helped create the reserves and protect the land. No
matter what the local negative effects are, the eco-
tourism boom in Monteverde has had an overall posi-
tive influence on bird conservation. If the boom con-
tinues, it may help create the funding and political
will to protect and restore Pacific slope habitats.THE INFLUENCE OF FRUIT-EATING BATS ON THE DYNAMICS AND
COMPOSITION OF NEOTROPICAL PREMONTANE CLOUD FORESTS
Eric Dinersteineotropical lower montane forests are rich in
bat species (Dinerstein 1983). The Phyllo-
stomidae, the family of bats that include spe-
cialized fruit-eaters, are particularly diverse in Monte-
verde (see Appendix 10). Fruit bats are abundant,
second only to insectivorous bats among mammals
recorded in the MCFP and surrounding forested habi-
tats. In an 18-month study of the feeding ecology of
frugivorous bats, I found that (1) fruit-eating bats con-
sume almost exclusively fruit, (2) the most common
fruits eaten by bats are early to mid-successional
shrub and tree species, (3) fruits of strangler figs
(Ficus spp.) are much less important for montane
bats than low-elevation bats, and (4) frugivorous bats
play an important role in the natural regeneration of
lower montane forests, removing fruits from at least
52 species of plants (Dinerstein 1983, 1986). Studies
of transects along trails and roads in Monteverde and
in naturally or anthropogenically disturbed habitats,
revealed an abundance of bat-visited species with
remarkably long fruiting seasons (e.g., Solarium
aphyodendron, S. umbellatum, Cecropia obtusifolia)
and relatively large fruit crops (e.g., Conostegia oer-
stediana, Piper amalago, P. auritum, P. lancifolium).
Bat-visited plants of lowland neotropical moist for-
ests, such as La Selva, typically have much shorter
fruiting seasons and smaller fruit crops (Dinerstein
1983).
The abundance of fruit bats and other frugivores
raises two questions related to forest conservation.
First, how much does fruit removal and seed dispersal
by frugivores affect the structure and distribution of
plants? Second, how will the selective defaunation of
tropical forests (Redford 1992) affect their future
composition? Data to answer the first question have
come from field investigations in Monteverde and
elsewhere. Transects in successional areas affirmed
that the most abundant shrub species were largely dis-
persed by bats (Dinerstein 1983). Studies in lowland
habitats in Venezuela and Brazil demonstrate that the
first shrub and successional tree species to colonize
abandoned human settlements tend to be bat-visited
plants. As shrubs and successional trees create roost-
ing perches and cover for other frugivores, the seed
rain increases in volume and diversity.
The second question is posed in response to the
provocative essay by Redford (1992) titled "The
Empty Forest," defined as a tropical forest with its im-
pressive trees seemingly intact but its fauna elimi-
nated. Redford hypothesized that the structure and
composition of neotropical forests will be affected by
the extirpation of large mammalian frugivores, fruit-
eating birds, predators, and herbivores, whose ab-
sence may greatly influence plant recruitment. Typi-
cally, large fruit-eating birds and mammals are among
the first species to disappear in heavily hunted for-
ests. The meat of large fruit-eaters is highly prized.
Most large frugivores reproduce at low rates and are
slow to recolonize hunted areas. Throughout the neo-
tropics, sites containing intact large frugivore, herbi-
vore, and predator assemblages are increasingly rare.
Redford (1992) used the term "minimum ecologically
operational population size" to describe situations
where tropical frugivores may still exist at very low
densities, but their numbers are so low that the eco-
logical processes in which they take part are reduced
to the point of having no significance.
However, "empty forests" are hardly empty of
frugivores; unlike their Asian counterparts, the
Pteropidae, neotropical fruit bats are not heavily
hunted. As long as adequate roost sites remain, it is
difficult to imagine a neotropical forest without an
ecologically viable population of fruit-eating bats.
Future research on bats in Monteverde should deter-
mine the role phyllostomid bats play in the regen-
eration of abandoned pastures. On a larger spatial
scale, several questions emerge. (1) How will the
structure of forests that have lost frugivores other
than bats be different from similar habitats that main-
tain the full frugivore assemblage? To what extent
will Redford's "empty forests" become fruit bat-
influenced forests? To what extent do bat-visited
plant species overlap with species dispersed by other
frugivores?434 Conservation BiologyN