158 THE MIGRATIONS OF BIRDS 



An allied species, the standard-wing night-jar 

 (Macrodipteryx longipennis)^ has somewhat similar 

 habits, and a like migration is suspected in the case 

 of other birds. 



i^i; Before leaving the subject of Africa it may be men- 

 tioned that thirty-six forms of sea-birds are found 

 on the southern coasts, most abundantly in the 

 winter period from March to October, which in the 

 breeding season leave for islands far distant in the 

 ocean, where they rear their young. The majority 

 of these — twenty-nine to be exact — are petrels, 

 shearwaters, and albatrosses, while the others are 

 mainly terns. 



Perhaps there are fewer data assembled on the 

 migration of birds in Australia than on this phenom- 

 enon in any of the other continents, yet a study 

 of the movement of birds here is highly important, 

 in the evidence it offers that may throw light on the 

 possible origin of migratory movement. There are, 

 as in other southern continents, a small number of 

 species that come in search of winter quarters. 

 Thirty of the migrant forms, other than pelagic 

 wanderers among sea-birds, which seem thus far 

 to have been recorded at all regularly, are shore- 

 birds or their relatives, while one of the remaining 

 three, the white-winged black tern (Chlidonias 

 leucoptera)^ is found only rarely in North Australia. 

 This leaves the spine-tailed swift (Chaetura cauda- 



