304 AisrisruAL eepokt Smithsonian institution, 1915. 



III. ORIOLES, FLYCATCHERS, FINCHES, AND THRUSHES. 



A comparative study of the notes and songs of the birds of the 

 Tropics and their familiar northern representatives is certainly not 

 less interesting than the study of their physical resemblances and 

 differences. And here it may be suggested that resemblances, which 

 are of greatest value as showing relationships, are even more elusive 

 and hard to follow out than are more physical characters. Differ- 

 ences are of negative importance ; resemblances alone count in tracing 

 racial affinities. 



In this respect the great family of tropical orioles hangs together 

 as a unit and ties closely to its more familiar northern offshoots. 

 From the tiny Mexican orchard oriole to the crow-sized oropendolas 

 there is some subtle quirk of tone that makes them all recognizable 

 to anyone having a single good acquaintance in the family. 



I think no birds in tropical America have given me more pure fun 

 with their vocal performances than the big yellowtails, or oropen- 

 dolas; Gymnostinops in southern Mexico, and the various species of 

 Ostinops in Colombia. I can not now remember any striking differ- 

 ences in their songs or calls, except that Gymnostinops combines more 

 gymnastics with his effort than mere Ostinops. But everywhere in 

 tropical America the loud rasps, chucks, and gurglings of these great 

 orioles are as characteristic as the steady flashing of black and gold 

 in the burning sky as they wing overhead from bank to bank of the 

 great rivers. 



They are all highly polygamous, and I have frequently seen them 

 demonstrate a most watchful and efficient warden service in favor of 

 the old males. After one shot you may stalk and stalk the big black 

 Sultan, " quisking " from the bare dead spike above the forest roof, 

 only to be defeated time after time by the party of six or eight silent 

 and watchful females perching around him at lower points. Silent — 

 that is, until you get within about twice gunshot of their lord — when 

 they suddenly squaAvk and j^ell, and the old boss " yips " loudly and, 

 with batting wings, leaves for foreign parts. 



The calls of the male, given from a high perch with a commanding 

 view, may be variously described : A loud, vigorous " quisk " ; an 

 equally carrying but very liquid " churg," ending inside an empty 

 cask; a series of dry, ascending clicks or twig snaps, probably done 

 with the enormously strong and hollowed bill. But his true song, to 

 call it so, defies description or imitation without all the " traps " of 

 the triangle man in the orchestra. Imagine a performance lasting 

 only about 2 seconds, commenced by breaking off a handful of willow 

 sticks, then running into a rising series of " choog-choog-choogs," to 

 end in loud, explosive " keow," easily audible at a quarter of a mile. 

 This is only the vocal part of the performance, and is accompanied 



