THESES FROM LITERATURE. 



4. Migration began when after the tertiary age the glacial period 

 set in ; this compelled the birds to pass to the tropics, whence 

 they returned in spring for breeding in those places which even 

 during the glacial preriod remained free of ice. 



5. In the course of time this to and fro movement became 

 instinct, which acts independently of weather and food, and 

 forces the birds to Migration, even when there is plenty of 

 food still. 



FiNSCH, Dr. O. (in: „Notes from the Leyden Museum" XXII. 1900/1 

 p. p. 121 125.) „l direct attention to the strangest wandering 

 instinct of one characteristic species of the southern Hemisphere, 

 the long-tailed Cuckoo (Urodynamis taitiensis) and its geographi- 

 cal distribution. With the exception of a single case elsewhere 

 (in New-Caledonia) this parasitic species is confined in its propa- 

 gation to New-Zealand, being here a regular summer visitor, 

 arriving at the beginning of October and leaving in February. Except 

 in these months it is observed in various Islands of the Pacific 

 as far north as the Carolines (Yap, Palau), as far east as the Mar- 

 quesas, as far west as New-Caledonia (but strangely enough not 

 yet in Australia or New-Guinea). The distribution therefore com- 

 prises nearly the whole of the Pacific, from North to South over 

 56 geographical degrees ( = 840 geographical miles), from West 

 to East over 86 degrees (=1300 g. m.). 



in contrast with all our Birds of Migration, w^hich migrate for 

 breeding from South to North, this species 



1. wanders for propagation from North to South;* 



2. as a rule not over land but, although not a good flier, chiefly 

 over ocean ; 



3. not in company, but singly; 



* The same as Chalcococcyx lucidus and Tanspiptera sylvia. 



10) 50 620 



