Birds by Land and Sea 



remains more or less stationary. The enormous 

 wastage of life this suggests would be more than 

 offset by the increase in numbers if only a quarter 

 of the young ones of one season returned to add 

 two broods to the colony in the following one. 



During September the swallows are much increased 

 in numbers by the advent of birds bred in the sur- 

 rounding country, which now come to fly up and 

 down the river in company with the host of sand- 

 martins. 



Of the latter species we have always a goodly 

 number, but towards the close of the season several 

 thousands frequent the river Mersey in our neigh- 

 bourhood. Where the banks have been sapped and 

 fallen in, leaving soft earthy or sand walls at the side 

 of the river, this little mouse-coloured martin makes 

 its nest. The colonies individually do not comprise 

 many nests, but they occur frequently along the 

 banks. There is no need to search for them, 

 because the birds belonging to any particular 

 colony have a certain beat on the river before it, 

 and by their presence indicate the site. The nesting- 

 holes are about four feet deep, being bored hori- 

 zontally into the bank at about ten feet above the 

 average level of the water. At the end of the passage 

 is a wider chamber, in which the nest a bedding of 

 fine grass lined with feathers is placed. I have 

 found these tunnels bored in converging lines so 

 as to meet in a common chamber at the end ; but 

 probably the birds themselves were not a little 



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