Overview

Rhinolophus denti – Thomas, 1904

ANIMALIA – CHORDATA – MAMMALIA – CHIROPTERA – RHINOLOPHIDAE – Rhinolophus – denti 

Common Names: Dent’s Horseshoe Bat (English), Dent se Saalneusvlermuis (Afrikaans)
Synonyms: No Synonyms 

Taxonomic Note: 
Though previously believed that Rhinolophus swinnyi might be a subspecies of R. denti (Csorba et al. 2003), a genetic study by Schoeman and Jacobs in 2008 indicated the two to be separate species. Historically, two subspecies have been recognised: the larger nominate R. d. denti Shortridge, 1942 from southern Africa and the smaller R. d. knorri Eisentraut, 1960 from West Africa (Mammal Diversity Database 2025). Recent phylogenetic evidence suggests potential genetic differentiation between the arid-adapted southern African population and central African populations (Taylor et al. 2024). In addition,  Herkt et al. (2017) demonstrated differential ecological niches models for southern versus West African taxa, lending support to the previously proposed subspecific delineation. 

Red List Status: VU – Vulnerable D1 (IUCN version 3.1)  

Assessment Information

Assessors: Taylor, P.¹, Balona, J.², Lotter, C.³, & da Silva, J.M.⁴ 

Reviewers: Howard, A.¹, Richards, L.R.⁵ & Naidoo, T.⁵ 

Institutions: ¹University of the Free State, ²Gauteng and Northern Regions Bat Interest Group, ³Inkululeko Wildlife Services (Pty) Ltd, ⁴South African National Biodiversity Institute, ⁵Durban Natural Science Museum 

Previous Assessors and Reviewers: Schoeman, C., Jacobs, D., Cohen, L., MacEwan, K., Monadjem, A., Richards, L.R., Sethusa, T. & Taylor, P. 

Previous Contributors: Roxburgh, L., Child, M.F. & Raimondo, D. 

Assessment Rationale 

Dent’s Horseshoe Bat has been uplisted from Near Threatened to Vulnerable under Criterion D1. Currently this species is known from only nine locations in the assessment region, with the latest location recorded in 2019 near Carnarvon (Inkululeko Wildlife Services unpubl. data), which extends its range south in the Northern Cape. Within its estimated extent of occurrence (EOO) of 80,094 km², this species depends predominantly on caves, abandoned mines, and similar habitats for roosting (Monadjem et al. 2020). Thus, its area of occupancy is 88 km². Colonies range in size from one to a few dozen individuals (Monadjem et al. 2020). Therefore, fewer than 1,000 mature individuals are suspected to occur within the assessment region. In addition, it is suspected that the species is declining in the assessment region due to: i) extensive renewable (solar and wind) energy development in the Northern Cape, particularly within this species’ EOO (such as around Upington, Kenhardt, Copperton, Kimberley, Postmasburg, and other towns (DFFE 2024); ii) closure of old mine tunnels as gazetted by the South African Department of Mineral Resources and Energy (Government Notice 446, 21 May 2021); iii) the low number of (three) reported locations for this species since 2012 (ACR 2024; Inkululeko Wildlife Services unpubl. data). As renewable energy development is expected to expand still further in the region (DFFE 2024), and since the species is known to be protected within a single formal protected area (the Meerkat National Park; Inkululeko Wildlife Services unpubl. data), the population within the assessment region may decline between 10-20% over the next two generations (10 –20 years). However, field surveys and monitoring are required to more accurately estimate population size and trend. Re-assessment will be necessary once more comprehensive population data are available.

Regional population effects: R. denti is a small bat with short and broad wings with low wing loading (Schoeman & Jacobs 2008) This suggests a limited ability to disperse long distances, and thus immigration into the assessment region by individuals from subpopulations occurring outside of the region is unlikely. There is preliminary evidence of genetic differentiation between southern and central African individuals; however, this finding requires further investigation with larger sample sizes (Taylor et al. 2024).  

Red List Index 

Red List Index: Uplisted 

Reasons for change: Credible and escalating threats from the rapid expansion of renewable energy developments within the core distribution range of the species in the assessment region, the potential closure of abandoned mines (an important roosting habitat for the species), the absence of additional recent distribution records, combined with an overall uncertainty regarding population trends, warrant an uplisting from Near Threatened to Vulnerable. This status may be further elevated to Endangered if evidence confirms significant and severe reductions in known roost population sizes. 

Recommended citation: Taylor P, Balona J, Lötter C & da Silva JM. 2025. A conservation assessment of Rhinolophus denti. In Patel T, Smith C, Roxburgh L, da Silva JM & Raimondo D, editors. The Red List of Mammals of South Africa, Eswatini and Lesotho. South African National Biodiversity Institute and Endangered Wildlife Trust, South Africa.

Regional Distribution and occurrence

Geographic Range 

This species is widely, but patchily, recorded in West and southern Africa. It ranges from southeastern Senegal, through northern parts of West Africa to northeastern Ghana; in Central Africa it appears to have only been recorded from eastern Congo and southern Angola; in southern Africa, it is present in Namibia, western Botswana and northern parts of South Africa (ACR 2024; Monadjem et al. 2020). Within the assessment region it occurs predominantly in the Northern Cape, but marginally in the North West and Free State provinces. Recent climate-based prediction is that the present-day range of R. denti is very limited in extent (Taylor et al. 2024), especially within the assessment region. It’s EOO is estimated to be 80,094 km² and its AOO is 88 km².  The type specimen is from Kuruman, Northern Cape, South Africa (Monadjem et al. 2020). Inkululeko Wildlife Services (unpubl. data) recorded a single bat roosting in a small, abandoned mine tunnel near Carnavon in 2019, which was verified through its echolocation structure, and thus represents the most southerly record for the species within the assessment region.  

Elevation / Depth / Depth Zones 

Elevation Lower Limit (in metres above sea level):  922 m asl (Monadjem et al. 2024) 

Elevation Upper Limit (in metres above sea level):  1,844 m asl (Monadjem et al. 2024) 

Depth Lower Limit (in metres below sea level): (N/A 

Depth Upper Limit (in metres below sea level): N/A 

Depth Zone: N/A 

Figure 1. Distribution records for Dent’s Horseshoe Bat (Rhinolophus denti) within the assessment region (South Africa, Eswatini and Lesotho). Note that distribution data is obtained from multiple sources and records have not all been individually verified.

Biogeographic Realms 

Biogeographic Realm: Afrotropical 

Occurrence 

Countries of Occurrence 

Large Marine Ecosystems (LME) Occurrence 

Large Marine Ecosystems: N/A 

FAO Area Occurrence 

FAO Marine Areas: (Not specified) 

Climate change

Taylor et al. (2024) reported a potential expansion in the range of this species under future climate models. The modelling indicated that precipitation of the wettest month was the most important environmental variable for this arid-adapted Rhinolophus species. However, given the limited dispersal capabilities of this small-sized horseshoe bat, it may not be able to realise this potential climate advantage, especially in the light of anthropogenic disturbances. 

Population information

This species is known from fewer than 200 locations in southern Africa, and from only nine locations within the assessment region. Colonies are predominantly small (Monadjem et al. 2020; ACR 2024), typically from one to a few dozen individuals (Smithers 1971). However, a large colony of approximately 480 individuals has been reported from Namibia (Churchill et al. 1997), and this species is a slow reproducer. Over 80 specimens were examined in Monadjem et al. (2020). The total population within the assessment region is suspected to consist of less than 1,000 mature individuals. While Herselman and Norton (1985) considered this species rare and possibly extinct in the assessment region, specimens were collected after this publication from Koegelbeen Cave, a cave near Warrenton, and a locality near Postmasberg (ACR 2024); with the most recent observation in an abandoned mine tunnel near Carnarvon in 2019. The most recent call recordings of this species were made at Soetfontein Cave (near Postmasburg) in February 2023, and at Koegelbeen Cave (near Grikwastad) in November 2023 and February 2024 (Inkululeko Wildlife Services unpubl. data). While it is difficult to determine population size from acoustic data, this species contributed only 4-9% of all bat calls recorded during surveys undertaken at Soetfontein (9 of 255 calls recorded for 1.5 hours after sunset) and Koegelbeen (26 of 286 calls recorded for 1 hour after sunset in November 2023; and 210 of 6435 calls recorded from sunset to sunrise over two nights in February 2024). From this call data we infer that these colonies comprised fewer than 100 mature individuals each. Due to threats including renewable energy development and closure of old mines, the population within the assessment region is projected to decline between 10-20% over the next two generations (10–20 years). 

Current population trend: Declining 

Continuing decline in mature individuals: Yes, suspected. 

Number of subpopulations: One (Taylor et al. 2024). May be attributable to the nominate R. d. denti. The southern population is thought to be in decline; however, this assumption requires confirmation through quantitative data. 

Extreme fluctuations in the number of subpopulations:  Recent data suggest that only a single population exists within the assessment region. 

Continuing decline in number of subpopulations: Recent data suggest that only a single population exists within the assessment region. 

All individuals in one subpopulation: Assumed to be. 

Number of mature individuals in largest subpopulation: <1000 individuals in the assessment region. 

Quantitative Analysis 

Probability of extinction in the wild within 3 generations or 10 years, whichever is longer, maximum 100 years: This cannot be determined without reliable population data, although there are notable concerns regarding the decline of the species within the assessment region on account of the above-listed threats.  

Probability of extinction in the wild within 5 generations or 20 years, whichever is longer, maximum 100 years: This cannot be determined without reliable population data, although there are notable concerns regarding the decline of the species on account of the above-listed threats. 

Probability of extinction in the wild within 100 years: This cannot be determined without reliable population data, although there are notable concerns regarding the decline of the species on account of the above-listed threats. 

Population genetics

No population genetic studies exist for the species; however, it has been incorporated in a few phylogenetic investigations on African horseshoe bats (Demos et al. 2019; Taylor et al. 2024). The arid-adapted R. denti from the western Escarpment of South Africa diverged from previously recognised R. denti from central Africa (W DRC and Gabon) approximately 3.13 (1.44–4.96) Ma, likely warranting the designation of the central Africa group as a separate species (Taylor et al. 2024). 

Based on hindcasting of climatic niches, it would appear that the distributional range in South Africa was far more extensive, extending throughout Namibia up to the Last Glacial Maxima, yet at present the distribution shows two greatly reduced disjunct localities in Namibia and South Africa. This could have impacted the population genetic structure and diversity considerably, possibly manifesting as population bottlenecks resulting in reduced genetic diversity. These inferences would need to be confirmed using a fine-scale population genomic assessment across the species range.  

Based on current population size estimates based on acoustic surveys of about 1,000 mature individuals, the estimates Ne for the species in the assessment region (based on 0.1-0.3 Ne/Nc conversion ratio) is quantified as 100-300 individuals (well below the Ne 500 threshold). 

Habitats and ecology

This species is associated with arid savannah habitats where suitable roosting sites occur; typically restricting it to broken country with rocky outcrops or suitable caves (Monadjem et al. 2020). Even the most southeasterly record in Africa comes from the drier southwestern part of the Free State Province (Watson 1998). Colonies are largely dependent on caves, caverns, crevices in rocky outcrops, abandoned mines (including asbestos mines; M. C. Schoeman unpubl. data), and similar habitats for roosting (Herselman & Norton 1985; Churchill et al. 1997), although they have also been found roosting in hollow trees, as well as under the thatched roof of a house and in a road culvert (Shortridge 1934). As it is not able to fly large distances, due to its short, broad wings (Schoeman & Jacobs 2008), individuals’ home ranges are thus suspected to be under 10 km². In the assessment region, the species is recorded from Kalahari Duneveld, Eastern Kalahari Bushveld, Nama Karoo Shrublands, and Dry Highveld Grassland. It is a clutter forager, with its diet consisting mainly of Lepidoptera (M.C. Schoeman, unpubl. data). 

Ecosystem and cultural services: As this species is insectivorous, it may contribute to controlling insect populations that damage crops (Boyles et al. 2011; Kunz et al. 2011). Ensuring a healthy population of insectivorous bats can thus decrease the need for pesticides. 

IUCN Habitats Classification Scheme 

Life History 

Generation Length: 5-10 years (presumably for an arid Rhinolophus species) 

Age at Maturity: Female or unspecified: Unknown 

Age at Maturity: Male: Unknown 

Size at Maturity (in cms): Female: Forearm mean = 4.35 ±0.08 cm (Monadjem et al. 2020) 

Size at Maturity (in cms): Male: Forearm mean = 4.27 ± 0.07 cm (Monadjem et al. 2020) 

Longevity: Unknown 

Average Reproductive Age: Unknown 

Maximum Size (in cms): Female maximum forearm length = 4.50 cm, Male maximum forearm length = 4.40 cm (Monadjem et al. 2020) 

Size at Birth (in cms): Unknown 

Gestation Time: Unknown 

Reproductive Periodicity: No reproductive information is available (Monadjem et al. 2020) 

Average Annual Fecundity or Litter Size: (Not specified) 

Natural Mortality: (Not specified) 

Breeding Strategy 

Does the species lay eggs? No 

Does the species give birth to live young: Yes 

Does the species exhibit parthenogenesis: No 

Does the species have a free-living larval stage? No 

Does the species require water for breeding? No 

Movement Patterns 

Movement Patterns: Its home range is suspected to be under 10 km². It is believed that, unlike other Rhinolophus species, this species may not undertake local migrations but instead remain at the same roost site throughout the year (Smithers 1983; Skinner & Smithers 1990; Taylor 2005). 

Congregatory: Colonies range from one to a few dozen individuals (Smithers 1971; Skinner and Chimimba 2005); however, a colony of approximately 480 individuals were recorded from a cave system in Namibia (Churchill et al. 1997).  

Systems 

System: Terrestrial 

General Use and Trade Information

Not known to be traded or utilised in any form. 

Local Livelihood: None reported 

National Commercial Value: (Not specified) 

International Commercial Value: (Not specified) 

End Use: (Not specified) 

Is there harvest from captive/cultivated sources of this species? (Not specified) 

Harvest Trend Comments: (Not specified) 

Threats

A recent climate-based prediction is that the present-day range of R. denti is very limited in extent (Taylor et al. 2024), especially within the assessment region. Roost disturbance and loss presents a serious threat, which should be closely monitored. Roost loss can occur through the reopening of old mines and through disturbance during recreational or tourism activities. Implementation of the Mine Closure Strategy of the South African Department of Mineral Resources and Energy (Government Notice 446, 21 May 2021) may threaten colonies that are roosting in old mine tunnels. Therefore, systematic monitoring of colony sizes and trends is needed, and the status of this species must be checked every few years or more often. Extensive renewable (solar and wind) energy development in the Northern Cape, particularly within this species’ EOO (such as around Upington, Kenhardt, Copperton, Kimberley, Postmasburg, and other towns; DFFE 2024) may present a major threat to this species. Due to wing morphology and the clutter foraging habits of this species, it is regarded as having a low risk of fatality from wind turbines (MacEwan et al. 2020). However, colonies could be compromised by destruction/disturbance/degradation of, and displacement from, roost sites, water sources, feeding areas, and movement paths due to e.g. clearing of vegetation for solar panels, noise and vibrations from construction activities, spinning turbines, and light pollution in the previously dark nighttime landscape of the Northern Cape. As a cavity-roosting species, R. denti could be particularly sensitive to light pollution. Indirect poisoning resulting from the use of insecticides, pesticides and similar chemicals, and light pollution may also decrease the natural prey base of this species within its arid range. 

Conservation

The species is not currently recorded from any formally protected areas in the assessment region except for the Meerkat National Park (Inkululeko Wildlife Services unpubl. data) which encompasses part of the Square Kilometre Array project. Thus, its occurrence in additional protected areas should be documented and collated through checklists. The South Africa Department of Mineral Resources and Energy should engage with the South African Bat Assessment Association with regards to future closure of old mine tunnels in the country, so as to minimise the impact of this on cavity-roosting bat species such as R. denti. Renewable energy developments must avoid encroachment into the prescribed buffers around confirmed and potential roosts of this species (for buffer recommendations see MacEwan et al. 2020 or later). Monitoring of population trends in response to the threat of mine closure or expansion, and renewable energy development, is strongly recommended. This species would also benefit from holistic land management techniques that reduce the needs for pesticides.

Recommendations for land managers and practitioners: 

• Identify, protect, and monitor important roost sites for this species. 
• The South Africa Department of Mineral Resources and Energy should engage with the South African Bat Assessment Association with regards to future closure of old mine tunnels in the country, so as to minimise the impact of this on cavity-roosting bat species such as R. denti. 
• Renewable energy development must avoid encroachment into the prescribed buffers around confirmed and potential roosts of this species (see MacEwan et al. 2020). 
• Reduce pesticide use in agricultural landscapes. 

Research priorities: 

• Further phylogenetic and phylogeographic research, combined with detailed morphological analyses, is required to clarify the taxonomic status of the identified genetic clades. 
• Systematic surveys to identify further colonies and assess population size and trend. 
• Research investigating the severity of identified threats, including the effects of climate change, and potential conservation interventions. 

Encouraged citizen actions: 

• Minimise disturbance to caves when visiting, particularly within this species’ distribution range. 
• Citizens can report sightings on virtual museum platforms (for example, iNaturalist and MammalMAP). 
• Deposit any deceased specimen material in a recognised museum or established biorepository. 

Bibliography

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Boyles, J.G., Cryan, P.M., McCracken, G.F. and Kunz, T.H. 2011. Economic importance of bats in agriculture. Science 332: 41–42. 

Churchill, S., Draper, R. and Marais, E. 1997. Cave utilisation by Namibian bats: population, microclimate and roost selection. South African Journal of Wildlife Research 27: 44–50. 

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Demos, T.C., Webala, P.W., Bartonjo, M. and Patterson, B.D. 2018. Hidden Diversity of African Yellow House Bats (Vespertilionidae, Scotophilus): Insights From Multilocus Phylogenetics and Lineage Delimitation. Frontiers in Ecology and Evolution 6: https://doi.org/10.3389/fevo.2018.00086. 

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