Most mammals use audible vocalizations to communicate but few
studies have documented the extent, range, or distinctiveness of these
calls. We report acoustic communication in two species of flying fox
that coexist in the Samoan archipelago, Pteropus samoensis and P.
tonganus. Flying foxes are large fruit and nectar eating bats restricted
to the Old World. They are members of the suborder Megachiroptera and
the family Pteropodidae. There are 60 recognized species in the genus
Pteropus. Species include the largest living bats, with wingspans up to
1.7 meters. No species of flying fox echolocates, a trait ubiquitous in
Microchiropterans. Communication within and between species involves
audible calls but remains largely unstudied. We compared the
vocalizations of P. samoensis and P. tonganus from Tutuila, American
Samoa in June 2001 using a Senheiser MKH-70 P 48 directional microphone,
Sony digital audio tape recorder TCD D 10 PRO II, and Canary
bioacoustical software for analysis. P. samoensis is a largely diu rnal
species that roosts within trees either singly or in small family groups
(male, female, and single offspring). It is highly territorial and
actively defends its territory against intruders. Vocal communication is
the primary means used to deter other flying foxes from landing within
an occupied territory. P. tonganus is a nocturnal species and roost in
large noisy camps with up to 5000 animals congregated in adjacent trees.
Interactions between the two species are minimal. Variation between
populations and species were examined from sonograms using five
parameters: peak frequency, pulse rate, maximum frequency, frequency 1
(high frequency of the peak harmonic) and number of harmonics.
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