Dr. THEODOR NEUMANN. 163 



but takes the precaution to close a portion of the exter- 

 nal aperture of its abode with clay so as to leave only a 

 sufficient space for its own passage. The object of this 

 proceeding is evidently to prevent woodpeckers and other 

 enemies from getting in, destroying the nest and taking 

 possession of the hole. When observing this bird at its 

 work, one cannot help thinking of it as of a little mason 

 that, in order to close a hole in a wall, puts in one stone 

 after another and fastens them with mortar. In the heat 

 of summer this wall dries and gees so firm that one can- 

 not break it with his finger, but must use a chisel. An- 

 other very curious mason bird is the variety of hornbill 

 known as Tockus melanoleucus, Licht. The nesting 

 habits of this hornbill are so extraordinary that they 

 have been repeatedly referred to by various writers, but 

 owing to the difficulty of finding the nests of the birds, 

 many details of the earlier accounts are not quite cor- 

 rect, while others are not touched upon at all. Dr. 

 Schonland, of Cape Town, has examined several nests 

 with the birds belonging to most of them. The birds are 

 often seen in winter in large numbers in the gardens at 

 Graham's Town, but in the summer they are only to be 

 met with in proximity to closely wooded kloofs, and this 

 is due to the fact that they nest in places where hollow 

 trees are to be found. All observers agree that during 

 incubation the female is a prisoner in a kind of cage, the 

 entrance to which is closed to such an extent that it has 

 to be broken before the female can leave the nest. In 

 all the cases he had seen the nests were built in hollow 

 trees, sometimes between the crowded stems of the tall 

 euphorbia. The birds have apparently no preference for 

 any particular tree so long it suits their purpose. The 

 essential point for them is that the hollow stem ishall be 

 sufficiently large for the female to move about in the 

 nest, and whether there is one or more entrances, all 

 must be of such a nature that they can be partly or 



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