4.4 Competition for resources in Huevos de Caballo
In Table 4 I have noted the number of antagonistic observations that
were made, the aggressor and the target, and again noted the length of
each bird in brackets. As previously noted, in Huevos de Caballothe number of seed husks that contained edible (and accessible fruit)
was limited at any time. Thus, it could be expected that antagonisms and
competition would be more
frequent. There were indeed more frequent instances of antagonism, and
in most instances the aggressor was the larger bird. However, there were
four instances where the aggressor was smaller — both antagonisms by
the Lesson’s Motmot, the antagonism of Great Kiskadee toward
White-winged Dove, and the antagonism by Red-legged Honeycreeper toward
Yellow-green Vireo. There was also one instance in which the aggressor
and recipient were the same length.
While there were more antagonisms in the Huevos de Caballos I
studied, nevertheless given that out of 299 feeding observations I
observed only 11 instances of antagonism and displacement, they were
still comparatively rare. In this respect my observations are consistent
with those made by McDiarmid et al. (1977) that interspecific
displacements are rare.
While one might impute these antagonisms to the relative belligerence of
each species (some flycatchers are known to be especially pugnacious),
there might be an alternative explanation. Looking at Table 4 and back
to my notes, I find that after the Yellow-green Vireo had fed it was
chased by a pair of Red-legged Honeycreepers, which subsequently fed
themselves (presumably on the same fruits). Thus, it took two birds to
dislodge one. In the two cases of Lesson’s Motmot aggressive behavior,
which occurred on the same day, the motmot chased away the Hoffmann’s
Woodpecker, after the woodpecker had fed; later, while it was itself
feeding, the motmot chased away a Baltimore Oriole which flew in
attempting to feed. The first situation of the Great Kiskadee is even
more complicated. According to my notes, both the White-winged Dove and
the Great Kiskadee had been feeding (presumably on different fruits)
prior to the altercation. With regard to the antagonistic behavior
toward the Clay-colored Thrush, the Great Kiskadee had been feeding
before it chased the Clay-colored Thrush away. Thus, excepting the
situation where a pair of birds dislodged a larger bird, there does not
seem to be enough evidence to support an alternative explanation, other
than that of an innate belligerence of a species, although further study
is clearly needed.
[ On March 3, 2022 I observed intraspecific antagonism. A
female Red-legged Honeycreeper was perched on a hanging (vertical)
branch, which enabled it to reach sideways and feed on an openedHuevos de Caballo fruit. When a second female Red-legged
Honeycreeper came down the branch to also feed from that fruit, the
first female aggressively chased it away. This is the only intraspecific
antagonism I ever noted in either tree].