NO. 9 CASQUED HORNBILLS — KILHAM 7 



in their bills, continually clamping on it to get a fresh grip. On No- 

 vember 20 I saw one knock off a piece of bark and juggle it about 

 until it dropped. He then fell straight from his perch toward the 

 ground and retrieved the bark with surprising agility. On November 

 29 a male, after much knocking on dead wood, finally broke off a 

 piece 10 inches long. This fell toward the ground and the bird 

 swooped down 50 feet but failed to catch it. My captive hornbills, 

 male and female, would seize a stick or piece of crumpled paper with 

 great gusto. Their clamping and tossing, however, would soon cause 

 them to loose it. They were amazingly quick at catching any piece of 

 food thrown at them, and when placed by a sunny window, they would 

 try to seize bits of floating dust. 



Notes and calls. — In addition to noises made by wings in flight and 

 whacking of bills, casqued hornbills made a din with their notes and 

 calls. At times they sounded somewhat like domestic hens. A pair, 

 perched in separate trees, would keep in touch with a series of hoarse 

 "cuk, cuk's." At times they made single notes such as "ugh" or 

 "woof." Most lugubrious noises might come from a male in search 

 of or temporarily separated from a mate. Thus on September 24 I 

 saw a lone male and a nearby pair of hornbills. The single bird made 

 "ka-ka-ka" and "ka-wack, ka-wack, ka-wack" noises of considerable 

 volume. He broke off a small stick, and when he bounced along a 

 limb with it in his bill, the pair flew away at his approach. The male 

 of nest I made Mpanga Forest resound with his cries when his mate 

 lost interest in nest building after weeks of futile effort. He was ap- 

 parently trying to entice her back to the nest hole. Calls associated 

 with nesting were of help in studying hornbills, for I could hear much 

 farther than I could see in the forest. A feeding visit might be 

 announced by a croak when a male came to perch near the nest. Then, 

 when clinging to the entrance and transferring food, males usually 

 made a low, rapid feeding chuckle as bills touched. Females sometimes 

 responded with low guttural notes. These birds, walled within the 

 nests, had a repertoire of their own. Two different noises were made 

 with the bill. The first was a rapid, woodpecker-like tapping made 

 with the tip of the bill, used broadside. Females tapped not only in 

 constructing the original nest wall, but also when walled inside the 

 tree. Sometimes they were repairing the nest wall, but at other times 

 I conjectured that they were tapping on the sides of the hollow tree 

 by way of idle amusement, for the persistence of tapping in some 

 nests was greater than could be expected from repair work alone. My 

 captive hornbills tapped in similar fashion on the walls of their cage 

 when 7 and 8 months old. Two further noises of nesting females 



