BULLETIN FLORIDA STATE MUSEUM


TABLE 16.-NICHE CHARACTERISTICS OF CLOSELY RELATED RESIDENT BIRDS OF THE
 CAYMAN ISLANDS.

 body bill feeding feeding food**
 size length habitat height methods type
Colaptes auratus1 2 2 1 3* 4*
Centurus superciliaris (
Tyrannus dominicensis 1 1
Tyrannus caudifasciatus 1 1 4 4 4 3
Elaenia martinica 3 4 1 4 4 4
Myiarchus stolidus 1 4
Vireo magister 2 2 ? 2
Vireo crassirostris C 4 4 2 2 2
Vireo altiloquus LC 4 4 2 2 ? ?
 CB
Dendroica petechia 2 1 4 4 1 1
Dendroica vitellina

* Differences: (4) strongly developed, (3) moderately well developed, (2) poorly
 developed, (1) absent or negligible.
** Based chiefly upon percent differences in animal and vegetable material and not
 upon different species of animals or plant materials consumed.

woodpecker, whereas Centurus spends much of its time in gleaning
arthropods (especially in bromeliads) and taking small fruits. Analyses
of stomach contents indicate differences in foraging techniques. From
Appendix III it can be seen that 19 Colaptes fed heavily (97% of the
diet) on arthropods, mostly on ants and termites. Although Centurus
has a diet high in insects (56% ), especially beetles, approximately one-
half of its diet is fruit. In fact, the frequent occurrences of this wood-
pecker at house sites are closely connected to the fruit-bearing trees,
especially papaya, cultivated there. Of interest also are the "herptiles"
taken by Centurus, the Hyla most likely captured by probing into brome-
liads.
 FLYCATCHERS (TYRANNIDAE).-Of all the closely related birds on the
Cayman Islands, the four resident species of Tyrannidae possess the most
interesting sets of ecological isolating features. No two species-pairs
have evolved precisely the same mechanisms, which are based on dif-
ferences in habitat choice, feeding height, feeding methods, and food
types (Table 16). Of particular significance is the fact that one of these
"flycatchers," Elaenia martinica, is chiefly a frugivore (Appendix III),
and as such does not compete with the other three insectivorous tyran-
nids. Also, Tyrannus caudifasciatus consumes both lizards and frogs, a
predatory habit not shared with the other tyrannids. Elaenia martinica
is one of the most widespread and abundant members of the resident


Vol. 19, No. 5