45 



A HISTORY OF 



southern parts of Europe. It is not unpleas- 

 ing to observe the order of their flight; they 

 generally range themselves in a long line, or 

 they sometimes make their march angularly, 

 two lines uniting in the centre like the letter 

 V reversed. The bird which leads at the 

 point seems to cleave the air, to facilitate the 



Eassage for those which are to follow. When 

 itigued with this laborious station, it falls 

 back into one of the wings of the file, while 

 another takes its place. With us they make 

 their appearance about the beginning of Oc- 

 tober, circulate first round our shores, and, 

 when compelled by severe frost, betake them- 

 selves to our lakes and rivers. Some, indeed, 

 of the web-footed fowl, of hardier constitutions 

 than the rest, abide the rigours of their nor- 

 thern climate the whole winter ; but when 

 the cold reigns there with more than usual 

 severity, they are obliged to seek for more 

 southern skies. They then repair with the 

 rest for shelter to these kingdoms; so that 

 the diver, the wild swan, and the swallow- 

 tailed sheldrake, visit our coasts but seldom, 

 and that only when compelled by the severity 

 of their winters at home. 



It has been often a subject of astonishment, 

 how animals to all appearance so dull and 

 irrational should perform such long journeys, 

 should know whither to steer, and when to 

 set out upon such a great undertaking. It is 

 probable that the same instinct which governs 

 all their other actions operates also here. 

 They rather follow the weather than the 

 country ; they steer only from colder or 

 warmer climates into those of an opposite 

 nature; and finding the variations of the air as 

 they proceed in their favour, go on till they 

 find land to repose on. It cannot be supposed 

 that they have any memory of the country 

 where they might have spent a former winter: 

 it cannot be supposed that they see the 

 country to which they travel, from their 

 height in the air; since, though they mount- 

 ed for miles, the convexity of the globe would 

 intercept their view : it must therefore only 

 be, that they go on as they continue to per- 

 ceive the atmosphere more suitable to their 

 present wants and dispositions. 



All this seems to be pretty plain : but there 

 is a circumstance attending the migration of 

 swallows which wraps this subject in great 



obscurity. It is agreed on all hardr-, that 

 they are seen migrating into warmer climates, 

 and that in amazing numbers, at the approach 

 of the European winter. Their return into 

 Europe is also as well attested about the be- 

 ginning of summer; but we have another ac- 

 count, v> hich serves to prove that numbers of 

 them continue torpid here during the winter, 

 and, like bats, make their retreat into old 

 walls, the hollow of trees, or even sink into 

 the deepest lakes, and find security for the 

 winter season by remaining there in clusters 

 at the bottom. However this latter circum- 

 stance may be, their retreat into old walls is 

 too well authenticated to remain a doubt at 

 present. The difficulty, therefore, is to ac- 

 count for this difference in these animals thus 

 variously preparing to encounter the winter. 

 It was supposed that in some of them the 

 blood might lose its motion by the cold, and 

 that thus they were rendered torpid by the 

 severity of the season ; but Mr. Buffbn having 

 placed many of this tribe in an ice-house, 

 found that the same cold by which their blood 

 was congealed was fatal to the animal; it re- 

 mains, therefore,a doubt to this hour, whether 

 there may not be a species of swallows to all 

 external appearance like the rest, but differ- 

 ently formed within, so as to fit them for a 

 state of insensibility during the winter here. 

 It was suggested, indeed, that the swallows 

 found thus torpid, were such only as were too 

 weak to undertake the migration, or were 

 hatched too late to join the general convoy ; 

 but it was upon these that Mr. Buffon tried 

 his experiment ; it was these that died under 

 the operation. 



Thus there are some birds which by mi- 

 grating make an habitation of every part of 

 the earth ; but in general every climate has 

 birds peculiar to itself. The feathered inha- 

 bitants of the temperate zone are but little 

 remarkable for the beauty of their plumage; 

 but then the smaller kinds make up for this 

 defect by the melody of their voices. The 

 birds of the torrid zone are very bright and 

 vivid in their colours; but they have scream- 

 ing voices, or are totally silent. The frigid 

 zone, on the other hand, where the seas 

 abound with fish, are stocked with birds of 

 the aquatic kind, in much greater plenty than 

 in Europe ; and these are generally clothed 



