THE COMMERCIAL VALUE OF BIRDS. 39 



as night wraps either the eastern or the western worlds 

 in gloom ? What injury are the Woodpeckers working 

 in searching out for creatures that are rapidly and surely 

 eating away into the very vitals of the timber, not only 

 in the woods and parks of civilised man but in the vast 

 primeval forests? What damage are the Rooks and 

 most other species of Crows working on the land in 

 ridding it of wire-worms and other fatal pests ? And as 

 a set-off to the bloodthirsty propensities of the Hawks, 

 they help to keep the smaller birds within proper limits, 

 preventing their undue increase, and thus preserving 

 Nature's delicate balance. And so we might go on right 

 through the realm of birds ; but sufficient has been said 

 to illustrate the great good this vast army of feathered 

 beings are daily and hourly performing in every corner 

 of the globe. Birds are also of considerable economic 

 value as agents for the dispersal of various seeds, and as 

 the fertilisers of certain flowers. Many kinds of plants 

 have been carried in the form of seeds from one part of 

 the world to another by birds, either when clinging to their 

 feet or plumage or in their crops and intestines. In this 

 way many isolated ocean islets have been clothed with 

 vegetation. The well-known mistletoe is largely spread 

 by birds, either accidentally, through them placing the 

 glutinous seeds in the crevices of the bark as they eat 

 the berries, or when cleaning and rubbing their beaks 

 against the branches. In tropical countries where 



