FAMILY ICTERIDAE 



365 



structed by a grackle measured 10 to 13 cm in internal diameter and 6 

 to 10 cm in depth. 



All the nests so far reported in Panama had a clutch of two eggs, 

 although in Guatemala Skutch found three-egg clutches most common. 

 The eggs have a "ground color . . . from bright blue to very pale bluish 

 gray, on which are dots, blotches, and intricate scrawls of brown and 

 black. The blue ground color of some eggs is locally washed with shades 

 of brown or pale lilac. The diversities of pattern are so great that, if 

 all the eggs in a populous colony were mixed together, each bird might 

 conceivably be able to recognize her own by its distinctive markings. 

 The measurements of 62 eggs . . . average 33.6 by 23.0 millimeters" 

 (Skutch, op. cit., pp. 328-329). Incubation is 13 or 14 days, and, like 

 all aspects of the nesting cycle except guarding the colony, is performed 

 only by the female; both sexes, however, drive away hawks and other 

 potential predators. The young hatch with pale salmon colored skin 

 and sparse long gray down on the head, back, wings, and legs. They 

 are fed insects and when 16 to 19 days old begin climbing outside the 

 nest, although they can not yet fly. At this stage they resemble females, 

 but with more grayish breasts, brown eyes, and faces and foreheads 

 still unfeathered. When 20 to 23 days old they begin to fly, and con- 

 tinue to follow their mothers for food for several days or weeks. In 

 Panama the adults molt between September and November. 



ICTERUS SPURIUS SPURIUS (Linnaeus): Orchard Oriole, 

 Parao de Huertos 



0.[riolus] spurius Linnaeus, 1766. Syst. Nat., ed. 12, 1, p. 162. (South Carolina.) 



Rather small; male with head, neck, upper back, wings, and tail black, 

 rest of body rich reddish brown; female with upper surface grayish 

 olive-green, undersurface bright greenish yellow. 



Description. — Length 148-165 mm. Adult male, head, throat, upper 

 breast, and upper back black; rest of body chestnut; lesser and middle 

 upper wing coverts and all underwing coverts chestnut; greater wing- 

 coverts black, tipped whitish and brown; remiges black with outer webs 

 narrowly edged whitish; tail black with all but central pair of rectrices 

 tipped whitish. 



Adult female, upper surface grayish olive-green, brighter on crown 

 and rump; undersurface dull greenish yellow; wings dusky; wing co- 

 verts edged with whitish forming two wing bars; tail bright olive-green. 



Immature male, like female, but lores, front of face, and throat black; 



