BIRD ENEMIES INTRODUCED BY MAN 153 



all nest in cavities or nesting-boxes. The sparrows 

 remain all the year round and begin to nest before 

 the native birds have returned in the spring, so that 

 when they do return, they frequently find their 

 nesting-sites already occupied. And even when the 

 native birds have found an unoccupied > site, and 

 have started to build their nests, the sparrows often 

 come and attempt to drive them away, and as there 

 are so many more of the sparrows than of the na- 

 tive species they are usually successful. 



The sparrows do not confine their persecution to 

 birds that seek similar nesting-sites, but may at- 

 tack other birds, such as the robin, vireo, and cat- 

 bird, and cause them to desert the places where 

 they are nesting. And the sparrows even attack 

 the nests of cliff swallows, and drive barn swallows 

 from the buildings where they are nesting. The 

 sparrows even go farther than this and sometimes 

 break the eggs and destroy young birds in the nests. 



Professor Barrows gives a list of seventy-five 

 species of our native birds which English sparrows 

 have been reported to molest. The following table 

 shows the number of times they were reported to 

 have attacked certain birds : — 



Bird attacked Number of different 



records of attacking 



Swallows and martins 440 



Bluebird 377 



Other sparrows , 273 



Wrens 191 



Robin 182 



