DISTRIBUTION OF THE NIGHTINGALE. 3 



the presence of a heavy, clayey soil, as opposed to a light, 

 sandy one, being necessary to its welfare. Walcot voiced a 

 popular belief in the south of England, that it is only to be met 

 with " where the cowsHp grows kindly." Many people in the 

 Midlands believe that it is unable to cross the Trent. But the 

 study of the following details covering the distribution in 

 each county will, we think, leave little doubt in the minds of 

 our readers that the real obstacles which prevent the general 

 distribution of this species over the greater part of England 

 and Wales are the ranges of elevated land, which it instinctively 

 avoids. Even in counties like Oxfordshire or Berkshire, 

 which lie well within its breeding-limits, it is common only in 

 the wooded lowlands. On the Lambourn Downs in Berkshire, 

 along the Chilterns in Oxfordshire and Buckinghamshire, and 

 on the Cotswolds, it is practically unknown. But these isolated 

 masses of hills and downs of no great height do not interfere 

 with the gradual dispersal of the species by means of the 

 river- valleys. The more important mountain-sj^stems, on 

 the other hand, rising to heights of 1,000 feet or more, present 

 insuperable obstacles. In the Devonian peninsula the high 

 plateau of Exmoor on the north and Dartmoor on the south, 

 mark the western limits of the species, except where a few 

 birds have skirted the coast line and reached the Tamar valley. 

 Similarly the great Cambrian system, extending from the 

 Berwyns south through Montgomery, Radnorshire, and Brecon- 

 shire to Glamorganshire, with outlying spars in Shropshire, 

 form an impassable barrier on the west.* From the northern 

 counties the great Pennine Chain, the backbone of England, 

 reaches down into the West Riding of Yorkshire, east Lanca- 

 shire, and north Derbyshire, while high-rolling plateaux 

 occupy parts of north Staffordshire and west Derbyshire. 

 The limits of this system practically mark the northern range 

 of the Nightingale. On the west side a comparatively small 

 stream of migrants work their way up from the Severn valley 



* In South Wales, however, a migratory stream passes along the 

 north coast of the Bristol Channel westward, avoiding the mountains of 

 Glamorganshire, and a pair or two appear to have penetrated up the 

 Towy valley as far as Llandovery, and it is said to have been once heard 

 in the Teifi valley. 



