NO, 9 CASQUED HORNBILLS — KILHAM 35 



COMPARATIVE STUDIES OF OTHER HORNBILLS 



Genus Tockus. — There were two other species of hornbills in the 

 vicinity of Entebbe, the crowned hornbill (Tockus alboterminatus) 

 and the pied hornbill (Tockus fasciatus). These two smaller horn- 

 bills are somewhat similar in size and appearance. I could never dis- 

 cover any basic difference in their habits. Their high piping cries, 

 erratic type of flight with many rises and dips, and greater concentra- 

 tion on insect food readily distinguished them from casqued hornbills. 

 All three species occurred in the same stretches of open country and 

 forest. 



On March 20, 1955, I noticed a crowned hornbill flying through 

 Zika Forest. He lighted on a treetop, then suddenly dropped down- 

 w^ard. Searching the area, I found a leaning tree with a bole, 40 feet 

 above the ground, with a 2-inch hole in the center. There was almost 

 no suggestion of a mud wall. I watched for 20 minutes. At one time 

 white feathers closed the entrance as the female pushed her vent to 

 the opening, and a stream of excreta shot out. The maneuver was 

 the same as I had witnessed with Bycanistes. Later the male returned 

 to perch on the bole and feed his mate a large insect (mantis?). He 

 did not linger, the briefness of his visits apparently being due to the 

 fact that he carried only one item in his bill tip ; there was no heaving 

 up of fruits from the gullet such as characterized visits of male 

 casqued hornbills to their nests. On March 25 an African, well 

 trained at the Institute, climbed up and inspected the nest for me. 

 There were three white eggs. The mother bird, when poked, backed to 

 the rear of the cavity. Unfortunately, preparations for leaving Africa 

 prevented an adequate study of these birds. I am indebted to Dr. 

 Friedmann (1925) for the following account, hitherto unpublished, 

 of the opening of a nest of this species in Kenya Colony. 



On April 7, at Tavcta, some natives cut down a large tree in which there was 

 a nest of this hornbill containing the adult female and two young birds. The nest 

 was about 50 feet up in the tree and was in a large hole, the entrance of which 

 measured roughly 10 inches in long diameter and 3 inches wide. This entrance 

 was plastered up with dry mud, bird feces, and bits of bark all mixed together, 

 leaving an opening about 2 inches long and i inch wide. As I picked away at 

 the mud the adult female pecked at me with its bill, about an inch and a half of 

 which could protrude through the opening. When finally I opened the nest and 

 took out the birds I found that the two young birds were of different ages, the 

 older of the two [pi. 6, fig. 2] being feathered on the back, wings, sides, legs, 

 and crown, while the tail feathers were free of their sheaths for their distal thirds 

 and the sheaths of the neck and breast feathers were beginning to burst. The other 

 bird was less well feathered, the wings and flanks being the only parts really well 

 covered. The tail feathers were about the same as in the older bird and the under 



