Animal Diversity Web

Ge­o­graphic Range

Ptero­pus ton­ganus is re­stricted to is­lands in the Pa­cific Ocean. It can be found dis­trib­uted widely from is­lands near New Guinea through the Cook Is­lands. (Grant, et al., June 1997)

• Biogeographic Regions
• oceanic islands
  • native

• Other Geographic Terms
• island endemic

Habi­tat

Ptero­pus ton­ganus lives in a va­ri­ety of habi­tats. These bats are typ­i­cally found in low­land or mon­tane na­tive forests. Bare, upper branches of very tall trees in ma­ture, pri­mary for­est are fa­vored as a roost­ing habi­tat. How­ever, roosts can lo­cated on cliff faces above the ocean or steep moun­tain­sides. These bats are also known to use coastal swamps, man­grove swamps, in­land swamp and marsh areas, as well as agri­cul­tural areas and human res­i­den­tial areas. (Brook, et al., June 2000; Miller and Wil­son, 1997)

• Habitat Regions
• tropical
• terrestrial

• Terrestrial Biomes
• forest
• rainforest
• scrub forest
• mountains

• Wetlands
• marsh
• swamp

• Other Habitat Features
• suburban
• agricultural

Phys­i­cal De­scrip­tion

Ptero­pus ton­ganus is a black-backed bat with a con­trast­ing or­ange or yel­low­ish man­tle, re­sem­bling many other sym­patric species of bats. The total length of these bats av­er­ages 231 mm, and the mass av­er­ages 565 g. The fore­arm length, use­ful in help­ing dis­tin­guish P. ton­ganus from sym­patric bat species, is be­tween 120 and 160 mm, and the ears are al­ways less than 31 mm in length. Some re­searchers think that males grow to be larger than fe­males, but fur­ther in­for­ma­tion on this pos­si­ble sex­ual di­mor­phism is not pre­sent in the lit­er­a­ture. (Miller and Wil­son, 1997)

Sep­a­ra­tion of P. ton­ganus from a sim­i­lar species, P. samoen­sis, is made based on tooth pat­terns. Ptero­pus samoen­sis has a shorter, broader ros­trum than does P. ton­ganus. Ptero­pus samoen­sis is also much larger than P. ton­ganus. It is eas­ily dis­tin­guished from P. ton­ganus both by its larger size and by the ab­sence of the white fur patch on the back of its neck which char­ac­ter­izes P. ton­ganus. The pres­ence of a buffy man­tle on the neck and upper back of P. ton­ganus is the only di­ag­nos­tic char­ac­ter­is­tic that dis­tin­guishes it from P. samoen­sis in the field. (Ba­nack, Sep­tem­ber 1998; Cox, 1983; Wil­son and En­g­bring, 1992)

• Other Physical Features
• endothermic
• bilateral symmetry

• Sexual Dimorphism
• male larger

• Range mass

  191 to 1,099 g

  6.73 to oz

• Average mass

  565 g

  19.91 oz

• Range length

  151 to 262 mm

  5.94 to 10.31 in

• Average length

  231 mm

  9.09 in

Re­pro­duc­tion

The mat­ing sys­tem of these an­i­mals is not doc­u­mented.

Adult fe­males gen­er­ally have only one young per year, with a ges­ta­tion of 140-192 days (4.6-6.3 months). The tim­ing of the breed­ing sea­son seems to vary some ge­o­graph­i­cally, and there are re­ports that these an­i­mals may breed year round in Amer­i­can Samoa.

Moth­ers carry their young in­fants with them, tucked be­neath a wing. Ob­served cop­u­la­tions often in­volve fe­males who are nurs­ing young, in­di­cat­ing that there may be a post-par­tum es­trus cycle.

Young begin to fly when they are ap­prox­i­mately three months old, and when they are only half to 3/4 of adult size. Weaned in­di­vid­u­als are often seen fly­ing and for­ag­ing with adults.

The young are usu­ally not weaned until they are 4-6 months old, and can re­main de­pen­dent on their moth­ers for a year. These an­i­mals do not reach sex­ual ma­tu­rity until they are 1.5- 2.0 years old. (Cox, 1983; Falan­ruw, 1998; Miller and Wil­son, 1997)

Al­though males and fe­males as­so­ci­ate with one an­other for most of the year, after mat­ing and be­com­ing preg­nant, fe­males are known to sep­a­rate them­selves from males to form "ma­ter­nity camps." When the young are weaned, the fe­males may re­join the males. (Miller and Wil­son, 1997)

• Key Reproductive Features
• iteroparous
• seasonal breeding
• year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• fertilization
• viviparous
• post-partum estrous

• Breeding interval

  These animals reproduce once per year.

• Breeding season

  Breeding season apparently varies geographically, with some populations breeding in June or July, and others possibly breeding year round.

• Range number of offspring

  1 to 2

• Range gestation period

  140 to 192 days

• Range weaning age

  4 to 6 months

• Range age at sexual or reproductive maturity (female)

  1.5 to 2 years

• Range age at sexual or reproductive maturity (male)

  1.5 to 2 years

The parental care of P. ton­ganus as not been well doc­u­mented. How­ever, it is known that fe­males pro­vide their off­spring with milk. The fe­male car­ries her off­spring when it is very small. Weaned off­spring often for­age with adults, which might be their par­ents. It is not known what role males of this species play in parental care. (Cox, 1983; Miller and Wil­son, 1997)

• Parental Investment
• altricial
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• post-independence association with parents

Lifes­pan/Longevity

Sur­vival rates of Ptero­pus in the wild are un­known, but the max­i­mum life span for a cap­tive an­i­mal is 31 years. (Pier­son and Rainey, 1992)

• Range lifespan
  Status: captivity

  31 (high) years

Be­hav­ior

Ptero­pus ton­ganus is pri­mar­ily noc­tur­nal. This species is gre­gar­i­ous, and may be found in large groups while for­ag­ing, and dur­ing day­time, when the bats gather at large colo­nial roosts, often with sev­eral hun­dred bats in a sin­gle tree. Colonies are ex­tremely noisy and have a dis­tinct odor that makes them easy to de­tect. (Brook, et al., June 2000; Cox, 1983; Craig, et al., Oc­to­ber 1994)

When roost­ing, these bats hang up­side-down from their feet, wrap­ping their wings around them­selves as a shel­ter against in­clem­ment weather. The feet are gen­er­ally kept close to­gether. When mov­ing around in the roost, these bats are able crawlers, using their wings to drag them­selves along. (Miller and Wil­son, 1997)

Ptero­pus ton­ganus uti­lizes a broad array of plants for food. It takes pollen, nec­tar, and fruit from these trees. For­ag­ing typ­i­cally be­gins after dark, al­though some pop­u­la­tions have been known to for­age well be­fore sun­set. Such pop­u­la­tions may be under hunt­ing pres­sure, or food short­ages may pro­duce a need for day­time for­ag­ing. (Miller and Wil­son, 1997)

While for­ag­ing, these bats may travel a long way from their roost­ing sites. They do not al­ways eat their meals at the for­ag­ing site, though, and are known to carry large pieces of fruit away from their trees of ori­gin. The bats ma­nip­u­late the fruits with their hind legs, then smash the fruit against their palate to ex­tract the juices and pulp, which are swal­lowed, and eject the seeds. (Miller and Wil­son, 1997)

Ptero­pus ton­ganus are known to de­fend food re­sources. They may chase, bat at, and vo­cal­ize at in­trud­ing bats to warn them away. (Miller and Wil­son, 1997)

The so­cial struc­ture of this species is not well un­der­stood. Males and fe­males are some­times found in the same colonies, but fe­males sep­a­rate from the males to form "ma­ter­nity camps", only re­join­ing the males when the young are weaned. (Miller and Wil­son, 1997)

• Key Behaviors
• arboreal
• flies
• nocturnal
• motile
• social
• colonial

Home Range

Home range size for this species has not been re­ported.

Com­mu­ni­ca­tion and Per­cep­tion

These bats are known to have high pitched vo­cal­iza­tions. Al­though not specif­i­cally men­tioned in the lit­er­a­ture, be­cause of the way they roost so close to one an­other, these is un­doubt­edly some tac­tile com­mu­ni­ca­tion be­tween an­i­mals when roost­ing. The mother also has tac­tile com­mu­ni­ca­tion with her off­spring, whom she car­ries. There are re­ports of P. ton­ganus chas­ing one an­other in the con­text of de­fend­ing a food re­source, and bat­ting at one an­other, in­di­cat­ing fur­ther vi­sual and tac­tile com­mu­ni­ca­tion. (Cox, 1983; Miller and Wil­son, 1997)

• Communication Channels
• visual
• tactile
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

P. ton­ganus is a gen­er­al­ist among fly­ing foxes, in that it con­sumes fruit, flow­ers, nec­tar, and pollen. Some­times, these an­i­mals have been known to eat leaves.

Fly­ing foxes swal­low mostly the juices ex­tracted after mas­ti­ca­tion of the fruit pulp and dis­card most of the fiber (in the form of an ejecta pel­let). These ejecta pel­lets are made as a bat feeds on fruit pulp, com­press­ing the fruit against the palate with the tongue. This ac­tion ef­fec­tively squeezes out the juices, which are swal­lowed, and cre­ates a pel­let of dry fruit pulp. Some of this pulp is swal­lowed, but the an­i­mals spit most of it out.

Most fruit con­sumed by fly­ing foxes have large seeds. These an­i­mals do not gen­er­ally con­sume fruits until they are fully ripe, as that is when the fruits are most juicy, and eas­i­est to smash up. They will con­sume un­ripe fruit in times of low avail­abil­ity of pre­ferred fruit re­sources.

The plant species most com­monly used for fruit in Samoa by P. samoen­sis and P. ton­ganus are Ar­to­car­pus al­tilus, Plan­chonella samoen­sis, and Syzy­gium ino­phyl­loides. P. ton­ganus is an ex­treme gen­er­al­ist and likely feeds upon more than 70 plant species. Be­cause it has so many sources for food, this species is well pre­pared to pe­riod en­vi­ron­men­tal dis­rup­tions, such as hur­ri­canes.

After a major dis­tur­bance, such as a hur­ri­cane, these an­i­mals may eat leaves.

P. ton­ganus is ex­tremely se­lec­tive in choos­ing fruit within a tree. An­i­mals will smell and oc­ca­sion­ally bite many fruits be­fore ei­ther eat­ing. They may eat the fruit in the tree, or may re­move one to eat in an­other lo­ca­tion.

P. ton­ganus can be an agri­cul­tural pest, for­ag­ing on bread­fruit, pa­payas, man­gos, ba­nanas and seasea fruits. Be­cause they do not dam­age cash crops, how­ever, they are thought mainly to be nui­sances, and not dam­ag­ing, by the Samoans. (Ba­nack, Sep­tem­ber 1998; Cox, 1983; Miller and Wil­son, 1997; Nel­son, et al., Oc­to­ber 2000)

• Primary Diet
• herbivore
  • folivore
  • frugivore
  • nectarivore

• Plant Foods
• leaves
• fruit
• nectar
• pollen
• flowers

Pre­da­tion

Ptero­pus ton­ganus has few nat­ural preda­tors, partly be­cause of its in­su­lar lo­ca­tion. (Brautigam and Elmqvist, 1990)

Rap­tors and snakes are thought to be some of the major preda­tors of fly­ing foxes on is­lands. Pere­grine fal­cons, Falco pere­gri­nus, are known to sub­sist al­most ex­clu­sively on fly­ing foxes in New Cale­do­nia , the Loy­alty Is­lands, the Solomon Is­lands, and Van­u­atu. Barn owls also have been re­ported to take P. ton­ganus. (Miller and Wil­son, 1997)

• Known Predators

  • peregrine falcons (Falco peregrinus)
  • barn owls (Tyto alba)

Ecosys­tem Roles

Ptero­pus ton­ganus is an im­por­tant as pol­li­na­tor and seed dis­perser in Pa­cific is­land ecosys­tems. With­out them, it would be dif­fi­cult to main­tain com­mu­nity di­ver­sity, be­cause of the dis­tur­bances by storms. These an­i­mals are needed to af­fect the re­gen­er­a­tion of dom­i­nant for­est trees. They are also nec­es­sary to main­tain ge­netic flow be­tween is­lands. The loss of fly­ing foxes may af­fect plants that have co­e­volved with them. About 30 per cent of plant species on Samoa are to­tally de­pen­dent on fly­ing foxes for pol­li­na­tion or seed dis­per­sal. This is re­mark­ably high com­pared with forests in con­ti­nen­tal areas. Fly­ing foxes like P. ton­ganus are key­stone pol­li­na­tors and seed dis­persers, and dis­rup­tions of their pop­u­la­tions would re­sult in chain re­ac­tion of other ex­tinc­tions--of plants and other an­i­mals that are de­pen­dent upon them. (Ba­nack, Sep­tem­ber 1998; Brautigam and Elmqvist, 1990; Craig, et al., Oc­to­ber 1994; Miller and Wil­son, 1997)

• Ecosystem Impact
• disperses seeds
• pollinates
• keystone species

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

These an­i­mals are hunted by local peo­ples for sub­sis­tence. Such hunt­ing is sus­tained year-round. They are also com­mer­cially hunted and over­har­vested on many Pa­cific Is­lands to sup­ply an ex­otic food mar­ket in Guam and for med­i­c­i­nal pu­poses. (Craig, et al., Oc­to­ber 1994)

• Positive Impacts
• food
• source of medicine or drug
• pollinates crops

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

Be­cause of their feed­ing habits, these an­i­mals can po­ten­tially do dam­age to crops. (Miller and Wil­son, 1997)

• Negative Impacts
• crop pest

Con­ser­va­tion Sta­tus

Be­cause of com­mer­cial and sub­sis­tance hunt­ing, this species is some­times sub­ject to over­hunt­ing. Be­cause of their key role in local ecosys­tems, the po­ten­tial dam­age to the area from de­creases in pop­u­la­tion size are ex­treme.

Since 1989, P. ton­ganus has been listed in CITES Ap­pen­dix I. The Ap­pen­dix I list­ing pro­vides for a pro­hi­bi­tion on in­ter­na­tional trade in those species that are listed. How­ever, the species is not listed as en­dan­gered, threat­ened, or oth­er­wize at risk by the US Fish and Wildlife Ser­vice, or by the IUCN Redlist. (Brautigam and Elmqvist, 1990; Miller and Wil­son, 1997)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Federal List

  No special status

• CITES

  Appendix I

Other Com­ments

Ptero­pus ton­ganus plays an im­por­tant role in the eth­no­bi­ol­ogy of the Samoan peo­ple. The leg­ends of these peo­ple say that the Queen, Leu­togi Tupa’itea, had dis­pleased her hus­band, the king of Tonga. She was bar­ren, so he chased her into the crotch of a Cal­lo­phy­lum ino­phyl­lum tree. The vil­lagers promptly set a huge fire be­neath the tree. Just as the flames reached the Queen, a large flight of P. ton­ganus put out the flames. (Cox, 1983)

Con­trib­u­tors

Leslie Ava­los (au­thor), Hum­boldt State Uni­ver­sity, Brian Ar­bo­gast (ed­i­tor), Hum­boldt State Uni­ver­sity.

Nancy Shef­ferly (ed­i­tor), An­i­mal Di­ver­sity Web.

Ref­er­ences

Ba­nack, S. Sep­tem­ber 1998. Diet se­lec­tion and re­source use by fly­ing foxes (genus Ptero­pus). ECOL­OGY, 79(6): 1949-1967.

Brautigam, A., T. Elmqvist. 1990. Con­serv­ing Pa­cific is­land fly­ing foxes. ORYX, 24(2): 81-89.

Brook, A., C. Solek, A. Tu­alaulelei. June 2000. Roost­ing be­hav­ior of colo­nial and soli­tary fly­ing foxes in Amer­i­can Samoa (Chi­roptera: Pteropo­di­dae). Pa­cific Sci­ence, 54(4): 301-311.

Cox, P. 1983. Ob­ser­va­tions on the nat­ural his­tory of Samoan bats. MAM­MALIA, 47(4): 519-523.

Craig, P., T. Morell, P. Trail. Oc­to­ber 1994. The de­cline of fruit bats in Amer­i­can Samoa due to hur­ri­canes and over­hunt­ing. Bi­o­log­i­cal Con­ser­va­tion, 69: 261-266.

Falan­ruw, M. 1998. On the sta­tus, re­pro­duc­tive bi­ol­ogy and man­age­ment of fruit bats of Yap. Mi­cronesica, 21: 39-51.

Grant, G., P. Craig, P. Trail. June 1997. Cy­clone-in­duced shift in for­ag­ing be­hav­ior in fly­ing foxes in Amer­i­can Samoa. BIOTROP­ICA, 29(2): 224-228.

Miller, C., D. Wil­son. 1997. Ptero­pus ton­ganus. Mam­malian Species, 552: 1-6.

Nel­son, S., M. Miller, E. Heske, G. Fahey. Oc­to­ber 2000. Nu­tri­tional qual­ity of leaves and un­ripe fruit con­sumed as famine foods by the fly­ing foxes of Samoa. Pa­cific Sci­ence, 54(4): 301-311.

Pier­son, E., W. Rainey. 1992. The bi­ol­ogy of fly­ing foxes of the genus Ptero­pus: A re­view. US Fish & Wildlife Re­source Bi­o­log­ica Re­port, 90(23): 134-147.

Wil­son, D., J. En­g­bring. 1992. The fly­ing foxes Ptero­pus samoen­sis and Ptero­pus ton­ganus:sta­tus in Fiji and Samoa. US Fish and Wildlife Ser. Biol. Rep., 90(23): 36-38.