122 INCREASE AND DISPERSAL OF BIRDS 



We must fall back, therefore, on the theory that 

 these newcomers have been pushed forward by 

 reason of over-population and congestion in old- 

 established centres. 



The jackdaw is another bird that has been 

 always with us, yet has recently increased in 

 numbers to a remarkable extent, so much so as, 

 in places, to constitute a nuisance. When the 

 larger birds of prey were more numerous in the 

 land they may have helped to keep the jack- 

 daws within reasonable limits ; but now they do 

 not appear to have any enemies. The increase 

 is so marked as to suggest pressure from outside 

 sources. 



A much more welcome visitor is the redstart, 

 surely one of the most brilliant and striking of 

 our summer migrants, and one that is certainly 

 much more numerous than it used to be only a 

 few decades ago. In the Fauna of Moray, 

 Harvie-Brown describes their increasing dis- 

 persal as * great waves,' and the writer recalls 

 their occurrence at the altitude of 1200 feet in 

 Spey-side. As suitable localities, such as old 

 birchwoods, are filled up, the overplus press on 

 in new directions. Much the same may be said 

 of the garden warbler, doubtless also an advanc- 

 ing species, although one easily overlooked were 

 it not for its striking song. The bullfinch, too, 



