Endangered Species in the Pacific Islands
Mariana Fruit Bats / Fanihi
The little Mariana fruit bat (Pteropus tokudae) is much smaller than the Mariana fruit bat, measuring 140 to 151 mm, with a wingspan of 650 to 709 mm. The abdomen and wings are brown to dark brown but with few whitish hairs. The mantle and sides of the neck vary from brown to pale gold. The top of the head is grayish to yellowish brown while the throat and chin are dark brown. The bat is called "fanihi" in Chamorro, a language spoken in Guam and the Commonwealth of Northern Mariana Islands (CNMI).
Habitat & Behavior:
Past & Present:
The Mariana fruit bat once occurred throughout Guam in forested areas that formerly occupied most of the island. In 1958, a maximum of 3,000 bats were believed to be on Guam. Monthly counts on military lands in the 1960s indicated that the island's bat population was dropping.
Fewer than 1,000 bats were believed to exist in 1972 and less that 100 bats from 1974 to 1977. During an intensive islandwide survey in 1978 it was concluded that fewer than 50 fruit bats survived. A count done in 1984 produced an estimate of 425 to 500 animals. The most recent counts indicate that fewer than 50 bats remain in Guam. In the CNMI, counts on all islands in 1983 yielded an estimated total of approximately 8,000 bats. The most recent counts CNMI-wide (in 2000) yielded an estimated total of around 4,500 bats.
Fanihi have been used as food since humans first arrived on the islands, and consumption of bats represents a significant cultural tradition. Overhunting, however, is cited as a causal factor in the initial fanihi declines on Guam, Saipan, and Tinian. Although hunting of bats has been illegal under local law in both Guam and the CNM1 since the 1970s, hunting remains a chronic threat.
The brown treesnake (Boiga irregularis), which has caused the extinction or extirpation of most native landbird species on Guam, is considered capable of preying on non-volant young bats, and may contribute to the lack of recruitment of young bats into the single remaining colony on Guam.
The small number of fanihi remaining on some islands (e.g., Guam and Saipan) may face significant risk of extirpation from natural disturbances, environmental changes, and other chance events to which small populations typically are vulnerable. Although this subspecies has evolved in the presence of natural disturbance, today a declining population and anthropogenic threats such as hunting erode the resilience of the population and reduce the likelihood of complete recovery in the wake of typhoons and volcanic eruptions. Typhoons, in particular, could eliminate bats that persist in small numbers on one or more of these islands. Military training activities such as live fire and aircraft overflight exercises in areas used by fanihi could disrupt the behavior of these bats. An increase in air traffic at Andersen Air Force Base, which harbors the single remaining fruit bat colony on Guam, is likely in conjunction with a base expansion that has been proposed and is currently under National Environmental Policy Act (NEPA) review.
The Guam National Wildlife Refuge provides protected habitat for the last remaining populations of the endangered Mariana fruit bats on Guam. The endangered Mariana crow and the endangered plant Serianthes nelsonii can also be found at the refuge.
The first Mariana fruit bat recovery plan was published in 1990, and a draft revised recovery plan was published in 2010.