ROOKS. 157 



resort to these, and dig in the mud for lame; nor 

 have they any objection to draw from a crevice of a 

 spring, that comes from a great depth and is com- 

 paratively warm, a frog which may be sometimes met 

 with, huddled into a corner, near such places. 



On some parts of the Continent rooks are migra- 

 tory ; as in France they are found most abundant 

 immediately before the winter, and in countries farther 

 to the north, in the spring. As is the case in this 

 island, they do not however approach the extreme 

 north, or the very wild and lonely places ; and the 

 fact of their migration shows that even rooks " manage 

 the matter differently in France," from the way in 

 which they manage it in England. We are not sure 

 whether sufficient allowance has been made in those 

 reports of migration for the flocking of the crows in 

 the autumn, and again in the early spring, before they 

 commence the building and repairing of their nests. 

 At those times the inmates of a large rookery appear 

 in clouds that absolutely darken the air, and other 

 birds mingle with them, probably to share in the pro- 

 duce of the digging ; but according to the observations 

 that we had the opportunity of making upon a very 

 large rookery for a number of years consecutively, we 

 have no reason to think that they were ever more than 

 the light of one day absent from their native forest. 

 When they fly out in these dense masses, and we have 

 seen a flight half a mile and more in length, and of 

 considerable breadth and depth, as closely convened as 

 they could be, so as to fly without inconvenience, -they 

 seldom fly two days in the very same direction, or at 

 least to the same fields. One would be almost tempted 

 p 



