MIGRATION. 269 



Scotland, confining itself entirely to the interior dur- 

 ing 1 the summer ; but towards the end of August, or 

 in September, when the young- are fully fledged, it 

 descends to the sandy shores ; and at a later period 

 moves southward, and disperses over all the coasts of 

 the island. This is also the case with the golden 

 plover, although in a less remarkable degree, as well 

 as with the curlew, which do not leave the kingdom 

 at any period of the year. The partial migration of 

 the crow is also well exemplified in Dumfriesshire ; 

 they breed in great numbers at Dalswinton and 

 Carruchaii, but forsake these places as soon as their 

 young are fully able to fly; during the autumn and 

 winter they frequently return to these localities, as if 

 to view the scenes of their incubatory labours. 



In the Philosophical Transactions*, Catesby, who 

 gave much attention to this subject, remarks that, be- 

 sides the migratory birds which remain and breed 

 throughout the summer, there are others which arrive 

 periodically at certain places, for the sake of some 

 sort of grain or other food of which their own country 

 may be supposed destitute. These birds, after a short 

 stay, depart, and are not again seen until that time 

 twelvemonth, at which time they return, and continue 

 repeating their annual visits. Pursuing the subject, 

 the same sensible naturalist, whose remarks on the 

 general subject of migration subsequent writers have 

 done little more than repeat, says, " though the secret 

 ways by which instinct guides birds and other irra- 

 tional creatures are little known to us, yet the causes 

 of some of their actions are apparent. Analogous to 

 the lucrative searches of man through distant regions, 

 birds take distant flights in quest of food, or what 

 else is agreeable to their nature ; and when they dis- 

 cover some new grain or pleasing food they return, 

 * Vol. xliv. part i. for the year .1746. 



