ON THE MIGRATION OF BIRDS. 389 



retire to Sweden, Poland, Pimssia, Norway, and 

 Lapland to breed ; as soon as the young can fly, 

 they return to us again ; because the frosts which 

 set in early in those countries totally deprive 

 them of the means of subsisting ; as the dryness 

 and hardness of the ground, in general, during 

 our summer, prevent them from penetrating the 

 earth with their bills, in search of worms, which 

 are the natural food of these birds. 



[The Courser and Pratincole are among the Courser. 

 rarest visitants of this island.] rah.ncole, 



Every species of these two genera continue Rails and 

 with us the whole year; the Crake GalUnule ex- nules" 

 cepted, which is not seen here in winter ; it like- 

 wise continues in Ireland only during the sum- 

 mer months, when they are very numerous, as 

 Mr. Smith tells us in the history of JVaterford, 

 p. 336. Great numbers appear in Anglesey the 

 latter end of May; it is supposed that they 

 pass over from Ireland, the passage between 

 the two islands being but small. As we have 

 instances of these birds lighting on ships in the 

 Channel and the Pay of Biscay, we conjecture 

 their winter quarters to be in Spain, 



ciunt, ne earum unicam quidem inter nos habltantem invenire 

 possumus. Amceii. Acad. IV. 588. 



Scolopaces et Glareolce incredibllibus multitudlnibus verno 

 tempore in Polonia et Borussia nidulantur ; appropinquante au- 

 tumno turnnatim evolant. Klein de av. errai. 187- 



