XV 
AN UNCAGED ZOO 
193 
When tick-picking the oxpecker rests on the whole 
tarsus and when in danger of being swept off by the tail 
of its host flattens itself or hops out of the way. It is 
stated that an oxpecker will attach itself to a particular 
animal. 
The oxpecker will pick parasites from oxen and is 
exceptionally fond of donkeys. White herons will perch 
Oxpeckers {Buphaya erythrorhyncha). 
Busy on submerged buffaloes. 
on the back of cattle and feed on ticks, flies, and other 
parasitic insects. When elephants approach water, buff- 
backed herons will swarm on their backs. 
Close to our camping ground near the lake there 
was an almost vertical wall of rock, about 300 
feet high, which formed one of the many irregular 
boundaries surrounding the deep depression which this 
