32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I3I 



from the ground. The hornbills made a clapping noise as they snapped 

 at the passing termites and were at the game for over lo minutes. 

 On May i I witnessed a similar spectacle, again late in the afternoon. 

 Compact swarms of small insects (not lake flies) were hovering at 

 the tops of tall trees adjacent to the Institute Compound. Smaller 

 birds were catching them, mostly by perching on a topmost spray. 

 These birds included splendid starlings {Lamprocolius splendidns), 

 bulbuls (Pycnonotus tricolor), Abyssinian gonoleks {Lanarius eryth- 

 rogaster), and didric cuckoo {Chrysococcyx caprius). Two casqued 

 hornbills were catching insects along with the smaller birds. For over 

 20 minutes they kept turning their heads to snap at the swarm around 

 them. 



Dr. W. H. R. Lumsden has contributed an observation which fur- 

 ther indicates the agility of these large hornbills. On September 6, 

 1953, he was in the woods of the Botanical Gardens. Three or four 

 hornbills were perched about 60 feet from the ground. They would 

 swoop down across an open space, pick up something in midair, then 

 rise to a perch in an opposite tree. They were after winged ants which 

 were swarming on ground and vegetation below the clearing. 



SOME ANATOMICAL FEATURES IN RELATION TO FUNCTION 



Some peculiarities of hornbill anatomy came to have more signifi- 

 cance with continued watching. The large eyes are unusually mobile 

 for a bird. Casqued hornbills can look up and down to a moderate 

 extent without cocking their heads as many birds do. This gives them, 

 by human interpretation, a more intelligent expression. The upper 

 and lower eyelids are continuous and in sleeping this fused eyelid is 

 pulled over the eye from back to front. The combined eyelids are 

 white in adult females. Considering that the eye is dark and sur- 

 rounded by blackish feathers, I have wondered whether these white 

 eyelids enable the male to see his mate better when looking into a 

 dark nest cavity. The head is covered by fluffy feathers, i^ to 2 inches 

 long. These are used in emotional expressions and when fully erect 

 the head is like a small, round feather duster. From front view the 

 topmost feathers, which may be the only ones erected, may resemble 

 two horns. My young captive hornbills demonstrate how these 

 feathers may be used. If I toss grapes to them, Mpanga may grab 

 them all. Zika, the female, then feels left out. This is obvious by her 

 expression. Her head feathers stand straight out in all directions as 

 though to say "Where do I come in?" When alarmed or excited, her 

 head feathers lie tightly back. If she next investigates some object, 



