SAND MARTIN. 253 



further remarked that some of these Martins 1 holes are 

 nearly as circular as if they had been planned out with a 

 pair of compasses, while others are more irregular in form ; 

 but this seems to depend more on the sand crumbling away 

 than upon any deficiency in the original workmanship. 

 The bird, in fact, always uses its own body to determine 

 the proportions of the gallery, the part from the thigh to 

 the head forming the radius of the circle. It does not 

 trace this out as we should do, by fixing a point for 

 the centre around which to draw the circumference : on 

 the contrary, it perches on the circumference with its 

 claws, and works with its bill from the centre outwards : 

 and hence it is that in the numerous excavations recently 

 commenced, which we have examined, we have uniformly 

 found the termination funnel-shaped, the centre being 

 always much more scooped out than the circumference. 

 The bird consequently assumes all positions while at work 

 in the interior, hanging from the roof of the gallery with 

 its back downwards as often as standing on the floor. We 

 have more than once, indeed, seen a Bank Martin wheeling 

 slowly round in this manner on the face of a sandbank, 

 when it was just breaking ground to begin its gallery. 



All the galleries are found to be more or less tortuous 

 to their termination, which is at the depth of from two 

 to three feet, where a bed of loose hay, and a few of 

 the smaller breast-feathers of geese, ducks, or fowls, is 

 spread with little art for the reception of the eggs. It 

 may not be unimportant to remark, also, that it always 

 scrapes out with its feet the sand detached by the bill ; but 

 so carefully is this performed that it never scratches up the 

 unmined sand, or disturbs the plane of the floor, which 

 rather slopes upwards, and of course the lodgement of rain 

 is thereby prevented." 



