522 BIRDS OF THE REPUBLIC OF PANAMA PART 3 



until the irregular mass of the nest proper takes shape. Finally there 

 is an elongated, hollow ball with an opening at the upper end, often 

 with the upper margin projecting hoodlike as a guard against rain. 

 The nest varies from 15 to 20 centimeters in length. Loose ends of the 

 longer fibers hang untidily as a flattened, pendant tail, perhaps with 

 a few dead leaves entangled in it. The eggs number two or three, and 

 are white without gloss, usually plain, but often with tiny dots of 

 warm brown. These markings may be widely scattered, with some so 

 small that they are visible only through a lens, or more rarely, if 

 abundant, grouped in open cap-shaped form over the larger end. In 

 shape the eggs are surprisingly variable, from oval (found in 

 many) to long oval, subelliptical, or rarely, even long elliptical. A 

 usual size is 1 5.0 X 11.0 to 16.1x11.6, with range to 17.7 X 11.3 or in 

 one set, to 18.0 X 11.8 mm. This range is found in six sets from the 

 southern Canal Zone collected by Major- General G. Ralph Meyer, 

 from March 27 to May 17, 1941, and E.A. Goldman, at Miraflores, 

 April 30, 1911, with two that I found at La Jagua, eastern Province 

 of Panama March 20 and 24, 1961. 



Skutch (Pac. Coast Avif. no. 34. 1960, pp. 475^99) describes a 

 dawn-song of "a slight sharp tic repeated over and over at varying 

 rates, sometimes as often as 110 times per minute, and for many 

 minutes together." He recorded the female as incubating and brood- 

 ing the young alone, but aided by the male in feeding the nestlings. 

 The incubation period was 17 days in one nest, and 18 days in 

 another. He heard both sexes regularly uttering a trilling song, to 

 maintain contact between the pair. 



The subspecies finitimum in its typical form, in Mexico and 

 northern Central America, differs in being more greenish above, as 

 compared to the grayer nominate cinereum of northern South Amer- 

 ica. The population of Panama is slightly intermediate, but on the 

 whole is nearer finitimum in somewhat greenish dorsal hue, though 

 many are faintly paler than typical individuals from Mexico. The 

 long series examined shows too much variation to warrant another 

 name. Those from Isla Coiba, for example, all are closely similar to 

 the more northern birds, though birds of the adjacent mainland show 

 the variation mentioned. * 



As another slight difference. Todiro strum cinereum cinereum 

 averages very slightly larger in wing and tail, as indicated by the 

 following measurements from a Colombian series. 



Males (10 from northern and western Colombia), wing 43.0-45.9 

 (44.5), tail 32.0-36.5 (33.8), culmen from base 14.8-17.1 (15.8), 

 tarsus 17.8-18.9 (18.2) mm. 



