192 
Mr. F. N. Chasen on the 
[Ibis, 
near as I could judge, this line crossed the mountains some¬ 
where to the W. of Rupel. There was a complete absence of 
Rooks in spring and summer—at any rate from the places 
visited. The evening flights of Rooks on the Struma plain 
are sometimes of stupendous size and easily mistaken for 
genuine migratory movements. An immense flock passed 
overhead on the 2nd of March, and the number of birds was so 
great that for several minutes there was a noise like the 
whirr of a sharp breeze. The movements of some flocks 
observed in early spring would lead one to believe that there 
is some justification for the old saying that Rooks go mad in 
the spring. Thirty or more would separate themselves 
from a larger flying flock and swoop towards the earth, 
performing the most wonderful antics for a short time. 
They would twist about, and on occasions topple over in 
most extraordinary style. When the whole crowd suddenly 
dropped to the earth, the noise was not unlike that of an 
approaching shell. 
Corvus monedula. Jackdaw. 
This is one of the most common birds in the country, and 
large numbers breed. Some of them paired as early as the 
middle of February, but there were flocks about several 
weeks later. A great deal of competition took place in 
Macedonia for available nesting-sites. This was due to the 
large number of Jackdaws inhabiting the country. Some of 
them did not breed at all, and flocks composed of from six 
to ten birds were roaming over the country, without showing 
signs of pairing, all through the spring and summer. 
The Jackdaws showed great adaptability in their choice of 
nesting-sites, and within a short radius from where I was 
living there were nests in the following sites:—In the 
minaret of a mosque and also somewhere in the ruinous 
roof of the same building, under the eaves of native houses 
(otherwise unoccupied), and in holes in a steep bank. The 
most interesting nest of all was placed in the lower branches 
of a Stork’s nest. The Storks and Jackdaws seemed to be 
on the most amicable terms, but the advantages of this 
