FAMILY COCHLEARIIDAE II7 



Measurements. — Males (3 from northern Colombia), wing 272- 

 281 (276), tail 108.6-115.1 (111.1), culmen from base 79.0-86.9 

 (82.9, average of 2), tarsus 78.0-84.2 (81.5) mm. 



Females (5 from Darien and northern Colombia), wing 259-266 

 (263), tail 102.5-107.6 (105.7), culmen from base 67.0-75.4 (70.4), 

 tarsus 75.0-82.7 (78.7) mm. 



Resident on the Rio Jaque, in southeastern Darien. 



This form of South America is so markedly different from the 

 race of the rest of Panama in its much lighter color — light gray 

 on the back, and pure white on the foreneck and side of the head, 

 in the adult — as almost to suggest a separate species. 



On the Rio Jaque, in April 1947, the boatbills were fairly com- 

 mon near our camp located at the mouth of the Rio Imamado. They 

 were nocturnal, coming out at dusk to walk in the shallows over 

 gravel bars along the Imamad6, and the Rio Chicao, or flying down 

 to the broader waters of the main river. One evening I sat in the 

 end of our large piragua that rested half in the water, to write the 

 day's notes, while a pleasant breeze kept mosquitoes away. The 

 river was in flood from a heavy rain that had come in late afternoon, 

 and when it became too dark to write I sat quietly, watching the water 

 and the forest border beyond. At full dark I had an indistinct view 

 of a large bird that approached with fluttering, wavering flight, in 

 search of a suitable spot to alight, appearing white, like an immature 

 little blue heron, or an egret. It stopped 10 meters away on a gravel 

 bar and stood quietly, until we turned a flashlight on it, when the 

 light revealed a boatbill watching the water intently. The bird took 

 flight almost instantly when the light beam touched it. A few nights 

 later I waited here for a possible shot until it had become so dark that 

 I was about to leave. Suddenly I had an indefinite view of a broad- 

 winged bird passing with steadily beating wings that I thought must 

 be an owl. A hasty shot at the almost invisible target, a splash as it 

 dropped in the river, and a moment later the boatbill was in my hand. 



We sometimes saw as many as half a dozen while night-hunting 

 but always found them so wild that they flew immediately when they 

 saw our light, even at a considerable distance. Often I heard them 

 calling in a low tone, qua qua qua, as they flew away. In skinning 

 the one taken I was impressed by the considerable development of 

 the muscles of the sides of the head and in the palatal area. 



Interestingly enough, the bird here proved to be the South Ameri- 

 can form that has not been reported previously in Central America. 

 The indication is that C. c. cochlearius ranges along the Pacific coast 

 only to the Rio Jaque, since C. c. panamensis is found in the Tuira 

 drainage a short distance to the north. 



