Guyana croissants

Guyana croissants
	Guyana squirrel ( Sciurus aestuans )
Systematics
Subordination :	Squirrel relatives (Sciuromorpha)
Family :	Squirrel (Sciuridae)
Subfamily :	Tree squirrel and flying squirrel (Sciurinae)
Tribe :	Tree squirrel (Sciurini)
Genre :	Red squirrel ( Sciurus )
Type :	Guyana croissants
Scientific name
	Sciurus aestuans
	Linnaeus , 1766

The Guyana squirrel ( Sciurus aestuans ) is a species of squirrel from the genus of squirrels ( Sciurus ). It occurs in large parts of South America from southern Brazil and the far north from Argentina to Venezuela and Colombia .

features

The Guyana squirrel reaches a head-trunk length of about 16.0 to 18.6 centimeters, plus a tail that is about 16.3 to 25.0 centimeters long. The weight of the animals ranges from about 160 to 380 grams. The back fur of the animals is olive to gray in color, interspersed with brown and yellow mottling. The belly is white or creamy white to sandy or yellowish. The tail corresponds to the color of the back on the upper side, it is a bit redder on the underside. The animals have a pale yellowish-brown eye ring around their eyes, and there is often a pale, sandy-colored postauricular spot behind the ears ("behind-the-ear spot"). Both albinism and melanism occur but are rare.

distribution

The Guyana squirrel occurs in large parts of South America from southern Brazil and the far north from Argentina to Venezuela and Colombia. In addition to the states mentioned, it can also be found in French Guiana , Guyana , Suriname and the far east of Bolivia .

Way of life

The Guyana squirrel lives mainly in tropical rainforest areas as well as in swamp regions and wet forests, but also in gallery forests on the Atlantic coast, secondary forests and in gardens, plantations and also in urban parks. The animals are diurnal and live on trees, but occasionally come to the ground to look for food. They occur in all tree layers, but prefer medium heights of five to twelve meters. They live as loners, although there are no exclusive territories and the territories of the individual animals strongly overlap. The average territory of the males is 6.5 hectares, about twice as large as that of the females (3.1 hectares), but after mating in winter the roaming areas become smaller. Guyana squirrels feed primarily on seeds and fruits from various tropical tree species and shrubbery. In addition, mushrooms are often used as a source of food in autumn and winter. The animals develop a pronounced skill in handling the various fruits of the palm family, which they learn from the adult animals. They are important seed dispersers in their area of distribution, as they build up supplies in autumn and winter; some of these can be in the branches of the trees at a height of 30 meters. In some regions with very strong forest fragmentation , especially in southeastern Brazil, they represent the most important users of seeds for various plant species with up to 96% of the use. The animals communicate with each other via a rich repertoire of calls, including high-frequency alarm calls, chatter, individual high-pitched ones Screams and drawn out howls. If they are startled by a potential danger, they run up the trees, chattering and shouting, and hide in the branches.

Guyana croissants on the ground

The nests ( Kobel ) are created from branches and leaves in the branches of the trees. The animals have two reproductive phases per year, mating takes place in late autumn and early winter and in late spring. The females are pregnant in winter as well as in summer and give birth to the young in spring and autumn.

The predators of the Guyana squirrels are likely numerous predatory predators that live in the forest, such as cats , raccoons , martens , dogs , primates , snakes and lizards . The ocelot ( Leopardus pardalis ) and capuchin monkeys (genus Cebus ) are documented.

Systematics

The Guyana squirrel is classified as an independent species within the genus of squirrels ( Sciurus ), which consists of almost 30 species. The first scientific description comes from Carl von Linné from 1766, who described the species in his 12th edition of the Systema naturae using individuals from Surinam .

Within the species, ten subspecies are distinguished together with the nominate form :

Sciurus aestuans aestuans : nominate form; occurs north of the Amazon in Brazil, Colombia, Venezuela, Guyana, French Guyana and Suriname. In this form, the postauricular spots are whitish and the dorsal fur and feet are washed in reddish.
Sciurus aestuans alphonsei : on the northern coast of Brazil. The back color is pale yellow, the ventral side is gray.
Sciurus aestuans garbei : In the Brazilian states of Espírito Santo and Bahia . In this form, the back fur is olive to chestnut brown, the belly is orange to ocher. The throat is pale.
Sciurus aestuans georgihernandezi : in the northwestern part of the range including Colombia.
Sciurus aestuans henseli : in the southernmost part of the distribution area in southern Brazil and in northeast Argentina. The sides of the body are ash gray, the belly is white.
Sciurus aestuans ingrami : on the eastern and southern coast of Brazil. The back color of the animals is olive brown, the belly is white to sand colored.
Sciurus aestuans macconnelli : in the mountainous regions in southern Venezuela, Guyana and probably also in northern Brazil. The shape is more brown-olive in color than the nominate shape.
Sciurus aestuans quelchii : in southern Guyana and north-central Brazil. The back color is olive, the belly yellow.
Sciurus aestuans sebastiani : endemic to the Brazilian island of Ilhabela (Ilha de São Sebastião). It is a large form with a dark brown color on the back, which is darker than that of the mainland forms. The tail is reddish-brown.
Sciurus aestuans venustus : near the Cerro Duida in Venezuela. It is a very small form that corresponds in color to the nominate form.

According to Wilson and Reader 2005, Sciurus aestuans poaiae is another subspecies, but Sciurus aestuans sebastiani does not appear there.

Status, threat and protection

The Guyana squirrel is classified by the International Union for Conservation of Nature and Natural Resources (IUCN) as "not endangered" (least concern). This is justified with the large distribution area and the assumed high population numbers, which do not decrease so quickly that inclusion in a hazard category is justified. However, since there is large-scale conversion of forest areas into agricultural areas in the distribution area of the species, this could be foreseeable at least regionally in the future. Deforestation and habitat fragmentation are viewed as a major risk for stocks. In most parts of the distribution area, the squirrels are hunted as a source of meat.

supporting documents

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 39-40 .

↑ ^a ^b ^c Sciurus aestuans in the IUCN Red List of Threatened Species 2015.1. Posted by: G. Amori, J. Koprowski, L. Roth, 2008. Retrieved October 8, 2015.
↑ ^a ^b ^c Sciurus aestuans In: Don E. Wilson , DeeAnn M. Reeder (Eds.): Mammal Species of the World. A taxonomic and geographic Reference. 2 volumes. 3. Edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .

literature

Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 39-40 .

Web links

Commons : Guyana Croissants - Collection of images, videos, and audio files

Sciurus aestuans inthe IUCN Red List of Threatened Species 2015.1. Posted by: G. Amori, J. Koprowski, L. Roth, 2008. Retrieved October 8, 2015.

[Thorington_et_al._2012-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Richard W. Thorington Jr. , John L. Koprowski, Michael A. Steele: Squirrels of the World. Johns Hopkins University Press, Baltimore MD 2012, ISBN 978-1-4214-0469-1 , pp. 39-40 .