8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I3I 



expressed alarm. One was a rattling of the slightly opened bill in 

 the aperture of the mud wall. The bill was visible from the ground, 

 A second alarm noise was a loud, wailing screech. I never heard this 

 call except from a nesting female in distress. Nest 15 was first lo- 

 cated by following such screaming through 700 yards of forest. A 

 foreign pair of hornbills was by the nest when I arrived. Such in- 

 trusions were a frequent cause of screaming. Similar screams were 

 heard from another female whose mate, early in the nesting season, 

 fed her comparatively infrequently, and from another female whose 

 mate had been recently killed. I seldom heard chirping of the young 

 inside a nest. A newly hatched chick observed in nest 10 made a 

 "chirpee, chirpee" note. Older young ones, as I learned from my 

 captives, can make an assortment of chittery, whistling, and screaming 

 noises. The whistling somewhat resembled that of a smaller species 

 of hornbill, Tockus fasciatus. 



NEST CONSTRUCTION 



Hole hunting. — I first noted nesting activities of hornbills late on 

 the afternoon of October 13. A male flew to the top of a high tree by 

 the lake shore and peered into a hole. He was soon joined by his mate, 

 who took her turn, looking into the hole for 10 minutes. Then she 

 went inside and excavated pieces of rotten wood up to 8 inches long 

 which she tossed out. The male hung his head down to watch what 

 was going on. When his mate finally came out, he started to inspect 

 a second hole nearby. He changed his mind, however, and flew away 

 with a dismal wailing to alight by a hole in another tree. Here he 

 called to his mate with a succession of "caks" and "ughs." He put 

 his head into the hole and pecked at the sides. Within a few minutes 

 his mate joined him. It was apparent from this episode that the male 

 pioneered exploration of possible nesting holes and enticed the female 

 to follow. This observation was borne out by subsequent experience. 

 On November 11, again late in the afternoon, I noticed a male hornbill 

 perched next to a likely looking hole. He flew away and shortly re- 

 turned with his mate. For the next 5 minutes she kept hanging her 

 head down into the hole and pecking at the entrance. Then she lit on 

 the lower rim, putting head and body inside. When she flew up by the 

 male, he hopped down for another inspection. In Mpanga Forest, I 

 had other examples of the lead taken by the male. Nest i had too 

 large an opening for successful nesting. A pair of hornbills spent 

 weeks trying to wall up the aperture, the male's interest persisting 

 longer than that of his mate. On November 7 I found the pair inspect- 



