FAMILY FORMICARIIDAE 177 



indication of occurrence, there are two specimens, now in the 

 Carnegie Museum, collected by Dr. John W. Aldrich in 1932 on 

 the western side of the Peninsula, inland from the Golfo de Montijo, 

 one on the Rio Mariato, taken February 24, and one at 600 meters 

 on Cerro Viejo, farther in the interior, on March 6. At the time in 

 question, species in some of the ant-wrens and their plumages were 

 not well understood as few specimens then were available. The two 

 mentioned, both immature males, were beginning to change to the 

 adult status with a few black feathers appearing on the throat. On 

 examination of them, through the courtesy of Dr. Kenneth Parkes, 

 they prove to be schisticolor instead of Myrmotherula fulviventris 

 as originally recorded (Aldrich, Sci. Publ. Cleveland Mus. Nat. Hist., 

 vol.7, 1937, pp. 87-38). 



In the highland forests of Chiriqui these ant-wrens were found in 

 the main with the groups of small birds that ranged in loose company 

 through the lower levels of the trees. It is their custom to move 

 quickly in fluttering flight among the branches. As they alight under 

 cover of leaves, usually they freeze motionless for several seconds, 

 and then if there is no alarm continue movement, but still under 

 cover, in search of the small insects and spiders that form their 

 principal food. Their soft calls give contact with others of the group. 



The single stomach on which I have made detailed analysis, a male 

 taken on Cerro Pirre in June, held remains of Homoptera (Fulgo- 

 ridae) and many fragments of spiders. 



In February those that I collected on the slopes of Cerro Tacar- 

 cuna were in full breeding condition. 



In Costa Rica, Skutch (Pac. Coast Avif., no. 35, 1969, pp. 209- 

 213) found them breeding from March through May. The nest, 

 placed in undergrowth in forest at from less than a meter to nearly 

 2 meters above the ground, was a small cup of fine black fibers bound 

 with cobweb, suspended in a horizontal fork, woven thinly so that the 

 contents were outlined from the sides and below. The two eggs are 

 white or cream colored with coarse dark markings and lines on much 

 of the surface, in some forming a band around the larger end. Mea- 

 surements made from seven ranged from 17.1-18.3x13.1-13.5 mm. 

 The young at hatching were dark skinned with no down. Male and 

 female incubated, the latter alone through the night, and both fed 

 the young. In one distraction display a male dropped from the nest 

 nearly to the ground where he clung to a slender stem with slowly 

 beating spread wings, displaying a small white area at each wing base. 

 The male may be slow in changing to adult dress, and so be mated 

 while still in a transition stage. 



