|January 6, 2005
The Mariana fruit bat - a medium-sized bat found only in Guam and
the Commonwealth of the Northern Mariana Islands (CNMI) - has been
reclassified from endangered to threatened status on Guam and newly
listed as threatened in the CNMI, the U.S. Fish and Wildlife Service
Known as "fanihi" in the Chamorro language, the Mariana fruit bat
was originally listed as endangered on Guam only, in the belief that
bats on Guam formed a distinct and separate population from those in
CNMI. Recent studies indicate the bats move from one island to
another, linking these colonies as a single population. Because of
the larger size of the total population, the species is being
"We believe that listing this species as threatened throughout its
range will retain an appropriate level of protection throughout the
Mariana Islands," said David B. Allen, Director of the Service's
Pacific Region. "Our ultimate goal is to recover the species
throughout the archipelago, so that future generations will still be
able to see and enjoy this important part of the islands' culture."
Currently, fewer than 100 individual Mariana fruit bats remain on
Guam and a fluctuating population of 1,100 remains on Rota. In the
northern islands (all islands north of Farallon de Medinilla) fewer
than 5,000 individuals remain. On Saipan and Tinian, few individuals
are known to inhabit or visit these islands.
Native forests are the primary habitat required by the fruit bat,
although some introduced plant species can provide roost sites and
sources of food. Important components of tropical forest systems,
fruit bats disperse seeds, which helps maintain forest diversity and
contributes to plant regeneration. The fruit bat feeds on a wide
variety of plant material but primarily eats breadfruit, papaya, and
Habitat loss and degradation pose a major threat to the bat. The
southern islands of the archipelago have lost significant habitat
due to land conversion for agriculture, military, commercial, and
residential development. In the northern islands, feral pigs, goats,
and cattle have destroyed or severely damaged the native forest
The Mariana fruit bat faces additional threats such as illegal
hunting, predation by introduced predators such as brown
tree-snakes, rats, and feral cats; vandalism; natural disasters or
random environmental events such as typhoons, volcanic eruptions,
and fire; and hunting in violation of territorial laws.
Strong fliers that traverse long distances, the Mariana fruit bat
can easily fly between islands (ranging from 18 to 62 miles apart).
Evidence indicates that bats from Rota visit Guam for several months
at a time.
The Mariana fruit bat is a member of the family Pteropodidae, which
is often referred to as flying foxes because of the canine
appearance of the face. The bats range in weight from 0.66 pounds to
1.15 pounds (males are slightly larger than females) and have an
impressive wingspan ranging from 2.75 to 3.5 feet. All animals have
grizzled black to brown fur and a golden brown mantle. The head
color varies from brown to dark brown.
Mariana fruit bats live in colonies ranging from a few individuals
to more than 800 and group themselves into harems (1 male with 2-15
females) or bachelor groups consisting primarily of males. The bat
colonies sleep during much of the day, but they perform many other
activities as well such as grooming, breeding, scent-rubbing,
marking, flying, climbing to other roost spots, and defending
roosting territories (harem males only). Bats gradually depart
colonies for several hours after sunset to forage.
The species is believed to reproduce year-round with the female
generally producing one offspring a year. This low reproductive
rate, for a mammal of this size, results in a low population growth
and thus a slow rate of recovery when the population numbers are
In the CNMI, the Mariana fruit bat occurs primarily on private and
Commonwealth lands, including inhabited and uninhabited islands. On
Guam, it is known to roost primarily on federal lands (Andersen Air
Force Base and the Ritidian Unit of the Guam National Wildlife
Refuge) and forage widely throughout the island.
The proposed rule for listing the species was published March 26,
1998. Since then, there have been three public comment periods
opened on March 26, 1998, May 29, 1998, and May 27, 2004.
Under a settlement agreement approved by the United States District
Court for the District of Hawaii on August 21, 2002, the Service is
required to make a final decision on the proposal to reclassify the
Mariana fruit bat from endangered to threatened on Guam and list the
Mariana fruit bat as threatened in the Commonwealth of the Northern
Mariana Islands by December 31, 2004.