Sengis: Macroscelidea

views updated

SENGIS: Macroscelidea

CHECKERED SENGI (Rhynchocyon cirnei): SPECIES ACCOUNT

PHYSICAL CHARACTERISTICS

Sengis (SEN-jeez) are commonly known as elephant shrews, although they are not related to the shrew. Sengis range in size from that of a mouse to a rabbit.

They have a head and body length of 3.5 to 12.5 inches (9.0 to 31.5 centimeters), a tail length of 3 to 11 inches (8.0 to 26.3 centimeters) and weigh from 1 ounce to 10 pounds (28 grams to 4.5 kilograms). They have long, spindly legs and a nose that is turned down. They have large heads and ears and large, dark eyes. Their hind legs are larger then their front legs. Sengis walk on their toe tips rather than the feet bottoms.

The larger species of sengis have brightly colored fur ranging in color from olive, brown, black, and red, while the smaller species are various shades of brown and gray. Some are multicolored, such as the golden-rumped sengi, which has upper body fur of a deep reddish brown and black, lighter fur on its undersides, and black feet, ears, and legs. Its tail is black except for the lower third, which is white with a black tip. There is a large patch of fur on its rump that is bright yellow. In the rufous sengi, the long, soft fur ion the upper body is light brown, light gray, or light orange. The underside fur is white or gray. The fur on its face is a patchwork of white spots and black streaks.

GEOGRAPHIC RANGE

Sengis are found throughout Africa except western Africa and the Sahara Desert region. They are most common and diverse in southern and eastern Africa.

HABITAT

Sengis live in deciduous forest, rainforest, grassland, and desert areas of Africa, especially where there is an abundance of water. They are found in the thick ground cover of coastal bush forests, rocky outcroppings, and highland and lowland forests.

DIET

Sengis are insectivores, meaning they eat primarily insects. Their diet of insects includes ants, termites, beetles, spiders, caterpillars, and worms. However, several species are omnivores, meaning they eat insects, flesh, and plants. Their diet includes toads, frogs, lizards, fruits, seeds, and plants. One species, the golden-rumped sengi, is an omnivore, meaning it eats only flesh, mainly insects and small animals.

BEHAVIOR AND REPRODUCTION

Sengis are mainly diurnal, meaning they are most active during the day, but during hot weather, they can be nocturnal, meaning they are most active at night. Several species are crepuscular, meaning they are most active during early morning and twilight. They have well developed senses of sight, hearing, and smell. Most species are territorial, meaning they are protective of an area they consider home and claim exclusively for themselves. Pairs of males and females usually have separate but overlapping and sometimes identical territories.

IDENTITY CRISIS

Sengis or elephant shrews have been one of the most often misclassified species of animals. Scientists who first classified the mammal in the mid 1800s placed it in the order Insectivora along with true shrews (family Soricidae). It got its name because its long down-turned nosed resembled an elephant's trunk and physically looked like a shrew. It was reclassified in the order Scandentia (tree shrews) and then reclassified again as an ungulate, a group of mammals with hooves that include horses and giraffes. Later, it was classified as a lagomorph, along with rabbits and hares. More recently, examination of the elephant shrew's molecular structure indicates it is a distinct order and the order Macroscelidea was established. Based on genetic evidence, the elephant shrew, now called the sengi, is related to the proposed superorder Afrotheria composed of six orders, whose members include elephants, manatees, and aardvarks.

Most species of sengis are believed to be monogamous (muh-NAH-guh-mus), meaning they have only one sexual partner during a breeding season or lifetime. Several species are solitary and males and females get together for only several days to mate. Females usually produce several litters a year, each with usually one or two babies, but more rarely with three or four. The gestation period, the time the female carries the young in her womb, is about sixty days.

SENGIS AND PEOPLE

Sengis are sometimes hunted in areas of Africa for their meat. Since they eat mostly insects, they help control insects such as termites, ants, and grasshoppers, that are problems for farmers because of the damage the insects cause to crops.

CONSERVATION STATUS

Three species of sengi are listed by IUCN as Endangered, facing a very high risk of extinction: Somali sengi, the golden-rumped sengi, and the black and rufous sengi. One species is listed as Vulnerable, facing a high risk of extinction: the checkered sengi. The reasons for the listings are severely fragmented populations and declining habitats. No other species are listed as currently threatened.

CHECKERED SENGI (Rhynchocyon cirnei): SPECIES ACCOUNT

Physical characteristics: The checkered sengi adult has a head and body length of 9 to 12.5 inches (23.5 to 31.5 centimeters) and a tail length of 7 to 10 inches (19.0 to 26.3 centimeters).

Geographic range: The checkered sengi is found in northern and eastern Democratic Republic of the Congo, Uganda, southern Tanzania, northeastern Zambia, Malawi, and northern Mozambique.

Habitat: Checkered sengis live in dense, lowland and mountain regions of tropical rainforest.

Diet: Checkered sengis are mainly insectivores, meaning they eat primarily insects. Their diet includes ants, termites, and beetles. However, they have also been known to eat small mammals, birds, bird eggs, and snails.

Behavior and reproduction: Checkered sengis are primarily diurnal, meaning they are most active during the day, They can on occasion become nocturnal, meaning they are most active at night, especially during hot weather. They can live alone, in mated pairs, or in small groups. They are monogamous, meaning they have only one sexual partner for life. They are extremely nervous animals and are always on the lookout for predators, such as pythons and other snakes, and birds of prey such as eagles, hawks, owls, and kestrels. Checkered sengis have an average lifespan in the wild of three to five years.

Checkered sengis are territorial, meaning they are protective of an area they consider home and claim exclusively for themselves. Pairs of males and females usually have separate but overlapping territories. Individuals` sleep in nests made of small pits covered with leaves. Checkered sengis build new nests every few days, digging a shallow depression in the ground and lining and covering it with leaves. Once constructed, it is difficult for humans to detect. A pair may build up to ten shelters in their territories.

The checkered sengi breed year-round and have several litters per year. The gestation period, the time the female carries the young in her womb, is about forty-two days. The litter size is one baby, which stays in the nest for about ten days before going out with its mother to forage for food. It goes its own way after five to ten weeks.

Checkered sengis and people: Checkered sengis are of no known significance to humans.

Conservation status: The checkered sengi is listed by the IUCN as Vulnerable, due primarily to severely fragmented populations and declining habitats. ∎

FOR MORE INFORMATION

Books:

Macdonald, David. The New Encyclopedia of Mammals. Oxford, U.K.: Oxford University Press, 2001.

Nicoll, Martin E., and Galen B. Rathbun. African Insectivora and Elephant Shrews: An Action Plan for Their Conservation. Gland, Switzerland: IUCN, 1990.

Nowak, Ronald M. Walker's Mammals of the World, 6th ed. Baltimore: Johns Hopkins University Press, 1999.

Periodicals:

Downs, Calleen T., and M. R. Perrin. "The Thermal Biology of Three Southern African Elephant Shrews." Journal of Thermal Biology (December 1995): 445–450.

Fredericks, Ilse. "Elephant Shrews May Help Astronauts." Africa News Service (September 21, 2003).

Koontz, Fred W., and Nancy J. Roeper. "Elephantulus rufescens." Mammalian Species (December 15, 1983): 1–5.

Rathbun, Galen B. "Rhynchocyon chrysopygus." Mammalian Species (June 8, 1979): 1–4.

Tabuce, Rodolphe, et al. "A New Genus of Mavroscelidea (Mammalia) From the Eocene of Algeria: A Possible Origin for Elephant Shrews." Journal of Vertebrate Paleontology (August 2001): 535–546.