2o6 TWO MOCKING-BIRDS 



house-swallows, Hirundo leucorrhoa, remain hidden 

 away in a torpid condition during cold weather, since 

 they could not otherwise reappear on any bright 

 warm day during the winter months as they fre- 

 quently do. Another species, a small Jtticora, has 

 actually been found in a semi-torpid state among 

 the roots of the tall grasses on the pampas in winter. 



Nor is it improbable that even so sedentary a 

 species as the partridge is wholly unaffected by the 

 disquieting impulse. We know that the red-legged 

 partridge made its appearance on one or two occa- 

 sions in England before its final introduction into 

 this country, and these strangers must have flown 

 over the Channel. The quail, a small partridge, is 

 one of the strictest migrants, yet we know that 

 some individuals do not go with the wave in autumn, 

 but remain and live through the European winter. 



Let me now give an example in two closely allied 

 species of the two extremes in bird behaviour prior 

 to migration — excessive disquiet in the one, while 

 the other appears quite unmoved. Patagonia has 

 two mocking-birds — the common, and the white- 

 winged or white-branded species; the first is an all- 

 the-year-round resident, the other a migrant from 

 Brazil and Bolivia. It appears in September or 

 October, breeds and departs in March, but long 

 before its departure its habits change. The most 

 voiceful of all our songsters during the summer 

 months, it is now silent except for the harsh alarm 

 cry uttered when taking flight. It becomes exces- 

 sively wild, and perches on the topmost twigs of 



