other circumflances will greatly regulate the arrival of birds in, and their fdght or removal from, a particular 
country. Sometimes, there is a difference of three weeks or a month between the arrival, or appearance, of the. 
fame fpecies, in two different years. This will appear from the following inflances, which are feleded from many 
others. 
s* ^v. 
From an infpedion of thefe Tables, it will appear, that the Alauda alpeflris, or Shore-Lark, the Alauda rubra, 
or Red-Lark, the Fringilla triflis, or Golden Finch, and fome others, were not obferved, in the vicinity of Phila. 
delphia, earlier than the twelfth of March, 1791 : whereas the fame birds were feen, in the fame neighbourhood, as 
early as the twenty-eighth of February, the following year, on their paffage northward. 
I have placed the Anas canadenfis (Wild-Goofe) between the 15th and the i8th of April, 1791, but in the year 
1794, thefe birds were obferved, on their migration from the fouth, as early as the 3d of March. In the firfl men¬ 
tioned year the Ardea Herodias, or Great Heron, was not obferved before the 15th or i6th of April; but in the 
latter year, numbers of thefe birds were feen as early as the ift of April. Many other inflances might be mentioned. 
§. XVI. 
How much the movements of birds from one country to another depend upon the flate of the feafons, will ap¬ 
pear from different parts of this little work; particularly from the Third Section. Here we find, that during our 
mild winters, feveral of thofe fpecies of birds which, in general, are undoubtedly migratory, continue the winter 
through in the neighbourhood of Philadelphia. Such, which I have denominated the Occasional, or Acci¬ 
dental, Resident Birds, are the Ardea Herodias, or Great Heron, Columba carolinenfis, or Turtle-Dove, the 
Turdiis Pc^^glottos^and feveral others: I doubt not many more than I have mentioned. The Columba migratoria, 
Paffenger-Pigeon, commonly returns from the northward late in the fall, and continues with us a few days, or 
weeks, feeding in our fields upon the feed of the buckwheat,* or in the woods upon acorns. But if the feafon be 
a very mild one, they continue with us for a much longer time. This was the cafe in the winter of 1792—1793, 
when immenfe flocks of thefe birds continued about the city, and did not migrate farther fouthward, until the weather 
became more fevere in the month of January. The winter of 179^2—1793? was one of the mildefl that had ever 
been remembered in Pennfylvania. It is a common obfervation in fome parts of this flate, that when the Pi¬ 
geons continue with us all the winter, we fhall have a fickly fummer and autumn. There is, perhaps, fome foun¬ 
dation for this notion. Large bodiesf of thefe birds feldom do winter among us unlefs the wdnter be very mild ; and 
the experience of fome years has taiight us, that fuch winters are often followed by malignant epidemics. The mild 
winter of 1792—1793? was fucceeded by a dreadful malignant fever, which deflroyed between four and five thoufand 
people in Philadelphia; and I am affured, that the fame fever in 1762 was preceded by an extremely open winter, 
during which the pigeons remained about Philadelphia, and in other parts of the flate. In the hands of a poet, a 
Lucretius, or a Virgil, this coincidence between the accidental hiemation of the pigeons and the appearance of the 
yellow-fever might be wrought up into a fyflem of beautiful extravagance. 
§. XVII. 
If birds, in their migration from one country to another, were impelled by a determinate,” or neceffary inflincl, 
the periods of their arrival and departure would be more uniform and fixed. But we have feen, that there is a 
confiderable difference in thefe refpecls, even in two years immediately in fucceffion. Such great regularity in the 
migrations of thefe animals by no means accords with thofe accommodating habits, which the naturalifl difcovers in 
his inveftigation of the manners of all animals; thofe habits which have been given to them, as to us, by a Cre- 
• Polygonum Fagopyrum. 
f I fay “ large bodies,” for I believe individuals of thefe birds continue with us almoft every winter. 
