Eidolon helvum (Kerr, 1792)

Don E. Wilson & Russell A. Mittermeier, 2019, Pteropodidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 16-162 : 115

95.

African Straw-colored Fruit Bat

Eidolon helvum

French: Roussette-paillée dAfrique / German: Palmenflughund / Spanish: Eidolon de Africa

Other common names: Pale Xantharpy, Straw-colored Flying Fox, Straw-colored Fruit Bat

Taxonomy. Vespertilio vampyrus helvus Kerr, 1792 ,

type locality not given. Fixed by K. Andersen in 1907 to “ Senegal.”

Widely used subspecific name annobonensis has been changed for gender agreement. Taxon dupreanum is often treated as subspecies of E. helvum , but it is a distinct species here. Three subspecies recognized.

Subspecies and Distribution.

E.h.helvumKerr,1782—widedistributionacrosssub-SaharanandequatorialAfrica,fromMauritaniaandSenegalEtoSudanandEthiopia,andStoNamibiaandSouthAfrica,includingBioko,Principe,andSaoToméIs,Pemba,Unguja,andMafiaIsinZanzibarArchipelago.

E.h.annobonense Juste,Ibanez&Machordom,2000—AnnobonI,offEquatorialGuinea.

E. h. sabaeum K. Andersen, 1907 — Arabian Peninsula in extreme SW Saudi Arabia and W Yemen.

Descriptive notes. Head-body 150-195 mm, tail 10-15- 5 mm, ear 27- 2-28 mm, hindfoot 31-5-38- 5 mm, forearm 117-132 mm; weight 230-350 g. Females are slightly smaller than males and often appear lighter in color. The African Straw-colored Fruit Bat has a bright orange, yellow, or brownish collar of longer hairs on throat that extends upward onto back of neck, and is brighter and more pronounced in males. Muzzle is nearly hairless and elongated, rhinarium is prominent, and nostrils are flush with broad rostrum. Eyes are large; irises are raw umber. Ears are hairless posteriorly, with fur at their bases and elongated ovals and dark brown auricles, and antitragus is short and nearly absent. Face is mostly hairless, with some short soft dark brown hairs around eyes extending onto rostrum. Short straw-colored pelage covers head and extends onto nape and dorsum. Uropatagium is split and extends partially off each leg; calcar is short and slightly haired dorsally. Tail is short, with 2-2-5 vertebrae protruding. Throat, chest, and belly are fully haired, with same bright orange to deep tawny pelage. Pelage extends over upper arm and slightly onto forearm and upper surfaces of legs and uropatagium but not onto wing membrane. Wings are long, pointed, somewhat narrow, and dark blackish brown. At rest, ends of wings are folded back with tips folded in. Second phalanges of third and fourth digits lie flat against lower surface of wing. Wings extend from sides of dorsum close to spine and from back of first toe. Wing area averages 739- 4 cm? in males and 545- 3 cm? in females. Second digit is clawed. Wing membranes extend from sides of dorsum and back of first toe. Metacarpal and first phalanx of first digit are within wing membrane. Basicranial axis is deflected, but occiput is neither elongated nor tubular. Rostrum is elongated, and nasals extend past canines, but premaxillae do not. Braincase is rounded. Postorbital process extends from frontal but is not connected to jugal. Ectotympanic is produced laterally as short tube, distinctive of the genus. Palate broadens posteriorly and is widest between M” to M?, it then narrows at posterior border to width about equalto that between lingual edges of P4 to P4. Front of orbit is located above middle to posterior part of M'. Mandible is thin, with tall sloping coronoid process, and condyle is above level of lower alveolar line. Ten palatal ridges are present: four anterior, three middle, and three posterior. Dental formula for all species of Eidolon is 12/2, C1/1, P 3/3, M 2/3 (x2) = 34. Dentition is conservative relative to element count and structure, without special modifications and with no secondary cusps in canines or cheekteeth, except for comparatively larger size of P'. Upper incisors are small, rounded, and subequal in size. Lower incisors are similar to uppers and usually in contact with each other and canines. Molars contain longitudinal medial groove separating higher outer and lower inner ridge. All post-canine teeth are slightly separated.

Habitat. Tropical forests, with migratory movements in open areas, riverine forests, swamp forests, savannas, and mosaics of those habitats, from sea level up to ¢. 2000 m.

Food and Feeding. Food availability determines occurrence of African Straw-colored Fruit Bats. It feeds entirely on fruiting and flowering trees and eats any sweet juicy fruit, buds and young leaves of certain trees, flowers, nectar, and pollen. It also chews into soft wood to obtain moisture. It feeds on at least ten genera of flowers, 34 genera of fruit, and four genera of leaves. Fruit is collected from a tree, taken to a feeding roost, mashed between teeth by rapid tongue movements, and sometimes stored in cheek pouches. All but the smallest seeds are spit out as dry pellets, afterjuice has been sucked from fruit. Food is held mostly in the mouth. African Straw-colored Fruit Bats occasionally hang by their thumbs and manipulate food with feet and mouth. They open large fruits at bottoms and can cling with feet and thumbs to outside of a fruit or adjacent branches. They leave feeding sites by dropping 0-5- 2 m before taking flight.

Breeding. Breeding of African Straw-colored Fruit Bats is seasonally monoestrous, with most copulations occurring in April-June. Egg is fertilized and develops until blastocyst stage, but it does not continue to develop until c.3-month implantation delay ceases in October. Births take place in February—-May prior to onset of the higher of two rainfall peaks. Females have one young/pregnancy/year that is ¢.18% of mothers’ weights. Births occur in maternity colonies that are clusters of females. Age of first reproduction is c.2 years for females.

Activity patterns. African Straw-colored Fruit Bats begin to feed at about sunset and stop just after sunrise. They remain alert and active during the day, with eyes open, ears erect, and constant motion. Day roosts are in tall trees, caves, and rocks. Large trees used as day roosts have spreading branches and are commonly found in dense groves with thick undercover. At night, roosts are chosen according to food availability. Trees are of various heights and sizes, some in groups and others widespread. Roosting clusters are on sturdy branches 6-20 m aboveground.

Movements, Home range and Social organization. The African Straw-colored Fruit Bat roosts in enormous colonies of up to 1,000,000 individuals; sleeping groups number c.100. Large parts of populations are non-migratory in sub-Saharan Africa, but some individuals will travel as far as several thousand kilometers. There is currently no indication for gender-specific migratory behavior. During migration periods (October— December in East Africa), colonies disperse into small groups and form temporary roosts from which they eventually form “regular” roosts. During migration phase, several populations might converge in a given region; reportedly, eight million bats concentrate for a few weeks in Kasanka National Park ( Zambia) to take advantage of exceptionally rich fruit in seasonal swamp forests. Wide-range movements of African Straw-colored Fruit Bat populations generate continent-scale panmixia and also favor transmission of several viral diseases that are serious human health issues in Africa.

Status and Conservation. Classified as Near Threatened on The IUCN Red List. In general, the African Straw-colored Fruit Bat is common, forming colonies of thousands to even millions of individuals. Colonies can show extreme roostsite fidelity. Recent evidence of widespread decline has been shown in a well-known colony in Kampala ( Uganda) that declined over 40 years from ¢.250,000 individuals to 40,000 in 2007. African Straw-colored Fruit Bats are eaten in all communities in south-western Nigeria and elsewhere; hunters often are hired to shoot them for hotels and restaurants. Most people eat whole bats, including bones. It occurs in many protected areas (e.g. Kasanka National Park), and because it crosses country boundaries,its global conservation requires international cooperation.

Bibliography. Allen (1917), Andersen (1907, 1908a, 1912b), Burland & Wilmer (2001), Funmilayo (1976, 1978, 1979), Heffner et al. (2006), Igado et al. (2012), Jones (1972), Juste et al. (2000), Kerr (1792), Kingdon (1974), Kulzer (1969), Lang & Chapin (1917a, 1917b), Marshall (1985), Mickleburgh, Hutson, Bergmans, Fahr & Racey (2008), Monadjem, Taylor et al. (2007), Mutere (1965, 1968, 1980), Nowak & Paradiso (1983), Okon (1975), Ossa etal. (2012), Peel, Sargan et al. (2013), Peel, Wood et al. (2017), Racey (2004a), Richter & Cumming (2006, 2008), Rosevear (1965).

Figures

95. African Straw-colored Fruit Bat (Eidolon helvum), 96. Madagascan Straw-colored Fruit Bat (Eidolon dupreanum), 98. Steadfast Tube-nosed Fruit Bat (Paranyctimene tenax), 99. Broad-striped Tube-nosed Fruit Bat (Nyctimene aello), 100. Round-eared Tube-nosed Fruit Bat (Nyctimene cyclotis), 101. Mountain Tube-nosed Fruit Bat (Nyctimene certans), 102. Happy Tube-nosed Fruit Bat (Nyctimene wrighiae), 103. Lesser Tube-nosed Fruit Bat (Nyctimene varius), 104. Common Tube-nosed Fruit Bat (Nyctimene albiventer), 105. Dragon Tube-nosed Fruit Bat (Nyctimene draconilla), 106. Demonic Tube-nosed Fruit Bat (Nyctimene masalai), 107. Malaita Tube-nosed Fruit Bat (Nyctimene malaitensis), 108. Umboi Tube-nosed Fruit Bat (Nyctimene vizcaccia), 109. Island Tube-nosed Fruit Bat (Nyctimene major), 110. Philippine Tube-nosed Fruit Bat (Nyctimene rabori), 111. Pallas’s Tube-nosed Fruit Bat (Nyctimene cephalotes), 112. Keast’s Tube-nosed Fruit Bat (Nyctimene keasti), 113. Queensland Tube-nosed Fruit Bat (Nyctimene robinsont)

Subspecies and Distribution. E.h.helvumKerr,1782—widedistributionacrosssub-SaharanandequatorialAfrica,fromMauritaniaandSenegalEtoSudanandEthiopia,andStoNamibiaandSouthAfrica,includingBioko,Principe,andSaoToméIs,Pemba,Unguja,andMafiaIsinZanzibarArchipelago. E.h.annobonense Juste,Ibanez&Machordom,2000—AnnobonI,offEquatorialGuinea. E. h. sabaeum K. Andersen, 1907 — Arabian Peninsula in extreme SW Saudi Arabia and W Yemen .