168 THE ZOOLOGIST. 
and possibly the larger gulls and the owls. At the present time 
and place man is undoubtedly their deadliest enemy. In places 
where game protection does not exist, the birds of prey are pre- 
sumably more numerous and more formidable than they are here, 
and in former times the same was no doubt true. Further, it 
is not too much to suppose that the birds of prey preceded 
man as destroyers, and a time was when their visits to the 
shore were of daily or even tidal occurrence, in place of being 
occasional as they now are in the more populous parts of our 
country. Realizing the important part predatory birds may 
have played in the lives of Waders in the past, the special de- 
velopment of evolutions by the smallest and weakest of the 
Waders, and the present success which attends the evolutions 
directed against the attacks of those birds, I look with some 
measure of confidence to birds of prey as probably the original 
cause of these movements. 
A difficulty which I do not underrate lies in the application 
of the present view of things to the more complicated move- 
ments. The only way out I am able to suggest is to realize the 
nature of the movements made under the direct attack of a bird 
of prey, and to proceed from these to the more complex pheno- 
mena, together with a search for the causes that apparently 
underlie them. Anyone who does so through a series of 
observations will appreciate the close gradations of the pheno- 
mena from the simple to the complex, and in raising a natural 
order of succession will understand the difficulty of deciding 
where one form ends and another begins. When they are fully 
developed the complex evolutions evade general description, and 
one can only mark their salient features. The most charac- 
teristic of these is the movement in the form of the spray, which 
I believe to be common to all the simple and complex evolutions 
above the line of the horizontal windward and leeward move- 
ments, though it may be discerned only with difficulty, when 
mutilated or disguised by the operation of special conditions. 
So also in the search for apparent causes one finds the element 
of danger common to all, whatever form they may take, and in 
the case of the more complex evolutions the associated dangers 
are correspondingly grave. It is a matter for observation that 
the evolutions assume the most bewildering forms during the 
