414 THE BIRDS OF HELIGOLAND 



traced to other causes ; these being indeed exclusively, as I am 

 able to assert in the most decisive manner, after many years of 

 observation, unfavourable conditions of weather in the atmospheric 

 strata nearest the earth's surface, which compel the travellers to 

 seek for their route in more favourable regions lying at higher 

 elevations and far above the range of observation. 



What has been said above will explain the late occurrence of 

 the autumn migration; and hence also, to this late departure at 

 the close of the year corresponds the early arrival of the birds at 

 its beginning. The individuals in pursuit of their journey to their 

 breeding homes not infrequently appear here as early as the last 

 week of February, and are observed until the end of March ; their 

 number in spring is invariably considerably smaller than in autumn. 



The breeding range of this species embraces the immense area 

 of the whole Old World from the Atlantic to the Pacific Ocean, 

 extending in breadth from this side of the Arctic Circle to the 

 40th parallel of North Latitude. Inasmuch as this Titmouse occurs 

 as a common breeding bird numerously in Scandinavia, Denmark, 

 and even Sleswick-Holstein, it must for the most part adhere rigidly 

 to a southerly line of migration, since the least deviation to the 

 west could not fail to bring individuals breeding in the extreme 

 north every autumn to Heligoland, not only regularly, but also in 

 large numbers. 



A species, P. minor, very similar to the Great Titmouse, but 

 slightly smaller, and with the under-side dull white instead of light 

 yellow, occurs in Asia. I happened casually to show a skin of this 

 species to Aeuckens, when he at once declared, in his most decisive 

 manner, that he had already had the species in hand here. 



214. Coal Titmouse [TANNENMEISE]. 

 PAKUS ATEK, Linn. 



Heligolandish : Liitj swart Rollows = /SmaW Blade Titmouse. 



Parus ater. Naumann, iv. 34. 



Coal Titmouse. Dresser, iii. 87. 



Mesange petite charbonniere. Temminck, Manuel, i. 288, iii. 209. 



I have not had this small Titmouse in hand since 1878, during 

 the October and November of which year P. major and P. cceruleus 

 once more, after a long interval, occurred in great abundance, a few 

 Coal Titmice, and several dozens of Long-tailed Titmice, being also 

 found among their numbers. In the autumn of 1847 this bird was 

 found ; though only in very small numbers, yet it was invariably in 

 company with the many great flocks of the above-named species; and 



