26o SIBERIA IN EUROPE. chap. xx. 



itself, and learn the way thither as best it may. That birds 

 have keen organs of sight is a fact well known to all who 

 have watched them obtaining their food or eluding their 

 enemies. That they must have wonderful memories for 

 place is shown by the distance they roam from their nests, 

 and the concealed spots in which they seem to have no diffi- 

 culty in finding them again. Amongst true migratory 

 birds, that is amongst birds which have a winter as well as a 

 summer home, as distinguished from gipsy migrants who per- 

 petually loaf about on the outskirts of the frost during 

 winter, continually changing their latitude with the tem- 

 perature, it appears to be a general rule that the farther 

 north a species goes to breed the farther south it goes to 

 winter. It is not known if this applies to individuals as well 

 as to species. The various times of arrival of many species 

 of birds in most latitudes of Europe are well known and care- 

 fully recorded, but of the dates of departure from the various 

 latitudes of Africa where they winter we know little or 

 nothing, otherwise this question might easily be settled. It 

 is obviously much easier to record the date of arrival of a 

 bird than of its departure. In the one case a single entry is 

 sufficient; in the other, memoranda may have to be daily 

 recorded for weeks. At Valkenswaad, in Holland, I noticed 

 that the earliest migrants were those with the widest range. 

 Birds whose breeding-range extended to or beyond Britain 

 were the earliest to breed, whilst those whose eggs I was 

 most anxious to obtain, those whose breeding-range did 

 not extend to our islands, were very late in arriving. It 

 seems to be a curious fact that, as a general rule, though 



