THE COMMERCIAL VALUE OF BIRDS. 29 



principally of the droppings of sea-birds, accumulated in 

 vast layers at their breeding stations during the course 

 of ages. The guano harvest is almost exhausted, most 

 of the known stations having been cleared of this costly 

 product, one of the finest known manures. Its com- 

 mercial value has been enormous ; fleets of ships were 

 engaged in carrying it from the wild ocean rocks where 

 it lay to the ports of the busy civilised world, where it 

 found a ready sale in agricultural markets. A con- 

 siderable quantity of guano is still obtained from the 

 celebrated bird caves of Borneo. 



By analysing the commercial value of birds a little 

 deeper still, we find that they absorb a fair amount of 

 solid capital every year for scientific purposes. Orni- 

 thologists must be supplied with specimens of birds and 

 eggs from all parts of the world to satisfactorily pursue 

 their studies. In the scientific world, a bird's value is 

 determined by its rarity. For instance, the skin of the 

 Caucasian Black Grouse fetched quite recently in 

 London the sum of 15 ; but that is nothing to the 

 value of the now extinct Great Auk, which is worth 

 200, or of its noble-looking egg, which was sold by 

 public auction in the present year for a hundred and 

 sixty guineas ! Our British Museum is another note- 

 worthy instance of the value of birds. Its noble 

 collections are almost of priceless value ; and in 

 gathering them an immense amount of money has been 



