Angonoka
Encyclopedia
The angonoka tortoise is a critically endangered species of tortoise
endemic to Madagascar
. It is also known as the angonoka, ploughshare tortoise, Madagascar tortoise, or Madagascar angulated tortoise.
zoologist Léon Vaillant
, who proposed it as the species Tesudo yniphora based on the distinguished shape of the anterior part of the plastron.
The angonoka tortoise (A. yniphora) along with the radiated tortoise
(A. radiata) are the only species in the genus Astrochelys
. Astrochelys is attributed to John Edward Gray
who used the name in his 1873 book Hand-list of the specimens of shield reptiles in the British Museum. The parent family for Astrochelys is Testudinidae, the tortoise family.
The name angonoka comes from the Malagasy
word which is used as the local name of the species. The alternative common name ploughshare tortoise refers to the appearance of the gular scute of the plastron.
is highly domed and light brown in colour with prominent growth rings on each scute. The outer parts of the vertebral is a darker brown. The gular scute of the plastron projects forward between the front legs and curves upward toward the neck.
Males are larger than females, reaching a carapace length up to 17 inches (43.2 cm). Fully grown male angonoka tortoises are larger, as well as heavier, than females. The average weight of an adult male angonoka tortoise in 414.8 millimetres (16.3 in) and the average weight of one is 10.3 kilograms (22.7 lb). Females measure at a 370.1 millimetres (14.6 in) average and weigh a 8.8 kilograms (19.4 lb) average.
. The distribution is a 25 sqkm range around Baly Bay. The angonoka tortoise enjoys the seasonal rainfall patterns that help make up the tropical climate.
The Baly Bay region is made up of savanna, mangrove swamps, and dry deciduous forest. They make use of bamboo-scrub habitat which is made up of different types of shrubs, savanna grasses, bamboo, and open areas with no vegetation. The flora includes shrubbery usually under 2 metres (6.6 ft) in height, such as Bauhinia
and Terminalia
species, and Perrierbambus
madagascariensis bamboo, which forms dense thickets. The elevation of this area is under 50 metres (164 ft) above sea level.
s and carnivore
s.
It is expected to become sexually mature at at least 15 years old. The tortoise can produce one to six eggs per clutch and up to four clutches every season. The reproductive season is from January 15 to May 30. With a 71.9% fertility rate and a 54.6% hatching success rate, about 4.3 hatchlings are produced per female tortoise.
In captivity males must be separated due to aggression towards each other, including ramming, pushing, and overturning with the enlarged gular scute. The aggression is used to establish dominance.
on the IUCN Red List
. The principal threats to the species are believed to be fires started to clear land for cattle grazing, and collection for the pet trade. The tortoise has a restricted distribution, likely a result of past collection for food, the expansion of agriculture, and accompanying fires. Fires made to clear land can get out of control, turning into wildfires, which cut back more of the angonoka tortoise's habitat. Following efforts to create firebreak
s through controlled fires in savanna fringes by conservation groups, out-of-control fires have decreased, until less than 50 hectares (123.6 acre) of its habitat were burnt in 2004. The angonoka tortoise is often captured to be sold in the international pet trade. Even though there is some successful enforcement of restrictions on illegal trade, including the confiscation of the illegally obtained tortoises, they remain in incredibly high demand for the global pet trade. This is a major threat to the tortoises remaining in the wild.
In addition to its Red List listing, the angonoka tortoise is now protected under the national law of Madagascar and listed on Appendix I of CITES, prohibiting international trade in the species. For the conservation of the angonoka tortoise, the Durrell Wildlife Conservation Trust
created Project Angonoka in 1986. The Water and Forests Department, the Durrell Trust, and the World Wide Fund for Nature
(WWF) work together on this project. A captive breeding facility was established for this species in Madagascar in 1986 by the Jersey Wildlife Preservation Trust (now the Durrell Trust) in collaboration with the Water and Forests Department. In 1996, 76 tortoises—2 adult females and 74 hatchlings—were stolen from the facility, approximately half of the offspring produced to date. The project ultimately was a success, achieving 224 captive-bred juveniles out of 17 adults in December 2004. After the 1990s, Project Angonoka started ecological research on the tortoise and the development of conservation plans that involved the communities surrounding the habitat. The work with the community involved local people in making firebreaks, along with the creation of a park proposed by the community to protect the tortoise and the forests. Although all these improvements have been made, monitoring of the angonoka tortoise in the global pet trade is still needed.
Tortoise
Tortoises are a family of land-dwelling reptiles of the order of turtles . Like their marine cousins, the sea turtles, tortoises are shielded from predators by a shell. The top part of the shell is the carapace, the underside is the plastron, and the two are connected by the bridge. The tortoise...
endemic to Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
. It is also known as the angonoka, ploughshare tortoise, Madagascar tortoise, or Madagascar angulated tortoise.
Taxonomy
This species was originally described in 1885 by FrenchFrance
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
zoologist Léon Vaillant
Léon Vaillant
Léon Louis Vaillant was a French zoologist. He is most famous for his work in the areas of herpetology, malacology, and ichthyology...
, who proposed it as the species Tesudo yniphora based on the distinguished shape of the anterior part of the plastron.
The angonoka tortoise (A. yniphora) along with the radiated tortoise
Radiated Tortoise
The radiated tortoise is a species in the family Testudinidae. Although this species is native to and most abundant in southern Madagascar, it can be also be found in the rest of this island, and has been introduced to the islands of Réunion and Mauritius...
(A. radiata) are the only species in the genus Astrochelys
Astrochelys
Astrochelys is a genus of tortoises in the family Testudinidae. There are two species, both found in Madagascar and both classified as Critically Endangered on the IUCN Red List.- Species :...
. Astrochelys is attributed to John Edward Gray
John Edward Gray
John Edward Gray, FRS was a British zoologist. He was the elder brother of George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray ....
who used the name in his 1873 book Hand-list of the specimens of shield reptiles in the British Museum. The parent family for Astrochelys is Testudinidae, the tortoise family.
The name angonoka comes from the Malagasy
Malagasy language
Malagasy is the national language of Madagascar, a member of the Austronesian family of languages. Most people in Madagascar speak it as a first language as do some people of Malagasy descent elsewhere.-History:...
word which is used as the local name of the species. The alternative common name ploughshare tortoise refers to the appearance of the gular scute of the plastron.
Description
The carapaceCarapace
A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...
is highly domed and light brown in colour with prominent growth rings on each scute. The outer parts of the vertebral is a darker brown. The gular scute of the plastron projects forward between the front legs and curves upward toward the neck.
Males are larger than females, reaching a carapace length up to 17 inches (43.2 cm). Fully grown male angonoka tortoises are larger, as well as heavier, than females. The average weight of an adult male angonoka tortoise in 414.8 millimetres (16.3 in) and the average weight of one is 10.3 kilograms (22.7 lb). Females measure at a 370.1 millimetres (14.6 in) average and weigh a 8.8 kilograms (19.4 lb) average.
Distribution and habitat
In the wild this species is only found in Madagascar where it is endemic to the dry forests in the Baly Bay area of northwestern Madagascar, near the town of SoalalaSoalala
Soalala is a town and commune in western Madagascar. It belongs to the district of Soalala, which is a part of Boeny Region. The population of the commune was estimated to be approximately 15,000 in 2001 commune census....
. The distribution is a 25 sqkm range around Baly Bay. The angonoka tortoise enjoys the seasonal rainfall patterns that help make up the tropical climate.
The Baly Bay region is made up of savanna, mangrove swamps, and dry deciduous forest. They make use of bamboo-scrub habitat which is made up of different types of shrubs, savanna grasses, bamboo, and open areas with no vegetation. The flora includes shrubbery usually under 2 metres (6.6 ft) in height, such as Bauhinia
Bauhinia
Bauhinia is a genus of more than 200 species of flowering plants in the subfamily Caesalpinioideae of the large flowering plant family Fabaceae, with a pantropical distribution. The genus was named after the Bauhin brothers, Swiss-French botanists....
and Terminalia
Terminalia
Terminalia can refer to:* Terminalia , a tree genus* Terminalia , a mosquito genus* a Roman festival to the god of boundaries Terminus...
species, and Perrierbambus
Perrierbambus
Perrierbambus is a genus of bamboo. It comprises 2 species, both of which are native to Madagascar....
madagascariensis bamboo, which forms dense thickets. The elevation of this area is under 50 metres (164 ft) above sea level.
Population
The population estimate for the angonoka tortoise in the wild is about 600 individuals, ranging from 440 to 770, but is still decreasing. The tortoise is at an extremely high risk of extinction; it is thought it will become extinct in the wild in the next 10 to 15 years. It can be found in five sub-populations, two east of the and three west of the Andranomavo river. The two to the east are Beheta and Sada; the three to the west are Ambatomainty, Andrafiafaly, and Betainalika.Ecology and behaviour
The angonoka tortoise has been observed feeding on grasses found in open rocky areas of bamboo scrub. It is also known to eat shrubs, forbs, and herbs. While it has been seen eating dead bamboo leaves, it has never been observed eating living bamboo. As well as these plants, the tortoise has also been seen eating the dried feces of bushpigBushpig
The bushpig, Potamochoerus larvatus, is a member of the pig family and lives in forests, woodland, riverine vegetation and reedbeds in East and Southern Africa. Probably introduced populations are also present in Madagascar and the Comoros archipelago. Bushpigs are mainly nocturnal. There are...
s and carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
s.
It is expected to become sexually mature at at least 15 years old. The tortoise can produce one to six eggs per clutch and up to four clutches every season. The reproductive season is from January 15 to May 30. With a 71.9% fertility rate and a 54.6% hatching success rate, about 4.3 hatchlings are produced per female tortoise.
In captivity males must be separated due to aggression towards each other, including ramming, pushing, and overturning with the enlarged gular scute. The aggression is used to establish dominance.
Conservation
This species is one of the rarest land tortoises in the world, classified as Critically EndangeredCritically Endangered
Critically Endangered is the highest risk category assigned by the IUCN Red List for wild species. Critically Endangered means that a species' numbers have decreased, or will decrease, by 80% within three generations....
on the IUCN Red List
IUCN Red List
The IUCN Red List of Threatened Species , founded in 1963, is the world's most comprehensive inventory of the global conservation status of biological species. The International Union for Conservation of Nature is the world's main authority on the conservation status of species...
. The principal threats to the species are believed to be fires started to clear land for cattle grazing, and collection for the pet trade. The tortoise has a restricted distribution, likely a result of past collection for food, the expansion of agriculture, and accompanying fires. Fires made to clear land can get out of control, turning into wildfires, which cut back more of the angonoka tortoise's habitat. Following efforts to create firebreak
Firebreak
A firebreak is a gap in vegetation or other combustible material that acts as a barrier to slow or stop the progress of a bushfire or wildfire. A firebreak may occur naturally where there is a lack of vegetation or "fuel", such as a river, lake or canyon...
s through controlled fires in savanna fringes by conservation groups, out-of-control fires have decreased, until less than 50 hectares (123.6 acre) of its habitat were burnt in 2004. The angonoka tortoise is often captured to be sold in the international pet trade. Even though there is some successful enforcement of restrictions on illegal trade, including the confiscation of the illegally obtained tortoises, they remain in incredibly high demand for the global pet trade. This is a major threat to the tortoises remaining in the wild.
In addition to its Red List listing, the angonoka tortoise is now protected under the national law of Madagascar and listed on Appendix I of CITES, prohibiting international trade in the species. For the conservation of the angonoka tortoise, the Durrell Wildlife Conservation Trust
Durrell Wildlife Conservation Trust
Durrell Wildlife Conservation Trust is a conservation organisation with a mission to save species from extinction.Gerald Durrell founded the Jersey Wildlife Preservation Trust as a charitable institution in 1963 with the Dodo as its symbol...
created Project Angonoka in 1986. The Water and Forests Department, the Durrell Trust, and the World Wide Fund for Nature
World Wide Fund for Nature
The World Wide Fund for Nature is an international non-governmental organization working on issues regarding the conservation, research and restoration of the environment, formerly named the World Wildlife Fund, which remains its official name in Canada and the United States...
(WWF) work together on this project. A captive breeding facility was established for this species in Madagascar in 1986 by the Jersey Wildlife Preservation Trust (now the Durrell Trust) in collaboration with the Water and Forests Department. In 1996, 76 tortoises—2 adult females and 74 hatchlings—were stolen from the facility, approximately half of the offspring produced to date. The project ultimately was a success, achieving 224 captive-bred juveniles out of 17 adults in December 2004. After the 1990s, Project Angonoka started ecological research on the tortoise and the development of conservation plans that involved the communities surrounding the habitat. The work with the community involved local people in making firebreaks, along with the creation of a park proposed by the community to protect the tortoise and the forests. Although all these improvements have been made, monitoring of the angonoka tortoise in the global pet trade is still needed.