NEW SOUTH WALES 77 



whole twelve months and will die through shortage 

 of grubs rather than shift to another part of the 

 country. 



The Regent Bird e.g., generally a fixed inhabitant 

 of the country between the Tweed and Hawkes- 

 bury Rivers, will once in fifty years make its way 

 north to the Mackenzie River, or south to Bega. 

 It is abnormal distribution, and must not be set 

 down to regular occupancy of larger areas. 



SPORADIC MIGRATION 

 (Plate 2, Fig. M) 



This form of migration is due mostly to reduction 

 of food through drought. Rats and mice will leave 

 Queensland for the plains of northern Victoria, and 

 the Grass Owl will follow in thousands, though 

 not in flocks. Even so, they are the silent birds of 

 the night, born for the purpose of checking waste- 

 ful and cancerous mice. 



For similar reasons, in relation to insects, the 

 Oriental Cuckoo will leave its usual haunts in 

 northern Queensland for New South Wales (Map 

 31). The great interior droughts of 1902, 1907 and 

 1919 have been the cause of tremendous eruptions. 

 On 12/6/02 thousands of ibises were seen flying 

 south to the Murray River Lakes (D. Le Souef). 

 In 1907 thousands of Wood Swallows (Artamus 

 personatus and A. superciliosus) left the interior 

 for eastern New South Wales (H. L. White), i.e. 



