Rhinolophidaehorseshoe bats

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Diversity

Rhinolophidae includes approximately 77 species in a single genus, Rhinolophus. Rhinolophidae has sometimes been considered to include members of the family Hipposideridae (Old World leaf-nosed bats, with 82 species in 9 genera) as well, with the two groups being considered subfamilies (Rhinolophinae and Hipposiderinae). There is little question that these two groups of bats are closely related, but current understanding suggests the two groups should be recognized as families. (Vaughan, et al., 2000; Wilson and Reeder, 2005)

Rhinolophids inhabit temperate and tropical regions of southern Europe, Africa, Asia, parts of Australasia, and many Pacific islands. All species are insectivorous, hawking insects in flight or gleaning them from surfaces. Their roost habits are diverse; some species are found in large colonies in caves, some prefer hollow trees; others sleep in the open, among the branches of trees. Members of northern populations may hibernate during the winter. Females of some rhinolophid species mate during the fall and store sperm over the winter, conceiving and gestating young beginning in the spring. (Hill and Smith, 1984; Nowak, 1991a; Nowak, 1991b; Vaughan, et al., 2000)

Geographic Range

Rhinolophids are widely distributed throughout both temperate and tropical regions of the Old World. They inhabit southern Europe, Africa, Asia, northern and eastern Australia, and many Pacific islands. (Hill and Smith, 1984; Nowak, 1991a; Nowak, 1991b; Vaughan, et al., 2000)

Habitat

Rhinolophids are found in a variety of temperate, tropical and desert biomes at both high and low elevations. They forage both within forests and in open spaces. Their roosting habits are also diverse: rhinolophids use caves, tree holes, foliage, mines, and buildings. Species that hibernate may use different roost types in the summer and winter months. While a cave may be used for hibernation in the winter, a tree hole may be used as a summer roost. (Nowak, 1991a; Nowak, 1991b; Vaughan, et al., 2000)

Physical Description

All rhinolophids have leaf or spear-like protuberances on their noses. The projection beneath the nostrils is horse-shoe shaped and pronounced in rhinolophids. Echolocation calls are emitted through these nasal structures, which may serve to focus the sound. The ears of these bats vary in size and lack a tragus. Most rhinolophids are dull brown or reddish brown in color. Their fur has a tendency to become bleached, so some individuals may become a bright reddish-orange. They vary in size from small to moderately large (4 to 28 grams). Males may be slightly larger than females. Their wings are broad and rounded, making them highly maneuverable in flight in cluttered spaces. (Hill and Smith, 1984; Nowak, 1991a; Nowak, 1991b; Vaughan, et al., 2000)

Rhinolophids have distinctive premaxillae, with palatal branches only. The premaxillae on opposite sides of the skull are neither fused with each other nor are they fused with the maxillary bones. Rhinolophid skulls often have distinct sagittal and lambdoidal crests. The palate is unusually short due to deep indentations at both ends. The molars are dilambdodont, and the dental formula is 1/2, 1/1, 1-2/2-3, 3/3 = 28-32. (Nowak, 1991a; Nowak, 1991b)

  • Sexual Dimorphism
  • sexes alike
  • male larger

Reproduction

Although there is little or no information available describing specific mating systems within Rhinolophidae, a few inferences may be drawn from the patterns of association between males and females. Some species form small family groups, and monogamy may be the mating systems in these cases. Others form larger colonies, either of mixed or separate sexes. In bat families (e.g., Vespertilionidae) that have been more extensively studied, this colony structure is often correlated with a promiscuous mating system. Some rhinolophids are solitary, it is not clear what mating systems are associated with these bats. (Hill and Smith, 1984; Nowak, 1991a; Nowak, 1991b)

All temperate rhinolophids are monestrous, having only a single reproductive cycle per year. These species typically mate in the fall before entering hibernation and undergo either delayed fertilization or delayed implantation to ensure that their young are born in the following spring, when resources are abundant. Tropical rhinolophids are probably monestrous but may be polyestrous. Adult females give birth to one offspring per breeding cycle. Young reach independence several weeks after birth and become sexually mature by 2 years of age. (Hill and Smith, 1984; Nowak, 1991a; Nowak, 1991b)

Parental care is provided exclusively by females in most rhinolophids (and in most bats in general). Males may provide some form of care or defense in those species that form family groups. Females that are near to giving birth bear a considerable burden; young may be up to 25% of the mother's weight when they are born. Heavily pregnant females are awkward flyers. Young are born in an altricial state, but develop rapidly. Females nurse their offspring for about a month before the young have learned to fly and hunt well enough to become independent. Juveniles may learn some aspects of foraging behaviors from their mothers. Females of many species of bats, including some rhinolophids, may use the same nursery roost site as their mothers when they have young of their own. (Hill and Smith, 1984; Nowak, 1991a; Nowak, 1991b)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • female
    • protecting
      • male
      • female
  • post-independence association with parents

Lifespan/Longevity

Rhinolophids, like many bats, can live exceptionally long lives for such small animals. The longest known lifespan of a wild rhinolophid is 30 years. (Nowak, 1991a)

Behavior

Rhinolophids have broad, rounded wings that permit excellent maneuverability at very slow speeds. Many rhinolophids can hover in place, which is helpful when they are picking prey from the surfaces of leaves or out of spider webs. All rhinolophids also capture flying insects; many species do so while in continuous flight, but others search for insects as they hang from a perch and then make short pursuit flights when prey is detected. Upon capturing food, they land and wait for another insect to fly nearby. Even those bats that do not hunt from perches will land to consume an especially large insect. Most rhinolophids hunt either very close to the ground or within 6 meters of the ground. (Hill and Smith, 1984; Nowak, 1991a; Nowak, 1991b; Vaughan, et al., 2000)

While some species are solitary, most rhinolophids roost in colonies. They generally forage alone. These bats do not defend feeding territories, but do tend to use well-defined foraging territories. Rhinolophids are all nocturnal and are active later in the evening than many other groups of bats. (Nowak, 1991a; Nowak, 1991b)

Horseshoe bats have a roosting posture that is unique among bats. Instead of hanging with their wings folded at their sides, they wrap their wings and tail membranes around their bodies, enshrouding themselves. (Nowak, 1991a)

All rhinolophids in temperate regions hibernate during the winter. Even during the active season, these bats enter daily torpor to conserve energy. Some species and populations migrate seasonally. (Hill and Smith, 1984; Nowak, 1991a)

Communication and Perception

All rhinolophids use echolocation as a primary means of navigating and finding food. Rhinolophid echolocation calls typically have two components: a constant frequency portion and a frequency-modulated sweep. The constant-frequency portion is about 20 milliseconds long. Unlike many other microchiropterans, rhinolophids can tolerate considerable overlap between outgoing calls and returning echoes. This tolerance allows them to spend more time calling, thus increasing their chances of detecting prey. Rhinolophids emit calls through their nasal passages, which lets them continue calling as they chew. Their echolocation calls are directed using motions of the head and the physical attributes of their complex noseleaves. The calls of many species have several harmonics, which increases their frequency range and thus the size distribution of detectable targets. (Hill and Smith, 1984)

Vision, olfaction, and touch are also important to varying degrees in bats. Scent plays an important role in many social interactions, such as in mating and in mother-infant bonding. Scent glands are common in many bats (as they generally are in mammals).

Food Habits

These bats either catch insects in flight or take insects and spiders from surfaces. Rhinolophids typically forage near the ground or near dense foliage, which allows them to detect non-flying prey. Rhinolophids are capable of extremely maneuverable flight, including the ability to hover. Bats that are capable of hovering can exploit prey sources on surfaces, a resource most bat species cannot exploit. Species in this family may use regular, well-defined foraging areas. (Hill and Smith, 1984; Nowak, 1991a; Nowak, 1991b; Vaughan, et al., 2000)

Predation

Predation on bats generally appears to be low, and this probably is true for rhinolophids as well. Most knowledge of bat predators comes from anecdotal observation of predation events or bat remains in scat. Groups that are known to eat bats are owls and other birds of prey, many carnivores, other bats, snakes, and other opportunistic vertebrate scavengers that encounter an injured or juvenile bat. Bats are probably most vulnerable to predators while they roost or as they emerge in the evening to forage. Some predators (e.g., snakes or hawks) may wait near cave entrances at dusk, attacking bats as they emerge. Juvenile bats that cannot fly are also at risk if they fall to the ground and are not quickly retrieved by their mothers. (Hill and Smith, 1984)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

All bats in the family Rhinolophidae eat only insects and other small arthropods. Their primary ecosystem function is probably to limit populations of insects and spiders. Bats harbor parasites such as fleas, mites and trematodes; thus, rhinolophids also serve as a resource for parasites. Bats are not typically important prey for other animals, but they are preyed upon by nocturnal birds of prey and snakes. (Hill and Smith, 1984)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Rhinolophids are all insectivorous and are likely to control populations of insect pests. Large guano deposits can be harvested commercially for fertilizer.

  • Positive Impacts
  • produces fertilizer
  • controls pest population

Economic Importance for Humans: Negative

Some rhinolophids may become household pests if they form large colonies in human dwellings. The buildup of guano from a large colony can produce a foul odor.

  • Negative Impacts
  • household pest

Conservation Status

Many bats are declining worldwide, and this is true for many rhinolophids as well (e.g., Rhinolophus hipposideros and Rhinolophus ferrumequinum). Disturbance of roosts, particularly winter hibernacula, can threaten a large number of bats in a short time. Habitat destruction (e.g., the reduction of appropriate forest habitat) is also a problem. Many insectivorous species are threatend by widespread pesticide use. Individual bats can eat hundreds of insects in an evening. If those insects have ingested harmful chemicals, the bats may suffer as a result. The International Union for the Conservation of Nature and Natural Resources (IUCN) currently lists 5 species of rhinolophids as vulnerable, 6 as near threatened, 4 as endangerd, and 1 as critically endangered (Rhinolophus hilli). Data is insufficient to evaluate the status of many other species, so this may be an underestimate of the groups overall vulnerability. (Hill and Smith, 1984; IUCN, 2004)

  • IUCN Red List [Link]
    Not Evaluated

Other Comments

The earliest rhinolophids in the fossil record are known from the Middle Eocene in Europe. (Hill and Smith, 1984)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Matthew Wund (author), University of Michigan-Ann Arbor, Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

delayed fertilization

a substantial delay (longer than the minimum time required for sperm to travel to the egg) takes place between copulation and fertilization, used to describe female sperm storage.

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

echolocation

The process by which an animal locates itself with respect to other animals and objects by emitting sound waves and sensing the pattern of the reflected sound waves.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

insectivore

An animal that eats mainly insects or spiders.

island endemic

animals that live only on an island or set of islands.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

migratory

makes seasonal movements between breeding and wintering grounds

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oceanic islands

islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

solitary

lives alone

suburban

living in residential areas on the outskirts of large cities or towns.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

ultrasound

uses sound above the range of human hearing for either navigation or communication or both

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Hill, J., J. Smith. 1984. Bats: A Natural History. Austin: University of Texas Press.

IUCN, 2004. "IUCN Red List of Threatened Species" (On-line). Accessed August 24, 2005 at www.iucnredlist.org.

Nowak, R. 1991. Horseshoe Bats. Pp. 253-256 in Walker's Mammals of the World, Vol. 1, 5th Edition. Baltimore: Johns Hopkins University Press.

Nowak, R. 1991. Old World Leaf Nosed Bats. Pp. 256-265 in Walker's Mammals of the World, Vol. 1, 5th Edition. Baltimore: Johns Hopkins University Press.

Simmons, N., T. Conway. 1997. "Rhinolophidae" (On-line). Tree of Life web project. Accessed February 08, 2009 at http://tolweb.org/Rhinolophidae/16126.

Teeling, E., O. Madsen, R. van den Bussche, W. de Jong, M. Stanhope, M. Springer. 2002. Microbat monophyly and the convergent evolution of a key innovation in old world rhinolophoid microbats. Proceedings of the National Academy of Sciences of the United States of America, 99/3: 1431-1436.

Vaughan, T., J. Ryan, N. Czaplewski. 2000. Mammalogy, 4th Edition. Toronto: Brooks Cole.

Wilson, D., D. Reeder. 2005. Mammal Species of the World, 3rd edition. Baltimore: Johns Hopkins University Press. Accessed February 07, 2009 at http://www.bucknell.edu/msw3/.