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Wahlberg’s epauletted fruit bat Least Concern

Description: Epomophorus wahlbergi is a large bat with a mass of around 100 g. The pelage is light sandy-brown. The underparts are slightly paler than the upper parts. The wings are light brown and sparsely covered in hair. Adult males are much larger than females, and may be distinguished by a broader muzzle with a folded upper lip and the presence of shoulder epaulettes. These epaulettes are pockets containing long (9 mm in length) white fur that can be erected to display prominent white shoulder patches. At rest, these patches disappear as the fur is retracted into the pocket. The ears have a patch of white fur at their base. The muzzle is dog-like and broader than that of the similar E. crypturus (Taylor and Monadjem 2008).

The skull is robust with sturdy zygomatic arches. Mature males have larger skulls (greatest length > 52 mm) than females (< 52 mm). In lateral profile, the entire skull is conspicuously dorsoventrally flattened; the braincase is without posterior downward deflection. The maxilla is distinctly broader than in E. crypturus (Taylor and Monadjem 2008). The sagittal crest is low, but usually clearly visible. The lambdoid crest is fairly well developed. There are six narrow palatal ridges present, but only one beyond the last molar. The dental formula is 2121/2132 = 28. Tooth eruption, and its use in aging, is presented in Sowler (1980).

Key identification features: The combination of white patches at the base of the ears and shoulder epaulettes (males) separates Epomophorus and Epomops from other fruit bats. The palatal ridges of Epomops are very different from those of Epomophorus; in the latter there are six narrow ridges. Adult E. wahlbergi can be distinguished from sympatric E. crypturus by the presence of one post-dental palatal ridge (two in E. crypturus) and broader muzzle (in E. wahlbergi, width of maxilla at labial posterior edges of the upper M3 > 13 mm, > 14 mm in females and males, respectively; in E. crypturus < 13 mm, < 14 mm in adult females and males, respectively) (Taylor and Monadjem 2008).

Echolocation call: This bat does not echolocate.

Distribution, habitat and roosting: Epomophorus wahlbergi is widespread and abundant in the eastern parts of the region, where it has been recorded from the Eastern Cape, through KwaZulu-Natal and Eswatini to Mozambique, eastern Zimbabwe, Zambia and the southern DRC. It is widespread in Malawi and western Angola, but is absent from Namibia, Botswana, Lesotho and the western two-thirds of South Africa. The type specimen is from near ‘Port Natal’ (= Durban), KwaZulu-Natal, South Africa.

A recent study used ensemble niche modelling to show that abiotic variables associated with productivity (synergistic effects of temperature and rainfall) were the primary determinants of habitat suitability for E. wahlbergi under both current and future climatic conditions (Arumoogum et al. 2019).

This species is well represented in museums, with over 280 records examined for this book (Volpers and Kumirai 1996).

External and cranial measurements (mm) and mass (g) for Epomophorus wahlbergi, males and females presented separately
	Mean	Min	Max	SD	N		Mean	Min	Max	SD	N
Males	Females
Mass 1	111.1	68.0	165.0	25.30	5	Mass 1	91.6	64.0	124.7	14.15	33
FA 1	85.1	75.0	93.0	4.07	5	FA 1	81.2	68.7	91.0	3.71	64
Total 1	145.3	105	211	23.20	4	Total 1	129.9	85	165	16.75	53
Tail 1	0	-	-	-	4	Tail 1	0	-	-	-	18
Tibia 1	-	-	-	-	5	Tibia 1	-	-	-	-	-
Ear 1	24.4	20	31	2.55	5	Ear 1	23.3	11	30	3.51	60
CI 1	51.9	44.2	54.7	2.95	5	CI 1	46.3	41.6	52.4	2.53	25

¹ Specimens measured by the authors

Epomophorus wahlbergi roosts singly or in small groups in the dense foliage of a large, leafy tree and may travel several kilometres each night to reach fruiting trees (Fenton et al. 1985). They may also roost under the eaves of buildings in urban environments (Rollinson et al. 2014). Roost switching is normal and may be partially explained by ambient temperature, since the basal metabolic rate of this species increases under colder conditions, for example, in winter (Downs et al. 2012a). The ability to sleep is also affected by ambient temperature in E. wahlbergi, with bats sleeping far less on hot summer nights than on cool winter nights (Downs et al. 2015). It is associated with forest and forest-edge habitats, including riparian forests that extensively incise savannas in the eastern part of the region. It may also penetrate peri-urban areas with extensive wooded gardens. It occurs sympatrically with E. crypturus in Mozambique, Malawi, northern South Africa (upper Levuvhu River, Limpopo Province), and eastern Zimbabwe. However, E. crypturus appears to prefer drier situations. For example, in Mozambique, E. wahlbergi is captured at high rates in the south, while the capture rate of E. crypturus increases in the north.

Figure 57. Skull and teeth of Epomophorus wahlbergi: (a) dorsal view, (b) ventral view, (c) lateral view, and (d) lateral view of mandible (DM 8627).

Extralimital: Epomophorus wahlbergi has also been recorded from Burundi, Cameroon, Congo, Equatorial Guinea, Ethiopia, Gabon, Kenya and Tanzania.

Foraging ecology: Epomophorus wahlbergi feeds on fruit, nectar, pollen and flowers, with a preference for low protein content (Mqokeli and Downs 2014); they do not show a specific preference for sugar concentration (Coleman and Downs 2012). The bats use both sucrose and glucose efficiently by varying total consumption depending on sugar concentration (Downs et al. 2012b). Furthermore, buccal morphology in the form of palatal ridges, an elongated papillate tongue, and wide flat molars appears well suited for feeding on fleshy fruit that are crushed in the mouth, after which the pulp is discarded (Mqokeli and Downs 2013). Fruits include a variety of cultivated and indigenous tree species, but figs appear to be favoured. At Mtunzini, KwaZulu-Natal, the following trees were recorded from ‘spit-outs’ collected from under feeding stations (C. Sapsford, personal communication): Ficus sur, F. trichopoda, F. natalensis, Voacanga thouarsii, Tabernaemontana ventricosa, Syzygium cordatum, Bridelia micrantha, Euclea natalensis, Eugenia capensis, Ekebergia capensis, Annona senegalensis, Podocarpus latifolius, P. falcatus, Sideroxylon inerme, Rauvolfia caffra, Halleria lucida, Sclerocarya birrea, Trichilia emetica, Harpephyllum caffrum and Mimusops caffra. In the Kruger National Park, this species specialises on the fruits of Ficus sycomorus (Bonaccorso et al. 2014). These bats also feed on exotic plants, particularly in urban environments (Rollinson et al. 2013), and may be effective dispersers of invasive species (Jordaan et al. 2012). They pollinate Adansonia digitata flowers. They feed while hovering in front of the fruit or flower, or after landing on a suitable branch alongside it (Fenton et al. 1985).

Recent telemetry work in the Kruger National Park, South Africa, has shown that Epomophorus wahlbergi individuals may travel over 13 km between roosting and feeding sites in a single night and that the same fruiting tree may be visited on subsequent nights (Bonaccorso et al. 2014). However, most flight activity was within 400 m of a Ficus sycomorus tree with ripe fruits, and home ranges averaged ∼16 hectares. By comparison, bats radio-tracked in the urban environment of Pietermaritzburg, Kwazulu-Natal, had home ranges that varied by sex and season, with females and males ranging between 18–61 hectares and 13–54 hectares, respectively (Rollinson et al. 2013). Mean maximum distances between roosting sites and foraging areas were 1.45 km and 0.88 km for winter and spring, respectively. These bats fed predominantly on exotic and invasive fruit growing in gardens, including Melia azedarach, Psidium guajava and Eriobotrya japonica, although between 20% and 30% of observations were of bats consuming the fruit of indigenous Ficus species (Rollinson et al. 2013).

Reproduction: Births occur throughout the year, but with peaks in July (winter) and the summer months (Monadjem and Reside 2012). Breeding males have particularly long epaulette hairs, as well as a brown discolouration of the skin in the vicinity of the testes and in the neck region. These males will sing from traditional lekking sites to attract females. One, or rarely two, young are born after a gestation period of five to six months.

Figure 58. Epomophorus wahlbergi: (a) female roosting showing white ear tufts, and (b) male showing covered epaulettes (a: © P. J. Taylor; b: © L. Lumsden).