Phyllostomus hastatus

Geographic Range

Greater spear-nosed bats are found from eastern Central America to southern South America. They are also found in Trinidad, Tobago Islands and Margarita Islands. There are two subspecies of Phyllostomus hastatus ; P. hastatus hastatus is found in Trinidad, Bolivia and southeast Brazil, and P. hastatus panamensis is found in Honduras and the Andes.

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

Greater spear-nosed bats occupy several habitats, including deciduous forests, man-made clearings and tropical evergreen forests. They preferentially roost in caves. Greater spear-nosed bats are usually found below 500 m but have also been found at elevations as high as 1,394 m.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest

• Other Habitat Features
• caves

Physical Description

Greater spear-nosed bats are the second largest American bat species. Vampyrum spectrum is larger. The ventral and dorsal surface fur is short and ranges from dark brown, black brown, reddish brown or greyish brown. The membranes, ears and face are black. The tips of the ears have a triangular shape and the tail is short. They have a simple and well developed nose leaf and the lower lip has a V-shaped groove. The spear-nosed bat shows sexual dimorphism. Male and female spear nosed bat skulls are most distinguishable by the greatest width of the skull (mastoid breadth), and secondarily most distinguishable by the breadth across upper canines, with males being greater in both characteristics. Males have a chest gland at the base of their throat, while the chest gland in females is amorphous. Males have greater wing loading than females, but females have a greater wingspan than males. The average wingspan of females is approximately 546 mm, while males have a slightly shorter average wingspan of 537 mm. The average length of the forearm is 84 mm in males and 82 mm in females. Total length of the body from head to tail is approximately 131 mm in males and 126 mm in females. The average mass of adult males is 104 g while adult females are 87 g. The glandular throat sac is more developed in males. The dental formula is I 2/2, C 1/1, P 2/2 and M 3/3. Phyllostomus discolor and Phyllostomus elongatus are closely related species that occur in the same range as greater spear-nosed bats. But both species are smaller than greater spear-nosed bats. The pelage of Phyllostomus discolor has white tips and the wings of Phyllostomus elongatus have white tips. The basal metabolic rate of greater spear-nosed bats is 1.19 ccO2/g-hr.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• ornamentation ornamentation

Reproduction

Greater spear-nosed bats have a polygynous mating system, where males will compete for and defend potential mates. Harems range from 7 to 25 females with a single resident male. Pre-reproductive females will remain in a non-harem group until they mature and join a harem. Males will defend their harems by wing beating, vocalization, and even attacking approaching males. In contrast, males will not respond to females moving among harems.

• Mating System
• polygynous polygynous

Copulation begins between October and December. Females give birth to a single offspring between April and May, during the dry season, and wean the young during the wet season. The timing of birth can vary depending on seasonal rainfall levels, but the occurrence of births is highly synchronous within harems. The mass of a 1 day old spear-nosed bat is quite variable, ranging from 10.8 to 22.5 g. Other than the first few days when the mother carries its offspring on its back during foraging flights, the babies are left in their roost for about 4 weeks, remaining attached to the mother’s breast whenever she is not away from the roost. During this time, offspring triple in size. After 4 weeks, the offspring will cling to its mother’s back whenever the mother is in the roost, until it reaches 6 weeks old, at which point it begins to fly on its own within the cave or roost. Weaning occurs at about 49 days of age. At 2 months old, offspring will start to go out on evening flights. Mothers continue to lactate for approximately 3 months post-partum. Reproduction in females begins at two years of age. Greater spear-nosed bat reproduction is monoestrous in Middle America and Trinidad and polyestrous in South America. Reproduction and growth rates are highest in polyestrous populations with large harems, and are lowest in monoestrous populations with either large or small harems. The greatest restriction on population growth in both monoestrous and polyestrous opoulations of greater spear-nosed bats is pup mortality.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Females within social groups exhibit alloparental care by means of “pup guarding”. When pups fall from their roost, they are retrieved by their mother. Females from the same social group as the pup and its mother will visit the fallen pup, their presence providing protection from females of a different social group that may attack fallen pups. Pups use unique isolation calls to communicate that they have fallen from their roost site. Mothers are able to discern isolation calls of their own offspring from the isolation calls of other pups. Once the young become independent, they are not recruited into their parental harems.

• Parental Investment
• precocial precocial
• female parental care female parental care
• pre-weaning/fledging
  • protecting
    • female
• pre-independence
  • protecting
    • female
• extended period of juvenile learning

Lifespan/Longevity

The lifespan for Phyllostomus hastatus is 18 years. Males have higher mortality than females.

Behavior

Greater spear-nosed bats live either in harems, with a dominant male and many females, or in bachelor groups of many unrelated males. Tooth wear indicates that harem males are older than bachelor males. Foraging occurs most frequently at 2 to 3 hours before sunset. Harem males forage more frequently but for an overall shorter time in comparison to females. Harem males do not defend foraging areas and do not forage in the same area as their harem females. Greater spear-nosed bats typically do not forage in groups, but they do forage in near proximity to each other. Greater spear-nosed bats have a wide variety of roost types, including caves, hollow trees or logs, buildings, in or under leaves, or in hollow termite nests. The roost size can range between 3 to 585 bats when cohabiting with other bat species such as Molossus molossus and Molossus rufus . In human capture-and-release experiments, greater spear-nosed bat homing ability shows a gradual decline as the release distance from its roost increases. Most bats are able to return to their roost when released 20 km away. When individuals are released 30 km away from their roost, the percentage of greater spear-nosed bats that are able to successfully return home drops below 50%.

• Key Behaviors
• flies
• nocturnal nocturnal
• crepuscular crepuscular
• motile motile
• sedentary sedentary
• territorial territorial
• colonial colonial

Home Range

Greater spear-nosed bats typically forage as much as 10 km away from their roost.

Communication and Perception

In addition to echolocation, where frequencies are 32 to 55 kHz, greater spear-nosed bats also use vocal, lower frequency communication in the vicinity of 6 to 12 kHz. Screech calls allow group-specific recognition to allow for coordination when foraging outside caves. These screech calls can be used to recruit conspecifics to foraging areas. Greater spear-nosed bats vision for orientation once objects are detected using sound localization.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• ultrasound ultrasound
• echolocation echolocation
• chemical chemical

Food Habits

Greater spear-nosed bats are omnivorous. Their diets consist mostly of insects, but also include fruits, nectar and pollen. Greater spear-nosed bats may be one of the only bat species with the ability to remove the shell of the jackfruit ( Artorcarpus heterophyllus ) and eat the fleshy inside while it remains attached to the tree. Because jackfruit is available year-round, greater spear-nosed bats may feed on this fruit when other food resources are low. Other fruiting plants that are consumed by greater spear-nosed bats are Cecropia species, Piper species, Solanum species, and Vismia species. Greater spear-nosed bats have been documented eating mice ( Mus musculus ), birds ( Cyanerpes cyaneus ), and even other bats, such as Hemiderma perspicillatum .

• Primary Diet
• omnivore omnivore

• Animal Foods
• birds
• mammals
• insects

• Plant Foods
• seeds, grains, and nuts
• fruit
• nectar
• pollen

Predation

Predators of juvenile greater spear-nosed bats include screech owls ( Otus choliba ), bullfrogs ( Rana catesbeiana ), tegu lizards ( Tupinambis teguixin ) and opossums ( Didelphis virginiana ). Pup survival drops dramatically following first flight and 40% of juvenile spear-nosed bats do not survive to independence, possibly as a result of predation, parasites, or from not being retrieved after falling from cave ceilings.

Ecosystem Roles

Greater spear-nosed bats have a variable diet that includes fruit and nectar. They are important pollinators in many plants, one of which is Ceiba pentandra , a large flowering tree. Because both greater spear-nosed bats and Phyllostomus discolor may forage in the same tree, resource exploitation results in their frequent movement between Ceiba pentandra , promoting cross pollination. Greater spear-nosed bats also promote pollination when they forage across large distances. Greater spear-nosed bats act as a reservoir for multiple parasites. Trichobius longipes is an ectoparasite that is found more frequently in female spear-nosed bats than males. This sex bias in parasite infection may be explained by the more stable host environment that females provide, as they typically stay in the same roost all year, while males tend to travel between roosts more often.

• Ecosystem Impact
• disperses seeds
• pollinates

Economic Importance for Humans: Positive

Greater spear-nosed bats may be involved in the recovery of ecosystems affected by deforestation in French Guiana. Greater spear-nosed bats contribute to recolonization of Cecropia species, Piper species, Solanum species, and Vismia species, which are pioneer plants that thrive in the large forests gaps left by habitat disturbance, and are critical for successful regeneration of later successional species that constitute complex forests. Seed dispersal of these tree specices by greater spear-nosed bats leads to habitat expansion and recolonization.

• Positive Impacts
• ecotourism ecotourism
• pollinates crops

Economic Importance for Humans: Negative

Greater spear-nosed bats are vectors for transmission of Trypanosoma cruzi , the causative agent of Chagas’ Disease that uses mammalian hosts, including humans. Chagas’ disease is prevalent in North, Central, and South America, and is life-long in its impacts.

• Negative Impacts
• injures humans
  • carries human disease

Conservation Status

Greater spear-nosed bats are listed as Least Concern (LC) under the IUCN. However, monoestrous populations have low reproductive rates and also live within Central America, a biological hotspot that globally has the second highest number of endemic vertebrates next to the Tropical Andes and has experienced severe habitat loss due to humans. Therefore, greater spear-nosed bats should be carefully monitored in areas undergoing disturbances to ensure that populations remain stable.

Additional Links

Encyclopedia of Life

Contributors

Sandhya Boyd (author), University of Manitoba, Jane Waterman (editor), University of Manitoba, Tanya Dewey (editor), University of Michigan-Ann Arbor.

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