in other habitats , including desert-like coastlines or high grasslands and scrubland.
habitat
Spectacled bears use numerous, very different habitats within their range. They live in the lowlands with little vegetation as well as in submontane and montane forest areas with seasonal and evergreen trees, in swamp areas, in the grassy areas of the Puna in the high mountains and in coastal desert areas in western Peru. Their main habitat are the damp cloud forests with rich vegetation and a rich supply of food. A survey of preferred habitats in Bolivia found that the bears use almost all of the available habitats except for the dry mountain forests. The cloud forests and the humid forests in the highlands were preferred, the humid forests in lower elevations and the humid grassland areas of the high Andes were used less frequently.
The food supply is the key factor in choosing a habitat. The spectacled bears only stay in certain habitats if suitable food such as special fruits is available. Accordingly, habitats with rich food supplies are used throughout the year. The fruiting cycles in areas with limited supply force the bears to migrate to find various food sources. Other factors influencing the choice of habitat are human habitation, the availability of hiding places and access to water. In addition to wilderness resources, spectacled bears also use agricultural land to forage and feed on crops and less often on farm animals.
Way of life
Information on the way of life of spectacled bears in the wild is comparatively rare. Observations often come from animals in captivity, further information from stories from natives in the area where the animals are distributed. The bears are usually diurnal with maximum activity in the morning and early evening. The activity times are very much dependent on the season and the region. The bears spend around 70% of their activity time eating. They mainly live on the ground, but are also skilled climbers and often stay in trees when foraging for food. There they sometimes build platforms out of broken or bent branches in order to reach fruit beyond their reach or to eat. Unlike other bears, they do not hibernate .
Spectacled bears live solitary outside of the mating season and form pairs during the mating season, but do not show any pronounced territorial behavior. Several individuals have been observed on the same food plants in areas with high levels of food, such as when certain plants are in season or in agricultural areas. They are not aggressive unless they are threatened or have young. The areas of action of the individual animals are probably relatively small and overlap strongly. On average, a spectacled bear moves in an area of around 600 meters per day, maximum daily distances are more than six kilometers. They use known paths and form paths in their territories, which they partially mark with scent marks and scratch marks.
Communication is limited to rare sounds that are mainly used between mother and young animals. The most common sound is a drawn out and loud rrr sound. The main sense is the sense of smell, while hearing and sight play a subordinate role. To expand the field of vision and smell, spectacled bears can stand on their hind legs like other bears.
Apart from humans, adult spectacled bears have no enemies; potential predators of the young are pumas ( Puma concolor ) and jaguars ( Panthera onca ) as well as adult male spectacled bears.
nutrition
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Spectacled bears are omnivores , but plants make up the main part of their diet. They consume shoots and fruits mainly from bromeliads and cacti as well as twigs and other plant material. The water-storing organs of the bromeliads and cacti play a special role in most of the distribution area; Depending on the season and the region, these account for between 15 and 90% of the bears' diet. The Puya species , which are available all year round, are a key source of food, especially in the high-altitude grasslands . In these plants, the bears remove the outer, hard and thorny layers in order to get to the soft tissue in the center of the plant. They are very picky and sometimes only use one in ten plants; the reason could be the composition of the plant material. In the forests, on the other hand, they mainly feed on Tillandsia species that grow epiphytically in the trees. They eat the basal meristem tissues and throw down the rest of the plant.
In addition to the succulents, fruits are the second important source of food. They eat fruits from trees as well as from shrubs close to the ground, especially from mulberry family (Moraceae), heather family (Ericaceae), laurel family (Lauraceae) and milkweed family (Euphorbiaceae). The availability of the fruit is very much dependent on the amount of precipitation. The bears also consume palm shoots , bamboo shoots , inflorescences of orchids and, in drier areas, cactus fruits and the soft bark of the Bombax discolor as additional plant material . The bears also eat field crops, especially maize, which can devastate large parts of a maize field.
The smallest part of the diet is made up of animal material, which mainly includes rodents , insects , snails and birds, as well as larger mammals such as deer or unguarded domestic cattle . The mountain tapir has only rarely been identified as a prey animal, although it is difficult for spectacled bears to hunt due to its flight behavior. It is assumed that the bears partly kill their prey and partly find it as carrion ; Attempts to attract people could prove that pieces of meat are very attractive. The animals sometimes stay for several days on a larger carcass.
Reproduction and development
Information about the reproduction of the spectacled bear is mainly based on observations of the animals in captivity, observations in the wild are rare or nonexistent.
The female bears are polyestrial , so they can mate and fertilize several times a year. Mating also occurs in the wild throughout the year, most commonly from March to October. For mating, the otherwise solitary animals find short-lived pairs together. During the average of one week in which males and females live together, there are repeated mating with a duration of 12 to 45 minutes each. After the mating season, the animals separate again. Mating includes non-aggressive fights and "games" between the partners; coitus is accompanied by high-pitched grunts from both partners.
In females, due to dormancy and delayed implantation of the egg in the uterus , the gestation period is longer, so that the time of birth can be seasonally adjusted. As with all bears, the actual gestation period is short, very variable and difficult to determine due to the delay in implantation. It can last a total of 160 to 260 days after mating, but the effective gestation period is only about 60 days. The births can take place all year round, the females usually give birth about six weeks before the fruit ripens, depending on the climatic conditions. A litter consists of one to four young animals, depending on the weight of the she-bear and the availability of food. The young are born in burrows and have a weight of 275 to 380 grams and a length of 25 to 35 centimeters at birth, whereby the females are usually about 30 grams lighter than the males and also grow more slowly. They are born with a complete fur, which corresponds in color to that of the old animals. The eyes are closed and open after 14 to 40 days, the first teeth break through after 25 to 35 days. At this time, the young animals also begin to run, they start to eat solid food after 80 to 95 days. The mother animals stay with them in hiding for about three to four months and give them milk for the entire first year of life. They look after them for up to 2 years until the young animals leave the mother animals.
After the young animals are weaned, it takes about four to six weeks for the dams to ovulate again and to be ready to mate again. If the young die at birth or are born as a miscarriage, the next ovulation can take place after two to three weeks.
The young animals reach sexual maturity after three to seven years, with the females ready to mate on average after four and the males after five years. The age depends on the availability of food and the weight of the animals. Females are usually around five years old when they are first born. Sexual activity in females ends after 15 to 17 years, and in males it continues until they are 28 to 30 years old. The maximum lifespan of females is around 35 and that of males 35 to 40 years.
Evolution and systematics
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Phylogenetic system of bears according to Krause et al. 2008
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The first scientific description of the spectacled bear was made in 1825 by the French naturalist Frédéric Cuvier in the seven-volume work Histoire naturelle des mammifères , written together with Étienne Geoffroy Saint-Hilaire . He assigned the species as Ursus ornatus to the then only named genus of the bear, in 1855 Paul Gervais transferred the species to his own genus Tremarctos , which he described .
The spectacled bear is the only bear species in South America and is assigned to the monotypical genus Tremarctos . Fossil is another representative of this genus known with the North American species Tremarctos floridanus . The genus Tremarctos appeared in North America in the late Miocene to early Pliocene 4.3 to 7.3 million years ago, when the genus Tremarctinae separated. The splitting of the two known Tremarctos species did not take place until the late Pleistocene to early Holocene about 0.13 million years ago. As a result, the spectacled bear is considered to be the youngest species of all recent bears in evolution. The oldest fossil remains of this bear species include finds from the Chaquil Cave in northeastern Peru, which are around 7,000 years old.
Within the bears, the genus of the subfamily of the short- nosed bears (Tremarctinae) is assigned, which also contains several extinct species such as the short- faced bears ( Arctodus simus ), which were native to North America until the end of the Pleistocene about 11,000 years ago, and the South American genus Arctotherium . The most original form is the genus Plionarctos , which was widespread in North America during the transition from Miocene to Pliocene . The Tremarctinae are contrasted with the real bears (Ursinae).
No subspecies of the spectacled bear are distinguished, although there are relatively clear differences in fur color between different populations. Genetic studies also indicate that, at least in the northern part of the distribution area, there is only a low level of genetic exchange between the subpopulations and that the genetic variability is higher. This division into subpopulations apparently goes back in part to before the time of the European conquest, so it is not exclusively a result of the more recent population losses.
Hazard and protection
Status and exposure
The spectacled bear is classified as endangered ( vulnerable ) by the International Union for Conservation of Nature and Natural Resources (IUCN) . It is assumed that the numbers of spectacled bears are continually declining due to the increasing loss of habitat of two to four percent per year due to clearing and conversion into agricultural land. This trend will continue in the near future. Concrete figures for the spectacled bear population are not available; information is usually based on projections and estimates. Worldwide, a population of around 24,000 to 25,000 animals is assumed, with the largest populations in Peru and Colombia with around 6,000 animals each. In Ecuador, the estimates are between 1500 and 3600 animals and in Venezuela between 1100 and 1500 animals.
The loss of habitat is primarily based on an increasing conversion of habitats into agriculturally used areas and an increase in human settlement. It consists of the direct transformation and destruction of habitats as well as islanding and fragmentation through transformed areas, settlements and infrastructure, especially roads. A particularly large expansion of less sustainable types of agricultural use such as monocultures , slash and burn and extensive highland livestock farming with large land requirements accelerates the decline in potential habitats for spectacled bears. In Venezuela in particular, large parts of the bear habitat were lost as a result; from 1990 to 2005 this is estimated to be 0.5% of the area. A further decline is due to the increasing development of ore deposits and oil production areas as well as the expansion of the industrial infrastructure in the form of dams, mines, gas and power lines. The cultivation of drug plants, the establishment of guerrilla forces and the associated problems for the stability of the administration also create problems for active bear protection.
The population killing of the bears plays an important role in the population decline. One of the main reasons for this is that they have the reputation of “cattle killers” and devastate corn fields while foraging. It is estimated that around 200 bears are killed each year in the northern Andes, mostly by farmers. The bear is also hunted for its meat and fur, and in Peru parts of the bears are believed to have medical abilities. Trade bans could not prevent international trade to Asia either. Young bears are caught for the pet market.
On the basis of projections of the spread of human activity in the bear habitat, the further dramatic decline of the species was predicted in perspective, according to estimates the spectacled bear will meet the IUCN criteria for threatened species in 2030.
Protective measures
The status of the spectacled bear has been observed since 1973, since then the species has been listed as endangered by the IUCN. In 1977 it was included in Appendix I of the Washington Convention on International Trade in Endangered Species of Wild Fauna and Flora and is accordingly under international protection. In all states in which the bear is found, there is a hunting ban, which is difficult or impossible to enforce.
The creation of protected areas can protect parts of the population, but the greater part of the total population remains at risk. A total of 58 protected areas were set up in the species' distribution area, but habitat conversion can also progress within the protected areas due to inadequate controls. Above all, research and education projects are intended to increase knowledge about the species, educate the population about the animals and promote the protection of bears. Individual scientists and conservationists such as Edgardo Mondolfi and Bernard Peyton as well as the Grupo de Especialistas del Oso Frontino , founded in 1980, are active here and bundle the activities to protect the bears. At the same time, the bear is being established by nature conservation groups and zoological gardens as a national symbol and "flagship" of species protection in the Andes. Breeding and reintroduction projects have been undertaken in Ecuador.
supporting documents
- ↑ a b c d e f g h “General Description.” In: Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; Pp. 85-87.
- ↑ a b c d e f g h i D.L. Garshelis: Family Ursidae (Bears). (448-497). In: Wilson, DE, Mittermeier, RA, (Eds.). Handbook of the Mammals of the World. Volume 1: Carnivores. Lynx Edicions, 2009, ISBN 978-84-96553-49-1 ; P. 488
- ↑ a b c d e “Form and Function.” In: Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; Pp. 85-87.
- ↑ LeeAnn Bies: Tremarctos ornatus in the Animal Diversity Net. Retrieved April 30, 2012.
- ^ A b "Genetics." In: Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; Pp. 91-92.
- ↑ a b c d e f Tremarctos ornatus in the IUCN Red List of Threatened Species 2011.2. Posted by: I. Goldstein, X. Velez-Liendo, S. Paisley, DL Garshelis (IUCN SSC Bear Specialist Group), 2008. Retrieved April 29, 2012.
- ↑ a b c d "Distribution." In: Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; P. 94.
- ↑ a b c d "Habitat Use." In: Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; Pp. 94-96.
- ↑ B. Ríos-Uzeda, H. Gómez, RB Wallace: Habitat preferences of the Andean bear (Tremarctos ornatus) in the Bolivian Andes. Journal of Zoology 268 (3), 2006; Pp. 271-278. doi : 10.1111 / j.1469-7998.2005.00013.x
- ↑ a b c "Behavior." In: Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; Pp. 99-104.
- ^ Bernard Peyton: Spectacled Bear Conservation Action Plan. In: C. Servheen, S. Herrero, B. Peyton: Bears: Status Survey and Conservation Action Plan. IUCN / SSC Bear and Polar Bear Specialist Groups, IUCN, Gland, Switzerland, and Cambridge, UK, 1999; Pp. 157-198. ( Full text ; PDF; 12.3 MB)
- ↑ Armando Castellano: Do Andean bears attack mountain tapirs? International Bear News 20, 2011, pp. 41-42
- ↑ Abelardo Rodriguez, Ruben Gomez, Angelica Moreno, Carlos Cuellar and Diego J. Lizcano: Record of a mountain tapir attacked by an Andean bear on a camera trap. Tapir Conservation 23 (32), 2014, pp. 25-26
- ↑ a b c d e f g "Reproduction." In: Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; Pp. 92-94.
- ↑ a b Johannes Krause et al. : Mitochondrial genomes reveal an explosive radiation of extinct and extant bears near the Miocene-Pliocene boundary. BMC Evolutionary Biology 2008, doi : 10.1186 / 1471-2148-8-220
- ↑ a b Don E. Wilson & DeeAnn M. Reeder (eds.): Tremarctos ornatus in Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed).
- ^ Tremarctos in the Paleobiology Database.
- ^ "Evolution, Phylogeny and Taxonomy." In: Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; Pp. 90-91.
- ↑ Marcelo Stucchi, Rodolfo Salas-Gismondi, Patrice Baby, Jean-Loup Guyot and Bruce J. Shockey: A 6,000+ year-old specimen of a spectacled bear from an Andean cave in Peru. Ursus 20 (1), 2009, pp. 63-68
- ↑ Leopoldo H. Soibelzon and Blaine W. Schubert: The Largest Known Bear, arctotherium angustidens, from the Early Pleistocene Pampean region of Argentina: With a Discussion of Size and Diet trends Bears. Journal of Paleontology, 85 (1), 2011, pp. 69-75
- ↑ a b c d e f g "Status and Conservation." In: Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; Pp. 104-109.
- ^ Sánchez-Mercado, A .; Ferrer-Paris, JR; Yerena, E .; García-Rangel, S .; Rodríguez-Clark, KM: Factors affecting poaching risk to Vulnerable Andean bears Tremarctos ornatus in the Cordillera de Mérida, Venezuela: space, parks and people . In: Oryx . 42, No. 3, 2008, pp. 437-447. doi : 10.1017 / S0030605308006996 .
- ↑ Marcel Cardillo, Andy Purvis, Wes Sechrest, John L. Gittleman, Jon Bielby, Georgina Mace : Human Population Density and Extinction Risk in the World's Carnivores. PLoS Biology 2 (7), 2004: e197. doi : 10.1371 / journal.pbio.0020197 ; the forecasts are shown in Figure 1.
literature
- DL Garshelis: Family Ursidae (Bears). In: Wilson, DE, Mittermeier, RA, (Ed.): Handbook of the Mammals of the World. Volume 1: Carnivores. Lynx Edicions, 2009, ISBN 978-84-96553-49-1 , pp. 448-497.
- Shaenandhoa García-Rangel: Andean bear Tremarctos ornatus natural history and conservation. Mammal Review 42 (2), 2012; Pp. 85-119. doi : 10.1111 / j.1365-2907.2011.00207.x
- Ronald M. Nowak: Walker's Mammals of the World . Johns Hopkins University Press, 1999, ISBN 0-8018-5789-9 .
- Bernard Peyton: Spectacled Bear Conservation Action Plan. In: C. Servheen, S. Herrero, B. Peyton: Bears: Status Survey and Conservation Action Plan. IUCN / SSC Bear and Polar Bear Specialist Groups, IUCN, Gland, Switzerland, and Cambridge, UK, 1999; Pp. 157-198. ( Full text ; PDF; 12.3 MB)
Web links
- Tremarctos ornatus inthe IUCN Red List of Threatened Species 2011.2. Posted by: I. Goldstein, X. Velez-Liendo, S. Paisley, DL Garshelis (IUCN SSC Bear Specialist Group), 2008. Retrieved April 29, 2012.
- LeeAnn Bies: Tremarctos ornatus in the Animal Diversity Net. Retrieved April 30, 2012.
