PHALACROCORACID^ PHALACROCORAX 7 



German South-west Africa, Elephant Eock off Oliphant's Eiver 

 mouth, Islands in Lambert's Bay, Paternoster Isle, Marcus, Jutteii 

 and Foundlings Islands near Saldanha Bay, Dassen Island, Dyers 

 Isle, near Danger Point in the Caledon division. Beyond this point 

 Trek Duikers have been observed at Knysna (Victorin), Port Eliza- 

 beth and East London (Eickard), Port St. Johns (not plentiful, 

 Shortridge), and about Durban Harbour. 



Habits. The Trek Duiker is extraordinarily abundant about 

 the coast of Western Cape Colony ; they are found along the shore 

 and never inland ; even in the harbour of Cape Town they may be 

 seen sitting in long rows about the jetties and piers, especially in 

 the less busy parts where there are fewer people about. They fly 

 to their fishing grounds in a long line, sometimes in small parties 

 of three or four, sometimes in enormous flocks, which must often 

 contain millions of birds ; their flight is straight and not high above 

 the water or very rapid, and they flap their wings all the time. 

 Their food consists chiefly of fishes, but also of mussels and other 

 marine animals, and during the course of the year they must be 

 responsible for the destruction of enormous numbers. They swim 

 and dive with great facility ; when diving they jump up clean out of 

 the water and then plunge down head first. The nesting season is 

 from December to July, though a few birds can be found breeding 

 at all times of the year. The nests are chiefly placed on the ground 

 in the interior of the little islands off the coasts of German South- 

 west Africa and of the Colony ; they are built up of sticks and stalks 

 of the low plants and grasses growing on the islands with little or 

 no lining ; the eggs, usually four, but varying from two to five in 

 number, are of the usual Cormorant type, oval and pale blue with 

 a chalky white covering ; they are usually much soiled after they 

 have been laid for a short time, and measure about 2-15 x T35. 



It is from this bird and from the Malagash (Sula capensis) tbat 

 the chief supplies of Colonial guano are obtained. After the birds 

 have left the islands this is collected from the nests on the rocks 

 and ground around. The amount varies very considerably from 

 year to year, but is usually at least 5,000 tons, and is often more. 

 Quite half of this amount is produced by the present species ; this 

 will perhaps give some idea of the enormous numbers of these birds 

 along the coast. 



