White-throated sloth

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White-throated sloth
White-throated sloth with young (Bradypus tridactylus), specimen

White-throated sloth with young (Bradypus tridactylus), specimen

Systematics
Order : Tooth arms (pilosa)
Subordination : Sloths (folivora)
Superfamily : Megatherioidea
Family : Three-toed sloth (Bradypodidae)
Genre : Three-toed sloth ( Bradypus )
Type : White-throated sloth
Scientific name
Bradypus tridactylus
Linnaeus , 1758

The pale-throated sloth or Ai ( Bradypus tridactylus sometimes only -) Three-toed Sloth called - is a mammal from the family of three-toed sloth (Bradypodidae). It is mainly native to northeastern South America in the area of ​​the Guiana Shield and inhabits tropical rainforests of the low and highlands there. In addition to the dark, speckled, gray fur pattern, a yellowish tinted face is typical. As a predominantly solitary tree dweller, the white-throated sloth feeds mainly on leaves. The way of life has not yet been adequately researched. The sloth species was first described in 1758. The entire population has so far been considered not endangered.

description

Habitus

The white-throated sloth has a head-trunk length of 45 and 76 cm, the rudimentary tail is between 2.2 and 11 cm long. The weight averages 4.6 kg, but varies between 3.6 and 6.5 kg. Females are only slightly larger than males; after examining 500 individuals in French Guiana , the two sexes only differ by 0.8 cm in average body length. The head is small and rounded and has ears a maximum of 2 cm long, which are not visible from the outside but are hidden in the fur. The face has a yellowish tint, as does the throat patch, to which the sloth species owes its common name . The body fur has a dark gray base tint and is covered with tight, black spots on the shoulders, back and hips. Males are also characterized by an orange-yellow spot with a black central stripe on the back. The fur consists of a short and dense undercoat of up to 2.5 cm long and overlying almost twice as long hair. The individual long hair partially form transverse fractures from where often symbiotically living algae settle so that the skin especially in the rainy season , sometimes depending on the light, gets a greenish hue. This symbiosis apparently serves in part to camouflage from predators. As with all sloths, the head of the fur lies on the stomach so that the rainwater can drain off better. The arms are significantly longer than the legs. They each end in three toes, which have strong, hook-shaped claws, the middle one being enlarged. The entire rear foot becomes up to 11.6 cm long.

Skull and dentition features

Skull of the white-throated sloth ( Museum Wiesbaden collection )

The length of the skull varies between 7 and 7.7 cm, the width at the cheekbones reaches a maximum of 4.7 cm, but only 2.5 cm behind the eyes. Furthermore, the zygomatic arch is typically not closed, and there is also an elongated, narrow, downwardly directed extension at the front attachment. Half of the set of teeth has 5 teeth in the upper jaw and 4 teeth in the lower jaw, a total of 18. The rear ones are designed like molars , the front ones are rather small. Canine and incisors are not developed. The length of the upper row of teeth is up to 2.6 cm.

Vocalizations

The only known utterance of the white-throated sloth is an ai or ai-ai . This whistling sound is described as being similar to that of birds or cicadas .

distribution

Distribution area (red-brown) of the white-throated sloth

The white-throated sloth occurs in northeastern South America in the area of ​​the Guiana Shield . Its main distribution area includes eastern Venezuela , large parts of French Guyanas , Guiana and Surinam as well as northeastern Brazil . It extends from the Orinoco delta to the south to the Amazon , from its estuary to the east of the Rio Negro . In the Amazon, the distribution area overlaps with that of the brown-throated sloth ( Bradypus variegatus ); both species of sloth were often confused with each other in the past. Due to similar landscape conditions, the white-throated sloth would also be possible in eastern Colombia , but it has not yet been detected there. The white-throated sloth lives in the tropical rainforests of the low and highlands and can also be found on the plateau of the Tepuis . The total size of the distribution area is given as 1 million square kilometers. The sloth species is quite common regionally, but with varying population density . On the Sinnamary River in French Guiana, for example, it reaches a size of 1.7 individuals per square kilometer, in swampy areas it can take up to 9 individuals in the same area. Around Cayenne , however, 3 to 6 individuals per hectare are assumed in adult secondary forests (this corresponds to 300 to 600 individuals per square kilometer). In contrast, in a forest area within the city limits of Paramaribo in Suriname there was again a population density of 20.1 animals per hectare. The population density in the Amazon region is also fluctuating. During investigations along the river banks, only 0.02 individuals per 10 km of river length could be observed, in the vicinity of Manaus , however, experts assume an individual density of 2.21 per hectare.

Way of life

Territorial behavior

White-throated sloth in the branches

The white-throated sloth is generally seen relatively rarely. It is a predominantly loner, males and females only meet to mate and the only closer social contacts exist between the mother and the offspring. Aggressive behavior usually takes place between male animals and is then carried out with the long claws, less by biting. The species lives largely in trees ( arboreal ), due to its fur color it is well camouflaged in the leafy forest. Individual individuals use activity areas from 1.4 to 3.6 hectares in size. Most of the day, around 18.5 to 20 hours, an animal spends sleeping. Sleep is interrupted by several phases of activity, with a longer rest phase taking place during the first half of the day. When sleeping, it prefers branches, sitting on the horizontal branch, enclosing the trunk with its hind legs and placing its arms around its body and its head lowered on its chest. Sometimes it is sunbathing stretched out high up in the treetops. The white-throated sloth only enters the forest floor to get to another tree or to drain its feces . For the latter, it sometimes digs small holes with its tail in the ground. In principle, the movements are rather slow and reach speeds of 0.25 to 0.35 km per hour, but an animal can cover a distance of several kilometers within a month. In addition, the white-throated sloth is an excellent swimmer and crosses rivers on its hikes. It paddles with its forearms, with the head looking three-quarters out of the water.

nutrition

There are only a few observations from the wild about the eating habits of the white-throated sloth. It is a pure herbivore and mainly consumes leaves . While eating, an animal hangs from a branch, the food is either impaled with the claws of the front legs or plucked directly with the mouth. Food is often consumed in the morning or in the afternoon. Preferred food plants are predominantly representatives of the genus Clitoria and ant trees, which each make up around 40 and 17% of the amount of food consumed. Trees from the Ceiba genus are also used , as are Elizabetha from the legume group and Hevea from the milkweed group . In addition, the consumption of leaves of the legume Parkia could also be observed.

Reproduction

The white-throated sloth becomes sexually mature at three years of age. The mating season is year round, but most births are seasonally limited and fall during the end of the rainy season and the beginning of the dry season . After mating, which also takes place in the trees, the sexes separate again. The gestation period is about six months (sometimes only 106 days are given), the female then gives birth to a young. The birth weight is 160 to 290 g and the body length 14 to 18 cm. The young animal is covered with a soft, brown-gray fur that appears spotted with white on the back. The face is yellowish and there is a black stripe on the eyes. The young animal spends the first few months of its life on its mother's stomach or back. From the third week onwards it is given pre-chewed food before it starts to eat leaves on its own after five weeks. Weaning ends after five months. The life expectancy of the white-throated sloth in the wild is unknown.

Predators and enemy behavior

The long-tailed cat is one of the white-throated sloth's predators

The predators include larger and smaller cats such as the jaguar and the long-tailed cat . They also include snakes such as the anacondas and larger birds of prey such as the harpy . Most of the time an animal remains still in the presence of a predator and is well camouflaged by its color. However, this approach is only partially successful.

Parasites and commensals

The external parasites ( ectoparasites ) are mainly ticks of the genus Amblyomma and mites of various genera, such as Edentalges , Lobalges and Psoralges . There are also mosquitoes of the genus Aedes . The infestation is very high and, according to studies, affects around 99% of all individuals in Manaus with an average of 33 ticks per animal. In addition, numerous live moth forms in the skin, often are here Cryptoses and Bradypodicola whose larvae from manure to feed the white-throated sloth. Based on studies on the closely related brown-throated sloth ( Bradypus variegatus ), a symbiotic relationship between the moths, the algae in the fur and the dung of the sloth species was determined. The sloths benefit from the moths, which release nitrogen compounds into the fur and thus to the algae, which in turn are eaten by the sloths. This gives them important additives for their rather low-energy leafy diet. Furthermore, beetles such as Trichillum on the elbows and knees and uroxys have been found in the fur, whose larvae also live on the dung of the white-throated sloth. The complex network of relationships between dung, white-throated sloths and beetles also includes the mites of the genus Macrocheles . Internal parasites are protozoa such as Endotrypanum and Pneumocystis as well as the single-cell Trypanosoma .

Systematics

Internal systematics of recent sloths according to Delsuc et al. 2004
  Pilosa  

 Vermilingua (anteaters) 


  Folivora (sloths)  
  Choloepodidae  

 Choloepus (two-toed sloth)


  Bradypodidae  

 Bradypus (three-toed sloth)




Template: Klade / Maintenance / Style

The white-throated sloth is a species of mammal from the genus of the three-toed sloth ( Bradypus ), to which three other species are included. The three-toed sloths form the monotypical family of the Bradypodidae , which, within the suborder of the sloths (Folivora), either faces all other groups of sloths as a sister group according to their skeletal anatomical characteristics or is assigned to the superfamily of the Megatherioidea according to molecular genetic studies and protein analyzes . Within today's sloths, the two-toed sloths ( Choloepus ) from the Choloepodidae family represent the closest related group. Together with the anteaters (Vermilingua), in turn, the sloths form the closer relatives of the tooth arms (Pilosa), an order within the secondary articulated animals (Xenarthra) . Molecular genetic studies have shown that the sloths split off from the common line with the anteaters in the late Paleocene around 58 million years ago. The two genera Bradypus and Choloepus , which are still alive today, separated in the Oligocene around 29 million years ago.

Internal systematics of the genus Bradypus according to Gibb et al. 2015
  Bradypus  

 Bradypus torquatus


   

 Bradypus pygmaeus


   

 Bradypus tridactylus


   

 Bradypus variegatus





Template: Klade / Maintenance / Style

The splitting of the genus Bradypus began very early. In the Lower Miocene, 19 million years ago, the collar sloth ( Bradypus torquatus ) separated from the common line of the white-throated and brown-throated sloth ( B. variegatus ) and the pygmy sloth ( B. pygmaeus ); the latter three diversified in the further course of the Miocene and in the transition to the Pliocene 12 to 5.7 million years ago. Subspecies of the white-throated sloth are not differentiated, the species is therefore considered to be monotypical. Fossil finds are not yet known.

The first description of the white-throated sloth was made by Linnaeus in 1758, he was then, however, also ordered the Actual two-toed sloth ( Choloepus didactylus ) in the genus Bradypus and differed both types based on the number of fingers of the forefeet. As the type locality he gave Americae meridionalis arboribus , it was not until 1911 that Oldfield Thomas established Surinam as the actual type locality. For a long time the white-throated sloth was confused with the brown-throated sloth, so that numerous descriptions in historical and partly also in more recent times apply to the latter species, this is especially true for regions where the white-throated sloth does not occur. Numerous museum exhibits were also partially incorrectly assigned. The species name tridactylus is of Latin origin and means something like "three toed", so it refers to the characteristic, three-pointed front feet.

Danger

There are no known major threats to the white-throated sloth. It is rarely hunted in French Guiana , but it is the second most common victim of road kills among all articulated animals . Individual animals are kept as pets by members of the Wayapi indigenous people . Due to the large distribution and the sometimes quite high population density, the species is listed in the IUCN Red List as "not endangered" ( least concern ). It can be found in several nature reserves, such as the Saracá Taquera National Forest in Brazil and the Guiana National Park in French Guiana.

literature

  • DP Gilmore, CP Da Costa and DPF Duarte: Sloth biology: an update on their physiological ecology, behavior and role as vectors of arthropods and arboviruses. Brazilian Journal of Medical and Biological Research 34 (1), 2001, pp. 9-25.
  • Virginia Hayssen: Bradypus tridactyla (Pilosa: Bradypodidae). Mammalian Species 839, 2009, pp. 1-9.
  • Jonathan N. Pauli: Bradypodidae (Three-toed sloths). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 8: Insectivores, Sloths and Colugos. Lynx Edicions, Barcelona 2018, pp. 118-132 (p. 131) ISBN 978-84-16728-08-4 .

Individual evidence

  1. ↑ a b C. Richard-Hansen, J.-C. Vié, N. Vidal and J. Kéravec: Body measurements on 40 species of mammals from French Guiana. Journal of Zoology 247, 1999, pp. 419-428
  2. ↑ a b c d e f g h i j k Virginia Hayssen: Bradypus tridactyla (Pilosa: Bradypodidae). Mammalian Species 839, 2009, pp. 1-9
  3. ↑ a b c D. P. Gilmore, CP Da Costa and DPF Duarte: Sloth biology: an update on their physiological ecology, behavior and role as vectors of arthropods and arboviruses. Brazilian Journal of Medical and Biological Research 34 (1), 2001, pp. 9-25
  4. ↑ a b c d e Jonathan N. Pauli: Bradypodidae (Three-toed sloths). In: Don E. Wilson and Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 8: Insectivores, Sloths and Colugos. Lynx Edicions, Barcelona 2018, pp. 118-132 (p. 131) ISBN 978-84-16728-08-4
  5. ↑ a b Nadia de Moraes-Barros, Ana Paula Giorgi, Sofia Silva and João Stenghel Morgante: Reevaluation of the Geographical Distribution of Bradypus tridactylus Linnaeus, 1758 and B. variegatus Schinz, 1825. Edentata 11 (1), 2010, p. 53 -61
  6. ↑ Erica Taube, Jean-Christophe Vié, Pascal Fournier and Christophe Genty: Distribution of Two Sympatric Species of Sloths (Choloepus didactylus and Bradypus tridacfylus) along the Sinnamary River, French Guiana. Biotropica 31 (4), 1999, pp. 686-691
  7. ↑ a b c François Catzeflis and Benoit de Thoisy: Xenarthrans in French Guiana: a letter overview of Their distribution and conservation status. Edentata 13, 2012, pp. 29-37
  8. ↑ Monique Pool, Ruby Boateng, Ann-Marie Ako-Adounvo, Rachelle Allen-McFarlane, Diana Elizondo, Henri Paturault, Haifa Alhawas and Georgee Middendorf: Sloths in the city: unexpectedly high density of pale-throated three-toed sloths (Bradypus tridactylus ) found in an urban forest patch in Paramaribo, Suriname. Edentata 17, 2016, pp. 25-33
  9. ↑ a b Juliana Laufer, Joyce A. Amador, Paula C. Conceição, Darren Norris and Fernanda Michalski: Use of boat surveys to provide complementary data on the ecology of Bradypus tridactylus (Pilosa: Bradypodidae) from northern Amazonia. Edentata 13, 2012, pp. 56-60
  10. ^ A b Adriano G. Chiarello and Nadia de Moraes-Barros: Bradypus tridactyla. Edentata 11 (2), 2010, p. 122
  11. ^ A b Adriano Garcia Chiarello: Sloth ecology. An overview of field studies. In: Sergio F. Vizcaíno and WJ Loughry (eds.): The Biology of the Xenarthra. University Press of Florida, 2008, pp. 269-280
  12. ^ Alberto Galvao de Moura Filho, Sara EspeHuggins and Salustiano Gomes Lines: Sleep and awaking in the Three-toed Sloth, Bradypus tridactylus. Comparative Biochemistry and Physiology 76A (2), 1983, pp. 345-355
  13. ^ Alfred L. Gardner: Mammals of South America, Volume 1: Marsupials, Xenarthrans, Shrews, and Bats. University of Chicago Press, 2008, pp. 158-164 ISBN 0-226-28240-6 , 9780226282404
  14. ^ Paula Lara-Ruiz and Adriano Garcia Chiarello: Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus (Xenarthra: Bradypodidae). Journal of Zoology 267, 2005, pp. 63-73
  15. ↑ Erica Taube, Joël Keravec, Jean-Christophe Vié and Jean-Marc Duplantier: Reproductive biology and postnatal development in sloths, Bradypus and Choloepus: review with original data from the field (French Guiana) and from captivity. Mammal Review 31 (3), 2001, pp. 173-188
  16. ↑ Jonathan N. Pauli, Jorge E. Mendoza, Shawn A. Steffan, Cayelan C. Carey, Paul J. Weimer and M. Zachariah Peery: A syndrome of mutualism reinforces the lifestyle of a sloth. Proceedings of the Royal Society B 281, 2014, p. 20133006, doi: 10.1098 / rspb.2013.3006
  17. ↑ a b Frédéric Delsuc, Sergio F Vizcaíno and Emmanuel JP Douzery: Influence of Tertiary paleoenvironmental changes on the diversification of South American mammals: a relaxed molecular clock study within xenarthrans. BMC Evolutionary Biology 4 (11), 2004, pp. 1-13
  18. ↑ Robert P. Anderson and Charles O. Handley, Jr: A new species of three-toed sloth (Mammalia: Xenarthra) from Panamá, with a review of the genus Bradypus. Proceedings of the Biological Society of Washington 114, 2001, pp. 1-33
  19. ↑ Timothy J. Gaudin: Phylogenetic relationships among sloths (Mammalia, Xenarthra, Tardigrada): the craniodental evidence. Zoological Journal of the Linnean Society 140, 2004, pp. 255-305
  20. ↑ Luciano Varela, P. Sebastián Tambusso, H. Gregory McDonald and Richard A. Fariña: Phylogeny, Macroevolutionary Trends and Historical Biogeography of Sloths: Insights From a Bayesian Morphological Clock Analysis. Systematic Biology 68 (2), 2019, pp. 204-218
  21. ↑ Frédéric Delsuc, Melanie Kuch, Gillian C. Gibb, Emil Karpinski, Dirk Hackenberger, Paul Szpak, Jorge G. Martínez, Jim I. Mead, H. Gregory McDonald, Ross DE MacPhee, Guillaume Billet, Lionel Hautier and Hendrik N. Poinar : Ancient mitogenomes reveal the evolutionary history and biogeography of sloths. Current Biology 29 (12), 2019, pp. 2031-2042, doi: 10.1016 / j.cub.2019.05.043
  22. ↑ Samantha Presslee, Graham J. Slater, François Pujos, Analía M. Forasiepi, Roman Fischer, Kelly Molloy, Meaghan Mackie, Jesper V. Olsen, Alejandro Kramarz, Matías Taglioretti, Fernando Scaglia, Maximiliano Lezcano, José Luis Lanata, John Southon, Robert Feranec, Jonathan Bloch, Adam Hajduk, Fabiana M. Martin, Rodolfo Salas Gismondi, Marcelo Reguero, Christian de Muizon, Alex Greenwood, Brian T. Chait, Kirsty Penkman, Matthew Collins and Ross DE MacPhee: Palaeoproteomics resolves sloth relationships. Nature Ecology & Evolution 3, 2019, pp. 1121-1130, doi: 10.1038 / s41559-019-0909-z
  23. ↑ a b c Gillian C. Gibb, Fabien L. Condamine, Melanie Kuch, Jacob Enk, Nadia Moraes-Barros, Mariella Superina, Hendrik N. Poinar and Frédéric Delsuc: Shotgun Mitogenomics Provides a Reference Phylogenetic Framework and Timescale for Living Xenarthrans. Molecular Biology and Evolution 33 (3), 2015, pp. 621-642
  24. ^ A b Nadia de Moraes-Barros, Juliana AB Silva and João Stenghel Morgante: Morphology, molecular phylogeny, and taxonomic inconsistencies in the study of Bradypus sloths (Pilosa: Bradypodidae). Journal of Mammalogy 92 (1), 2011, pp. 86-100
  25. ↑ Manuel Ruiz-García, Diego Chacón, Tinka Plese, Ingrid Schuler and Joseph Mark Shostell: Mitogenomics phylogenetic relationships of the current sloth's genera and species (Bradypodidae and Megalonychidae). Mitochondrial DNA Part A 29 (2), 2018, pp. 281-299, doi: 10.1080 / 24701394.2016.1275602
  26. ↑ Oldfield Thomas: The mammals of the tenth edition of Linnaeus; an attempt to fix the types of the genera and the exact bases and localities of the species. Proceedings of the Zoological Society of London 1911, pp. 120-158
  27. ^ Adriano G. Chiarello and Nadia de Moraes-Barros: Bradypus tridactyla. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. ( [1] ); last accessed on January 23, 2014
  28. ↑ Leonardo de Carvalho Oliveira, Sylvia Miscow Mendel, Diogo Loretto, José de Sousa, Silva Júnior and Geraldo Wilson Fernandes: Edentates of the Saracá-Taquera National Forest, Pará, Brazil. Edentata 7, 2006, pp. 3-7

Web links

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