ABITAT REQUIREMENTS Pe‘a fanua mainly roost in primary forest and forage in agroforest. Primary and secondary forests and developed areas are also used for foraging (29,48). Habitat examples:
Cropland. Coconut plantations for foraging
Forest land. Primary forest, secondary forest, and agroforest for foraging and roosting
Other rural land. Rural yards for foraging
Cultivated fruit (48,51)
Fruit bats eat cultivated and wild fruit, however, in doing so they also pollinate plants, disperse seeds, and help perpetuate cultivated and wild fruit trees and the forests that sustain life
Primary forests provide bats with a more nutritionally-balanced diet
Bats may eat more cultivated fruit when they need an energy boost or wild-growing fruits are scarce
By conserving native forest through protection, restoration, or agroforestry (vs. monocultures), landowners help ensure native fruits are available, may reduce the chances of wildlife crop damage, as well as maintain the watershed
See Appendix D (FAQs about Crops and Pe‘a) for more on this topic.
ood. Pe‘a fanua are primarily frugivorous, feeding on fruit but also nectar, pollen, and leaves. They feed on at least 42 plant species (29). Bats emerge from day roosts to feed around sunset and return to roosts before sunrise (49). Favorite fruit include those of the māmālava, ‘ala‘a, tropical almond, breadfruit, and papaya. Flowers of asi, māmālava, coral tree, and banana are frequently visited. Leaves of trees such as breadfruit, sogā (29), and tamanu supplement diets with calcium and other minerals needed for reproduction (50). See Appendix C for a partial list of native and Polynesian plants that could be used for habitat enhancements.
Cover (foraging). The species forages in primary forest, secondary forest, agroforest, and plantations. Some pe‘a fanua regularly forage in primary forest (29), but more foraging occurs in mixed agroforests (secondary forests with cultivated fruit trees) (48). Pe‘a fanua forages more often in agroforests than pe‘a vao (29).
Cover (roosting). Colonies range from 10-4000 bats. Roosts are generally located on sea cliffs or steep mountainsides in areas inaccessible to people. Bats use primary and secondary, coastal and montane forests and usually avoid agroforests for roosting. Colonies may relocate if disturbed by hurricanes or people, but may use favored roost sites for long periods if left undisturbed. Commonly-used roost trees also provide forage such as the fish-poison tree, coral tree, fetau, and maota (45). Typical roost trees are large and emergent and have widely-spaced branches with sparse foliage, which allows for the “free-fall’ launch into flight (47).
Roost characteristics (45)
Height of roost trees
49 ft (15 m); ranged from 13-98 ft (4-30 m)
Slope of site
46° (range 0-71°)
Distance to nearest house
2395-3868 ft (730-1179 m)
220 ft (67 m) - coastal; 463 ft (141 m ) - inland
Pe‘a fanua can carry Polynesian chestnut fruit, representing 36% of its weight, to protected foraging sites >2.5 mi (4 km) away. Mother fruit bats fly with young representing 50-66% of their weight (49).
ater. Foods meet water requirements because fruit bats live largely on a liquid diet. Fruit bats “drink” by squeezing fruit between the roof of the mouth and tongue. The juices are swallowed, and pulp is discarded.
Interspersion of habitat components. Suitable roosting habitat that doubles as or is near protected foraging areas is preferable.
Minimum habitat area. Pe‘a fanua require large areas that may encompass an entire forest or a small oceanic island, and have been radio-tracked exploring up to 29 miles (47 km) on a single night. The distance bats travel nightly from roosting to foraging areas generally increases when food is limited (average 3-14 miles [5-23 km]) (49) and decreases when food is plentiful (average 0.5-3 miles [1-5 km]) (48).
A sustainable agroforest provides many benefits.
Flying foxes in Samoa are an important component of the agroforest ecosystem.
This unique habitat is under threat of modernization and mechanization (52).
Nutritional Single-crop systems (monocropping)
Cultural/Social “Matai” system land disputes
Ecological Improper gathering practices
Economic Misuse of pesticides
Agroforest trees beneficial to pe‘a include papaya (‘esi), pandanus (fasa), coral tree (gatae), Polynesian chestnut (ifi), mango (mago), ylang-ylang (moso‘oi), coconut (niu), tropical almond (talie), breadfruit (‘ulu), and tava. Families important to pe‘a: Sapodilla (Sapotaceae), Myrtle (Myrtaceae), Mulberry (Moraceae), Indian Almond (Combretaceae), Pea (Fabaceae), Soapberry (Sapindaceae) (29). For more info see Appendix C, also Traditional Tree Initiative: http://www.traditionaltree.org/.
POTENTIAL THREATS TO FRUGIVOROUS BATS Several major threats exist for Mariana fruit bats, Samoan flying foxes, and Pacific flying foxes:
Illegal hunting. Although fruit bats are protected, an unknown number are illegally killed each year, primarily for human consumption. It is against Federal law to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect Mariana fruit bats. It is against local and international laws to hunt or export Mariana fruit bats and Samoan and Pacific flying foxes. In the 1970s and 1980s, depleted populations of fruit bats in the Mariana Islands, where bats are a delicacy, triggered a market demand for fruit bats in Samoa and other islands (36,53). In 1992, hunting of Samoan bats was banned when populations dipped to dangerously low numbers (e.g., <500 Samoan flying foxes on Tutuila) from the combined effects of overharvest and hurricanes, illustrating the unforeseen “ripple effects” of fruit bat depletions in other countries (22). Landowners can help by reporting illegal activities as soon as possible to the local wildlife authorities listed below.
Roost disturbance. Human presence and activity can alarm fruit bats, particularly if frequent, because bats associate humans with being hunted. Entire colonies can abandon roosts for less suitable habitat, and be exposed to unfamiliar territory and predators. Mariana fruit bats are very sensitive to roost disturbance and often become agitated and frightened after detecting the human scent. Pacific flying foxes appear more sensitive to human activity than Samoan flying foxes.
Prevent new invasions Bats disperse seeds of native plants, but bats and birds could also disperse seeds of invasive species, if we aren’t careful. Seeds of invasive trees, such as strawberry guava, can infest the landscape and be detrimental to native forests. Landowners can help by not importing, selling, or growing fruit trees known to be highly-invasive on other Pacific islands. For more info checkout:
Hawaii and Pacific Ecosystems at Riskhttp://www.hear.org/
Weed Risk Assessments
abitat loss. Loss of native forest to agriculture, urbanization, military expansion, and invasive species threatens bat populations. Feral ungulates can prevent native forest regeneration, cause soil erosion, and facilitate the spread of invasive plants. On Guam, introduced Philippine deer and feral pigs suppress seeded breadfruit recruitment through browsing and seed predation (54). Insect pests such as the cycad aulacaspis scale and the erythrina gall wasp threaten the cycad (Guam) and coral tree (Guam and American Samoa), respectively, both important plants for fruit bats (22). In American Samoa, steep slopes of montane rainforest limit human activity, however, almost all the lowland rainforest of the Tafuna Plains (Tutuila) has been replaced by urban development and plantations. New roads could be sources of erosion and sedimentation and pathways for invasive species and poachers. Conversion of primary habitats could cause bats to use agroforest and plantations more frequently, which could lead to more human-bat conflicts. Human population growth is a major driver of habitat loss worldwide.
Hurricanes/typhoons. Small, fragmented populations are more vulnerable to natural catastrophes than large, stable ones. Fruit bats generally bear only one young per year, thus, recovery is a long-term process. In the early 1990s, post-storm studies showed the less common Samoan flying foxes were, surprisingly, more resilient than the Pacific flying foxes. First of all, Pacific flying foxes had a pup-rearing peak that coincided with the hurricane season (Dec-Feb) and experienced high mortality; whereas, Samoan flying foxes had their pup-rearing season outside hurricane season. Secondly, starving Pacific flying foxes entered villages to feed on fallen cultivated fruit and were subject to opportunistic predation by domestic cats, dogs, and pigs and harvest by people; in contrast, Samoan flying foxes remained in the forest and fed primarily on leaves and the fleshy bracts of the storm-resistant, native ‘ie‘ie. Severe storms can sometimes lead to dramatic increases in bat poaching, as occurred on Tutuila (American Samoa) and Rota (CNMI) (38,46).
Predation by brown tree snake. On Guam, the brown tree snake is the main suspect in the ongoing disappearance of Mariana fruit bat pups. It’s believed that pups, too large to be carried by their mothers but too young to fly, left at the roost while mothers forage at night are falling victim to brown tree snakes (22,55). Currently, no pups are known to survive to maturity (23).
ASSESSMENT OF LIMITING FACTORS – Frugivorous bats Using the habitat characteristics above, subjectively rate the (a) availability and quality of bat habitat and (b) presence or absence of potential threats within a planning area. Habitat components rated “low” or “absent” or potential threats rated “present” could be limiting habitat quality.
(a) Habitat component
Quality / Availability
Minimum habitat area
Brown tree snake
MANAGEMENT RECOMMENDATIONS – Frugivorous bats Management treatments should address the habitat components that appear to limit habitat potential for bats. Specific management options are lacking for the species. Thus, general advice for frugivorous bats is given below that may increase the quality or availability of each habitat component. NRCS Conservation Practices and various programs that may provide financial or technical assistance to carry out practices are also listed.
General management options for increasing habitat quality or availability
Minimize adverse effects of pesticides on non-target species by developing an integrated pest management plan; include role of native plants and animals in reducing pest outbreaks
Cover (foraging and roosting)
Emphasize protection, enhancement, and restoration of mature native forests to benefit multiple species of native birds and bats
In native forest, protect, enhance, and restore community structure and function
In agroforest, enhance native forest canopy; e.g., retain or plant large trees to improve watershed functions, protect farm, and maintain habitat
Consult with NRCS Biologist, Forest Ecologist, or Plant Materials Center for best plant sources, spacing, care, and maintenance (See Appendices B-C for native plants associated with bats)
314, 472, 595, 612, 643, 645
Control invasive plants that threaten the continued existence of native forests and may be spread by bats and birds; also incipient weed populations (e.g., inkberry)
Consider removing highly-invasive cultivated fruit trees, maintain as few as possible, or make plants bird/bat-inaccessible (e.g., netting)
Plant threats to Pacific islands: http://www.hear.org/Pier/
Control insect pests that threaten the continued existence of native forests (e.g., cycad scale, erythrina gall wasp); consult with local Cooperative Extension Service for wildlife-friendly pest control methods