94 
KATURAL HISTORY. 
to clifeafe than other creatures, yet they are 
liable to one to which no others are expoftcl; 
this is the ficknefs attending the annual reno- 
vation of their plumage, which is called their 
moulting time. 
Generation . — In the fpring, when naturf 
affords abundance of food, birds are ftimu- 
lated to pair, to increale their fpecies. Hav- 
ing chofen their mate for the enfuing year, 
they proceed to thole official cares which 
diftinguiffi the approach of being made pa- 
rents. With all the fondnefs of fuch expec- 
tations, they proceed to colleft materials for 
their nefts, which they build with the Ikill 
of the moll; expert architeft. They difco- 
ver fo much conltancy to each other, with 
fuch unabating care and affeftion in breed- 
ing and rearing their young, that they 
might be taken as examples by the human 
fpecies. 
Habitation. Birds are particularly at- 
tached to the place of their nativity. A 
rook, if undifturlred, will never quit its na- 
tive grove ; the blackbird and redbrealt are 
tenacious of their birth-rights; and many 
others, that are known to emigrate annually 
Irom this country, have been found, by fre- 
quent experiments, to return to their ufual 
breeding places. 
Migration — Is that paffage of birds from 
one climate to another, according as they are 
impelled by fear, hunger, or change of fea- 
fons. Many have been the conjeftures of 
naturalifts 
