By Steven Burns
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)
Biogeographic Regions:
neotropical 
(native ).
Other Geographic Terms:
island endemic .
Habitat
(984 ft)
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)
These animals are found in the following types of habitat:
tropical ; terrestrial .
Terrestrial Biomes:
forest ; scrub forest .
Other:
caves.
Physical Description
(0.14 to 0.25 oz)
(3.15 to 4.33 in)
(2.76 to 3.54 in)
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, Hecht, and Lidecky-Janecek, 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, Hecht, and Lidecky-Janecek, 1957)
Some key physical features:
endothermic ; heterothermic ; bilateral symmetry .
Sexual dimorphism: sexes alike.
Reproduction
Bahaman funnel-eared bats breed once yearly.
Birth occur in the late dry season, suggesting that mating occurs after the late dry season.
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)
Mating systems:
polygynous .
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, Hecht, and Lidecky-Janecek, 1957)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous .
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)
Communicates with:
acoustic .
Perception channels:
visual ; tactile ; acoustic ; echolocation ; chemical .
Food Habits
Chilonatalus tumidifrons feeds exclusively on flying insects. (Dalquest, 1950; Grzimek's Animal Life Encyclopedia, 2005; Koopman, Hecht, and Lidecky-Janecek, 1957; Miller, 1903)
Primary Diet:
carnivore (insectivore ).
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: Negative
Chilonatalus tumidifrons has no negative economic impact on humans.
Economic Importance for Humans: Positive
Bahaman funnel-eared bats eat insect pests.
Ways that people benefit from these animals:
controls pest population.
Conservation Status
IUCN Red List: [link]:
Vulnerable.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
Bahaman funnel-eared bats are listed as "vulnerable" under the IUCN's standards for threatened species. (International Union for Conservation of Nature and Natural Resources, 1995)
Other Comments
These bats were previously recognized as Natalus tumidifrons.
For More Information
Find Chilonatalus tumidifrons information at
Contributors
Tanya Dewey (editor), Animal Diversity Web, University of Michigan Museum of Zoology.
Steven Burns (author), University of Wisconsin Stevens Point. Chris Yahnke (editor, instructor), University of Wisconsin Stevens Point.
