Bat-eared fox
The bat-eared fox is a species of fox found on the African savanna. It is the only extant species of the genus Otocyon, and is the sister species to all other members of the tribe Vulpini. Fossil records indicate this canid first appeared during the middle Pleistocene. There are two separate populations of the bat-eared fox, each of which makes up a subspecies. The bat referred to in its colloquial name is possibly the Egyptian slit-faced bat, which is abundant in the region and has very large ears. Other vernacular names include big-eared fox, black-eared fox, long-eared fox, Delalande's fox, cape fox, and motlosi.
It is named for its large ears, which have a role in thermoregulation. It is a small canid, being of comparable size to the closely related cape fox and common raccoon dog. Its fur varies in color depending on the subspecies, but is generally tan-colored and has guard hairs of a grey agouti color. The bat-eared fox is found in Southern and East Africa, though the two subspecies are separated by an unpopulated region spanning approximately. In its range, the bat-eared fox digs dens for shelter and to raise its young, and lives in social groups or pairs that hunt and groom together.
The bat-eared fox eats mainly insects—a diet unique among canids. It forages in arid and semi-arid environments, preferring regions with bare ground and where ungulates keep grasses short, and locates prey by using its hearing, walking slowly with its nose to the ground and ears tilted forwards. Most of its diet is made up of harvester termites, which also hydrates the bat-eared fox, as it does not drink from free-standing water. By feeding on harvester termites, it acts as a means of population control for these insects, which are considered pests in regions populated by humans. In such regions, it has been hunted for its fur. No major threats to the bat-eared fox exist, and as such it is considered to be a least-concern species.
Etymology
The bat-eared fox's generic name Otocyon is derived from the Greek words otus for ear and cyon for dog, while the specific name megalotis comes from the Greek words megas for large and otus for ear. The common name for the bat-eared fox is likely taken from the Egyptian slit-faced bat, due to the bat's similarly large ears and abundance in the bat-eared fox's geographic range. Other vernacular names for the bat-eared fox include big-eared fox, black-eared fox, long-eared fox, Delalande's fox, cape fox, and motlosi.Taxonomy and evolution
The bat-eared fox is the only living species of the genus Otocyon. Its scientific name, given by Anselme Gaëtan Desmarest, was initially Canis megalotis, and later changed by Salomon Müller which placed it in its own genus, Otocyon; its large ears and different dental formula warrant inclusion in a genus distinct from both Canis and true foxes.Due to its unusual dentition—, the largest number of teeth known in any non-marsupial land mammal—the bat-eared fox was previously placed in a distinct subfamily of canids, Otocyoninae, as no relationship to any living species of canid could be established.
Phylogeny
Otocyon megalotis is regarded as having affinities with the vulpine line, and Otocyon was placed with high confidence as sister to the clade containing both the raccoon dog and true foxes.The following cladogram is based on figures by Lindblad-Toh et al., 2005:
Subspecies
Currently, there are two recognized subspecies:| Image | Subspecies | Distribution |
| Otocyon megalotis megalotis | Southern Africa | |
| Otocyon megalotis virgatus | East Africa |
Fossils
Otocyon is poorly represented in the fossil record. It is suggested the genus forms a clade with Prototocyon, an extinct genus of canid. In the Olduvai Gorge, Tanzania, fossils of the related extinct fox species first considered Otocyon recki have been found that date back to the late Pliocene or early Pleistocene. O. recki is now often placed in Prototocyon; fossil records specifically of Otocyon megalotis have been identified in sediments only as old as the middle Pleistocene. These fossils, known from the Lainyamok locality of Kenya, date back.Description
Bat-eared foxes range in weight from. Their head and body length is, tail length is, shoulder height is, and the notably large ears are long. The species displays a degree of sexual dimorphism, in that females are generally larger and heavier than males.Generally, the pelage is tan-colored, with gray guard hairs of an agouti coloration. The undersides and throat are pale. The limbs are dark, shading to dark brown or black at their extremities. The muzzle, the tip and upperside of the tail and the facial mask are black. The insides of the ears are white. Individuals of the East African subspecies, O. m. virgatus, tend toward a buff pelage with dark brown markings, as opposed to the black of O. m. megalotis. The proportionally large ears of bat-eared foxes, a characteristic shared by many other inhabitants of hot, arid climates, such as the desert cottontail, help to distribute heat. They also help in locating prey.
Dentition and jaw adaptations
The teeth of the bat-eared fox are much smaller those of other canid species, excepting the bush dog and dhole. The molars are much more blunted and the roots are stronger than those of other canids, and the teeth have less shearing capability. These are adaptations to its insectivorous diet and avoidance of soft foods. The bat-eared fox possesses 4-5 lower molar teeth and 3-4 upper molars, a number notable as it is greater than the number of lower or upper molars possessed by any other extant eutherian or canid, respectively.The teeth are not the bat-eared fox's only morphological adaptation for its diet. On the lower jaw, a step-like protrusion is present called the subangular process, which is present in only a few canid species and both increases the bite force of the masseter muscle and anchors the large digastric muscle to allow for rapid chewing. The digastric muscle is also modified to allow for opening and closing the jaw five times per second.
Distribution and habitat
The bat-eared fox has a disjunct distribution across the arid and semi-arid regions of Eastern and Southern Africa, in two allopatric populations separated by approximately. Subspecies O. m. virgatus extends from southern Sudan, Ethiopia and Somalia, through Uganda and Kenya to southwestern Tanzania; O. m. megalotis occurs in the southern part of Africa, ranging from Angola through Namibia and Botswana to South Africa, and extends as far east as Mozambique and Zimbabwe, spreading into the Cape Peninsula and toward Cape Agulhas. Home ranges vary in size from. The two disjunct ranges of O. megalotis were likely connected to each other during the Pleistocene epoch.Bat-eared foxes are adapted to arid or semi-arid environments. They are commonly found in short grasslands, as well as the more arid regions of the savannas, along woodland edges, and in open acacia woodlands. They prefer bare ground and areas where grass is kept short by grazing ungulates and tend to hunt in these short grass and low shrub habitats. However, they do venture into areas with tall grasses and thick shrubs to hide when threatened.
In addition to raising their young in dens, bat-eared foxes use self-dug dens for shelter from extreme temperatures and winds. They also lie under acacia trees in South Africa to seek shade during the day.
Behavior and ecology
Bat-eared foxes are social animals. They live in pairs or groups, depending on the subspecies. In southern Africa, bat-eared foxes live in monogamous pairs with pups, while those in eastern Africa may live in pairs, or in stable family groups consisting of a male and up to three closely related females with pups. Individuals forage, play, and rest together in a group, which helps in protection against predators. They engage in frequent and extended allogrooming sessions, which serve to strengthen group cohesion, mostly between mature adults, but also between young adults and mature adults.Visual displays are important in communication among bat-eared foxes. When they are looking intently at something, the head is held high, eyes are open, ears are erect and facing forward, and the mouth is closed. When an individual is in threat or showing submission, the ears are pulled back and lying against the head and the head is low. The tail also plays a role in communication. When an individual is asserting dominance or aggression, feeling threatened, playing, or being sexually aroused, the tail is arched in an inverted U shape. Individuals can also use piloerection, which occurs when individual hairs are standing straight, to make it appear larger when faced with extreme threat. When running, chasing, or fleeing, the tail is straight and horizontal. The bat-eared fox can recognize individuals up to away. The recognition process has three steps: First they ignore the individual, then they stare intently, and finally they either approach or attack without displays. When greeting another, the approaching individual shows symbolic submission which is received by the other individual with a high head and tail down. Few vocalizations are used for communication, but contact calls and warning calls are used, mostly during the winter. Glandular secretions and scratching, other than for digging, are absent in communication, although they appear to establish pair bonds by scent marking.
In the more northern areas of its range, they are nocturnal 85% of the time. However, around South Africa, they are nocturnal only in the summer and diurnal during the winter.