MOZAMBIQUE TERRITORY (III) 65 
As the weeks went by and the fruits of different trees became 
ripe, the hornbills always made a bee-line from one fruit-bearing 
tree to another, however distant. To us, looking down on the 
scene, all the trees of the forest looked alike, but no searching 
on the part of the birds was ever observed; to find a particular tree 
buried among thousands of others surely requires some guiding 
instinct. There is no doubt that hornbills are highly intelligent 
and have excellent memories, and this may have a bearing on 
their precision flights. 
One of their favorite fruits is the wild fig, of which there are 
many species. Some of the trees reach an enormous size, but fre- 
quently the fruits are no bigger than cherries or at most damsons, 
and so are easily swallowed whole by the hornbills. Their bills, 
although having the appearance of being ungainly, are really 
instruments of great delicacy, and are ideal weapons for the 
business of fruit-plucking. You may wonder how a hornbill gets 
its food from the tip of its long bill down its throat. The tech- 
nique is to toss it up, at the same time opening the bill wide so 
that the tit-bit drops right into the gullet. 
When feeding, these birds keep up a constant bleating noise 
very much resembling that of goats. 
They are long-lived creatures, and one of the pair that I caught 
here died only recently after twenty-one years in the London Zoo. 
While in the Siluvu Hills, I witnessed for the first time the 
nesting habits of hornbills. They always choose a hole in a tree 
which is walled up with self-made plaster, leaving a narrow slit 
through which the male feeds his imprisoned mate. In this retreat 
she elects to sit during the whole of the incubation period, relying 
entirely on the male to bring her food. It was thought once upon 
a time that the male alone was responsible for the business of 
building the prison walls, but it now seems that both take part 
until the work is nearing completion, then the female enters the 
nest and finally seals herself in. This is evidently a protective 
measure and one that is very long-established, for all the horn- 
bills of Africa and the Far East have the same peculiar nesting 
habits. 
The substance used for this wall-making, according to observa- 
tions made on certain hornbills in the wild state, is earth brought 
