134 ON THE INSTINCTS OF BIRDS. 
Whinchat, Great Titmouse, &c., when introduced to 
their nests after having been forcibly removed to a 
distance from their unfledged young, remain quietly 
upon them as if they had not been molested. Yet, 
although this instinct, the transient effects of which 
depend most likely on a temporary excitation of the 
parental feelings by some physical modification of 
the corporeal organs, thus for a time powerfully 
predominates, its manifestations are, nevertheless, fre- 
quently influenced by the active cooperation of the 
intellectual faculties, as in the following examples. 
“The Flycatcher,” says Mr. White*, “builds every 
year in the vines that grow on the walls of my house. 
A pair of these little birds had one year inadvertently 
placed their nest on a naked bough, perhaps in a 
shady time, not being aware of the imconvenience 
that followed. But a hot sunny season coming on 
before the brood was half fledged, the reflection of 
the wall became insupportable, and must inevitably 
have destroyed the tender young had not affection 
suggested an expedient and prompted the parent 
birds to hover over the nest all the hotter hours, 
while, with wings expanded and mouths gaping for 
breath, they screened off the heat from their suffering 
offspring.” 
“A further instance,” continues the same author ft, 
“T once saw of notable sagacity in a Willow-Wren, 
* «Natural History of Selborne,’ p. 151. 
+ Ibid. 
