persers of seeds dispersed primarily by birds (Byrne and
Levey 1993, Levey and Byrne 1993); their importance
has not been investigated in Monteverde. Seed-eating
ants appear to be considerably less dense in Monteverde
than in the lowlands of Costa Rica (see Chap. 4, Insects
and Spiders). There is a general paucity of ant-dispersed
plant species in Monteverde; predation by ants on seeds
in the leaf litter and soil appears to be lower than in other
forests (K. G. Murray, unpubl. data).
Vertebrates Vertebrates disperse seeds by three
methods: (1) caching and scatterboarding, (2) exter-
nal adhesion, and (3) consumption. Plants adapted for
dispersal by mammals and birds that store seeds for
later consumption typically have no specialized struc-
tural features other than a thick protective seed coat.
Most seeds are consumed later, but those whose loca-
tions are forgotten have usually been stored in pro-
tected sites where the probability of germination and
survival is high. Seeds adapted for this form of dis-
persal (probably by Variegated Squirrels and Agoutis
in Monteverde) include oaks and Inga spp.
Seeds adapted for dispersal by adhesion to the
exteriors of animals usually have seed coats or other
structures modified as hooks or spines that become
stuck to a vertebrate's fur or feathers. In Monteverde,
as in the temperate zone, the best examples are weedy
members of the Fabaceae (e.g., Desmodium sp.) and
Asteraceae (e.g., Bidens pilosa). More conspicuous
examples in the MCFP are Uncinia hamata (Cypera-
ceae), which adheres via a bent floral bract, and
Pisonia sp. (Nyctaginaceae), which has sticky glands.
Among plants adapted for dispersal in vertebrate
guts, recognizable syndromes are associated with dif-
ferent animal groups. Fruits adapted for consumption
by bats are usually pale yellow, green, or white in
color, are often aromatic, and contain a reward rich
in carbohydrates or lipids. Fruits eaten by nonflying
mammals (primarily monkeys, but also carnivores
such as Kinkajous and White-nosed Coatis) are usu-
ally a shade of green, brown, white, or yellow, are
often aromatic, and often contained within a capsule
or pod. Fruits eaten by birds typically are brightly
colored, lack any obvious smell, and contain carbo-
hydrates, lipids, and/or proteins as the major reward.
Many are contained within capsules that open to re-
veal seeds with brightly colored arils (fleshy, nutrient-
rich appendages that partially or entirely cover the
seed). A subset of bird-dispersed plants bears fruits
that contain relatively high concentrations of lipids
and proteins and a single large seed, and are dispersed
primarily by large frugivores such as toucans or Re-
splendent Quetzals.
Among the plant species that use bright colors to
attract visually oriented foragers such as birds, cer-
tain fruit colors and combinations of colors are more
common than others. Of the 252 species of "bird"
fruits surveyed by Wheelwright and Janson (1985) in
Monteverde, 41% were classified as "black" (includ-
ing very dark blue and reddish black), 25% as "red"
(including scarlet and pink), 11% as orange, 10% as
white, 6% as "blue" (including violet and purple), 4%
as "brown" (including dull dark red), 3% as yellow,
and 1% as green. These proportions are consistent
with those of fruits from forests in Manii National
Park, Peru (Wheelwright and Janson 1985), south
Florida (Long 1971), Europe (Turcek 1963), and New
Zealand and Australia (Willson et al. 1989). Many
plant species in Monteverde, as elsewhere, combine
fruit colors with strongly contrasting colors of unripe
fruits, bracts, pedicels, or other accessory structures
to produce more conspicuous displays (Fig. 8.2).
Among such species, the combination of black and red
is most frequent. This pattern occurs in 18% of all
species at Monteverde, representing 21 plant families
(Wheelwright and Janson 1985).
Elsewhere in the world, plants are adapted for dis-
persal by reptiles, fish, and land crabs, but we areFigure 8.2. The showy fruits of Heisteria acuminata
contain a disproportionately large seed and little pulp.
Photograph by Nathaniel Wheelwright.257 Plant-Animal Interactions