to the uniqueness of avian evolution in the Neotropics.
One of the most common and widely distributed
birds of the tropics is the Blue- gray Tanager (Thraupis
episcopus; plate 15- 49), which is well described by its
name.
Tanagers devour both fruit and arthropods, and
though the various species in a mixed foraging flock
appear to the casual observer to be feeding in much
the same manner, studies have suggested that species
do specialize their foraging in various ways, perhaps
reducing the potential for interspecific competition. For
example, some species are most commonly observed
in the canopy, while others forage lower. Even their
various behaviors, as they glean insects or select fruit,
vary among species. Nonetheless, many species forage
heavily on various Miconia species (Melastomataceae)
and mistletoes (Loranthaceae).
Cloud forests provide habitat for a group of colorful
and robust tanagers called mountain tanagers. They are
often seen in mixed flocks with other tanagers and, like
many tanager species, can be attracted to bird feeding
trays that offer fruit. The Blue- winged Mountain
Tanager (Anisognathus somptuosus; plate 15- 50) is one
representative of this group.
Honeycreepers (plates 15- 51– 52), which include
dacnises and conebills, are nectarivorous, though they
also include ample amounts of fruit and arthropods in
their diets. Warbler- size, they have fairly long, down-
curved bills.
Some tanagers, such as the ant- tanagers (genus
Habia), are army ant followers, and many other
tanagers, including honeycreepers, move with
antbirds, woodcreepers, and other species in large
mixed foraging flocks. Studies by Charles Munn and
John Terborgh have revealed the high diversity and
intriguing complexity of behavior within both canopy
and understory mixed- species flocks in the Peruvian
Amazon. Each flock type consists of a core of five to
10 different species, each represented by a single bird,
a mated pair, or a family group. Up to 80 other species
join flocks from time to time, including 23 tanager
and honeycreeper species, a remarkably high diversity.
Mixed foraging flocks occupy specific territories, and
when another flock is encountered, the same species
from each flock engage in “singing bouts” and displays
as boundary lines are established. Adult birds tend to
remain flock members for at least two years. Nesting
occurs in the general territory of the flock, the nesting
pair commuting back and forth from nest to flock.Plate 15- 50. Blue- winged Mountain Tanager. Photo by Andrew
Whittaker.Plate 15- 51. The Purple Honeycreeper (Cyanerpes caeruleus)
is found from southern Central America (Panama) through
Amazonia. This bird is a male. Photo by James Adams.Plate 15- 52. The Green Honeycreeper (Chlorophanes spiza) is
widely distributed throughout the Neotropics and is common
in open habitats and gardens. This bird is a male. Most
honeycreepers are smaller than the Green. Photo by James
Adams.chapter 15 neotropical birds: the bustling crowd 281