jecture : but it. is a conjecture wliicb derives support from many interesting facts wliicli I have collected, and -wliicli 

 will be mentioned and explained in my Geographical View of the Trees and Shrubs of North-America. In that work, 

 I shall show, that the southern trees and shrubs (that is, those vegetables which attain to their gi'eatest perfection in 

 the southern climates of our continent, particularly of the United-States) are, in general, found much farther 

 north in the western than they are in the eastern parts of our country. This fact seems to show, and the point is 

 put beyond any manner of doubt, by thermometrical observations, that the western climate, in the same lati- 

 tudes, is more temperate than the eastern. Of course, it were natural to suppose, that the southern birds, to whom 

 heat is so genial, woidd often be solicited farther north in the western than in the eastern district. This, with respect 

 to some birds, is actually the case. Mr. Jefferson has observed, that " Perroquets even winter on the Sioto, in the 

 39th degree of latitude." * I have certain information, that these birds winter still farther north than is here mentioned. 



§• IX. 



Birds, in migrating, are fond of following the courses of rivers, and other large streams of water. This circum- 

 stance, in my opinion, partly explains the reason, why some of the birds of the southern parts of the United-States, 

 and also some of the South-American birds, which have never, or very rarely, been discovered in the Atlantic coun- 

 tries of North-America, are not uncommon in the countries west of the Alleghaney-Mountains. These southern 

 birds, following the courses of the Mississippi, and its branches (the Ohio, the Illinois, &c.) are spread or dispersed 

 through the rich and extensive territories that are washed by these waters. Whether or not this explanation be 

 admitted, the fact is certainly as I have stated ; and to the naturalist it cannot but appear interesting. The Psittacus 

 pertinas is one of the birds of Brazil ; and the Muscicapa Tyrannus, which is held in so much esteem by the Nau- 

 dowessies, and other western Indian tribes, is a native of Surinam, and of the country bordering on the river Plata. 



§.x. 



It is, I thinli, in general, a just observation, that our Spring and Summer birds of passage continue witli us 

 about six mouths, and are absent for the same leugtli of time. Accordingly, those birds which anive early in the 

 spring disappear early in the autumn, and those which arrive late in the spring do not disappear until late in the au- 

 timin. Our late springs are commonly succeeded by late and warm autumns, which, by keepiug alive the numerous 

 species of insects, wluch are the favourite food of almost all our summer birds of passage, detain these birds for a 

 considerable time among us. 



§. XL 



The greater number of the Spring and Summer birds of passage, which I have mentioned, build and breed in 

 Pennsylvania.! Perhaps, they all breed in some part of this extensive state, with the exception of the Vultur 

 Aura (Turkey-Buzzard), and a few others, which do not visit us until towards the close of the summer. It has latelv 

 been ascertained, that the Ampelis Garrulus, or Prib-Chatterer (Cedar-Bird) does breed in Pennsylvania; and I 

 doubt not, that the same will, in time, be discovered to be the case with the Emberiza Oryzivora (Rice-Bird, 

 Reed-Bird), and others whose nests have not hitherto been seen in Pennsylvama. It is not unhkely, however, that 

 scime of these birds of passage continue their loigration farther northward, to New- York, New-Englaud, Vermont, 

 &c. and there breed and raise their young, returning southward, through Pennsylvania, in the fall. 



§. XII. 



It is an interesting fact, for which we ai'e indebted to Mr. William Barti'am, that very few of our birds of passage 

 from the south '' build or rear their young in the south or maritime parts of Virginia and Carolina, Georgia and 



» Notes on the State of Virginia. Page 1 J9. The original edition. 



t See Appendix I. where I have designated with an aaterisk (*) those birds wluch are known to breed in Pennsylvania. The greater number of them 

 thus marked breed witliin a few miles of Philadelphia. 



