Rhinolophus hildebrandtii, Peters, 1878

Burgin, Connor, 2019, Rhinolophidae, Handbook of the Mammals of the World – Volume 9 Bats, Barcelona: Lynx Edicions, pp. 280-332 : 289

17 . Hildebrandt’s Horseshoe Bat

Rhinolophus hildebrandtii

French: Rhinolophe de Hildebrandt / German: Hildebrandt-Hufeisennase / Spanish: Herradura de Hildebrandt

Taxonomy. Rhinolophus hildebrandtii Peters, 1878 ,

Ndi, Taita Hills , Kenya .

Rhinolophus hildebrandtii is in the fumigatus species group along with R mabuensis , R cohenae, R smithersi , R mossambicus , R fumigatus , and R eloquens . The fumigatus group seems to be sister to the ferrumequinum species group and in a large Afro-Palearctic clade that includes Zantferi, capensis , euryale , fumigatus , ferrumequinum , xinanzhongguoensis , and maclaudi species groups. Rhinolophus hildebrandtii formerly included populations now attributed to R mabuensis , R cohenae , R smithersi , and R mossambicus , based on morphometric and phylogenetic research. It is included in a clade along with R mabuensis , R cohenae , and A smithersi , which is sister to A JtiossatnZwctzs. Rhinolophus hildebrandtii might still represent a species complex because there are specimens known throughout Nigeria, South Sudan, Ethiopia, DR Congo, Zambia, Malawi, Mozambique, Zimbabwe, and Botswana that still need to be assessed for their specific status. Distributional maps of R hildebrandtii and the other four species split from it do not include all specimens from Zambia, Zimbabwe, Malawi, Mozambique, and Botswana because their specific status is still too uncertain. Monotypic.

Distribution. Restricted confidently to Kenya, Tanzania, Rwanda, and Burundi, but specimens from C Nigeria, N DR Congo, S South Sudan, and SW & S Ethiopia are tentatively assigned to this species. There is a possible record from S DR Congo. Populations in Zambia, Malawi, and Zimbabwe might represent this species, but their specific status is uncertain. Additional sampling is needed to clarify these uncertainties.

Descriptive notes. Head-body c. 77-84 mm, tail 37-41 mm, ear 33-38 mm, hindfoot 11-15 mm, forearm 61-66 mm; weight 22- 5-25 g. Hildebrandt’s Horseshoe Bat is very similar to Smithers’s Horseshoe Bat (A smztAmi). Dorsal pelage is gray to grayish brown; venter is slightly paler. There is no orange morph. Males lack axillary tufts. Ears are medium-long in length (44-52% of forearm length). Noseleaf has long subtriangular lancet, with straight or slightly concave sides and rounded tip; connecting process is low and rounded, forming continuous arch to tip ofsella; sella is moderately covered in longish hairs and has concave sides near base but parallel sides near broad and rounded top; and horseshoe is broad at 10—15 mm, covers muzzle, has lateral leaflets, and has deeply notched median emargination. Lower lip has one groove. Wings and uropatagium are dark grayish brown. Skull is robust and comparatively long, with robust zygomatic arches and zygomatic width much larger than mastoid width; nasal swellings are relatively high and longer than they are broad; frontal depression is weak to moderately developed, and supraorbital ridges are well developed; and sagittal crest is well developed. Dental formula of Hildebrandt’s Horseshoe Bat differs from other species of Rhinolophus : I 1/2, C 1/1, P 1/2, M 3/3 (x 2) = 28 or I 1/2, C 1/1, P 2/2, M 3/3 (x 2) = 30. P 2 is tiny and fully displaced labially or completely absent, allowing C1 and P4 to touch or almost touch, and P3 is absent, allowing P2 and P4 to touch. Chromosomal complement has 2n = 58 and FN = 60.

Habitat. Semiarid and mesic woodland savannas (including mopane and miombo woodlands), riverine riparian forests, and submontane and montane forests from sea level to elevations of c. 1300 m in the Udzungwa Mountains.

Food and Feeding. Hildebrandt’s Horseshoe Bat is insectivorous and forages by perchhunting and slow hawking under canopies in woodland and riverine areas, often close to the ground or just above understory vegetation. It will also forage close to or in buildings and along corridors of vegetation next to water, preferring areas with dense vegetation rather than open ground. It will perch 2- 2-5 m aboveground, where it can detect prey. It seems to prey largely on moths and beetles.

Breeding. Hildebrandt’s Horseshoe Bat is seasonally monoestrous. Conception and implantation probably occur in July, with births at the end of October. Litter size is consistently one. Weaning seems to occur after c.3 months, and lactating individuals have been recorded well into December.

Activity patterns. Hildebrandt’s Horseshoe Bats are nocturnal, foraging through the night with short periods of rest in night roosts. They can enter torpor and are known to become torpid during the day at ambient temperatures of 21-24°. Night roosts are in foliage 2-4 m aboveground. Day roosts have been found in caves, hollowed out trees, mine shafts, abandoned holes of Aardvark ( Orycteropus afer ) and Warthogs ( Phacochoerus africanus ), building roofs, and fissures and cavities between and under rocks. Call shape is FM/CF/FM, with F component of 42-3—43-2 kHz in Kenya and 39-8 kHz in Tanzania.

Movements, Home range and Social organization. Hildebrandt’s Horseshoe Bat roosts singly or in small clusters of up to c.50 individuals in caves that contain hundreds of individuals in multiple clusters. Maternity colonies are created during breeding season. While hanging, individuals do not touch each other but hang apart in clusters. They do not seem to be territorial and individual foraging areas overlapped in one study.

Status and Conservation. Classified as Least Concern on 77 ze IUCN Red List. Hildebrandt’s Horseshoe Bat has a wide distribution and is considerably common throughout its distribution.

Bibliography. ACR (2018), Cotterill & Happold (2013c), Csorba et al. (2003), Happold & Happold (1990), Monadjem & Jacobs (2017a), Peterson & Nagorsen (1975), Stanley & Goodman (2011), Taylor et al. (2012), Trentin & Rovere (2011).

Figures

On following pages: 4. Lander's Horseshoe Bat (Rhinolophus landeri); 5. Guinean Horseshoe Bat (Rhinolophus guineensis); 6. Blasius's Horseshoe Bat (Rhinolophus blasii); 7. Peters's Horseshoe Bat (Rhinolophus lobatus); 8. Swinny's Horseshoe Bat (Rhinolophus swinnyi); 9. Cape Horseshoe Bat (Rhinolophus capensis); 10. Gorongosa Horseshoe Bat (Rhinolophus gorongosae); 11. Roberts's Horseshoe Bat (Rhinolophus rhodesiae); 12. Bushveld Horseshoe Bat (Rhinolophus simulato/); 13. Dent's Horseshoe Bat (Rhinolophus denti); 14. Cameroon Horseshoe Bat (Rhinolophus alticolus); 15. Mehely's Horseshoe Bat (Rhinolophus mehelyi); 16. Mediterranean Horseshoe Bat (Rhinolophus euryale); 17. Hildebrandt's Horseshoe Bat (Rhinolophus hildebrandtii); 18. Mount Mabu Horseshoe Bat (Rhinolophus mabuensis); 19. Cohen's Horseshoe Bat (Rhinolophus cohenae); 20. Smithers's Horseshoe Bat (Rhinolophus smithersi); 21. Mozambican Horseshoe Bat (Rhinolophus mossambicus); 22. Rüppell's Horseshoe Bat (Rhinolophus fumigatus); 23. Eloquent Horseshoe Bat (Rhinolophus Bloquons).

Distribution. Restricted confidently to Kenya , Tanzania , Rwanda , and Burundi , but specimens from C Nigeria , N DR Congo , S South Sudan , and SW & S Ethiopia are tentatively assigned to this species. There is a possible record from S DR Congo . Populations in Zambia , Malawi , and Zimbabwe might represent this species, but their specific status is uncertain. Additional sampling is needed to clarify these uncertainties.