920 Col. R. Meinertzliagen on the Altitude [Ibis, 



and some are to be seen until the end of October. Twenty- 

 eight eggs^ some fresh, others more or less incubated, were 

 brought to me from the mountains, north of Chinwangtao, 

 on the 25tli of June, 1917, and a clutch of three, slightly 

 incubaterl, from the same locality on the 2nd of July 

 following. I saw on the 16th of September, 1915, numbers 

 travelling along the sea-shore, hovering and feeding on the 

 dunes as they passed by. 



181. Cerchneis tinnunculus japonicus (T. & S.). 



Falco tinnunculus D. & 0. p. 30 (part). 



Cerchneis japonicus La T. p. 578. 



The Japanese Kestrel passes in spring and in September 

 an;l October. A few winter in the vicinity. Some breed 

 in the mountains to the north of Chinwangtao. A clutch 

 of four slightly incubated eggs was brought to me with the 

 female on the Srd of May, 1917. 



[To be continued.] 



XXXIV. — Some prcUmlnarij remarks on t/ie Altitude of the 

 Migratorij Flif/ht of Birds, ivith special reference to the 

 Fakmrctic R>^gion. By Col. R. Meinertzhagen, D.S.O., 

 M.B.O.U., F.Z.S. 



A GREAT deal has been written on this little-known subject, 

 but in ne;irly all cases tiieories have been advanced which 

 have been supported by unsatisfactory evidence, or by 

 evidence of: a very scanty nature. 



Let us see what evidence is availalde. 



Gietke affirms that the altitude of migratoi-y flight under 

 normal conditions is so great as to be completely beyond the 

 powers of human observation, whilst be regards such portions 

 of it as are brought within our notice as disturbances and 

 irregularities of the migratorv movement. In other words, 

 he considers visible mio;ratiou to be abnormal and invisible 



