BIRD-ASSOCIATIONS IN SCOTLAND 49 
BIRD- ASSOCIATIONS IN SCOTLAND. 
By the late Captain SYDNEY E. BROCK, M.C. 
(Concluded from p. 21.) 
ASSOCIATIONS OF SEA-CLIFFS, ROCKY ISLANDS, ETC. 
A heterogeneous section, with a common faunal charac- 
teristic that the food-supply is entirely, or almost entirely, 
drawn from the sea. A feature of the avifauna, and a 
prominent one as contrasted with those hitherto dealt with, 
is the marked social habit of its members, a_ character 
evidently independent of relationship, since it is common 
to the various families represented—Gulls, Auks, Petrels, 
and Gannets. 
Broadly speaking, it might, I think, be laid down as a 
safe general principle that birds are relatively less social in 
the nesting-season than at other times of the year, and it is 
easy to understand why this should be so. The approach 
of the breeding season originates feelings of jealousy and 
rivalry which militate against a continuance of the more 
friendly and sociable habits of the winter, when food and 
relaxation are the only pressing interests. There are not 
many exceptions to the rule in land-birds, and the tendency 
is common to many distinct groups, as for example, Tits, 
Wagtails, Pipits, Larks, Crows, Plovers, Rails, game- 
birds and Pigeons. One member of the Crow family, the 
Rook, might at first sight appear to be an exception, but I 
believe it is not so in effect. It is certainly the case that 
this bird is exceedingly social in the nesting-season, but it 
can be shown that it is infinitely more so at other seasons. 
To give a concrete example: In the small county of West 
Lothian, with a total area of 120 sq. miles, there are, roughly 
speaking, 40 rookeries, comprising, say, 8000 pairs of birds, 
or an average of 200 pairs to each colony. During the 
nesting-season these colonies lead an isolated existence, feed- 
ing only within a short range from their nests. But in 
winter the conditions are widely different. In place of our 
JOU ZN) @ G 
