162 OBSERVATIONS ON BIRDS. 



viour of caged birds, who seem to experience a plea- 

 surable sensation in carrying about in their bills, at 

 the proper season for building, any little pieces of 

 thread, straw, or other materials, which happen to 

 be within their reach, even when they have no mate, 

 and no convenience for making a regular nest. This 

 is evidently an instinctive action occasioned by the 

 excitement of unsatisfied desire, increased perhaps 

 by high and stimulating food. 



SAND MARTIN.* 



I ONCE met with a person who assured me posi- 

 tively, he had in former years seen swallows taken 

 in a torpid state during winter from the holes and 

 crevices in the gravelly banks by the side of the road 

 near Quy Water. At this place, which is between 

 three and four miles from hence, I observe a small 

 colony of sand martins every year ; and, if the above 

 fact be correct, which is very doubtful, it was proba- 

 bly this species of swallow which was discovered 

 there. Yet White mentions instances f in which 

 the holes of sand martins had been expressly searched 

 during the cold months, with a view to discovering 

 whether they used them as hybernacula, without 

 finding a single torpid bird. 



The locality above mentioned is the only one I 

 know of in this neighbourhood, for many miles 

 round, frequented by this species of swallow; and 

 they are not numerous there. The soil being prin- 



* Hirundo riparia, Linn. 



t Naturalists' Calendar (by Aikin), p. 83. 



