( 2l8 ) 
Some Thoughts on the Pallage of BIRDS. 
y Have faid fomething on this Subjed in a former Part of this Work ; but as there 
I remains much Uncertainty in what we know as yet, I am willing to fpeak to 
it again Irr the beft Manner I am able, in Hopes of giving fome ufeful Hints at 
leaft, to future Inquirers. 
My good Friend, the late Mr. Mark Catejby , I remember, fometime before his 
Death, prefented a Paper to the Royal Society, relating to the Paftage of Birds, which 
was read at one of their Meetings. This Paper I have not by me, but well remem- 
ber the general Opinion advanced in it was, that he imagined fuch Birds as were 
Inhabitants with us only Part of the Year, departed from hence to inhabit 
Southern Countries, on the other Side of the EquinoBial Line , juft of the fame 
Degree of Latitude with thofe they departed from, on the Northern Side : Such a 
Conjecture, at firft Sight, feems to be probable enough, becaufe, in general, it is 
fuppofed, that during our Winter Seafon, the Temperature of the Weather, in the 
Southern Latitudes, is nearly the fame as it is with us in our Summer ; and then 
of Confequence, a Bird of Paftage thatpaftes from ftxty Degrees of Northern, to iixty 
Degrees of Southern Latitude, will meet not only with the fame Altitude of the Sun, 
in both Latitudes, provided the Paftage is made'in September, or March, but with near- 
ly the fame Degrees of Heat. But if weconfider, that there are many Birds of Paftage 
found far to the Northward, in feventy Degrees of Latitude (where I believe all 
the Fowls are Birds of Paftage, it not being a Climate fit for their Subfiftance in 
Winter) they muft have a long Way to pafs, according to Mr. Catejby* s Notion ; 
for feventy Degrees to the EquinoBial Line , and feventy Degrees again to the 
South of it, are an hundred and forty Degrees, which, at our loweft Compu- 
tation of a Degree of Latitude, make eight thoufand four hundred Miles, which is 
a prodigious Voyage for a Bird to perform in a ftiort Time. Birds that are conftant 
Inhabitants between the Tropicks, it is very likely, may make Tranfits acrofs the 
EquinoBial , to accommodate themfelves with proper Food at different Seafons, or to 
avoid the Inconveniency of the exceftive Rains in one Place, by feeking the more 
dry and pleafant Seafons in another ; but to imagine that Birds who inhabit the high 
Latitudes, either of the Northern or Southern Hemifpheres, fhould change their 
Habitations from an extream Northern, to an extream Southern Latitude, or vice 
verfa, is contrary to all Reafon, and to the Nature of Things ; for Birds inhabiting 
frigid, or temperate Climates, would find themfelves almoft out of their proper 
Element, while pafting through a Trad of more than forty-five Degrees of the 
horrid Zone, before they could arrive at their natural and cooler Climates on the op- 
pofite Side of the Torrid Zone \ nor is there any Reafon at all for Birds to pals 
from the Northern to the Southern Hemifphere, in order to arrive at a Place of a- 
Vol. IV. R proper 
