Collared sloth

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Collared sloth
Ring-necked sloth (Bradypus torquatus) (specimen, Barcelona Zoological Museum)

Ring-necked sloth ( Bradypus torquatus )
(specimen, Barcelona Zoological Museum)

Systematics
Order : Tooth arms (pilosa)
Subordination : Sloths (folivora)
Superfamily : Megatherioidea
Family : Three-toed sloth (Bradypodidae)
Genre : Three-toed sloth ( Bradypus )
Type : Collared sloth
Scientific name
Bradypus torquatus
Illiger , 1811

The necked sloth ( Bradypus torquatus ) is a species from the family of the three-toed sloths (Bradypodidae). It represents the largest representative of the genus Bradypus . Typical features are a uniform brown coat color and a dark mane on the neck. The main distribution area of ​​the crested sloth are the Atlantic coastal forests in eastern Brazil . There it lives largely tree-dwelling and solitary and feeds mostly on leaves, rarely on fruits and flowers. However, little research has been done into the way of life. The population of the ringed sloth is endangered by forest destruction, the species is one of the most threatened mammals in South America.

features

Habitus

The collar -necked sloth is the largest species of the three-toed sloth . Adults are between 59 and 75 cm long, the short tail reaches 4.0 to 5.4 cm in length. The females are slightly larger and weigh 5.1 to 10.1 kg, while the males are 4.6 to 9 kg. The body size also varies within different populations : individuals from low altitudes (0 to 350 m) are significantly heavier and larger than those from higher altitudes (600 to 1000 m). No outer ears can be seen on the small round head, as these remain hidden in the fur. The fur has a dense undercoat, above which there are longer and significantly coarser hairs, which give the collared sloth its uniform, light brown to brown color. Only in the shoulder area there is long, black hair that forms a kind of mane, which is usually more pronounced in males. In females, sometimes only two irregular tufts are formed, in young animals the mane is completely absent. In contrast to the other three-toed sloths, the males of the collar sloth do not have a back mark. The individual hairs are partially broken across, whereby symbiotically living algae nest in these breaks , so that the fur shimmers greenish mainly in the rainy season, depending on the incidence of light. This symbiosis partially serves as a camouflage from predators. As with all sloths, the top of the fur lies on the stomach so that the rainwater can drain away better. The arms are significantly longer than the legs. Arms and legs each end in three-pronged hands and feet, which are equipped with long, hook-shaped claws, the middle claw being enlarged. The rear foot length is about 11 cm.

Skull and dentition features

The skull is between 7.3 and 8.4 cm long and up to 4.1 cm on the cheekbone , but only 2.4 cm wide behind the eyes. There is also an elongated, narrow, downwardly directed extension at the base of the zygomatic arch , and the arch is typically not closed. The dentition has 5 teeth in the upper jaw and 4 teeth in each half in the lower jaw, a total of 18, of which the rear teeth are designed like molars . Canines and incisors do not appear. The length of the upper row of teeth is 2.3 cm.

distribution

Distribution area (green) of the collar sloth

The collar-necked sloth lives on a narrow coastal strip in eastern Brazil , but the range is fragmented. The focus is from the southern part of the state of Bahia to the state of Espírito Santo . Between 2004 and 2009, for the first time, several records of the species were found in the state of Sergipe, bordering to the north of Bahia , but these were found in highly fragmented forest remains. Originally, the distribution extended further as far as Pernambuco , but the collar sloth is no longer found there today. There is a natural biogeographical gap of almost 100 km between the Rio Mucuri and the Rio Doce in northern Espírito Santo, which may be related to the higher proportion of deciduous trees in this region. The collar sloth was reintroduced in the state of Rio de Janeiro, among others . The distribution area overlaps with the eastern habitats of the brown-throated sloth ( Bradypus variegatus ).

The preferred habitat includes the Atlantic coastal rainforests ( Mata Atlântica ), where the crested sloth occurs from sea level to altitudes around 1290 m, but mainly inhabits the lower regions up to 200 m. There it lives in tropical rainforests , but also in secondary forests and in so-called cabrucas , cocoa plantations in natural forests, with an annual rainfall of 1200 mm and more. Individual animals have also been sighted in forest fragments of only 20 hectares , for example in the state of Sergipe, but their long-term chances of survival there are rather slim. Occasionally, they also use semi-deciduous forests. The collar sloth is thus bound to dense forests. In fragmented landscapes with around 35% forest cover, the number of animals drops sharply, with less than 20% forest cover the species no longer occurs. The total distribution area is given as 90,000 km², estimates for the actually inhabited area amount to about 1000 km². The population density is about 0.09 to 1.25 individuals per hectare.

Way of life

Territorial behavior

The collar-necked sloth is a solitary animal that lives mainly arboreally in the Atlantic coastal forests. The only closer social contacts are between the mother and the offspring. The individuals live in activity areas of 0.6 to 10.8 ha, with an average size of 5.4 to 5.6 ha. Studies on three individuals over a period of 14 months showed that the activity times consisted of 60 to 80% Rest, 7 to 17% eating, 6 to 17% movement and 1 to 2% other things like grooming. The time used for eating increases in the dry season by almost double that in the rainy season . The collar-necked sloth only descends on the forest floor to get to another tree; within 24 hours an animal covers about 24 m. The time of activity of the individual populations seems to be different. Groups in the lowlands are more active at twilight and at night, while those in the highlands are more active during the day. The reason for this is likely to be the existing temperature differences between highland and lowland regions.

nutrition

The ring-necked sloth is a pure herbivore and feeds about 99% on leaves , in addition to which it also eats fruits and flowers . In the above-mentioned investigations of three individuals over a period of more than a year, 21 preferred plant species could be observed, including 16 tree and 5 liana species . Individuals only ate from 7 to 12 species, with young leaves predominating, especially during the rainy season. The most important food plants include representatives of Prunus , Ficus , Micropholis and Mandevilla , which each make up between 12.2 and 19.5% of the total amount of food. The latter also consumes the flowers and, in addition, Cecropia the fruits. Furthermore, a very selective feeding behavior of the individual animals can be demonstrated, as these only feed on a few tree species which comprise less than 4% of the total stock of all trees in a habitat and are not the most widespread. Since individual individuals of the crested sloth only use certain plant species, they are very specialized leaf-eaters, but the entire population of a region eats leaves from significantly more tree species and is therefore less selective.

Reproduction

Little is known about the reproduction of the ring-necked sloth; it has rarely been observed in the wild. The collar sloth becomes sexually mature at around three years of age. The mating season is most likely all year round, but due to the season most births fall between the end of the rainy season and over the first half of the dry season and thus in a rather low-stress phase, as temperatures are higher and the preferred food sources more frequent. This makes it likely that most matings will occur at the beginning of the dry season, given the six-month gestation period known for other three-toed sloths . The female always gives birth to a young. The length of the newborn is 20 cm, the birth weight is 300 to 350 g. The young animal spends the first few months of its life on its mother's stomach or back. The young animal eats leaves for the first time at two weeks. Weaning takes two months and can last up to four. In total, the young animal stays with the mother for eight to eleven months. The life expectancy of the ring-necked sloth in the wild is unknown; the oldest animal studied was around 12 years old and still reproductive.

Parasites and commensals

Almost all collar sloths are infested with ticks of the genus Amblyomma , often of the species Amblyomma varium . Numerous moth forms of the subfamily Chrysauginae live on and in their fur , the most common genus being Cryptoses . Studies on the closely related brown-throated sloth ( Bradypus variegatus ) revealed a symbiotic relationship between the moths, the algae in the fur and the dung of the sloth species. The sloths benefit from the moths, which release nitrogen compounds into the fur and thus also to the algae. These are in turn eaten by the sloths while grooming, which means that they receive important supplements in addition to their rather low-energy vegetable diet. The moth is also believed to offer some degree of protection from predators , the collar-necked sloth . In addition, Trichilium , a genus of beetles , parasitizes mainly in the thigh area.

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 collar sloth is a species within the genus of the three-toed sloth ( Bradypus ), to which three other species can be assigned. The three-toed sloths belong to the monotypical family of Bradypodidae today , 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 . The next related group within the recent sloths are the two-toed sloths ( Choloepus ) from the Choloepodidae family . With the sloths, the anteaters (Vermilingua) form a closer relationship, both groups together establish the order of the tooth arms (Pilosa). According to molecular genetic studies, the sloths split off from the common line with the anteaters in the late Paleocene around 58 million years ago , whereas the two genera Bradypus and Choloepus , which are still alive today, separated in the Oligocene around 30 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, when the collar -necked sloth split off from the common line of the brown-throated ( Bradypus variegatus ) and white-throated sloth ( Bradypus tridactylus ) and the pygmy sloth ( Bradypus pygmaeus ); the latter three separated in the further course of the Miocene and in the transition to the Pliocene about 12 to 5.7 million years ago. Sometimes the collar sloth is placed in its own subgenus Scaeopus , which is justified in the striking morphological differences to the other three-toed sloths. The subgenus is monotypical and therefore contains only one species. The different morphology combined with the very early splitting off of the collar- necked sloth advocates the generic independence of Scaeopus , according to individual authors .

The species itself is also considered to be monotypical. However, there are marked genetic differences between the northern populations in Bahia and the southern ones in Espírito Santo and Rio de Janeiro. These were most likely caused by the natural biogeographical gap between the Rio Mucuri and the Rio Doce in northern Espírito Santos, which does not allow gene flow . Molecular genetic findings indicate a separation of the two populations in the Lower Pleistocene between 2.5 and 1.8 million years ago. So far it is unclear whether both groups represent independent subspecies, which, however, cannot be distinguished externally. There are no known fossil recordings of the collar sloth.

The collared sloth was first described in 1811 by Johann Karl Wilhelm Illiger , but without specifying a type locality. The authorship of Illiger has been questioned in the past because he also used the scientific name Choloepus torquatus in the first description , according to which Anselme Gaëtan Desmarest would be the first to describe it with a mention of the collared sloth from 1816. However, numerous scientists now refer to Illiger. The species name torquatus is of Latin origin and means something like "banded".

Danger

Since the collar sloth is highly adapted to its habitat, it is extremely sensitive to disturbances. In particular, the destruction of the Atlantic coastal rainforests has increased dramatically since the 1980s. The areas now serve as arable land, mining areas or the expansion of human settlements. The forests today only extend over about 7% of their original range. Furthermore, especially in southern Bahia, numerous cocoa plantations have been converted into pastureland due to economic constraints. Although it is prohibited by law in Brazil, individual animals are also killed as a food resource, and crested sloths occasionally fall victim to road accidents. In the Red List of the IUCN , the species is "critically endangered" as the ( vulnerable ) out. The ring-necked sloth is one of the most critically endangered mammals in South America. One of the protective measures of the IUCN is a program to create suitable corridors, which should enable the low genetic diversity of the individual, sometimes separated populations to be increased. In addition, captured or confiscated animals are to be subjected to genetic testing in order to find suitable relocation areas. A relocation of several individuals was successful in 1994. It is also suggested that separate protective measures should be taken for the northern and southern populations to prevent genetic interbreeding of these two long-separated groups. The ring-necked sloth is present in several protected areas, including in the Poco das Antas National Park in the state of Rio de Janeiro and in the Augusto Ruschi National Park in the state of Espírito Santo .

literature

  • DP Gilmore, CP Da Costa, DPF Duarte: Sloth biology: an update on their physiological ecology, behavior and role as vectors of arthropods and arboviruses. In: Brazilian Journal of Medical and Biological Research. 34 (1), 2001, pp. 9-25.
  • Virginia Hayssen: Bradypus torquatus (Pilosa: Bradypodidae). In: Mammalian Species. 829, 2009, pp. 1-5.
  • Markus Lambertz: Notes on the original description of the maned three-toed sloth, Bradypus torquatus (Mammalia, Pilosa, Bradypodidae), by Johann Karl Wilhelm Illiger in 1811 . In: Bionomina. 6, 2013, pp. 49-51.
  • Jonathan N. Pauli: Bradypodidae (Three-toed sloths). In: Don E. Wilson, Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 8: Insectivores, Sloths and Colugos. Lynx Edicions, Barcelona 2018, pp. 118-132 (pp. 131-132) ISBN 978-84-16728-08-4 .

Individual evidence

  1. ↑ a b Bernardo B. Dias, Luis Alberto Dias dos Santos, Paula Lara-Ruiz, Camila Righetto Cassano, Laurenz Pinder, Adriano G. Chiarello: First observation on mating and reproductive seasonality in maned sloths Bradypus torquatus (Pilosa: Bradypodidae). In: Journal of Ethology. 27, pp. 97-103, doi: 10.1007 / s10164-008-0089-9 .
  2. ↑ a b c Paula Lara-Ruiz, Adriano Garcia Chiarello: Life-history traits and sexual dimorphism of the Atlantic forest maned sloth Bradypus torquatus (Xenarthra: Bradypodidae). In: Journal of Zoology. 267, 2005, pp. 63-73.
  3. ↑ a b c d e f g h i Virginia Hayssen: Bradypus torquatus (Pilosa: Bradypodidae). In: Mammalian Species. 829, 2009, pp. 1-5.
  4. ↑ a b c d e f D. P. Gilmore, CP Da Costa, DPF Duarte: Sloth biology: an update on their physiological ecology, behavior and role as vectors of arthropods and arboviruses. In: Brazilian Journal of Medical and Biological Research. 34 (1), 2001, pp. 9-25.
  5. ↑ a b c d e f Jonathan N. Pauli: Bradypodidae (Three-toed sloths). In: Don E. Wilson, Russell A. Mittermeier (eds.): Handbook of the Mammals of the World. Volume 8: Insectivores, Sloths and Colugos. Lynx Edicions, Barcelona 2018, pp. 118-132 (pp. 130-131) ISBN 978-84-16728-08-4 .
  6. ^ Renata Rocha Déda Chagas, João Pedro Souza-Alves, Leandro Jerusalinsky, Stephen F. Ferrari: New Records of Bradypus torquatus (Pilosa: Bradypodidae) from Southern Sergipe, Brazil. In: Edentata. 8-10, 2009, pp. 21-23.
  7. ^ André Hirsch, Adriano Garcia Chiarello: The endangered maned sloth (Bradypus torquatus) of the Brazilian Atlantic forest: a review and update of geographical distribution and habitat preference. In: Mammal Review. 42 (1), 2012, pp. 35-54.
  8. ^ A b c Adriano Garcia Chiarello, Nadia Moraes-Barros: Bradypus torquatus. In: Edentata. 11, 2010, pp. 119-120.
  9. ^ A b c Adriano Garcia Chiarello, Nadia Moraes-Barros: Bradypus torquatus. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.2. ( iucnredlist.org ); last accessed on January 9, 2014.
  10. ↑ Paloma Marques Santos, Larissa Lynn Bailey, Milton Cezar Ribeiro, Adriano Garcia Chiarello, Adriano Pereira Paglia: Living on the edge: Forest cover threshold effect on endangered maned sloth occurrence in Atlantic Forest. In: Biological Conservation. 240, 2019, p. 108264, doi: 10.1016 / j.biocon.2019.108264 .
  11. ^ Adriano G. Chiarello: Activity budgets and ranging patterns of the Atlantic forest maned sloth Bradypus torquatus (Xenarthra: Bradypodidae). In: Journal of Zoology. (London). 246, 1998, pp. 1-10.
  12. ^ A b Adriano Garcia Chiarello: Sloth ecology. An overview of field studies. In: Sergio F. Vizcaíno, WJ Loughry (Ed.): The Biology of the Xenarthra. University Press of Florida, 2008, pp. 269-280.
  13. ^ Adriano G. Chiarello: Diet of the Atlantic forest maned sloth Bradypus torquatus (Xenarthra: Bradypodidae). In: Journal of Zoology. (London). 246, 1998, pp. 11-19.
  14. ↑ 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. In: Proceedings of the Royal Society. B 281, 2014, p. 20133006, doi: 10.1098 / rspb.2013.3006 .
  15. ↑ a b Frédéric Delsuc, Sergio F Vizcaíno, Emmanuel JP Douzery: Influence of Tertiary paleoenvironmental changes on the diversification of South American mammals: a relaxed molecular clock study within xenarthrans. In: BMC Evolutionary Biology. 4 (11), 2004, pp. 1-13.
  16. ↑ Robert P. Anderson, Charles O. Handley, Jr: A new species of three-toed sloth (Mammalia: Xenarthra) from Panamá, with a review of the genus Bradypus. In: Proceedings of the Biological Society of Washington. 114, 2001, pp. 1-33.
  17. ↑ Timothy J. Gaudin: Phylogenetic relationships among sloths (Mammalia, Xenarthra, Tardigrada): the craniodental evidence. In: Zoological Journal of the Linnean Society. 140, 2004, pp. 255-305.
  18. ↑ Luciano Varela, P. Sebastián Tambusso, H. Gregory McDonald, Richard A. Fariña: Phylogeny, Macroevolutionary Trends and Historical Biogeography of Sloths: Insights From a Bayesian Morphological Clock Analysis. In: Systematic Biology. 68 (2), 2019, pp. 204-218.
  19. ↑ 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, Hendrik N. Poinar : Ancient mitogenomes reveal the evolutionary history and biogeography of sloths. In: Current Biology. 29 (12), 2019, pp. 2031-2042, doi: 10.1016 / j.cub.2019.05.043 .
  20. ↑ 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, Ross DE MacPhee: Palaeoproteomics resolves sloth relationships. In: Nature Ecology & Evolution. 3, 2019, pp. 1121-1130, doi: 10.1038 / s41559-019-0909-z .
  21. ↑ a b c Gillian C. Gibb, Fabien L. Condamine, Melanie Kuch, Jacob Enk, Nadia Moraes-Barros, Mariella Superina, Hendrik N. Poinar, Frédéric Delsuc: Shotgun Mitogenomics Provides a Reference Phylogenetic Framework and Timescale for Living Xenarthrans. In: Molecular Biology and Evolution. 33 (3), 2015, pp. 621–642.
  22. ↑ Nadia de Moraes-Barros, Juliana AB Silva, João Stenghel Morgante: Morphology, molecular phylogeny, and taxonomic inconsistencies in the study of Bradypus sloths (Pilosa: Bradypodidae). In: Journal of Mammalogy. 92 (1), 2011, pp. 86-100.
  23. ↑ Manuel Ruiz-García, Diego Chacón, Tinka Plese, Ingrid Schuler, Joseph Mark Shostell: Mitogenomics phylogenetic relationships of the current sloth's genera and species (Bradypodidae and Megalonychidae). In: Mitochondrial DNA Part A. 29 (2), 2018, pp. 281-299, doi: 10.1080 / 24701394.2016.1275602 .
  24. ^ A b Alfred L. Gardner: Mammals of South America, Volume 1: Marsupials, Xenarthrans, Shrews, and Bats. University of Chicago Press, 2008, ISBN 978-0-226-28240-4 , pp. 158-164.
  25. ↑ Manuel Ruiz-García, Diego Chacón, Tinka Plese, Joseph Mark Shostell: Molecular phylogenetics of Bradypus (Three-toed sloth, Pilosa: Bradypodidae, Mammalia) and phylogeography of Bradypus variegatus (Brown-throated three-toed sloth) with mitochondrial gene sequences . In: Journal of Mammalian Evolution. , 2019, doi: 10.1007 / s10914-019-09465-w .
  26. ↑ a b c Paula Lara-Ruiz, Adriano G. Chiarello, Fabrício R. Santos: Extreme population divergence and conservation implications for the rare endangered Atlantic Forest sloth, Bradypus torquatus (Pilosa: Bradypodidae). In: Biological Conservation. 141, 2008, pp. 1332-1342.
  27. ^ Adriano G. Chiarello, David J. Chivers, Clarisse Bassi, Maria Amélia F. Maciel, Leandro S. Moreira, Mariel Bazzalo: A translocation experiment for the conservation of maned sloths, Bradypus torquatus (Xenarthra, Bradypodidae). In: Biological Conservation. 118, 2004, pp. 421-430.

Web links

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