MIGRATION. 37 



the summer birds of passage visit the southern parts of the 

 country a few clays, or even weeks, before they make their 

 appearance in the northern districts. Thus, the common 

 swallow (Hirundo rustled) appears in Sussex about the 

 beginning of the third week of April ; while in the neigh- 

 bourhood of Edinburgh it is seldom seen before the first of 

 May. The cuckoo appears in the same district about the 

 last week of April ; in Edinburgh seldom before the second 

 week of May. The reverse of this holds true with these 

 summer visitants at their departure. Thus, dotterels (Cha- 

 radrius morinellus) forsake the Grampians about the be- 

 ginning of August, and Scotland by the end of that month; 

 while they return to England in September, and remain 

 there even until November. A difference of nearly a month 

 takes place between the departure of the goatsucker (Ca- 

 primulgus Europceim) from Scotland and from the south 

 of England. 



Having thus ascertained the winter haunts of our sum- 

 mer birds of passage, let us now endeavour to find out the 

 summer retreat of our winter visitants. The conclusions 

 which we have already established dispose us to look for 

 these birds in countries situated to the northward. And as 

 we are much better acquainted with the ornithology of those 

 countries than of Africa, it will be in our power to prose- 

 cute our researches with greater certainty of success. 



The snow-bunting (Ember iza nivalis), which is among 

 the smallest of our winter guests, retires to the hoary 

 mountains of Spitzbergen, Greenland, and Lapland, and 

 there executes the purposes of incubation, making its nest 

 in the fissures of the rocks. In these countries it is there- 

 fore a summer visitant, as it retires southward in autumn, 

 to spend the winter in more temperate regions. To the 

 sea-coasts of the same countries, the little auk ( Aka allc) % 

 and the black-billed auk (Alca pl-co), repair for similar 



