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Kitti's hog-nosed bat
Kitti's hog-nosed bat
Kitti's hog-nosed bat
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Kitti's hog-nosed bat
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Superfamily: Rhinolophoidea
Family: Craseonycteridae
Hill, 1974
Genus: Craseonycteris
Hill, 1974
Species:
C. thonglongyai
Binomial name
Craseonycteris thonglongyai
Hill, 1974
Kitti's hog-nosed bat range

Kitti's hog-nosed bat (Craseonycteris thonglongyai), also known as the bumblebee bat or hog-nosed bat, is a near-threatened species of bat and the only extant member of the family Craseonycteridae. It occurs in western Thailand and southeast Myanmar, where it occupies limestone caves along rivers.

Kitti's hog-nosed bat is the smallest species of bat and arguably the world's smallest mammal by body length (the Etruscan shrew is regarded as the smallest by body mass). It has a reddish-brown or grey coat, with a distinctive pig-like snout. Colonies range greatly in size, with an average of 100 individuals per cave. The bat feeds during short activity periods in the evening and dawn, foraging around nearby forest areas for insects. Females give birth annually to a single offspring.

Although the bat's status in Myanmar is not well known, the Thai population is restricted to a single province and may be at risk of extinction. Its potential threats are primarily anthropogenic, and include habitat degradation and the disturbance of roosting sites.[1]

Description

[edit]
Stuffed specimen at the National Museum of Nature and Science, Tokyo, Japan.

Kitti's hog-nosed bat is small at about 29 to 33 mm (1.1 to 1.3 in) in length and 2 g (0.071 oz) in mass,[2][3] hence the common name of "bumblebee bat". It is the smallest species of bat and may be the world's smallest mammal, depending on how size is defined. The main competitors for the title are small shrews; in particular, the Etruscan shrew may be lighter at 1.2 to 2.7 g (0.042 to 0.095 oz) but its body is longer, measuring 36 to 53 mm (1.4 to 2.1 in) from its head to the base of the tail.[4]

The bat has a distinctive swollen, pig-like snout[3] with thin, vertical nostrils.[5] Its ears are relatively large, while its eyes are small and mostly concealed by fur.[6] In the jaw, the premaxillae are not fused with surrounding bones, and the coronoid process is significantly reduced.[7] Its teeth are typical of an insectivorous bat.[6] The dental formula is 1:1:1:3 in the upper jaw and 2:1:2:3 in the lower jaw,[5] with large upper incisors.[6]

The bat's upperparts are reddish-brown or grey, while the underside is generally paler.[6] The wings are relatively large and darker in colour, with long tips that allow the bat to hover.[3] The second digit of the wing is made of a single short phalanx. And the humerus has an increased number of locking tubercles on its head and beyond. There is a considerable fusion in the axial skeleton, concerning the thoracic (three posterior vertebrae), lumbar (two posterior) and sacral (all) sections. The bat has particularly slender legs, with rather thin fibula.[7] Despite having two caudal vertebrae, Kitti's hog-nosed bat has no visible tail.[6] There is a large web of skin between the hind legs (the uropatagium) which may assist in flying and catching insects, although there are no tail bones or calcars to help control it in flight.[3][6][8]

Range, habitat and diversity

[edit]

Kitti's hog-nosed bat occupies limestone caves along rivers within dry evergreen or deciduous forests.[3] In Thailand, it is restricted to a small region of the Tenasserim Hills in Sai Yok District, Kanchanaburi Province, within the drainage basin of the Khwae Noi River.[3][9] While Sai Yok National Park in the Dawna Hills contains much of the bat's range, some Thai populations occur outside the park and are therefore unprotected.[3]

Since the 2001 discovery of a single individual in Myanmar, at least nine separate sites have been identified in the limestone outcrops of the Dawna and Karen Hills outside the Thanlwin, Ataran, and Gyaing Rivers of Kayin and Mon States.[9] The Thai and Myanmar populations are morphologically identical, but their echolocation calls are distinct.[9] It is not known whether the two populations are reproductively isolated.[9]

Despite its restricted geographical range and specialized habitat requirements, Kitti's hog-nosed bat exhibits remarkable genetic diversity within its populations. Molecular analyses using microsatellite markers have revealed moderate levels of genetic differentiation among cave roosts in Thailand and Myanmar, suggesting historical isolation and limited gene flow between populations.

Biology and reproductive structure

[edit]
Roosting in Thailand

Kitti's hog-nosed bat roosts in caves in limestone hills, far from the entrance. While many caves contain only 10 to 15 individuals, the average group size is 100, with a maximum of about 500. Individuals roost high on walls or roof domes, far apart from each other.[10] Bats also undertake seasonal migration between caves.

Kitti's hog-nosed bat has a brief activity period, leaving its roost for only 30 minutes in the evening and 20 minutes at dawn. These short flights are easily interrupted by heavy rain or cold temperatures.[10] During this period, the bat forages within fields of cassava and kapok or around the tops of bamboo clumps and teak trees, within one kilometre of the roosting site.[3][10] The wings seem to be shaped for hovering flight, and the gut contents of specimens include spiders and insects that are presumably gleaned off foliage. Nevertheless, most prey is probably caught in flight.[10] Main staples of the bat's diet include small flies (Chloropidae, Agromyzidae, and Anthomyiidae), hymenopterans, psocopterans, and spiders.[10][11]

Kitti's hog-nosed bat suggest a unique reproductive strategy characteristic of microchiropterans. Females of this species typically give birth to a single offspring per reproductive event, with births occurring during the dry season between March and May. Maternity colonies composed of a small number of females are formed within cave roosts, providing communal protection and thermoregulatory benefits for nursing offspring. Male mating behaviors, such as courtship vocalizations and scent marking, have been documented in captive populations, indicating potential sexual selection mechanisms.

Taxonomy

[edit]

Kitti's hog-nosed bat is the only extant species in the family Craseonycteridae, which is grouped in the superfamily Rhinolophoidea as a result of molecular testing. Based on this determination, the bat's closest relatives are members of the families Hipposideridae and Rhinopomatidae.[5]

Kitti's hog-nosed bat was unknown to the world at large prior to 1974. Its common name refers to its discoverer, Thai zoologist Kitti Thonglongya. Thonglongya worked with a British partner, John E. Hill, in classifying bats of Thailand; after Thonglongya died suddenly in February 1974, Hill formally described the species, giving it the binomial name Craseonycteris thonglongyai in honour of his colleague.[12][13][7]

Ecological role and conservation

[edit]

As a microchiropteran species, Kitti's hog-nosed bat plays a crucial ecological role in its habitat, primarily as an insectivore. This species preys predominantly on small flying insects, including mosquitoes, moths, and beetles. By controlling insect populations, particularly those of agricultural pests and disease vectors, Kitti's hog-nosed bat contributes to ecosystem balance and human well-being. Furthermore, its presence in cave ecosystems may also influence nutrient cycling and the distribution of guano-dependent organisms.

As of the species' review in 2019, Kitti's hog-nosed bat is listed by the IUCN as near-threatened, with a downward population trend.[1]

Soon after the bat's discovery in the 1970s, some roosting sites became disturbed as a result of tourism, scientific collection, and even the collection and sale of individuals as souvenirs. However, these pressures may not have had a significant effect on the species as a whole, since many small colonies exist in hard-to-access locations, and only a few major caves were disturbed. Another potential risk is the activity of local monks, who have occupied roost caves during periods of meditation.[10]

Currently, the most significant and long-term threat to the Thai population could be the annual burning of forest areas, which is most prevalent during the bat's breeding season. In addition, the proposed construction of a gas pipeline from Myanmar to Thailand may have a negative impact.[14][10] Threats to the Myanmar population are not well known.[3][15]

In 2007, Kitti's hog-nosed bat was identified by the Evolutionarily Distinct and Globally Endangered project as one of its Top 10 "focal species".[16]

See also

[edit]

References

[edit]

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Kitti's hog-nosed bat

View on Grokipedia
from Grokipedia
Kitti's hog-nosed bat (Craseonycteris thonglongyai), commonly known as the bumblebee bat, is the world's smallest , with an adult body length of 29–33 mm, forearm length of 22–26 mm, and weight ranging from 1.7–2.0 grams. This tiny, insectivorous is characterized by its pig-like snout, large ears (9–10.2 mm), small eyes often hidden by fur, and lack of a tail, with brownish-red or gray fur on the upper body and paler underparts. Endemic to a restricted range along the Thailand-Myanmar border, it roosts exclusively in caves and forages in nearby forests, making it highly vulnerable to habitat disturbances. The species inhabits warm, humid cave systems in western Thailand's and southeastern (Kayin and Mon states), where it prefers roosting sites near cave ceilings for thermal regulation. Colonies typically consist of up to 100 individuals, though they exhibit limited , and bats forage within a 1 km radius of their roosts at and dawn, using high-frequency echolocation calls (up to 220 per second at 70–80 kHz) to detect prey. Their diet primarily comprises small aerial insects such as beetles, flies, and spiders, captured mid-flight with hovering flight enabled by long, wide wings. Reproduction occurs seasonally, with breeding in late to May, resulting in a single offspring per female; mothers isolate with their young in roosts, and the estimated lifespan is 5–10 years in the wild. Classified as Near Threatened by the , the global population is estimated at approximately 10,000 mature individuals as of 2019 and declining due to threats including cave tourism, limestone mining, , and guano collection for . Conservation efforts focus on protecting key roost sites within national parks like Sai Yok in to mitigate these pressures.

Physical characteristics and taxonomy

Description

Kitti's hog-nosed bat (Craseonycteris thonglongyai), also known as the bumblebee bat, is the smallest bat species by mass and one of the smallest mammals overall, with adults measuring 29–33 mm in head-body length, weighing approximately 2 g, and possessing a of about 130–145 mm. Its diminutive size rivals that of the (Suncus etruscus), which is similar in length but typically heavier. The bat's external morphology is highly distinctive, featuring a pig-like snout equipped with a thickened, vertical narial pad forming a triangular flap that separates the large nostrils. It has relatively large ears measuring 9–10.2 mm, which are pointed and equipped with a well-developed tragus about half the ear's length, while its eyes are small and often concealed by fur. The fur is reddish-brown to gray on the upper body, paler on the underside, and there is no visible external tail, though internal caudal vertebrae are present; the broad, long wings, supported by a forearm of 22–26 mm, are adapted for high maneuverability and hovering flight. For navigation, Kitti's hog-nosed bat relies on echolocation, emitting high-frequency multiharmonic constant-frequency pulses with a base frequency around 35 kHz, prominent second harmonic at 70–80 kHz, and weaker third harmonic up to 105–115 kHz, enabling precise detection of small prey and obstacles in cluttered environments. These calls, produced at rates up to 220 per second during hunting, sweep broadly from approximately 30 to 115 kHz across harmonics.

Taxonomy

Kitti's hog-nosed bat (Craseonycteris thonglongyai) is the sole extant member of the monotypic Craseonycteridae, classified within the order Chiroptera, suborder (previously grouped under Microchiroptera), and superfamily Rhinolophoidea. This classification reflects its position among the echolocating microbats, distinguished by unique cranial and dental features that set the family apart from related groups. Common names for the include bumblebee bat, reflecting its diminutive size comparable to a , and Kitti's hog-nosed bat, honoring its discoverer and the distinctive pig-like . The was first collected in 1973 by Thai zoologist Kitti Thonglongya from limestone caves near Sai Yok National Park in , with over 50 specimens obtained during surveys. Thonglongya recognized its novelty but passed away before formal description; in 1974, British mammalogist John E. Hill published the original description in the Bulletin of the (Natural History), establishing Craseonycteris thonglongyai as a new , , and family based on its aberrant morphology. Initial assessments noted resemblances to small-bodied bats in families like Rhinopomatidae and due to shared traits such as reduced size and certain nasal structures, leading to early taxonomic uncertainty. Molecular phylogenetic studies have clarified its evolutionary position, confirming Craseonycteridae as a distinct lineage within Rhinolophoidea, closely related to the families (hipposiderid bats) and Rhinolophidae (horseshoe bats). sequence analyses support its placement as a rhinolophoid rather than affiliated with emballonurids or rhinopomatids, resolving prior morphological ambiguities. The family represents an ancient divergence within this superfamily, with estimates indicating the split from other rhinolophoids occurred approximately 35 million years ago during the Eocene epoch. This early separation underscores its phylogenetic uniqueness as a lineage persisting as the only surviving member of Craseonycteridae.

Distribution and habitat

Geographic range

Kitti's hog-nosed bat (Craseonycteris thonglongyai) has an extremely restricted geographic range, confined to and southeastern along their shared border. The ' extent of occurrence is estimated at 22,333 km² (as of 2019), reflecting its dependence on a small number of isolated sites. In , the bat is primarily known from , especially Sai Yok District in Sai Yok National Park, where it inhabits s along the basin. The was first documented in 1974 from a near Sai Yok Waterfall in . Surveys between 2010 and 2013 confirmed its presence in 11 out of 24 s in Sai Yok District, including key sites like Tham Kaeng Kaew. In , populations are found in the , , and . The first confirmation was in 2001 from a single individual in . A 2002 survey identified the bat at nine caves out of 19 examined, spanning approximately 102 km from north to south near in and in . A 2025 biodiversity assessment in discovered several new colonies, extending the known range southward. Access challenges in have limited further surveys, resulting in fragmented knowledge of its distribution there. The bat's range is associated with limestone formations, though detailed habitat characteristics are addressed elsewhere.

Habitat preferences

Kitti's hog-nosed bat (Craseonycteris thonglongyai) exclusively inhabits landscapes, roosting solely in caves with complex structures featuring multiple chambers, high ceilings, and domed or conical shapes that provide protection and thermal stability. These caves are preferentially selected for their small side chambers or upper conical sections, where the bats cluster in groups averaging 100 individuals, often far from entrances to minimize disturbance. Roosting occurs on walls or ceilings in the warm upper regions, typically 1–3 meters above the floor, allowing the bats to maintain body temperature while avoiding ground-level threats like flooding during seasonal river overflows. The surrounding environment consists of dry evergreen or mixed deciduous forests, including bamboo stands, with the bats requiring an intact forest canopy within approximately 1 km of the roost to support nearby populations essential for survival. These caves are situated along rivers in systems, ensuring proximity to water sources while the forested buffer zones filter light and maintain ecological connectivity. Microhabitat conditions within preferred caves include high relative levels around 80–90% and stable s of 28–32°C, which support the bats' small size and high metabolic demands, alongside minimal exposure for resting. The avoids flooded chambers and heavily touristed sites, as activity disrupts these delicate conditions through , , and alterations in and . While highly sensitive to direct cave disturbances like limestone mining, Kitti's hog-nosed bat demonstrates some adaptability to peripheral habitat modifications, tolerating agricultural edges adjacent to intact forests as long as sufficient vegetative cover persists for insect foraging. This limited tolerance underscores the species' dependence on undisturbed ecosystems for long-term persistence.

Biology and behavior

Foraging and diet

Kitti's hog-nosed bat exhibits a strictly nocturnal activity cycle, with primarily occurring during brief bouts at and dawn. Evening foraging sessions typically last 30–45 minutes immediately after sunset, while morning sessions are shorter, around 20–30 minutes before sunrise, resulting in a total daily flight time of less than one hour. These short activity periods are adapted to the bat's small size and high metabolic demands, allowing it to enter during the day to conserve energy. The foraging range is limited to within approximately 1 km of roosting caves, often in the upper canopy of dry evergreen or bamboo forests, along river edges, or in nearby open areas. In these cluttered environments, the relies on sophisticated echolocation to detect and pursue prey, emitting high-frequency calls (around 70–80 kHz) at rates up to 220 per second during hunting. This enables precise navigation and prey location despite and other obstacles. The diet consists primarily of small insects such as flies (Diptera), ants and bees (Hymenoptera), small beetles (Coleoptera), and spiders (Araneae), all captured mid-air. These tiny prey items, often 1–6 mm in size, suit the 's diminutive stature. Hunting employs aerial hawking techniques, characterized by agile, fluttering flight with speeds of about 4 m/s and sharp 180° turns executed in 40–80 ms, allowing the to seize prey directly with its mouth without gleaning from surfaces. This maneuverability is facilitated by the 's long, wide wings, which provide exceptional control and hovering capability in confined spaces.

Reproduction and social structure

Kitti's hog-nosed bats reproduce annually, with females typically giving birth to a single offspring during the late dry season from late April to May. Little is known about the precise mating behaviors or gestation period. Females provide all parental care, carrying newborns attached to specialized finger-like projections on their lower abdomen while roosting in caves; the young are left alone in the roost during the mother's brief foraging excursions. Mothers roost individually with their offspring despite sharing caves with other bats. Colonies of Kitti's hog-nosed bats are small and variable in size, generally comprising 10 to 100 individuals that share limestone roosts, though numbers can reach up to 500 during peak seasons. The social structure is loose, with minimal observed interactions or dominance hierarchies among individuals, enabling flexible group composition that supports through shared roosting warmth and occasional mating opportunities. Developmental details remain poorly documented due to the species' elusive nature, but juveniles remain dependent on maternal care in the roost for several weeks post-birth, gradually becoming independent as they develop flight capabilities.

Ecology and conservation

Ecological role

Kitti's hog-nosed bat (Craseonycteris thonglongyai) serves as a strict within its tropical forest and ecosystems, primarily on small flying such as beetles, flies, and spiders in the upper canopy of forests near rivers. By capturing these prey aerially during brief evening and dawn periods, individuals and small colonies contribute to the regulation of insect , aiding natural despite their limited overall impact due to the species' diminutive size and low total of approximately 10,000 mature individuals. This trophic role helps maintain balance in forest insect communities, reducing potential outbreaks of agricultural and disease-vector pests in and southeastern . Due to its insectivorous diet focused on tiny arthropods rather than or , it has minimal potential as a for night-blooming , unlike larger nectar-feeding bats in the region. Its high local density in roost colonies of up to 100 individuals per cave, combined with low individual , allows for concentrated but ecologically subtle influences on local food webs. Guano deposits from roosting colonies enrich cave floors with nutrients like and , fostering microbial growth and supporting communities such as that form the base of subterranean food chains. These inputs enhance nutrient cycling in systems, where the bats' year-round presence in humid, river-adjacent s promotes a stable environment for guano-dependent organisms. As a strictly confined to undisturbed forests, the presence of Kitti's hog-nosed bat indicates intact quality, serving as a indicator for healthy tropical ecosystems characterized by caves, cliffs, and high . Its vulnerability to habitat alterations underscores the need to monitor such environments, where local densities reflect the overall integrity of these specialized, biodiverse landscapes.

Conservation status and threats

Kitti's hog-nosed bat (Craseonycteris thonglongyai) is classified as Near Threatened on the , with the assessment conducted on 31 August 2018 (published in the 2019 version) and no major updates reported as of 2025. The global population is estimated at ~10,257 mature individuals (approximately 3,770 in and 6,487 in ), reflecting its restricted range and vulnerability to localized pressures. The species faces multiple anthropogenic threats, primarily habitat loss due to and , which has degraded areas around roost caves. Roost sites are disturbed by cave , guano collection for fertilizer, and limestone mining activities that directly impact limestone habitats essential for the . Population trends indicate an overall decline driven by these threats. Subpopulations in protected areas of remain relatively stable, but those in are declining due to habitat pressures and ongoing political instability limiting monitoring efforts; the fragmented nature of subpopulations heightens risk. Conservation measures include legal protection under Thai wildlife laws, with key roosts safeguarded in Sai Yok National Park. Recommended actions encompass enhanced cave monitoring to minimize disturbances, enforcement against and impacts, and establishment of transboundary protected areas along the Thailand- border. Significant research gaps persist, particularly regarding comprehensive population surveys in Myanmar, where access challenges due to conflict impede data collection.

References

  1. https://animaldiversity.org/accounts/Craseonycteris_thonglongyai/
  2. https://www.batcon.org/bat/craseonycteris-thonglongyai-2/
  3. https://www.ecologyasia.com/verts/bats/kitti%27s-hog-nosed-bat.htm
  4. https://www.iucnredlist.org/species/5481/22072935
  5. https://www.dimensions.com/element/bumblebee-bat-craseonycteris-thonglongyai
  6. https://www.guinnessworldrecords.com/world-records/70467-smallest-mammal
  7. https://www.science.smith.edu/departments/biology/VHAYSSEN/msi/pdf/i0076-3519-160-01-0001.pdf
  8. https://link.springer.com/article/10.1007/BF00164341
  9. https://pmc.ncbi.nlm.nih.gov/articles/PMC3038382/
  10. https://www.mammaldiversity.org/taxon/1004554/
  11. https://www.researchgate.net/publication/270041036_Craseonycteris_thonglongyai_Chiroptera_Craseonycteridae_is_a_Rhinolophoid_Molecular_Evidence_from_Cytochrome_b
  12. https://www.researchgate.net/publication/269396192_The_distribution_of_Kitti%27s_hog-nosed_Bat_Craseonycteris_thonglongyai_in_Kanchanaburi_Province
  13. https://thesiamsociety.org/wp-content/uploads/2020/04/NHBSS_038_2g_Duangkhae_EcologyAndBehav.pdf
  14. https://www.mammalwatching.com/community-post/tips-on-kittis-hog-nosed-bats-thailand/
  15. http://www.rhinoresourcecenter.com/pdf_files/171/1712413987.pdf
  16. https://www.researchgate.net/publication/229087272_Status_of_the_world%27s_smallest_mammal_the_bumble-bee_bat_Craseonycteris_thonglongyai_in_Myanmar
  17. https://www.darwininitiative.org.uk/documents/DAR11019/4144/11-019%20FR%20-%20edited.pdf
  18. https://thesiamsociety.org/wp-content/uploads/2020/04/NHBSS_039_1e_Duangkhae_SearchForKittis.pdf
  19. https://www.jw.org/en/library/magazines/g201002/The-Worlds-Smallest-Bat/
  20. https://www.thainationalparks.com/species/kittis-hog-nosed-bat
  21. https://marinebioacoustics.wordpress.com/wp-content/uploads/2018/11/27-surlykke-et-al-1993-hog-nosed-bat-thailand.pdf
  22. https://www.encyclopedia.com/environment/encyclopedias-almanacs-transcripts-and-maps/kittis-hog-nosed-bats-craseonycteridae
  23. https://critter.science/the-tiny-bumblebee-bat/
  24. https://www.researchgate.net/publication/275648543_Are_bats_karst-dependent
  25. https://www.researchgate.net/publication/346061306_The_Life_Hidden_Inside_Caves_Ecological_and_Economic_Importance_of_Bat_Guano
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