in long) hummingbirds and they conserve energy by
actually walking on the ground and only briefly flying
up to capture an insect or to feed on low flowers.
Unlike other hummingbirds, helmetcrests rarely hover
at flowers. Instead they perch, methodically plucking
insects and obtaining nectar from within Espeletia and
other favored nectar plants.
A Bear in the Andes? You Bet!
The Spectacled Bear (Tremarctos ornatus; plate 13- 20)
is named for its facial pattern of beige lines surrounding
its eyes and cheeks. Otherwise, the creature is black. It
is a medium- size bear, weighing about 200 kg (approx.
440 lb). The only species of bear found in South
America, it inhabits low- elevation montane cloud
forests from Panama through Peru and Bolivia. The
species is considered a relict, as it once ranged from
the southern United States (California to the eastern
seaboard) and throughout Central America. Like most
bear species, it is omnivorous, feeding on a wide variety
of vegetation (including hearts of bromeliads) as well
as small vertebrates and invertebrates. Mostly solitary,
Spectacled Bears have been reduced in population
in many areas by hunting, and are among the most
difficult large Neotropical mammals to observe in the
wild.
Elevational Migrants: Follow the
Food
The Resplendent Quetzal is one of many bird species to
engage in elevational (also called altitudinal) migration.
Nesting from January to June in mid- elevation cloud
forests, such as Monteverde (1,500– 1,800 m/4,920– 5,900
ft) in Costa Rica, these quetzals eventually migrate to
lower elevations (1,100– 1,300 m/3,610– 4,265 ft) along
the Pacific slope of Costa Rica, where they remain until
October. At that time they move back to the nesting
areas, where they remain for a few weeks. Then they fly
to the Caribbean slope (700– 1,100 m/2,300– 3,610 ft)
until returning upslope to nest. This complex pattern,
discovered by attaching small radio transmitters to the
birds, describes their general movement, but there is
much annual variability, suggesting that the birds are
seeking fruiting plant species in the family Lauraceae,
their principal food. The migration pattern of the quetzal
demonstrates strong ecological connectivity between
high- and low- elevational areas on both slopes. Other
frugivorous bird species also have complex elevational
migrations. Most hummingbird species at Monteverde
move upslope to breed during wet season and migrate
to lower elevations during dry season. Insectivorous
bird species do not engage in elevational migration,
suggesting that the driving force for these migrations is
fruit availability, not factors such as seasonal changes in
weather.
Butterflies are also elevational migrants. At
Monteverde, more than half of the 658 butterfly species
undergo seasonal elevational migration. Butterflies’
migration patterns vary among families and species,
but in general, most migrating butterflies depart
lowlands at the end of wet season, moving higher
in elevation, into the cloud forest life zones. At one
location, Windy Corner (the entrance to Monteverde
Cloud Forest Biological Reserve), on December 16,
1994, about 6,000 migrating butterflies were observed
over a five- hour period. Other insects, such as certain
dragonflies, flies, beetles, bugs, parasitic wasps, and
moths, are also known to be elevational migrants.
Some bat species, as well as Baird’s Tapir (Ta p i r u s
bairdii) and the White- lipped Peccary (Tayassu pecari),
are also suspected to be elevational migrants, at least at
Monteverde Cloud Forest Reserve.
The existence of elevational migration in such diverse
groups of animals has strong ecological and conservation
significance. Elevational migration is a clear example of
ecological linkages among life zones. Many frugivorous
birds, for example, are important seed dispersers (chapter
10), and their elevational migratory movements may
prove to be an important influence on the distribution
of various plant species whose seeds they disperse.
Ecological corridors that preserve suitable habitat for
elevational migrants permit the movement of animals
among various life zones. It is essential to recognize
the need to preserve contiguous habitats that form
elevational migratory corridors. At Monteverde Cloud
Forest, the evidence of elevational migration helped in
the creation of the Children’s Eternal Rainforest and
the establishment of Arenal Volcano National Park to
protect pre- montane rain forest essential to elevational
migrants (as well as nonmigrants).
Elsewhere in Costa Rica, a contiguous corridor has
been established linking high- elevation Braulio Carrillo
National Park with lowland La Selva Biological Station, a
corridor that represents an elevational range of 2,871 m
(9,419 ft). This corridor crosses six ecological life zones242 chapter 13 scaling the andes