National Geographic : 1910 May
RHINOS FEEDING Note the birds on their backs. These birds eat the ticks, which infest the beasts. They also act as sentinels, by their fluttering warning their companions of approaching enemies THE LOWER PICTURE IS OF ONE OF THE SAME PAIR IN THE ACT OF CHARGING The horn is about 24 inches long, and is composed of hair or bristles closely pressed. A rhinoceros' horn's only value is as a trophy, though some are sent to China, where they are pulverized and sold for medicinal purposes.