LIFE AT HIGH ALTITUDES HINGSTON 341 



under ledges and stones. A great number of the birds make their 

 nests in holes, and in this ^Yay shelter their offspring from the wind. 

 The mountain finches and the ground choughs place their nests in 

 pika burrows, often at a great depth. The magpie builds an enor- 

 mous nest. I think it serves the parent birds as a permanent shelter 

 in addition to serving as a home for the young. The birds that build 

 on the ground place their nests behind tufts. The short-toed lark 

 showed in one case an interesting modification; it built a rampart 

 of pebbles on the exposed side of its nest so as to protect the struc- 

 ture by an artificial wall. 



Certain of the butterflies show interesting adaptations. The 

 Parnassius or Apollo butterflies are characteristic of high altitudes. 

 In Tibet they haunt the passes up to 17,000 feet where the wind 

 sweeps furiously across the range. They are capable of only feeble 

 flight, and are easily carried along by a gale. They escape being 

 swept away by their unwillingness to fly, except when the air is com- 

 paratively still. Moreover, when disturbed, they made but short 

 flights; also when they alight they choose sheltered nooks, and 

 their resting attitude is to spread their wings, pressing them down 

 close against the ground so as to offer the least resistance to the air. 

 Furthermore, their wings are stiff and rigid and not likely to be torn 

 when being battered about. Also their bodies are clothed in fur, 

 which must serve as a protection against both cold and wind. 



The Swallowtails and Vanesidse also haunt the plateau. They 

 used to come about our base camp at 17,000 feet. But these butterflies 

 are particularly powerful fliers, and by their strength alone can con- 

 tend with the wind. Other kinds live at slightly lower altitudes. 

 There is a Melitea on the plateau which has the habits of the ApoUos. 

 It escapes the wind in the same way by flattening itself tight against 

 the ground. The Lyceenids like to keep in sheltered places. One 

 kind ^ets into the tufts of vetches, another conceals itself in coarse 

 grass. The high-altitude moths that resemble Anuria adapt their 

 habits to the fierce winds. They haunt the tracts of fallen rocks, 

 the bare hills, and deposits of moraine. They fly about by day, 

 alighting on the sand. When the wind is strong they enter clefts in 

 the rocks or else shelter between the stones. Their flight is swift 

 and of short duration. When they alight they behave like the 

 Apollo butterflies, flattening themselves with outstretched wings 

 against the rock, thus offering the smallest obstruction to the wind. 



The Diptera that haunt the cliffs at 16,000 feet like to keep close 



in amongst the stones and rocks. Moreover, they make only short 



quick flights. Their actions are more like the leaps of a grasshopper 



than the ordinary movements of a fly. There is one kind, a Tachimd, 



76041—26 ^23 



