OCCASIONAL, OR ACCIDENTAL, RESIDENTS. 
There is a propriety in the divifion of the Refident Birds, into fuch as coidmonly continue ill the country the wnole 
year through, and fuch as only occafionally continue. The latter may be called Occasional, or Accidental, 
Residents. They feldom continue with us except in open, mild winters. Thefe, in the preceding lift, are 
marked with an afterifl^.* I have had the lefs hefitation in blending them together, becaufe it is highly probable, 
that in a tradl of country fo extenfive and various as the ftate of Pennfylvania, fome of the birds, which about 
Philadelphia are only occafionally refident, may be more generally fo in other parts of the country. 
OCCASIONAL VISITANTS. 
Some of the birds which are obferved in Pennfylvania may, with propriety, be thrown into a feflion called Occa¬ 
sional Visitants. Of thefe I have already made mention in the Introduflion to thefe Fragments. Thefe 
Occafional Vifitants are fuch birds as occafionally come to Pennfylvania, either from the more northern or from 
the more fouthern parts of North-America. With all the caufes which induce them to vifit us, I am not fuftici- 
ently acquainted to fpeak on the fubjed, with confidence* The following, however, are certainly fome of thefe 
• caufes, viz. feverity of cold, fcarcity of food, and intenfity of heat. 
I. The birds which are driven by the feverity of cold all come to us from the northward. Thefe occafional vifit¬ 
ants are pretty numerous, during our -very fevere winters, when fom6 of the birds of Canada and Labrador are 
feen among us. The two following fpecies of Strix deferve to be mentioned under this head, viz. the Great 
White Owl (Strix Nydea ?). This fpecies is never feen in the vicinity of Philadelphia, except in thofe winters 
which are very fevere, long, and clofe. This and the following fpecies (See the Tables) were feen about Phila¬ 
delphia, at the clofe of the winter of 1791-92, which was one of our fevered; winters. The Tawney-Faced 
Owl (Strix ftridula ?) is a very beautiful fpecies. It makes its appearance, in the day-time, near houfes and barns, 
watching for mice, or for thofe weakly birds which have been compelled by the feverity of the cold to take fhelter 
there. 
II. It may readily be imagined, that a fcarcity of food, particularly of their favourite food, is one of the caufes 
which induce birds to make occafional vifits to other countries than their own. I am even of opinion, that this 
has been the original caufe of fome of thofe migrations which are now regular and extenfive. 
III. I have mentioned intenfity of heat, or very warm weather, as one of the caufes which fometinies impel or induce 
birds to migrate to us. It is probable, however, that this caufe more frequently operates in a lecondary manner; 
that is, by producing a fcarcity of food. All the Occafional Vifitants that fall under this fedion come from the 
fouthward. See the Introduction, where I have mentioned fome of thefe vifitants. 
ADDITIONS TO THE LIST of BIRDS. 
The following deferve a place in an hiftory of the birds of Pennfylvania. They are all, except the Pfittacus, found 
in the vicinity of Philadelphia, or within eighty miles of it. 
ACCIPITRES. 
1. Falco OfTifragus? Sea-Eagle. I mention this on the authority of my ingenious friend Mr. G. S. Oppelt, of 
Nazareth, in Pennfylvania. Fie fays it agrees with the Falco Oftifragus, “ only that the cera is not lutea but 
obfcura.” The one which he examined meafured feven feet from wing to wing. Killed near Nazareth. MS- 
2. Strix Aluco. Speckled Owl. On the authority of Mr. Oppelt. 
3. Strix Naevia. Mottled Owl. On the authority of Mr. Oppelt* 
4. Strix paflerina. Little Owl. 
PICiE. 
5. Pfittacus pertinax ? Illinois Parrot ? Either this or fome other fpecies of tire genus deferves to be mentioned 
among the birds of Pennfylvania. It has been feen in Shareman’s Valley. See Introdua:ion, §. VII. 
D 
