BONACCORSO: A PANAMANIAN BAT COMMUNITY


 Crespo et aL (1972) and Morrison (in press) have demonstrated that vampires and
fruit bats avoid flying during intense moonlight. Whole-night samples were taken only
between the last and first quarter of the moon. Thus activity cycles were measured dur-
ing phases of the lunar cycle that did not produce enough light to influence bat flight
activity.
 Nets and traps were checked at least twice every hour. When possible net checks
were made more frequently to prevent bats from chewing out of nets. Upon removal
from a net or trap each bat was placed in an individual cloth bag. Usually within an
hour after capture the bats were banded, as described in Bonaccorso et al. (1976), and
released at the sampling station. The following data were recorded for each individual:
species, hour and location of capture, sex, age class, reproductive condition of females,
food in feces or mouth, weight, and forearm length.
 Age classes were distinguished as follows: infants were unable to fly and were en-
countered only when carried by the mother; juveniles were able to fly but still had the
infant pelage; subadults had the adult pelage but were smaller in weight than adults
and were reproductively immature; adults possessed both adult pelage and weight.
 Pregnancy, lactation, and reproductive inactivity of adult females were determined
by palpation. Additionally, females could be distinguished as nulliparous or post-
lactating by examining the condition of the teats.
 Fecal pellets obtained from individual animals were placed in separate glassine
envelopes for laboratory identification of food species. Fruits and pollens in fecal pellets
were identified to species by comparing unknowns with seeds, pulp fibers, and pollen
grains in a reference collection I assembled. Pellets collected from insectivorous bats
are in the process of analysis, and this information will be published elsewhere. Pollen
on the fur was collected by swabbing with a gelatin as described by Beattie (1971). The
pollen-containing gelatin was then melted on slides for microscopic identification. In
calculating feeding niche breadths and overlaps the fecal pellets in a single glassine
envelope were scored as a sample of one for the given food species it contained (pollen or
fruit). For the stenodermine fruit bats the fecal pellets from a single defecation seemed
to represent part of a single fruit that was eaten. Food passage along the digestive tract
is very rapid (Klite 1965), and a given defecation probably represents the last fruit
eaten by the bat. For carolline bats a single fecal pellet sometimes contained two types
of seeds. This probably resulted from eating very small fruits and switching food
species within very short intervals.
 Occasionally animals were captured with whole fruits held in the mouth. Additional
 information on food habits was gathered by placing plastic sheets under two roost trees
 of Carollia perspicillata to gather discarded fruits and fecal matter.
 Niche breadth is calculated as log, B = Ep, log, p,, where p, is the number of the i'
 food species divided by sample size (Levins 1968). Values approaching zero indicate nar-
 row niche breadths and specialists. Values approaching one indicate niche breadths of
 generalists. Niche overlap is calculated as CX = 2EX,/EX, + Y,, where X, is the propor-
 tion of the i'" food species in the diet of bat species X, and Y, is the proportion of the i'
 food species in the diet of bat species Y (Morista 1959). I follow Zaret and Rand (1971) in
 considering species with overlap values greater than 0.6 to be critically similar in terms
 of food overlap.

 PHENOLOGY OF FOOD RESOURCES

 Most of the bat species on BCI depend largely on fruit, flowers, or
 insects as food resources. Only a few species eat flesh or blood of
 vertebrates or non-insect invertebrates. The abundance and diversity


1979