Roosting Behavior of Colonial and Solitary Flying Foxes in American Samoa (Chiroptera: Pteropodidae)1

Abstract

We examined characteristics of roosting sites utilized by two flying fox species (Pteropus tongunw and I! samoensis) in American Samoa. The colonial roosting sites of I! tonganus were observed over a ten-year period, including two years when severe hurricanes devastated bat populations and destroyed roost trees. Prior to the hurricanes, roosts were located on cliff faces above the ocean or steep mountainsides, locations that were either inaccessible to people or in protected areas where hunting was not allowed. In the years immediately following the hurricanes, I! tongunw colonies split into smaller groups that moved frequently to different locations. Four years after the second hurricane, colonies had coalesced and returned to many of the traditional roosting sites used before the hurricanes. Common tree species in upland and coastal forest were selected as roosts. The isolated locations selected for l? tonganus roosts were apparently the result of hunting pressure on the colonies. The solitary roosts of I! sumoensis were observed during 29 months. Roosting bats were well concealed and hard to detect within the forest; even bats on exposed branches were cryptic. Mature primary forest was favored as roosting habitat. Individual bats used specific branches or trees as roosts and returned to them for up to 29 months. Unlike I! tongunus, people did not alarm roosting I! samoensis easily and some roosts were located near houses and along roads.

Pacific Flying Foxes (Mammalia: Chiroptera): Two New Species of Pteropus from Samoa, Probably Extinct

“…Furthermore, while 20th-century specimens of P. samoensis and P. tonganus from Samoa are not uncommon in museums (e.g., AM, AMNH, ANSP, USNM, ZMUC), we know of no museum specimens of P. coxi collected since the type series was taken more than 160 years ago. Regardless of whether more than two species of Pteropus survive today in Samoa, it is clear to us from our own experiences and from our close reading of relevant literature that it is indeed only P. samoensis and P. tonganus that have been regularly encountered by field biologists working in Samoa during the past 15 years (e.g., Wilson and Engbring, 1992;Craig and Syron, 1992;Elmqvist et al, 1992Elmqvist et al, , 1994Craig et al, 1994aCraig et al, , 1994bMorrell and Craig, 1995;Banack, 1995, 1999;Banack, 1996Banack, , 1998Pierson et al, 1996;Grant et al, 1997;Miller and Wilson, 1997;Richmond et al, 1998;Thomson et al, 1998Thomson et al, , 2002Brooke et al, 2000;Nelson et al, 2000;Webb et al, 2000;Brooke, 2001;Grant, 2002, 2003).…”

Exploitation of Bats for Bushmeat and Medicine

“…Banack 1996; Brooke et al 2000;Gumal 2004;Stier and Mildenstein 2005). Hence, bats may be reluctant to leave when hunting starts and may find it difficult to find alternative roost sites after fleeing hunters.…”

Spatio-temporal vigilance architecture of an Australian flying-fox colony

“…Also, the colony was easily accessible on foot, with the soft ground cover of ferns and herbs making it possible for the observer to walk quietly. The animals had been habituated to the regular presence of a "man with hat" since the onset of ecological studies in 2001 to minimize observer bias, a habituation that is easily accomplished in flying-foxes (Brooke et al 2000;Welbergen 2006). These ideal observation conditions make us confident that the observed differences in behavior were representative and not primarily due to the shape or density of the colony or differential visibility of animals.…”