Otocyon Research Articles

Can we outfox rabies?

In our rabies free islands most of us give little thought to this disease except when passing through customs or worrying about illegal entry of rabid French foxes through the Channel tunnel. After watching this Encounters programme no one can be in any doubt about the worldwide extent and the human and animal cost of rabies infection. Rabies is seen through the eyes of Sarah Cleveland, a young English vet working in the Serengeti Park, Tanzania. Here she has noticed an increase in rabies in infected bat eared foxes and dogs, with increasing risk of transmission to cattle and humans. Grim footage of a 9 year old boy foaming at the mouth and writhing in his cot made abundantly clear the distress caused by rabies. In Tanzania post-exposure vaccine is both in short supply and expensive (more than $100 per shot), and an elderly man tells how his sister delayed getting vaccine after a bite, eventually travelling to Kenya to borrow money from …

A canine distemper virus epidemic in Serengeti lions (Panthera leo).

CANINE distemper virus (CDV) is thought to have caused several fatal epidemics in canids within the Serengeti–Mara ecosystem of East Africa, affecting silver-backed jackals (Canis mesomelas) and bat-eared foxes (Otocyon megalotis) in 1978 (ref. 1), and African wild dogs (Lycaon pictus) in 1991 (refs 2, 3). The large, closely monitored Serengeti lion population4,5 was not affected in these epidemics. However, an epidemic caused by a morbillivirus closely related to CDV emerged abruptly in the lion population of the Serengeti National Park, Tanzania, in early 1994, resulting in fatal neurological disease characterized by grand mal seizures and myoclonus; the lions that died had encephalitis and pneumonia. Here we report the identification of CDV from these lions, and the close phylogenetic relationship between CDV isolates from lions and domestic dogs. By August 1994, 85% of the Serengeti lion population had anti-CDV antibodies, and the epidemic spread north to lions in the Maasai Mara National reserve, Kenya, and uncounted hyaenas, bat-eared foxes, and leopards were also affected.

Predation on bat-eared foxes <i>Otocyon megalotis </i>by Cape hunting dogs <i>Lycaon pictus</i>

The predatory habits of the Cape hunting dog Lycaon pictus have been well documented, and have been found to include almost exclusively mammalian herbivores (Childes 1988). The prey species chosen varies from area to area according to availability, with wildebeest Connochaetes taurinus and Thompson's gazelle, Gazella thomsonii being recorded as preferred prey in East Africa (Malcolm & Van Lawick 1975), whereas impala Aepyceros melampus, kudu Tragelaphus strepsiceros and duiker Sylvicapra grimmia are predominantly selected in southern Africa (Fuller & Kat 1990). This paper documents a case of a pack of Cape hunting dogs preying specifically on bat-eared foxes.

Gnathomandibular Morphology and Character Displacement in the Bat-Eared Fox

Relations in mandibulo-dental size were evaluated in a sample of 74 (42 male) bat-eared foxes ( Otocyon megalotis ). Mesiodistal and buccolingual dental measurements, together with eight mandibular measurements (intercondylar distance, intercarnassial breadth, mandibular length, condylar height, canine-condylar length, mandibular width, mandibular height) were allometrically scaled to total length of the skull. These results were then compared with those on domestic dogs and on three small southern-African canids: Vulpes chama , Canis adustus , and Canis mesomelas . I suggest that canine dimorphism in size may not be related to body-size dimorphism. In contrast to previous studies, I show that the specialized soft diet of the bat-eared fox is not reflected in an increase of shearing facets of the molars. Indeed, the species is characterized by robust dentinal development, blunted pulp-horns, and multicuspal molars. Finally, I provide cautious evidence of character displacement in the trophic apparatus within this southern-African guild of canids.

Molecular epidemiology of rabies virus in South Africa: evidence for two distinct virus groups.

In order to derive phylogenetic relationships between rabies virus isolates from different geographical locations and host species in South Africa, two genome regions of the virus, viz. the cytoplasmic domain of the glycoprotein and the G-L intergenic region (pseudogene), were sequenced. A high level of nucleic acid sequence conservation indicated a close phylogenetic relationship between virus isolates from domestic dogs, jackals and bat-eared foxes, i.e. Canidae. These isolates appeared to be distinct from but closely related to European strains of rabies virus. However, a phylogenetically distinguishable and distant group, which contained isolates from mongooses (i.e. Viverridae) was identifiable. The latter group appears to be distantly related to European and vaccine strains of rabies virus and may have evolved uniquely on the central plateau of South Africa. Our data also indicate that spillover from mongooses (or other viverrids) to canid hosts occurs occasionally.

Tolerance of Aardwolves to Defense Secretions of Trinervitermes trinervoides

Trinervitermes trinervoides provides over 90% of the diet of aardwolves ( Proteles cristatus ) in South Africa. The soldiers of this termite possess highly effective chemical-defense secretions preventing most myrmecophagous mammals from specializing on them as a primary source of food. Soldiers of T. trinervoides were collected, liquidized in oil, and then added in different concentrations to the diets of captive aardwolves, African civets ( Civettictis civetta ), and bat-eared foxes ( Otocyon megalotis ). The foxes refused to feed on the termite mixture, whereas the civets and aardwolves tolerated concentrations of 1.0% and >7.5% respectively; this supports the hypothesis that ancestral aardwolves were phylogenetically preadapted, via their viverrid-like ancestors, to tolerate noxious chemicals and hence the defense secretions of soldiers of Trinervitermes .

Surveillance and control of anthrax and rabies in wild herbivores and carnivores in Namibia

Anthrax has been studied intensively in Etosha National Park, Namibia since 1966; in addition, since 1975, mortality due to rabies and all other causes has been recorded, totalling 6,190 deaths. Standard diagnostic procedures demonstrated that at least 811 deaths (13%) were due to anthrax and 115 deaths (2%) were caused by rabies. Of the total number of deaths due to anthrax, 97% occurred in zebra (Equus burchelli), elephant (Loxodonta africana), wildebeest (Connochaetes taurinus) and springbok (Antidorcas marsupialis) while 96% of rabies deaths occurred in kudu (Tragelaphus strepsiceros), jackal (Canis mesomelas), bat-eared fox (Otocyon megalotis) and lion (Panthera leo). Anthrax deaths were highest in the rainy season for zebra, wildebeest and springbok, while elephant mortality peaked during dry seasons. No statistical relationship existed between seasonal rainfall and overall incidence of either anthrax or rabies. Control of anthrax is limited to prophylactic inoculation when rare or endangered species are threatened. Incineration of anthrax carcasses and chemical disinfection of drinking water are not feasible at Etosha. Rabies control consists of the destruction of rabid animals and incineration of their carcasses when possible.

Functional analysis of the feeding apparatus and digestive tract anatomy of the aardwolf Proteles cristatus

The aardwolf is unique amongst the myrmecophagous mammals in that it feeds almost exclusively on one genus of termite, Trinervitermes, yet it possesses none of the obvious external physical features (elongated snout, powerful limbs and claws) characteristic of this feeding style. Externally it looks simply like a diminutive hyaena. Behaviourally the aardwolf differs from the other typical ‘anteaters’, in that it does not dig for its prey, but licks them off the soil surface. Nevertheless, the aardwolf does have a number of anatomical features which are clearly adaptations to this diet. The most obvious of these are a broad spatulate tongue covered with large, hardened papillae, a broad palate, large mandibular salivary glands, and a muscular pyloric region in the stomach. A relatively short small intestine facilitates the rapid processing of large volumes of termites, while a distensible large intestine allows for the accumulation of faecal material. Some of these features associated with feeding and digestion are compared with those of the domestic dog Canis familiaris, the bat‐eared fox Otocyon megalotis and the black‐backed jackal Canis mesomelas.

Diet of bat-eared foxes <i>Otocyon megalotis </i>in the Karoo

The diet of bat-eared foxes Otocyon megalotis was studied from March 1988 to September 1989 at two sites near Beaufort West in the central Karoo. In a near-natural habitat (Karoo National Park), insects and wild fruit contributed almost equally to the diet, while more insects than plant material were consumed on a sheep farm (Saucyskuil). Adult and larval Coleoptera (KNP) and Orthoptera (Saucyskuil) were predominantly preyed upon in an opportunistic manner, influenced by food availability. A higher volume of Isoptera was consumed at Saucyskuil, suggesting higher availability in the farming area.

Phylogenetic relationships of the fox‐like canids: mitochondrial DNA restriction fragment, site and cytochrome b sequence analyses

The fox‐like canids include taxa from the genera Alopex, Otocyon, Fennecus, Urocyon and Vulpes. Previous morphological analysis indicated that species from the latter three genera are very similar and should be included in the same genus whereas Alopex and Otocyon are sufficiently different to be included in separate genera. Using phylogenetic methods, we analyse mitochondrial DNA (mtDNA) restriction fragment and restriction site data, and 402 bp of cytochrome b sequence variation in fox‐like canids. Our results suggest that Alopex lagopus, the arctic fox, is actually a very close relative of the swift fox, a species in the genus Vulpes. Similarly, the fennec, Fennecus zerda is related to the co‐existing desert species, the Blanford's fox, Vulpes cana. The grey fox, Urocyon cinereoargenteus, and the bat‐eared fox, Otocyon megalotis, are not closely related to each other or to any of the sampled fox taxa. Our results indicate that desert adaptations have evolved independently at least twice in the Canidae, and that Pleistocene glaciations and character divergence may be important causes of morphological change in canids.

Foraging and feeding by bat-eared foxes <i>Otocyon megalotis</i> in the southwestern Kalahari

Bat-eared foxes Otocyon megalotis feed in pairs or groups of three when utilizing clumped prey in patches, e.g. termites, and cover 0,87-1,28 km/h. When feeding on dispersed prey, e.g. insect larvae, they are widely spaced and cover 0,56-0,83 km/h. Food patches are never re-utilized on the same day. Patch size diameter varied from 6-30 m, and patches were 10 to > 100 m apart, while from 1,17 min to 15 min were spent in patches. There were no significant correlations between patch size and distance moved to next patch, or time spent in a patch and distance moved to next patch, or time spent in a patch and patch size. Patches were seldom (1,6 ) returned to immediately. A male and a female had similar numbers of feeding bouts per sampling period during winter or summer, but when accompanied by cubs the male fed less frequently. The male had significantly longer feeding bouts than the female in winter, with the reverse applying in summer. Within-sex comparisons show that the number of feeding bouts of the male did not vary significantly between winter and summer. Conversely the female showed significant differences in the number but not the duration of feeding bouts in winter and summer. Optimal foraging in this species probably relates to prey profitability, i.e. highest ingestion rate.

Winter activity of bat-eared foxesOtocyon megalotison the Cape West coast

Diurnal activity budgets of bat-eared foxes Otocyon megalotis in winter (June) at the Postberg Nature Reserve, West Coast National Park, were analysed to determine the influence of environmental factors on their activity. Abiotic factors such as effective temperature, wind speed, cloud cover and rainfall have an effect on prey availability and thermoregulation of the foxes and therefore affect their activity rhythm. Low effective temperature and high wind speed result in more resting and less foraging by foxes. The reverse applies at high effective temperature and low wind speed. No foraging occurred during rain, and only for short periods when the sun shone on overcast days. With the start of pair formation in June–July allogrooming, which was not influenced by abiotic factors, increased. Foxes resumed activity from the same resting sites each day.

Chromosomal evolution of the Canidae. I. Species with high diploid numbers.

The Giemsa banding patterns of seven canid species, including the grey wolf (Canis lupus), the maned wolf (Chrysocyon brachyurus), the bush dog (Speothos venaticus), the crab-eating fox (Cerdocyon thous), the grey fox (Urocyon cinereoargenteus), the bat-eared fox (Otocyon megalotis), and the fennec (Fennecus zerda), are presented and compared. Relative to other members of Canidae, these species have high diploid complements (2n greater than 64) consisting of largely acrocentric chromosomes. They show a considerable degree of chromosome homoeology, but relative to the grey wolf, each species is either missing chromosomes or has unique chromosomal additions and rearrangements. Differences in chromosome morphology among the seven species were used to reconstruct their phylogenetic history. The results suggest that the South American canids are closely related to each other and are derived from a wolf-like progenitor. The fennec and the bat-eared fox seem to be recent derivatives of a lineage that branched early from the wolf-like canids and which also includes the grey fox.

Notes on food and foraging of the Honey Badger<i> Mellivora capensis</i> in the Kalahari Gemsbok National Park

Contents of faeces indicated that honey badgers in the Kalahari eat mostly rodents, followed by lizards and scorpions, all of which are caught by digging. Larger mammals (aardwolf, bat-eared fox, springhare) and large snakes are also eaten. Foraging behaviour is described and individual differences in foraging strategies are discussed.

Small mammal bone accumulations produced by mammalian carnivores

Small mammal bone assemblages from the scats of three families of mammalian carnivores are described here as a means of assessing paleontological bone assemblages. These are the Viverridae, Canidae, and Mustelidae. Marking behavior by the carnivores or their use of latrine areas can produce concentrations of bone comparable with those produced from owl pellets, but the nature of the bone assemblages is very different. Skeletal element preservation has a characteristic pattern related to the relative strength of the individual elements, so that the strongest elements are the ones that best survive the physical abrasion of the predator's teeth. Bone breakage is greatest in canids and least in some viverrids. Digestion of the bone occurs to a certain extent with all carnivores, with moderate rounding but little corrosion of either bones or teeth in viverrid-derived bone assemblages, very great rounding and severe corrosion of bone and tooth enamel (but little corrosion of tooth dentine) in canids, and moderate rounding and slight to moderate corrosion of bone and tooth dentine (but less of enamel) in mustelid-derived bone assemblages. Tooth marks are generally rare except in canid-derived bone assemblages. These patterns may enable the identification of predators responsible for the accumulation of fossil predator assemblages, and a consideration of the hunting and other behavior of that type of predator then permit the identification of possible biases in the fossil fauna. In the viverrids, for instance, the mongoose selected for large prey size and against cranial elements, while the genet took all prey sizes available to it and all body parts. Larger canids such as foxes and coyotes took both large and small species, but proportionally more of the most common prey species were present. Skulls were underrepresented. The small canid, the bat-eared fox, selected for the smallest prey species available to it but took all body parts. Mustelids took all sizes of prey, although not necessarily in proportion to their abundance in the habitat, and large species were underrepresented. If the predator type is known, therefore, for a fossil assemblage, these biases can be taken into account in assessing the paleoecological significance of the fauna. An example from the Olduvai Pleistocene deposits is given.

Field observations on activity and feeding of bat‐eared foxes (Otocyon megalotis) at Nxai Pan, Botswana

SummaryA short field study at Nxai Pan in Botswana showed that bat‐eared foxes (Otocyon megalotis) are diurnally active in that area although nocturnal activity could not be excluded. Activity appears to be closely related to availability of insects, particularly termites, which show maximum abundance on the surface of the pan around noon. Analysis of scats shows that termites constitute the main food item of foxes at Nxai Pan. Pairs of bat‐eared foxes do not appear to be territorial and intolerance between pairs was not observed.RÉSUMEÉUne brève étude de terrain au Nxai Pan (Botswana) a montré que l'otocyon (Otocyon megalotis) est diurne a cet endroit tout en n'excluant pas une activité nocturne. L'activité semble ětre étroitement liée à la disponibilité d'insectes, particulièrement de termites, lesquels montrent un maximum d'activitèà la suface de la cuvette aux environs de midi. L'analyse des fèces montre que les termites constituent le principal élement de nourriture de ces renards au Nxai Pan. Les couple d'otocyon ne semblent pas ětre territoriaux et l'on n'a pas observé d'intolérance entre les couples.

Comparison of the myoglobin of the bat-eared fox ( Otocyon megalotis) with that of the domestic dog (Canis familiaris)

The tryptic and peptic peptides obtained from the myoglobin of the bat-eared fox (Otocyon megalotis) were compared with those from the myoglobin of the domestic dog (Canis familiaris). No differences were found. The classification of Otocyon as the only living genus of a separate subfamily of the Canidae is questioned.

Breeding the Bat-eared fox at Utlca Zoo

Breeding the Bat-eared fox at Utlca Zoo

A note on the occurrence of Bat-Eared Fox <i>Otocton Megalotis</i> (Desmarest) in the Kruger National Park

A note on the occurrence of Bat-Eared Fox Otocton Megalotis (Desmarest) in the Kruger National Park

Supernumerary Molars of Otocyon

The occurrence of abnormal upper third molars and lower fourth molars in the Caninae is reviewed. It is proposed that the extra molars normally found in the adult dentition of Otocyon megalotis (Desmarest) are the result of a mutation that caused the duplication of the upper first molar and the lower second molar. Supporting evidence for this is presented. This makes the upper third molar of Otocyon the homologue of the normal canid second molar, and the lower fourth molar the homologue of the normal third molar of all of the remaining canids. The presence of an anomalous upper third molar is a relatively common variant in the genus Canis. Bertram, Windle and Humphreys (1890) recorded ABSTRACT: The occurrence of abnormal upper third molars and lower fourth molars in the Caninae is reviewed. It is proposed that the extra molars normally found in the adult dentition of Otocyon megalotis (Desmarest) are the result of a mutation that caused the duplication of the upper first molar and the lower second molar. Supporting evidence for this is presented. This makes the upper third molar of Otocyon the homologue of the normal canid second molar, and the lower fourth molar the homologue of the normal third molar of all of the remaining canids.