the area of Connecticut. Only 45 bat species regularly
occur in the entire continental United States.
The adaptive radiation of microchiropteran bats
in the American tropics is nothing short of amazing.
These animals evolved to feed on insects captured in the
air using echolocation. Indeed, many species still feed
in this “traditional” way (plate 8-20). However, there
are also fruit- eating, nectar- eating, pollen- eating, fish-
eating, frog- eating, bird- eating, lizard- eating, mouse-
eating, bat- eating, and even blood- eating bats, and
examples of all of these may be found in Neotropical
forests. From an insectivorous ancestor (or ancestors)
tropical bats have radiated into dramatically different
feeding niches, taking advantage of the tremendous
diversity of rain forest resources.
Daniel Janzen and D. E. Wilson made a classic study
of the pattern of bat diversity in Costa Rica and tallied
a total of 103 species. Of these, 43 are insectivorous; 25
frugivorous; 11 nectarivorous; two carnivorous; one
piscivorous (fish eating); three sanguivorous (blood
feeders); and 18 feed on some combination from the
above list. Among the insectivorous bats, some capture
prey by aerial foraging and some by foliage gleaning.
Aerial foragers catch insects on the wing, while foliage
gleaners pick their prey from leaves, branches, and even
the ground.
The False Vampire Bat (Vampyrum spectrum) is a
generalized carnivore. It captures sleeping birds as well
as rodents and other bats, and is suspected of locating
some of its prey by olfaction. Many bats have a keenly
developed sense of smell. The False Vampire is one of
the largest of the Neotropical bats, with a wingspread
of approximately 75 cm (30 in). It has prominent ears,
a long snout, a large “leaf ” nose, and long, sharp canine
teeth. Its generally ferocious appearance misled people
into believing it to be a vampire, which it is not.
Flattened leaf- like noses are common among fruit-
eating bats as well as carnivores (plate 8- 21). The
flattened nose may be an adaptation aiding the bat
with echolocation. These bats typically carry large food
items and must therefore emit their sonar vocalizations
through their noses rather than mouths. The leaf nose
is thought to aid in focusing the signal.
The widespread fishing Bulldog Bat (Noctilio
leporinus; plate 8- 22), is another excellent example of
adaptive radiation. This species uses its sonar not toPlate 8- 20. The Greater White- lined
Bat (Saccopteryx bilineata) is typical of
insect- foraging bats. It is commonly
seen around dwellings and forms large
colonies. Males court females in part by
emitting a “song” audible to humans.
Photo by Dennis Paulson.
Plate 8- 21. The small fruit- eating
Chestnut Short- tailed Bat (Carollia
castanea) displays a leaf- shaped nose.
The eyes of this species are relatively
large, and thus it likely has good vision,
helpful in locating fruit on a tree. Photo
by John Kricher.Plate 8- 22. The fishing Bulldog Bat in
typical roosting posture (but on the
gloved finger of a bat handler). Photo by
Bruce and Carolyn Miller.122 chapter 8 evolutionary cornucopia