NO. 9 CASQUED HORNBILLS — KILHAM 15 



passed with his bill tip to that of his mate directly below. At least 

 10 pellets were passed in rapid succession. The male then bounced 

 along to another part of the stump and tried to whack off bits of dead 

 wood. In a few moments he bounced back to the hole. He shook his 

 head from side to side, with bill half open, as though a pellet had 

 gotten stuck. Then for a while he held his head low over the hole to 

 watch what was going on. A week later I found him carrying on 

 much the same. He spent considerable time looking down and even 

 putting his head and neck through the hole. Sometimes his mate 

 accepted two pellets and refused a third. At such periods of active 

 construction, the only sound was the rapid tapping of the female's 

 bill, which could be heard some distance away. 



Male hornbills did no work on the walls, although they might peck 

 and explore about a nest entrance. A male usually sat by like a brick- 

 layer's helper. He would fetch building material and supply it to his 

 mate as needed. The pair at nest i would spend the larger part of a 

 morning in this fashion, settling down to work at about 8:30 a.m. 

 Work at the Botanical Garden nest was done from midafternoon on. 

 At this time the sun shone directly into the nest entrance. Possibly 

 this pair was taking advantage of the illumination. I could see the 

 female's bill tapping inside. Details of how the tapping was done 

 could not be perceived readily in high nests. I had a better opportunity 

 at nest 7 which was comparatively low. The female was already 

 walled in but on January 29 she was repairing the entrance with 

 material from the nest floor. She applied this material with rapid 

 tapping of the side of her bill tip. Tapping was again seen to good 

 advantage in my captive pair of hornbills. In September I955> when 

 9 months of age, both birds would get in a corner of their cage and 

 plaster the wall with any litter, feces, or food matter which might 

 serve as mud. Both sexes did the tapping. This activity was carried 

 on daily, as judged by the appearance of the wall and the amount of 

 tapping we heard. 



Abortive nesting. — On November 7, following coition, the pair of 

 hornbills from nest i had worked all morning on the nest wall. By 

 the following weekend their interest had obviously declined. The hole 

 was too large to wall in. On the afternoon of November 13 the male 

 kept returning to the nest rim. Then he would fly back to the forest 

 to join his mate. Sometimes the pair would fly together to the nest 

 tree, making a tremendous noise. It was a dismal wailing. The male, 

 however, would look into the nest alone. On the following day I 

 observed the same behavior from 7:15 a.m. until 12:30 p.m. These 

 two were the noisiest hornbills in the forest. It appeared that he was 



