FAMILY PARULIDAE 



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469102-4) taken in 1958 on the Western River, Almirante, Bocas del 

 Toro, show this variability admirably. One is light underneath, as at- 

 tributed to typical leucopygia, another is much burner, while the third 

 is extremely dark, the underparts except the throat and midline of 

 belly being entirely suffused with dusky. Certain individuals from 

 Chiriqui are as light as any from farther north, while others from 

 Nicaragua and Costa Rica are as buffy as some from Code or Chiriqui. 

 Therefore, these populations are listed under the name leucopygia, 

 with veraguensis as a junior synonym. 



There is a narrow zone of intergradation between leucopygia (sensu 

 lato) and semicervina in the Canal Zone and slightly eastward. Two 

 birds collected by E. A. Goldman labeled "Rio Indio, Canal Zone" (a 

 tributary of the Chagres, not the following Rio Indio in western Colon 

 Province) and another taken from Chilar, on the Rio Indio, Colon, are 

 typical of leucopygia, as are all those from farther west. Birds from 

 Cerro Chucanti, Serrania de Maje, eastern Panama Province, and from 

 there east through San Bias and Darien and most of Colombia are 

 typical of semicervina. Except for the 2 Goldman specimens above, 

 all birds from the Canal Zone proper (Gamboa, Gatun, Cocoli River), 

 Cerro Azul, Utive, and the upper end of Madden Lake in eastern 

 Province of Panama (Candelaria and Peluca Hydrographic Stations) 

 are clearly intergrades. An exception is an individual from the Peluca 

 Station (1 of 4 taken there) that appears perfectly typical of semicer- 

 vina, suggesting that the zone of intergradation probably does not ex- 

 tend much farther east than this locality. 



Some authors merge the B. fulvicauda complex in B. rivularis 

 (Riverside Warbler) of eastern, Amazonian, and southern South 

 America south to northern Argentina (Meyer de Schauensee, Species 

 Birds S. Amer, 1966, p. 453). 



The Buff-rumped Warbler dwells along the shores of streams or, 

 more rarely, boggy areas and mangrove swamps. Eisenmann has gen- 

 erally seen this species only at rapid-flowing, narrow, clear streams over 

 rocky beds, but in coastal Bocas del Toro east of Almirante, on the 

 slow-moving, dark, muddy, rather wide Western River, on October 19, 

 1965, he saw two pairs at different places in waters navigable by motor 

 launch. In many aspects of behavior this species resembles a water- 

 thrush, but it hops rather than walks, fanning and wagging its tail 

 from side to side, exposing the conspicuous light patch on the upper 

 tail coverts and base of the tail feathers. I have always found this a 

 rather shy species, continually flying ahead and rarely affording one a 

 good look. 



