Pteronotus davyi individuals produce multiharmonic echolocation calls with an initially short constant frequency (CF = 67.0-68.1 kHz), followed by a downward frequency modulated sweep ending in a short segment of constant frequency (CF = 51.0-58.0 kHz). Calls lasted 4.6 to 6.7 msec, with most energy expended in the second harmonic.
This species can detect, approach, and capture 2-3 mm sized prey from a 0.5 to 0. 75 m distance in 0.5 sec. Detection to approach is characterized by an increase in the number of calls from 10-12 pulses/sec during search flight to 35 pulses/sec, followed by a burst of 200 pulses/sec immediately prior to capture.
Communication Channels: acoustic ; chemical
Perception Channels: visual ; tactile ; ultrasound ; echolocation ; chemical
The destruction of habitats used as foraging sites by P. davyi potentially may endanger some populations. However, due to the undesirability of the unusually hot, humid caves preferred by this species, P. davyi roosting sites are relatively protected against human development.
CITES: no special status
IUCN Red List of Threatened Species: least concern
Individuals of this species have tested seropositive for rabies at localities in Trinidad and western Mexico.
Negative Impacts: injures humans (carries human disease); causes or carries domestic animal disease
Because of their insectivorous diet, P. davyi individuals reduce the number of potentially costly agricultural pests.
Positive Impacts: produces fertilizer; controls pest population
Pteronotus davyi provides an essential function in the ecosystem: pest management through its insectivorous diet. In addition, this species is host to several ecto- and endoparasites. Unfortunately, little information is know about the parasites of this particular species; it is thought to harbor fewer parasites due to the high roost temperatures preferred by this species.
Commensal/Parasitic Species:
The diet of P. davyi is mainly comprised of moths (Lepidoptera), supplemented occasionally with flies (Diptera) and earwigs (Dermaptera) which are captured while foraging over water bodies. Water is consumed while in flight, referred to as drinking on the wing.
Animal Foods: insects
Primary Diet: carnivore (Insectivore )
Pteronotus davyi, Davy's naked-backed bat or lesser naked-backed bat, occurs in Mexico (with the exception of the northern interior) south through Central America into coastal Columbia and Venezuela to eastern Brazil. An isolated population of P. davyi has been reported from northwestern Peru. Additionally, P. davyi occurs in Trinidad and Tobago and the Lesser Antilles.
Biogeographic Regions: neotropical (Native )
This species most commonly occupies moist to seasonally dry habitats within deciduous tropical forests along a wide altitudinal range. Less commonly, this species has been reported in open areas of mesic lowlands. Within these habitats, P. davyi may roost within man-made structures, such as houses, chicken coops, and barns, but tends to prefer the darker recesses of hot, humid caves and mines. Flyways between roosting and foraging sites are maintained along densely vegetated watercourses, with distances of up to 3.5 km between roosting and foraging sites.
Range elevation: 0 to 2300 m.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: savanna or grassland ; chaparral ; forest ; rainforest
Other Habitat Features: riparian ; caves
No information on lifespan has been reported.
This species exhibits little sexual dimorphism throughout most of its range, with the exception of the most northern populations where males are significantly larger than females with regards to forearm length and several cranial measurements. A negative correlation exists between longitude and body size, with larger individuals recorded in the southern portion of the its range. The range in morphological measurements (in mm) for this species are as follows: total length, 71-85; length of foot, 9-12; forearm length, 40.6-49.6; length of ear, 16-19; length of tail, 18-25, extending two-thirds the length of the uropatagium. Mass of an adult P. davyi can range from 5-10 g. Pteronotus davyi is considered the smallest member of the family Mormoopidae.
This species has rounded wings with an average aspect ratio and low wing loading, allowing greater maneuverability in cluttered habitats. The wings are attached along the midback, covering the dorsal fur which gives the naked-backed appearance. An annual molt results in variations in pelage coloration between 2 phases, clove brown fading to a tawny brown dorsally and cinammon brown ventrally but some may appear bright ochraceous orange. Pelage is fine and densely distributed, but varies in length (8-9 mm under wings, 4-5 mm elsewhere). Short, bristle-like hairs, thought to aid in catching prey, surround the mouth. Lips are prominent, large, and can be formed into a funnel-shape, possibly used to focus echolocation emissions at a specific target.
Range mass: 6.5 to 10 g.
Range length: 71 to 85 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Roosting deep within caves and mines provides this species with some protection from most terrestrial predators, with the exception of one reported instance of a giant centipede (Scolopendra gigantea) preying on a presumably roosting individual in the interior of a Venezuelan cave. Predation on this species has only been reported one other time, in Mexico, bones from two individuals were recovered from barn owl (Tyto alba) pellets.
Known Predators:
Anti-predator Adaptations: cryptic
Female P. davyi exhibit seasonal monestrous, with mating occurring in January and February; however, limited information has been reported regarding the mating system exhibited by this species.
Adult, female P. davyi are seasonally monoestrus, with ovulation dominated by the right ovary. Copulation typically occurs during January and February throughout most of its range; however, copulation may occur earlier in the southern portions of its range. Implantation of the fertilized egg most frequently occurs in the right uterine horn. Litter size is always one, with no reports of twins. Parturition (birth) occurs during the onset of the rainy season, coinciding with an increase in insect abundance. Lactation can continue through late July, but maturation of young is relatively rapid due to the bounty of seasonal insects.
For adult, male P. davyi, testes size fluctuates throughout the year, with greatest lengths recorded during the mating season. No baculum is present.
Breeding interval: Breeding occurs once yearly (monestrus).
Breeding season: Copulation typically occurs in January and February, but may be earlier in the southern portions of its range.
Range number of offspring: 1 to 1.
Average gestation period: 60 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
No information on parental investment has been reported. However, like other bats, females invest heavily in a brief period of lactation.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)
Davy's (lesser) naked-backed bat (Pteronotus davyi) is a small, insect-eating, cave-dwelling bat of the Family Mormoopidae. It is found throughout South and Central America, including Trinidad, but not Tobago, Guyana, Suriname, or French Guiana.[3] Specimens of this bat had been found infected with rabies in Trinidad during the height of that island's vampire-bat-transmitted rabies epidemic of the early half of the 20th century, but not in recent times.[4]
The lesser naked-backed bat (also known as Davy's naked-backed bat,) earns its name from the appearance of its backside. The bat species appears to have a hairless or "naked" back due to the attachment of its wings on the mid-line of its dorsal surface.[3] The wing membranes give the bat's back its shiny appearance. The lesser-naked backed bat shares this diagnostic feature with two other species of bat of the same family (Mormoopidae,) named Pteronotus fulvus and Pteronotus gymnonotus. Pteronotus dayvi is easily distinguishable from other species in the Genus Pteronotus by sparsely distributed hairs on the membranes of its wings.[3] P. dayvi is characterized by very dense pelage that changes color throughout the seasons.[3] Little sexual dimorphism is observed in this species, except within the most northern populations located in Sonora. Males of this population are observed to be significantly larger than females.[3] The wing aspect ratio of this species is very high in comparison to many Microchiroptera, allowing these bats to fly long distances at fast speeds. The lips of these bats are large, perhaps allowing for focusing of the soundwaves that are emitted from their pharynx during echolocation.[3]
Pteronotus davyi are nocturnal, insectivorous bats that tend to roost in communities within their own species. Daytime roosts are seen to be shared between other species within the family Mormoopidae.[3] This species uses echolocation to target prey and navigate in the dark, deciduous forests they reside in. Insects preyed upon include moths, flies and earwigs.[5]
Pteronotus davyi are known to be seasonally monogamous, and usually mate in the months of January and February.[3] These bats have one offspring per mating season. The birth of the offspring occurs during the rainy season. The rainy season provides a surge in the insect population, which proves to be important for these insectivorous bats, allowing the young to mature at a fast rate.[3]
Due to their high wing-aspect ratio, these bats can fly at quick burst speeds for long distances, although their long wingspan inhibits them from having great agility.[3][6] They are also sufficient climbers. It is believed that they climb high to the top of their roost in order to quickly fly away from the entrance and avoid any nearby predators.[3][7] During nighttime foraging for insects, flight usually occurs near the ground.[3]
Although predation has not been intensely observed in this species, researchers have found that P. davyi has been hunted by American kestrels (Falco sparverius,) a very common North American falcon. These falcons have been seen to hide at the entrance of the bat roosts and dive after the bats as they are exiting the cave.[7]
These bats are found most commonly in moist habitats that sustain a high volume of insects. Nighttime roosts of these animals are most commonly found in warm, dark, moist caves. P. davyi are found as far north as Mexico and as far south as South America and Honduras.[3] They typically prefer low elevations, but some individuals have been observed at elevations as high as 2,000 meters above sea level.[3] There has been no recorded observance of this species in Guyana, Suriname, or French Guiana.[3] Studies of this species have revealed genetic divergence between the Southeastern P. davyi population, and the Pacific and Gulf Coast populations.[8] This is believed to be a result of geographical barriers that separate these populations. These geographical barriers are Sierra Madre Occidental, Sierra Madre Oriental, and Sierra Madre del Sur.[8]
Davy's (lesser) naked-backed bat (Pteronotus davyi) is a small, insect-eating, cave-dwelling bat of the Family Mormoopidae. It is found throughout South and Central America, including Trinidad, but not Tobago, Guyana, Suriname, or French Guiana. Specimens of this bat had been found infected with rabies in Trinidad during the height of that island's vampire-bat-transmitted rabies epidemic of the early half of the 20th century, but not in recent times.
