BIRDS IN AUTHORITY 49 



of certain species cxliibit a pood deal of anxiety about 

 the proper care of the eggs, and exercise supervision and 

 authority over the females, compelling them during the 

 period of incubation to return to the nest when they are 

 inclined to stay out too long. Our swift is a familiar 

 example. But has any one ever observed an individual 

 of any species, one of a colony, presumably a male, 

 exercising this kind of mastership over a number of 

 females in the absence of their mates? Yet this is 

 exactly what I witnessed on one occasion, and if I were 

 to ask a dozen or fifty naturalists to name the species 

 they would all guess wrong, for the bird in question was 

 the small, delicate, gentle, moth-like sand-martin — the 

 "mountain butterfly," as it is prettily named in Spain. 



Near Yeovil I found a breeding-place of these birds 

 in a vast old sand-pit. It was in IMay, and no doubt 

 they were incubating. There were about fifty holes 

 in the steepest side of the sand-bank, and when I began 

 watching them there were about fourteen or fifteen 

 birds flying round and round within the basin of the pit, 

 hawking after flies, and perhaps prolonging their play- 

 time after their morning feed. By-and-by I noticed one 

 bird acting in a singular manner; I saw him come out 

 of one hole and go quickly into another, then another 

 still, until he had visited several, remaining about five 

 or six seconds in each, or as long as it would take him 

 to run to the end of the burrow and return. Finally, 

 having finished inspecting the holes, he began pursuing 

 one of the birds flying aimlessly about in the pit; the 

 chase increased in speed and violence until the hunted 



