locate insects in the air but instead to locate fish just
beneath the water’s surface. It gets the name Bulldog
Bat from its flattened puffy face, with small eyes, short
pointed ears, and prominent cheek pouches. It is a
large bat, with a wingspread of 61 cm (24 in). It has
long toes, with prominent, sharp claws. Using its sonar,
the bat detects small fish and crustaceans breaking
the surface of calm rivers and pools. It swoops down,
gaffing the fish with its large well- clawed feet. It then
transfers the prey to its mouth, where it stuffs it in its
large cheek pouches and then grinds it up, bones and
all. It is thrilling to watch Bulldog Bats feed, as they
seem to scoop up prey unerringly, but you must hit
the right conditions of a moonlit night, a quiet lake or
pool, and, of course, the bats.
Undoubtedly, the most notorious Neotropical bat
species is the Vampire Bat (Desmodus rotundus; plate
8- 23). This extraordinary animal feeds entirely on the
blood of mammals such as tapirs and peccaries. In
many areas Vampire Bats have prospered because of
the presence of cattle and swine, both of which afford
an easily accessible source of blood. Vampires fly from
their roosting caves at night to locate prey. The bat finds
its victim both by olfaction and vision. Remarkably
agile (for a bat), the Vampire scurries over the ground
on its hind legs and thumbs, and then climbs onto
the sleeping animal. Using specialized incisors, the
bat slices into the superficial skin layers and initiates
bleeding. The cut is so sharp that the prey animal rarely
awakens. The bat’s saliva contains an anticoagulant, so
the blood flows freely while the bat feeds. The bat’s
digestive tract is modified to deal with blood, which is
extraordinarily high in protein.
Vampires occasionally attack humans. I have seen
Mayan people in Belize who have been bitten about
the face and fingers by vampires. Fortunately for these
people, none of the bats was a carrier of rabies, though
in some places Vampire Bats are vectors for this serious
viral disease. Vampires carrying rabies may show
no symptoms themselves, and that indicates a long
evolutionary relationship between the Vampire Bat
and the rabies virus.
Bats exhibit adaptive radiation not only in their
diverse feeding behaviors but also in their choice of
roosting sites. Bats normally roost upside down, using
sharp claws on their feet to attach (plates 8- 24– 25).
A bat spends approximately half of its life at the roost
site, which is where most social interactions such as
mating, rearing young, and food digestion occur. Bats mayPlate 8- 23. Vampire Bat, in the gloved hand of a skilled bat
handler, showing its upper incisors, used to cut into skin and
allow the animal to lap flowing blood. Photo by Bruce and
Carolyn Miller.Plate 8- 24. These small leaf- nosed bats (family Phyllostomidae)
are roosting beneath a big palm leaf. Photo by Sean Williams.Plate 8- 25. The ghost bats (Diclidurus spp.) are small white
bats of South America whose ecology is poorly known. They
are thought to feed mostly in the rain forest canopy. Photo by
Kevin Zimmer.chapter 8 evolutionary cornucopia 123