Chilonatalus tumidifronsBahamian lesser funnel-eared bat

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Geographic Range

Chilonatalus tumidifrons (Bahaman funnel-eared bats) is the only species of bat that is endemic to the Bahamas. Currently, Bahaman funnel-eared bats are found on just two islands in the northern Bahamas: Great Abaco, and Watling (San Salvador). Historically they were also found on Andros and other southern Bahamian islands. Post-glaciation climate changes such as raised sea levels and disrupted thermal ecology are considered the largest contributor to the shrinking range of this species. Some human impacts may also have played a role. (Dalquest, 1950)

Habitat

Bahaman funnel-eared bats are found exclusively in Bahamian dry-deciduous forests. The forest found on Great Abaco is more lush and has a taller over story than the low scrubby forest type which dominates much of Watling. Deep caves, where hot and moist conditions are maintained continuously, are the single most important habitat requirement. These caves provide C. tumidrifrons with necessary roosting habitat. During their active hours Bahaman funnel-eared bats forage for insects in the dense understory of surrounding forests. (Grzimek's Animal Life Encyclopedia, 2005; Miller, 1903)

  • Other Habitat Features
  • caves
  • Range elevation
    300 (high) m
    984.25 (high) ft

Physical Description

Chilonatalus tumidifrons is similar in appearance to its close relative Chilonatalus micropus, Cuban funnel-eared bats. However, Bahaman funnel-eared bats are slightly larger than Cuban funnel-eared bats. The fur is reddish to chestnut brown dorsally and pale yellow on the ventral surface. There is no evidence of sexual dimorphism in Bahaman funnel-eared bats. The wings are relatively long and narrow, their thumbs are short, and almost completely enveloped in the skin of the wing. (Dalquest, 1950; Grzimek's Animal Life Encyclopedia, 2005; Koopman, et al., 1957)

Species in the family Natalidae are named for their characteristic large, funnel-like ears. The external ear is covered in small glandular papillae. A special characteristic of male natalids is known as the “natalid organ”. Located near the base of the muzzle, it is a rounded projection made up of sensory cells. The exact function of the organ is unknown, but it is specific to natalids. The tip of the nose is capped with a small, fleshy tragus that is not considered a true noseleaf. The fragile skull is elongate, with a swollen braincase and a narrow, tubular rostrum.

Dental formula: 2/3; 1/1; 3/3; 3/3 (Dalquest, 1950; Grzimek's Animal Life Encyclopedia, 2005; Koopman, et al., 1957)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    4 to 7 g
    0.14 to 0.25 oz
  • Range length
    8 to 11 cm
    3.15 to 4.33 in
  • Range wingspan
    7 to 9 cm
    2.76 to 3.54 in

Reproduction

Nothing is known of the reproduction or mating systems of Bahaman funnel-eared bats, but they are most likely polygynous. (Buden, 1987; Grzimek's Animal Life Encyclopedia, 2005)

Little information is available on the general reproductive behavior of Bahaman funnel-eared bats. Members of the family Natalidae characteristically give birth to a single young towards the end of the dry season. Females gather in maternity colonies to give birth to and raise their young. Offspring are relatively large, often close to 50% of their mothers’ weight. The closely related Mexican funnel-eared bat (Natalus stramineus) breeds during the late dry season and has a gestation period of about 10 months. (Grzimek's Animal Life Encyclopedia, 2005; Koopman, et al., 1957)

  • Breeding interval
    Bahaman funnel-eared bats breed once yearly.
  • Breeding season
    Birth occur in the late dry season, suggesting that mating occurs after the late dry season.
  • Range number of offspring
    1 to 1
  • Average gestation period
    10 months

Female Bahaman funnel-eared bats form maternity colonies in which they give birth to and care for their young. Females are completely responsible for the care of their young. Giving birth to just one offspring per event means that females allocate all of their efforts to the single young. (Grzimek's Animal Life Encyclopedia, 2005)

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

Lifespan/Longevity

Nothing is known of the longevity/lifespan of Bahaman funnel-eared bats.

Behavior

Bahamian funnel-eared bats are nocturnal. Generally colonies of Bahaman funnel-eared bats leave their roost 30 minutes after sundown. Agile flyers, they are able to forage among dense foliage for their insect prey. The most intense foraging activity among natalids occurs about two hours after leaving the roost. Bahaman funnel-eared bats are such agile flyers that they are rarely caught in mist nets. For this reason, little is know about their natural history. (Buden, 1987; Grzimek's Animal Life Encyclopedia, 2005)

Home Range

Nothing is specifically known about the home range of Bahaman funnel-eared bats. Their home ranges are likely centered around their roosting caves. (Buden, 1987; Grzimek's Animal Life Encyclopedia, 2005)

Communication and Perception

Members of the family Natalidae echolocate using high frequency pulses, up to 170 kHz. This gives them a detailed picture of their environment. Whether Chilonatalus tumidifrons is a nasal or oral emitting bat is still unknown. All funnel-eared bats have, as the name suggests, very large, funnel-shaped ears. These allow them to detect faint sounds and return echoes from their echolocation pulses. The ears of these bats are covered in small papillae, which may increase auditory sensitivity. Like other mammals, they are likely to use olfactory and tactile cues in communication as well. (Dalquest, 1950; Grzimek's Animal Life Encyclopedia, 2005)

Food Habits

Chilonatalus tumidifrons feeds exclusively on flying insects. (Dalquest, 1950; Grzimek's Animal Life Encyclopedia, 2005; Koopman, et al., 1957; Miller, 1903)

  • Animal Foods
  • insects

Predation

No predators of Bahaman funnel-eared bats have been recorded. Being active at night reduces their exposure to diurnal predators. As with most bat species, owls and climbing snakes may pose a threat to adults in flight and roosting animals, respectively. (Dalquest, 1950; Miller, 1903)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

Insectivorous bat species, such as Bahaman funnel-eared bats, can have an enormous effect on insect populations in the vicinity of their colonies. Many insects that bats prey on are agricultural pests, making them highly beneficial to agriculture.

Economic Importance for Humans: Positive

Bahaman funnel-eared bats eat insect pests.

  • Positive Impacts
  • controls pest population

Economic Importance for Humans: Negative

Chilonatalus tumidifrons has no negative economic impact on humans.

Conservation Status

Bahaman funnel-eared bats are listed as "vulnerable" under the IUCN's standards for threatened species. ("IUCN The World Conservation Union", 1995)

Other Comments

These bats were previously recognized as Natalus tumidifrons.

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Steven Burns (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor, instructor), University of Wisconsin-Stevens Point.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

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.

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.

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).

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

polygynous

having more than one female as a mate at one time

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

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

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.

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

International Union for Conservation of Nature and Natural Resources. 1995. "IUCN The World Conservation Union" (On-line). Accessed November 26, 2006 at http://www.iucn.org/themes/ssc/redlist.htm.

Buden, D. 1987. A Guide to the Identification of the Bats of the Bahamas. Carribean Journal of Science, 23: 362-367.

Dalquest, W. 1950. The Genera of the Chiropteran Family Natalidae. Journal of Mammalogy, 31: 436-443.

Grzimek's Animal Life Encyclopedia, 2005. "Answers.com" (On-line). Accessed October 22, 2006 at http://www.answers.com/topic/bahamian-funnel-eared-bat.

Koopman, K., M. Hecht, E. Lidecky-Janecek. 1957. Notes on the Mammals of the Bahamas with special reference to bats. Journal of Mammalogy, 38: 164-174.

Miller, G. 1903. The mammals of the Andaman and Nicobar Islands. Proceedings of the United States National Museum, 24: 751-795.