64 BULLETIN 133, UNITED STATES NATIONAL MUSEUM 



THERISTICUS CAUDATUS (Boddaert) 



8colopa<v caudatus Boddaert, Tabl. Planch. Enl. Hist. Nat, 1783, p. 57. 

 (Cayenne.) 



This large ibis was common in the Paraguayan Chaco, west of 

 Puerto Pinasco, from September 7 to 26, 1920. The birds ranged 

 in small flocks of 9 or 10 individuals in openings among palms near 

 the borders of lagoons, where at times they were accompanied by 

 one or two crested ibis {Molyhdophanes caerulescens) . It was usual 

 to find them walking about in search for food in short grass beneath 

 the palms or at rest on fallen palm trunks or on the ground. Their 

 call note was a loud kree kree hree-ee^ a trumpetlike call similar to 

 that of the crested ibis, but higher in pitch. A wounded bird 

 emitted a grunting note like hwah-ah. In flight they travel directly, 

 with head and feet extended, and steady, regular wing beat. In 

 silhouette the head appears more slender than in the crested ibis, so 

 that they may be distinguished in situations where colors are not 

 readily visible. In Guarani the species is known as Gurucau yohi^ 

 and otherwise as handurria. 



In a male and two females killed on September 13 the colors of 

 the soft parts were similar in the two sexes. In a female they were 

 as follows: Bill and bare skin on head dull black, save for lower 

 eyelid, which is pale vinaceous lilac; iris nopal red; tarsus eugenia 

 red, shading on toes to old rose ; nails dull black. 



Salvadori *^ has given an excellent account of the South American 

 ibises of the genus Theristicus^ to which there is little that may be 

 added. It may be noted that caudatus^ in which the undersurface 

 below the neck is more or less uniform, has the transverse grayish 

 band, prominent on the upper breast in melanopis and hranicldi., 

 indicated by a distinct grayness of the feathers of that area, while 

 in addition in one female caudatus secured the feathers of the breast 

 below this band are washed distinctly with a rusty color, an indica- 

 tion of the light breast patch prominently developed in the two 

 other species. The three known species of this genus are comple- 

 mentary in their ranges and differ from one another in a series 

 of characters in such regular and progressive manner as to indicate 

 close affinity ; indeed, it is not impossible that eventually intergrades 

 may be secured that will link the three as geographic forms of one 

 wide ranging speciop. The following key (adapted in large part 

 from Count Salvadori's paper) may serve to identify them : 



a\ Breast and abdomen black or blackish (save for faintly indicated grayish 

 band) ; greater wing-coverts white; culmen 145 mm. or more in length. 



caudatus. 



a*. Breast, below transverse gray band, white with more or less nifescent wash; 

 greater wing coverts not clear white ; culmen 135 mm. or less in length. 



«Ibis, 1900, pp. 501-517. 



