HOW CONVERGENT IS THE AMERICAN REDSTART (SETOPHAGA-RUTICILLA, PARULINAE) WITH FLYCATCHERS (TYRANNIDAE) IN MORPHOLOGY AND FEEDING-BEHAVIOR

Possible convergence between the unique aerial-feeding American Redsta rt (Setophaga ruticilla) and the tyrannid flycatchers was considered u sing skeleton, external morphology, substrate use, and locomotory feed ing movements. The redstart is a typical paruline in the broader funct ional units of forelimb, hindlimb, and body axis, as well as in propor tionate lengths of the main axial elements of both the forelimb and hi ndlimb. It retains and utilizes the advantageous features of the wood- warblers, including the capacity to hop rapidly through the vegetation . To this it has added the long and broad bill, and long rictal briste s (adaptations for aerial feeding) of the tyrannids. The wing shape re mains wood-warblerlike, but it is convergent with the flycatchers in i ts low wing loading. The tail is long, as in the flycatchers, for bett er aerial control, but is spread and, apparently, used to flush insect s from vegetation, as in the specialized Australo-Papuan fantails (Rhi pidura). The redstart is a unique adaptive and ecomorphological type a mong north American passerines.