52 BIRDS OF THE REPUBLIC OF PANAMA PART 4 



Bocas del Toro in April 1979 when he crossed the divide at 1700 meters 

 from Cerro Colorado, eastern Chiriqui. 



This race also occurs on the Caribbean slope of Costa Rica; other 

 forms are found north to eastern Mexico. 



Family CINCLIDAE: Dippers, Mirlos Acuaticos 



The 5 species of this family, all of small size with heavy bodies and 

 short tails, in general appearance suggest wrens. They are peculiar in 

 the Order Passeri formes for their specialization for aquatic life, espe- 

 cially through their dense, water-repellant plumage. Dippers are found 

 along swift streams in hill country, where they enter the water to range 

 along the bottom in search of food. In this they move by using the 

 wings as in flight, or walk through skillful use of oblique currents and 

 eddies made by stones and similar obstacles. They spend their lives en- 

 tirely along streams, even through colder seasons, unless ice prevents 

 their entering the water. 



Their bulky, domed nests may be placed at the border of waterfalls, 

 or sheltered by stones along swift-flowing channels. The glossy white 

 eggs, rather large in size, range from 4 to 6 in number. From observa- 

 tions, as yet somewhat limited, it appears that for a period during molt 

 the primary and secondary wing feathers may be renewed in such a 

 manner that the bird may be incapable of aerial flight, but is still capable 

 of its usual aquatic activities. 



The 5 species known are widely distributed — one in the Andes of 

 South America; another in southern South America; one in Central 

 America and western North America; one in Europe, northwestern 

 Africa, and central and southern Asia; and a fifth in eastern and south- 

 ern Asia. 



CINCLUS MEXICANUS ARDESIACUS Salvin, American Dipper, 

 Mirlo Acuatico Americano 



Figure 6 



Cinclus ardesiacus Salvin, Ibis, vol. 3, no. IX, January 1867, p. 121, pi. 2. (Cordil- 

 lera de Tole, inland from Tole, Chiriqui, Panama.) 



Medium size; heavy body, short tail; adult gray, immature with 

 undersurface white to grayish white. 



Description. — Length 165-180 mm. Adult (sexes alike), crown and 

 sides of head dull brownish slate, shading on hindneck to the slate gray 

 of the upper surface, this including the scapulars; wings and tail 



