82 



On the 11th, with winds B.S.E., moderate; a.m., rain; 

 p.m., clear; in evening, E.N.B., light, clear. — There was a large 

 migration of several species. This was continued in lessened 

 volume on the following day, with winds changing from N.N.E. 

 to S.W., with rain showers. 



October 15th appears to have been a very changeable day, the 

 weather being described as " S.B., slight, clear, middle high clouds 

 from W. by S. ; noon, light, cloudy, wind B. by N., clouds from 

 S. In evening, E. by N., violent, clouds from S. by E. In 

 night, E., very violent, thick clouds from S.E. This erratic 

 weather was accompanied by very strong migration of several 

 species, and the author appends the following note : — "According 

 to the weather in the morning, there ought to have been con- 

 siderable migration — Thrushes and Woodcocks — but prominent 

 westerly currents in higher regions acted adverse." It is difficult 

 to understand, however, why these species should not have taken 

 advantage of the " most favourable conditions" which prevailed 

 at the time in the strata of the atmosphere nearest the earth's 

 surface, for in the night of the 16th, during the prevalence 

 of the violent weather before described, there occurred an 

 " extraordinary strong migration of Larks, Thrushes, Starlings, 

 Numenius and Gharadrius." 



On the 17th the winds and weather are described as northerly, 

 light, quite thick with rain, low loose clouds slowly from N.W. 

 and N., after midnight, dead calm. — " During the early, hours 

 until 9 o'clock extremely large flights of Thrushes flying about 

 high, just as if bad weather was approaching." However, the 

 predicted storm did not take place, for the following days appear 

 to have been pretty calm and at times even sunny. 



It is difficult to account for the behaviour of these Thrushes 

 on Herr Gatke's theories as to the height at which migration is 

 performed. Here we have unfavourable conditions to visible 

 migration prevailing near the earth, i.e., northerly winds quite 

 thick, with rain and low loose clouds slowly from N.W. and 

 N., and yet these Thrushes did not seek favourable conditions 

 in the upper strata of the air, but fly about the neighbourhood of 

 Heligoland instead of continuing their journey in the normal 

 manner, at a height of 20,000 feet or more. 



