Compass-bearing of Migration 109 
returning northwards along the same route in the month of March. 
The numbers that are sometimes seen on these occasions are 
well-nigh incredible. Colonel Irby and Dr. Stark, both most 
trustworthy observers, have recorded how on one occasion they 
reckoned that over 4,000 had in one day passed over the spot which 
I am about to describe. This was on 11 March 1874, and it is 
typical of the marvellous regularity of all birds when on migration 
that upon the same day in 1907, exactly thirty-three years later, 
the passage of the Cranes northward was once again at its maximum 
at the same place. The well-known V-shaped formation in which 
they usually fly varies in composition from a few individuals to 
fourscore or more on either side. At times they drop the V 
formation and move in long undulating ‘skeins.” 
The direction taken by the successive flocks (as well as of that 
of the Storks, which pass northwards in flocks, at times numbering 
from 400 to 500 each, but some weeks earlier than the Cranes), 
in accordance with the observations made by me for many years in 
the same district, is almost invariably the same, namely a line which 
when plotted on the map passes about 6 miles west of the old town 
of Tarifa and runs from S, by E. 3 E. to N. by W. 3 W. 
From this region they seem to spread all over Europe, their 
nests having been obtained in the far north in 1853 by the naturalist 
Wolley, who, as is well known, was the first British ornithologist 
to find the nest; his delightful description of it amid the birch- 
grown bogs of Finland has given pleasure to very many. They 
have also an eastern stream of migration which I have myself 
witnessed in the Levant. 
About thirty years ago, considerable numbers of Cranes 
remained to nest in south-west Andalucia; but constant egging 
by professional “collectors” has sadly reduced their numbers. In 
some districts they have ceased to nest altogether while in others 
where I can recall seeing over thirty pairs in the nesting season 
