482 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



Almirante Bay area of western Bocas del Toro and in eastern Costa 

 Rica. 



MITROSPINGUS CASSINII COSTARICENSIS Todd 



Mitrospingus cassinii costaricensis Todd, 1922, Proc. Biol. Soc. Washington, 35, 

 p. 93. (El Hozar, Costa Rica.) 



Characters. — Very similiar to nominate cassinii, but undertail co- 

 verts duller, less reddish, upper surface slightly darker, almost bluish, 

 less gray; throat somewhat darker. 



A male collected at Almirante, Bocas del Toro, on February 15, 

 1958, had the iris very light grayish white; maxilla black; mandible 

 neutral gray; tarsus and toes fuscous. 



Measurements. — Males (10 from Bocas del Toro and Costa Rica), 

 wing 86.5-92.3 (87.3), tail 69.0-79.7 (74.2), culmen from base 18.4- 

 21.3 (20.0), tarsus 22.2-25.8 (24.5) mm. 



Females (8 from Bocas del Toro and Costa Rica), wing 83.2-86.5 

 (85.8), tail 70.7-77.3 (73.9), culmen from base 19.9-21.2 (20.5), tar- 

 sus 22.8-26.4 (24.8) mm. 



Resident. Known in Panama only from western Bocas del Toro, 

 and found also in eastern Costa Rica. H. von Wedel collected it at 1050 

 m on the Boquete Trail and at Guabo (Peters, Bull. Mus. Comp. Zool., 

 vol. 71, 1931, p. 343). R. Hinds found it on the Rio Changuena at 720 

 m, and I have seen it at the border of swampy woods near Almirante 

 and in the undergrowth of high forest above Western River. 



In Costa Rica, Skutch (Publ. Nutt. Orn. Club, no. 10, 1972, pp. 

 205-208) found that several members of a group assist in raising the 

 young in one nest. In late April, he found a nest containing 2 young 

 that were fed by at least 3 of the 7 individuals that frequented the vi- 

 cinity. The young were fed insects. The nest was a bulky open cup 

 placed in a tree 3 m above a stream. The nest was made mainly of long, 

 brown, threadlike, dry pistillate infloresences of Myriocarpa, mixed 

 with rootlets and rhizomes of an epiphytic fern. The lining was of 

 black fungal filaments. An egg in the collection of the Western Foun- 

 dation of Vertebrate Zoology is white, with large reddish brown 

 splotches, almost forming a cap on the large end. It measures 21.15 X 

 16.80 mm. 



MITROSPINGUS CASSINII CASSINII (Lawrence) 



Tachyphonus Cassinii Lawrence, 1861, Ann. Lyc. Nat. Hist. New York, 7, p. 297. 

 (Lion Hill, Panama Railroad.) 



Characters. — Undertail coverts brighter, more reddish than in cos- 

 taricensis; upper surface and throat slightly lighter gray. 



