( 2l8 ) 
Some Thoughts on the Pailage of BIRDS. 
Have faid fomething on this Subjedt in a former Part of this Work ; but as there 
remains much Uncertainty in what we know as yet, I am willing to fpeak to 
it again in the bed; Manner I am able, in Hopes of giving fome ufeful Hints at 
lead:, to future Inquirers. 
[M .y good Friend, the late Mr. Mark Catejby , I remember, fometime before his 
Death, prefented a Paper to the Royal Society , relating to the Padage 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 Equinoctial Line , jud: of the fame 
Degree of Latitude with thofe they departed from, on the Northern Side: Such a 
Conjecture, at drd 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 Padage that palfes from dxty Degrees of Northern, to fixty 
Degrees of Southern Latitude, will meet not only with the fame Altitude of the Sun, 
in both Latitudes, provided the Padage is made’in September , or Marche but with near¬ 
ly the fame Degrees of Heat. But if wecondder, that there are many Birds of Padage 
found far to the Northward, in feventy Degrees of Latitude (where I believe all 
the Fowls are Birds of Padage, it not being a Climate fit for their Subddance in 
Winter) they mud have a long Way to pafs, according to Mr. Catejby's Notion ; 
for feventy Degrees to the Equinoctial Line , and feventy Degrees again to the 
South of it, are an hundred and forty Degrees, which, at our lowed 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 daort Time. Birds that are condant 
Inhabitants between the Tropicks , it is very likely, may make Trandts acrofs the 
Equinoctial , to accommodate themfelves with proper Food at different Seafons, or to 
avoid the Inconveniency of the excedive 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, daould' 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 alinod out of their proper 
Element, while paffmg through a Trad of more than forty-five Degrees of the 
'Torrid 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 pafs 
from the Northern to the Southern Hemifphere, in order to arrive at a Place of a 
V o l. IV. R proper 
