SOME THREATENED BRITISH SPECIES 197 



counties of England from Cornwall eastwards, 

 thence northwards along the Thames valley and 

 through some of the Midland districts — Worcester- 

 shire, Leicestershire, Derbyshire, to the extreme 

 south of Yorkshire, where years ago we have 

 taken its nest. A few may also breed in Cambridge- 

 shire, Norfolk, and Suffolk. The Dartford Warbler 

 is another of those species which, in the event of 

 the indigenous stock becoming extinct, can never 

 be replaced by normal means. This species has 

 been considerably reduced of late years by severe 

 winters — a contingency to which our summer 

 migrants are not exposed. To this cause the late 

 Henry Swaysland attributed its almost complete 

 disappearance from the gorse coverts of Sussex. 

 Collectors of birds and eggs also harass this inter- 

 esting little Warbler not a little. Fortunately, it is 

 of secretive habits, and its nest is very difficult to 

 find ; but, notwithstanding these facts, the bird 

 should be carefully protected during the breeding 

 season, and the taking of its eggs made illegal in 

 the several counties which it frequents. 



Our next threatened species is the Chough 

 (Pyrrlwcorax grac ulus). This species was formerly 

 much commoner and more widely dispersed than 

 it is now, and though " once upon a time " a dweller 



