be colonial or solitary roosters. Roost sites include caves,
crevices, hollow trees, and even tree trunks (plate 8- 26).
Some bats roost in foliage, often modifying it to suit their
needs. The small Sucker- footed Bat (Thyroptera tricolor)
roosts in furled heliconia and banana leaves, attaching
to the slick leaf with adhesive disks on the legs and wrist
joints of the wings. The Honduran White Bat (Ectophylla
alba), a small, all- white bat, goes one step further. It is one
of several species to actually construct a tent, in this case
out of a heliconia leaf. The white bat forces the huge leaf to
droop by carefully chewing veins that are perpendicular
to the midrib. The leaf is only partially chewed, and the
result is a protective, thick tent in which a half dozen or so
of these diminutive bats can cuddle in safety.
Adaptive Radiation in Tyrant Flycatchers
One of the most diverse families of birds in the world,
Tyrannidae provides another example of the evolutionary
process of adaptive radiation. There are 410 species of
tyrannids, or tyrant flycatchers, all of which are confined
to the New World. The vast majority of species occupy
Central and South America, though some migrate to
North America to breed. Tyrant flycatchers occupy
all terrestrial habitats: towns, villages, rain forests,
cloud forests, fields, scrub, savannas, marshes, and the
South American puna, páramo, and pampa ecosystems
(chapters 13 and 14). Though the name flycatcher is
meaningful in most cases, the methods of capture and
the types of insects and other arthropods taken varyPlate 8- 26. This group of Long- nosed (also called Proboscis)
Bats (Rhynchonycteris naso) is roosting, as the species
habitually does, in the open on a tree trunk along a stream.
These bats, which are common and widespread throughout
Amazonia, are often seen on river trips. They are known
to rock back and forth like leaves hanging in the wind. If
approached too closely they will fly off, resembling moths in
flight. Photo by Kevin Zimmer.
Plate 8- 27. The Tropical Kingbird ranges from southern Texas
south to central Argentina. It is displaying the typical posture
of a foraging tyrant flycatcher, sitting in the open as it awaits an
opportunity to snatch prey from the air. Photo by Bruce Hallett.Plate 8- 28. This Short- crested Flycatcher (Myiarchus ferox), seen
from below, shows the light- colored lower mandible of the
wide beak. The rictal bristles are obvious, protruding from the
area where the beak meets the mouth. Photo by John Kricher.124 chapter 8 evolutionary cornucopia