14 
PROCEEDINGS OF THE CALIFORNIA ACADEMY OF SCIENCES 
Series 4, Volume 65, Supplement I 
use by recreational four-wheel drive vehicles (Pierson et al., 1996a). Banack and Grant (2003) also 
note that penetration of roads into primary forest facilitates hunting by humans. 
Notes and Comments. — During the day Samoan flying foxes will soar on thermal currents 
with fully extended wings (Cox, 1983). Diurnal activity increases the risk of hyperthermia in these 
bats at times when daily temperatures and solar radiation are greatest, and mid-day activity may be 
lower than at dusk and dawn (Thomson et al., 1998; Banack and Grant, 2003). However, soaring 
can also reduce the energetic costs of flight and under favorable ambient conditions can instead 
decrease the risk of hyperthermia (Thomson et al., 2002). Samoan flying foxes have wing mor¬ 
phology and flight mechanics more conducive to soaring flight than does the sympatric Pacific fly¬ 
ing fox (Norberg et al., 2000). 
Males and females seem to form pair bonds (Cox, 1983; Pierson and Rainey, 1992; Banack 
and Grant, 2003). These bats will scent-mark branches with their chins and sebaceous glands on 
the back of the neck (Brooke, 2001; Banack and Grant, 2003). Aggressive patrolling and aerial 
chases between bats seem to be involved with defense of temporary foraging areas; aggressive 
encounters between bats at feeding sites involve biting, striking with closed wings, and wing clap¬ 
ping (Brooke, 2001; Banack and Grant, 2003). 
Stenoderma rufum — Red fruit bat (Family Phyllostomidae) 
Conservation Status. — National and International Designations: U.S. Fish and Wildlife 
Service (1994, 1996a,b): Species of Concern (inactive, former Category 2 candidate for listing 
under the U.S. Endangered Species Act). U.S. Forest Service (2005a,b): Sensitive Species. Inter¬ 
national Union for the Conservation of Nature (2017): Near Threatened. 
Territorial Designations. — Puerto Rico Department of Natural and Environmental 
Resources (2015): Species of Greatest Conservation Need (Vulnerable). U.S. Virgin Islands 
(Platenberg et al., 2005): Species of Greatest Conservation Need. 
Description. — The red 
fruit bat has a simple nose-leaf, 
red-tinted tan to dark brown 
pelage, a small white spot near 
the shoulder at the junction of 
each wing with the body, and a 
small white crescent at the anteri¬ 
or base of each ear (Fig. 3; 
Genoways and Baker, 1972). 
Ventral hairs are tipped with 
gray, and males have scent 
glands under the white shoulder 
patches (Gannon et al., 2005). 
Forearm lengths range 46 to 51 
millimeters and body mass 20- 
31 grams; females average 
slightly larger than males on Puerto Rico (Jones et al., 1971; Gannon, 1991; Gannon et al., 2005). 
Distribution and Systematics. — This species is known from Puerto Rico (including 
Vieques Island), and from the three islands of St. John, St. Thomas, and St. Croix of the U.S. Vir¬ 
gin Islands where it is considered rare (Fig. 4; Gannon et al., 2005; Kwiecinski and Coles, 2007). 
This is the only species within the genus Stenoderma. Two living subspecies are recognized: 
Figure 3. Red fruit bat, Stenoderma rufum (photo by Michael Gannon, 
courtesy of the American Society of Mammalogists Mammal Images Library). 
