360 BIRDS OF DAMARA LAND. 



less, but it tucks them in a moment or two before it 

 touches the water. The Gannet is the most valuable 

 depositor of guano in South Africa. A single bird pro- 

 duces about four inches in depth annually, or 16 to 

 17 lbs. weight to the square foot. The chief strong- 

 holds of this species are Ichaboe, Mercury, and Posses- 

 sion islands. 



So valuable have the deposits of this species been 

 found, that the lessees of Ichaboe have considered it 

 worth while to enclose the middle of the island for a 

 distance of 300 feet by 180 feet, exclusively for the con- 

 venience of this bird. The chief object is to prevent the 

 Penguins from mingling their adulterated deposits with 

 those of the Gannets ; and the proprietors have succeeded 

 admirably. The former are of course kept out from 

 want of wings available for flight. 



The Gannet incubates about October and November. 

 It makes no nest, and lays only one e^g., of a pure white 

 colour, tapering at one end, and of an oval form. Average 

 of three eggs: length 3" 10"', breadth 1" 11'". The 

 young, which are at first covered with white down, 

 remain on the island where they are hatched until well 

 able to fly, when they all suddenly disappear and are 

 never seen again in that locality in their first plumage ; 

 when they reappear it is in the adult dress. In the 

 interval I have frequently seen and shot them about 

 Walwich Bay. The old birds leave the islands about 

 the end of April and beginning of May, and at this time 

 are generally observed in the open sea, often at a con- 

 siderable distance from land ; they return late in July. 



