248 HIRUNDINID^E. 



been adverted to. This singular fact in their economy has 

 been particularly attended to by Mr. John Blackwall, and 

 the following particulars are derived from that gentleman's 

 published " Researches in Zoology." It did not come to 

 my knowledge that these late broods are sometimes de- 

 serted by the parent birds before they are capable of 

 providing for themselves, till the spring of 1821 ; when a 

 pair of House Martins, after taking possession of a nest 

 which had been constructed in the preceding summer, drew 

 out the dried bodies of three nearly full-fledged nestlings 

 which had perished in it, preparatory to appropriating it to 

 their own purposes. About the same time, and near the 

 same spot, a similar attempt was made by another pair of 

 House Martins ; but all their efforts to dislodge the young 

 proving ineffectual, they entirely closed up the aperture 

 with clay, and so converted the nest into a sepulchre. 

 At first I was disposed to attribute the untimely fate of 

 the nestlings, thus unexpectedly discovered, to the acci- 

 dental destruction of one or both of the parents ; but a 

 little reflection induced me to change my opinion. So 

 many instances were called to mind of the sudden de- 

 parture of House Martins, at periods when, to all appear- 

 ance, they were most busily engaged in providing for their 

 families, that what before was regarded as the unavoidable 

 consequence of a fortuitous circumstance, I now began to 

 suspect might be occasioned by a voluntary act of deser- 

 tion. To clear up this doubtful point several examinations 

 were made, at the second of which on the 22nd of October, 

 1822, several riests, both of Swallows and Martins, were 

 found to contain dead young ones. At a third search on 

 the 19th of November, 1825, fourteen nests were ex- 

 amined ; five of them contained dead nestlings, and one 

 nest contained two eggs, whose contents very evidently 



