i62 THE MIGRATIONS OF BIRDS 



a pochard {Nyroca australis)^ and a darter {Anhinga 

 novaehollandiae), are noted as irregular visitants, 

 indicative of slight migratory wanderings among 

 these species, which carry them beyond their native 

 continent of Australia. In New Zealand, too, we 

 find two cuckoos (Lamprococcyx lucidus and Urody- 

 namis taitensis) which are present only in summer 

 and disappear in cold weather. The long-tailed 

 cuckoo migrates through the Pacific Islands to Fiji 

 and beyond. The winter home of the other species 

 is not certainly known. 



Considerable numbers of birds found on the 

 Australian continent are so distinctly irregular in 

 their occurrence that they may be best termed 

 nomadic, since they wander with climatic changes 

 and are not seasonal in their occurrence. Many of 

 these are directly affected by rains in their move- 

 ments, as failure of water supply in the more arid 

 sections may drive them to more favored areas, 

 while conversely an excess of rain recalls them. A 

 gallinule {T^ribonyx ventralis), according to Captain 

 S. A. White, visits South Australia every few years, 

 where it remains from July to November. After 

 appearing regularly for a time, it may be absent 

 entirely for a number of years — an erratic habit 

 that is apparently common to it throughout the 

 continent. Various lorikeets are said to be governed 

 in their nomadic forays by the blossoming of the 



