JOHNSTON: CAYMAN ISLAND AVIFAUNA


avifauna (Tables 3-10) and is also extremely belligerent both intra- and
interspecifically. In the hundreds of interspecific behavioral encounters
I observed, it appeared that Elaenia was always dominant. Among the
four species, within-habitat feeding strata clearly differed from species
to species (Figure 18); in no case did two species spend more than about
20 percent of the time feeding at the same stratum, and even when they
did, each selected different foods.
 In summary, the tyrannids provide a classic case of the partitioning
of environmental resources such that coexistence of four resident forms
is possible on Grand Cayman. Elaenia is chiefly a frugivore, whereas
the others are chiefly insectivorous; Tyrannus dominicensis is a large
insectivore feeding at tree-top levels in open sites around towns and


 100-






Z 75-

LaJ
LUJ
LL
Ld

5o-
LL
0
I--


 25-

W


 Q0-

 0-


FIGURE 18.-Feeding


 I I I I
0-Im 1-3m 3-6m >-6m
heights and percentages of time feeding for flycatchers.


0-0 Elaenia GC
A- Elaenia CB
0*- Myiarchus GC
 A Tyrannus dominicensis CB


1975