XXVIII 
BEAKS 
341 
In some hornbills the grease supplied by the oil-gland 
is bright yellow, and if the hand be rubbed over the 
feathers it will be stained with this pigment. 
Hornbills are not only odd in appearance and 
structure, but they have some curious domestic habits. 
Hornbills abound in Uganda and the Mau forest and are sure 
to attract attention, for they are big birds and possess 
great bills of curious shape. In spite of the apparent 
clumsiness of the beaks, hornbills use them dexterously, 
especially in catching grapes. 
During incubation the hen is enclosed in a hollow tree 
and diligently fed by the male bird until the chicks are 
hatched. Livingstone noticed this breeding habit of 
the Ked-billed Hornbill during his journey down the 
Zambesi. Most of the arboreal species have this habit. 
The material used for fastening up the hole in the tree 
appears to be the droppings from these birds ; as the 
