Rhinonicteris aurantia (J.E. Gray, 1845)

Don E. Wilson & Russell A. Mittermeier, 2019, Rhinonycteridae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 194-209 : 204-205

1.

Orange Diamond-faced Bat

Rhinonicteris aurantia

French: Rh n nyctère d ré German: Orangefarbene Au sn B attna Spanish: R n dorado

Other common names: Go den H rseshoe Bat Orange H rseshoe Bat Orange Leaf n sed Bar P barn Leal nosed Bat

Taxonomy. Rhínolophm aumnlim]. E. Gray in Ewe, 1845 .

“Port Essington, near the Hospital," Northern Territon, Australia.

There are no formally recognized subspecies of R. aurrmha, although an isolated population in the Pilbara region of northern Western Australia was suggested to represent a separate “fonn. Available evidence does not fully support its distinct status. Differences were in call frequencies among populations not completely concordant with documented pattern of genetic variation, although it is expected that populations have been isolated for about 30,000 years. Monotypic.

Distribution. Endemic to Australia, in two di¶ unct regions separated by Great Sandy Desert: W region is smallcst and comprises the W part of Pilbara region of Westem Australia, and E region largest and includes NE Western Australia (Kimberley region), N Northern Territory, and NW Queensland.

Descriptive notes. Head-body 40-56 mm, tail 23-29 mm, ear 10-4-14-4 mm, forearm 45-51 mm; weight 6-12 g. No specific data are available for hindfoot length. The Orange Diamond-laced Bat a medium-sired rhinomcterid. Individuals in the Pilbara population are slightly smaller than those in nonhem Australia. Pelage has similar tinge dorsally and \ entrally, usualh bright orange; in some individuals, t is pale brown, pale yellow, or white; hairs can be darker around mes. Wing membranes are dark brown, and noseleaf and ears are pale pinkish to very pale grayish brown. Noseleaf is large (width 5 -3-8-9 mm) and diamond-shaped, with strap-like longitudinal projection across anterior part of anterior leaf and lving abore deep anterior medial emargination. Poste rior leaf of noseleaf has no tall posterior projections, and its anterior part has long and narrow projection, with rounded tip in medial position. Central and posterior pans of posterior leaf are scalloped with numerous cells, separated from each other b\ fleshy septa. Thickened ridge lies beneath anterior leaf. Ears are small, triangular, and sharply pointed. Skull has dorsalh and lateralh prominent nasal swellings, depression between rostrum and braincase that is markedly higher than rostrum, and sagittal crest that coveis onlw central and posterior parts of braincase. Wide plates are present on dorsal sides of zygomatic bones. Greatest skull lengths are 15-9-18 mm, condflofanine lengths are 13-9-15 -7 mm, zygomatic widths are 8-9-1 mm, and upper tooth row (C -M lengths are 5 -4-6-4 mm. l’ is bilobed; C‘ is slender, with slight cingulum and large posterior secondary l” is small and extruded; C' and P‘ in contact and M‘ is little cusp; are; only reduced and has metacone. All lower incisors are tricuspid, C, is slender, P, has about one-half the crown area and height of P‘, and M, is unreduced. Baculum is gracile and 2 -1-2-3 mm long, with broadly pyramid-like proximal epiphysis and bluntly terminating simple distal epiphysis, slightly curved dorsally; it has narrow diaphysis (5-7% of baculum length) and proximal epiphysis (0-5-0-6 mm wide; 24-26% of baculum length).

Habitat. Variety of habitats, including monsoon rainforests, tall open forests, open savanna woodlands, grasslands, and shrublands at elevations up to c. 800 m in dry habitats and up to 400 m in more humid habitats. The Orange Diamond-faced Bat seems to be more limited by availability of roosts than vegetative cover type, although dry open habitats represent much larger part of overall distribution than humid and closed forests. Geographically isolated population in Pilbara inhabits the most arid zone in overall distribution.

Food and Feeding. The Orange Diamond-faced Bat is an aerial hawker and preys on flying insects of various sizes, mainly smaller moths and beetles. Diet composition shows opportunistic prey selection; during wet season, it clearly prefers flying tennites that provide fat-rich diets for pregnant and laetating females. Annually, diet averages 70% moths, 17% beetles, 7% termites (but in December, 056%), 5% flies, and mosquitoes, with occasional ants, wasps, mantises, lacewings, bugs, and cockroaches (representing 1 —2% together). Individuals forage along gorges, ravines, and larger watercourses and in open woodlands and over grassland hills.

Breeding. The Orange Diamond-faced Bat seasonallv monoestrous. Females give birth to one young in late December or earlyjanuary after five-month gestation. First three months of pregnancy and sperm production occur during periods of low food availability, and late pregnancy and lactation coincide with maximum food availability. Gestation is prolonged for c.1550 days, although sperm storage and delayed embryonic development have not been observed. Females leave their dry season roosts during late pregnancy and lactation, returning only after young are weaned and independent in late February. This suggests they use separate roosts for birth and rearing of young in wet season. Females are reproductively mature at c.7 months old; males do not mate until 16-18 months old. Males have enlarged testes and mate injuly; mature spermatozoa were observed in testes in April, with increasing numbers up until copulation and declining numbers from August to October; and none were observed in December-March (wet season).

Activity patterns. The Orange Diamond-faced Bat is unable to enter torpor and does not hibernate or estivate; remains active year-round and forages in all seasons. lt is strong and highly acrobatic flier; it flies rapidly (up to 26 km h) with fast wingbeats, tends to forage with an erratic ziglagging flight pattem, and remains in flight all the time while foraging. 1 t forages at various heights: low to the ground or water surface at c.0 -1 m, up to the height above tree crowns, and in all stories in between, including understories and tree canopies. When leaving the day roost, flight is most enatic, which is considered anti-predator behavior. It roosts in underground spaces in natural caves, man-made mines, and occasionally buildings. might roost in tree hollows, but this has not been confirmed. Because the Orange Diamond-faced Bat cannot enter torpor, it needs to roost in relatively wann and humid spaces (28-32 C and 85-100% relative humidity) that naturally occur in deep caves or mines. Underground spaces with such conditions are relatively uncommon in most rocky landscapes of north-westem Australia, but in the monsoonal nonh, humid conditions probably allow use of more caves and rarely buildings. Orange Diamond-faced Bats are often seen flying along roads at night. They leave day roost 10-20 minutes after sunset and forage for several hours (mostly 1 -5-4 hours) or the entire night; however, most individuals return to roosts c.2 hours before sunrise. Sometimes, there is a second activity period of 1-2 hours before sunrise. When roosting, they hang freely from the cave ceiling or on cave walls and are separated from each other by 10-15 cm. Echolocation consists of multihannonic QCF calls where pulse is composed of long CF component, complemented at start and end by two short FM components (FM-CF-FM). The CF component of the first hannonic lasts c. 5-8 milliseconds, initial FM component is short upward sweep (not always detectable), and tenninating FM component is steep sweep of c. 20 kHz. Geographical variation in peak frequencies of calls was reported: 109-119 kHz (mean 114 -6 kHz) in northern Australia and 116-126 kHz (mean 121 kHz) in the Pilbara region.

Movements, Home range and Social organization. The Orange Diamond-faced Bat is colonial and creates colonies of a few to se \ eral thousand individuals, typically up to several hundred. large colonies in the thousands are the exception, with only two currently known. Although there are reports of colonies of 20,000 -25,000 individuals, such a size has not been confinned. Both sexes occur in larger colonies to mate in dry season (] uly), but later during late pregnancy and lactation (December-February), many females disappear from these caves, returning only after young are weaned and independent. Because there no evidence of migrations, the two main populations of Orange Diamond-faced Bats separated by the Great Sandy Desert (c. 1400 km wide) probably have isolated for many thousands of years. Movements within regional popu-Iations are probablyjust related to searching for suitable roosts, with limited exchange among them.

Status and Conservation. Classified as Least Concern on The IUCN Red List. A national law in Australia protects the Orange Diamond-faced Bat.

Bibliography. Armstrong (2002 2005 2006a 2006 b) Armstrong G« Co es (2007) Baud nette er a (2000). Church) (1991, 1994, 1995. 2008), Cramer 6 M (2016). Gray (1845). Hand (1997). H (19828)

Figures

1. Orange Diamond-faced Bat (Rhmonícteris aurantia), 2. Persian Trident Bat (Triaenops persicus), 3. Yemeni Trident Bat (Tnaenops paruus), 4. African Trident Bat (Triaenops afer), 5. Rufous Trident Bat (Triaenops menamena), 6. Percival`s Trident Bat (Cloeotis pemivali), 7. Grandidiefs Trident Bat (Paratnaenops auritus), 8. Trouessart’s Trident Bat (Paratriaenops furcula), 9. Paulian ’ Trident Bat s (Paratriaenops pauliani)

Distribution. Endemic to Australia , in two di¶ unct regions separated by Great Sandy Desert: W region is smallcst and comprises the W part of Pilbara region of Westem Australia , and E region largest and includes NE Western Australia (Kimberley region), N Northern Territory, and NW Queensland.