OF THE INTELLIGENCE AND OF INSTINCT. 



163 



species has its own habits and its own relations with other 

 animals, with which it consorts or avoids or pursues. These 



Fig. 108. Nest of the Baya. 



Fig. 109. Nest of the 

 Sylvia Sutoria. 



associations are sometimes permanent, at others only tem- 

 porary. The hyaena and wolf unite in groups only when 

 pressed by hunger. Swallows also assemble for the purpose 

 of travelling. Still more remarkable is the so-called pigeon of 

 America. They collect in almost countless millions. The 

 celebrated American ornithologist* Wilson, calculated at 

 '2,( M M ,( K X), a single hand which he saw in Indiana ; and 

 Audubon relates that oue autumn day he left his house at 

 Henderson, on the banks of the Ohio, and whilst traversing 

 the uncultivated plains near Harsdenburgh, he saw these wild 

 pigeons in considerable numbers, flying from north-west to 

 south-east ; as he journeyed on to Louisville the flock of birds 

 became move and more numerous,, until the light of midday 

 was obscured as in an eclipse ;. the droppings fell like snow : 

 before sunset he arrived at Louisville, a distance of fifty-five 



M2 



