PRESSURE FROM RESIDENTS 215 



But birds, like savage tribes and civilized nations, 

 have boundaries to consider, and if they invade the 

 territories of others, must sooner or later have to 

 fight for a place or return whence they came. And 

 in such a contest, which must be inevitable in the 

 tropics when food and favourable locations get at 

 all scarce, the advantage is all on the side of the 

 residents, which are generally speaking birds of 

 a superior type mentally and morally, even when 

 less specialized physically, and perhaps, indeed, on 

 that very account. They generally excel the birds 

 of temperate regions in courage, social instincts, 

 and intelligence, as is shown by their much greater 

 power of combination, and by the far superior 

 nests they often build. Finches of the typical 

 temperate-zone groups have a poor time in an 

 aviary if crowded along with Weavers, and the 

 Tree-Ducks know how to make the migratory 

 temperate-zone Ducks respect them, while the 

 solitary Thrushes would have a poor chance against 

 the Babblers, with their powers of combination 

 which enable them often to resist even Hawks. 



There is a popular belief that birds in temperate 

 climates sing better than in the tropics, but all the 

 foundation for this idea is the fact that the Nightin- 

 gales are birds of the temperate zone, and that 

 some very common Thrushes are good singers ; 

 with the exception of the Nightingales no singers 

 of the north of the Old World can surpass, or even 

 equal, the Shama (Cittocincla macrura) and Orange- 

 headed Ground-Thrush (Geocichla citrina) of India, 



