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Asellia tridenstrident leaf-nosed bat

By Ryan Anderson

Geographic Range

Trident nose-leaf bats are found in Northern Africa and the Middle east. Asellia tridens lives in some of the hottest areas in the world, spanning the region from Morocco to northern India.

There are two sub-species, A.t. tridens and A.t. murriana. Asellia t. murriana is commonly found only from Egypt to Saudi Arabia and into Israel and Jordan, , while A.t. tridens is found on either side of the range of A. t. muriana. (Qumsiyeh, 1996; Qumsiyeh, et al., 1991; Weber, 1955; Yom-Tov and Kadmon, 1998)

Habitat

Although successful in all habitats within its range, from from the desert to the Mediterranean coast, the sub-species A. t. murriana is found in some of the hottest areas of the desert where no other bats can seem to survive. (Qumsiyeh, et al., 1991; Weber, 1955)

Although mainly a desert species, Asellia tridens has made some headway into coastal and mountainous regions. It roosts in a variety of sheltered areas, from caves to sheds and temples. (Qumsiyeh, 1996; Qumsiyeh, 1996)

Physical Description

Asellia tridens is a member of the family Rhinolophidae, which is known for its nose-leaves. The nose-leaf is distinct, with three cusps (trident) on the leaf; the outer two are blunted, whereas the central one is pointed. (Pint and Pint, 2005; Fergusun, 2002; Pint and Pint, 2005; Weber, 1955)

There are two distinct color phases in this species, with one other variant sometimes appearing. The first phase is pale grayish-brown, and the second is pale orange-brown or silty-yellow with a whitish underside. The additional variant is described as having a reddish hue. (Fergusun, 2002; Qumsiyeh, 1996; Weber, 1955)

Some other important characteristics for identifying these bats in the field are its lack of a tragus, and its projecting tail, which can extend up to 5 mm beyond the flight membrane. Specimens are generally 66-90 mm in total length. (Hoath, 2003)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    66 to 90 mm
    2.60 to 3.54 in

Reproduction

The mating system of Asellia tridens has yet to be studied in much detail.

Not much is known about the details of mating behavior and reproduction within the species, however, the gestation period is estimated to be 9 to 10 weeks. These bats normally bear a single offspring, which is born in early June. They probably mate just before moving back to their summer roosts. ("African Wildlife Foundation", 2006; Qumsiyeh, et al., 1991)

  • Breeding interval
    Once yearly
  • Breeding season
    Early spring
  • Average number of offspring
    1
  • Range gestation period
    9 to 10 weeks
  • Average weaning age
    4 months
  • Range time to independence
    5 to 6 weeks
  • Average age at sexual or reproductive maturity (female)
    2 years
  • Average age at sexual or reproductive maturity (male)
    2 years

No specific information is available for this species. However, as in all mammals, females care for and nourish their young until they reach independence.

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

No information regarding the lifespan of these bats could be found.

Behavior

Asellia tridens is a highly mobile, highly colonial species. These bats tend to roost in the hundreds to thousands in whatever shelter they can find, usually in caves, cliff crevices, and older or abandoned buildings.

They leave their roosts in the late evening when their prey items (especially moths) are abundant and easier to catch. Their flight pattern is described as low, with rapid swerving and twisting, much like a butterfly. They become torpid during daily roosting.

There is no evidence to suggest any social hierarchies or systems, though in most bats social grooming is common. (Qumsiyeh, et al., 1991; Roberts, 2006)

Home Range

No information is available.

Communication and Perception

It is not known to what extent members of this species communicate with one another; however, it is likely that there is some scent communication, like pheromones, because they are mammals. In fact there is extensive use of scent marking within another Chiropteran order, Emballonuridae.

The most intriguing thing about bats must be their use of echolocation. Within the sub-order Microchiroptera all species use this as one of their primary sources of perception.

Because this species is nocturnal and insectivorous, individuals rely mainly on echolocation to locate and hunt down prey. In fact, this species' ability to negotiate through complex environments has been extensively researched, Asellia tridens can detect and avoid wires with a diameter of only .65 mm. ("Echolocation and obstacle avoidance in the hipposiderid bat Asellia tridens ", 1979)

Food Habits

An in-depth study of Asellia tridens gives us a good estimate of its diet. The following is a list of the main prey found in guano in Israel:

Beetles (Coleoptera): this is the main prey item in the diet of A. tridens. The diet of the other bats in the area also consisted mainly of this prey item, in fact compared to the competition; Asellia was the least successful with this particular prey item.

Butterflies and moths (Lepidoptera): Asellia tridens was much better at catching this prey compared to the competition. This isn't too surprising, as many people have described their flight to be very quick and agile.

Crickets and grasshoppers (Orthoptera): Asellia tridens was also much more successful at catching these prey items than were their competitors.

Flies (Diptera): Asellia tridens was also quite successful at catching these prey items.

True bugs (Heteroptera): Asellia tridens was the worst amongst other bats in the area at catching these prey items, however, this group did not make up a significant portion of any of their diets.

Caddisflies (Trichoptera) and wasps and bees (Hymenoptera) were also found within the guano of A. tridens in the study.

Comparatively, A. tridens had the most diverse diet of all sympatric bat species, and excelled above all in their ability to catch moths and butterflies. (Whitaker Jr., 2002)

  • Animal Foods
  • insects

Predation

There are no known natural predators of this species. Young in roosts may be taken by predators such as snakes or other small, agile carnivores.

Ecosystem Roles

Asellia tridens plays a large role in controlling insect populations in its habitat. Nothing is known about its parasites, except that it is host to a tick (Argas fischeri). (Weber, 1955)

Commensal/Parasitic Species
  • Argas fischeri

Economic Importance for Humans: Positive

Colonies of A. tridens can consume vast numbers of insects, which may be crop pests or disease vectors.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

There are no recorded negative economic impacts due to Asellia tridens, although it could be considered a nuisance since it at times roosts within man-made structures. (Weber, 1955)

  • Negative Impacts
  • household pest

Conservation Status

Trident leaf-nosed bats are not currently protected by any legislation, populations seem stable and the species is widespread. Like all bats, populations may be threatened by roost disturbance, pesticides, and human persecution.

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Ryan Anderson (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

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.

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.

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.

insectivore

An animal that eats mainly insects or spiders.

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).

motile

having the capacity to move from one place to another.

native range

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

nocturnal

active during the night

pheromones

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

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

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

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 savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

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

2006. "African Wildlife Foundation" (On-line). African Wildlife Foundation. Accessed March 20, 2006 at http://www.awf.org/wildlives/62.

1979. Echolocation and obstacle avoidance in the hipposiderid bat Asellia tridens . Journal of Comparative Physiology A: Sensory, Neural, and Behavioral Physiology, Volume 131, Number 2: 161-167.

Fergusun, W. 2002. Mammals of Israel. Hewlett, NY: Gefen Publishers.

Hoath, R. 2003. A Field Guide to Mammals of Egypt. Cairo: American University in Cairo Press.

Pint, J., S. Pint. 2005. "Saudi Bats" (On-line). Accessed March 17, 2006 at http://www.saudicaves.com/saudibats/.

Qumsiyeh, M., Z. Amr, R. Al-Oran. 1991. Family Hipposideridae Leaf-Nosed Bats Genus Asellia. Turkish Journal of Zoology, Volume 22, Issue 4: 279. Accessed March 17, 2006 at http://journals.tubitak.gov.tr/biology/index.php.

Qumsiyeh, M. 1996. Mammals of the Holy Land. Texas Tech University: Lubbock : Texas Tech University Press.

Roberts, C. 2006. "Hipposideros commersoni" (On-line). Animal Diversity Web. Accessed March 20, 2006 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Hipposideros_commersoni.html.

Weber, N. 1955. Notes on Iraq Insectivora and Chiroptera. Journal of Mammalogy, Vol 36. No1: pp. 123-126. Accessed March 17, 2006 at http://links.jstor.org/sici?sici=0022-2372%28195502%2936%3a1%3c123%3anoiiac%3e2.0.co#b2-t.

Whitaker Jr., J. 2002. The diet of some insectivorous bats from northern Israel. Mammalian Biology, Volume 67, Number 6: 378-380. Accessed March 17, 2006 at http://www.ingentaconnect.com/content/urban/161/2002/00000067/00000006/art00053;jsessionid=41ii53pkh7iad.alice.

Yom-Tov, Y., R. Kadmon. 1998. Insectivorous bats in Israel. Diversity and Distribution, Volume 1: 63-70.

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