INTRODUCTORY 11 



to man ; while simultaneously a corresponding- outburst 

 of furious tropical plant-growth chokes the land with an 

 impervious cane-jungle. Behind an impenetrable veil 

 Nature proceeds with secret schemes. 1 



When, or at what season birds breed in the Sudan it 

 is virtually impossible to ascertain. What can be stated 

 with certainty is that the breeding-season is a chaotic 

 jumble of dates. Some species or some genera are found 

 nesting at all seasons. Thus in mid-winter we discovered 

 various eagles and vultures, falcons, owls, certain weaver- 

 finches, shrikes, sunbirds, silver-bills, larks, hammer-head 

 and many more, all with eggs; while others, though con- 

 generic, were living under purely winter conditions. 



No better example of this topsyturvydom can be 

 adduced than the Nile geese {Chenalopex czgyptiaca}. 

 These we found in mid-winter in precisely that condition 

 which is common to all European wild-geese at a similar 

 season that is, they were strong, wild, and watchful in 

 the extreme, virtually inaccessible. Closer acquaintance, 

 however, revealed the singular fact that amidst their man- 

 defying flotillas swam others that were absolutely incap- 

 able of flight the adults because, being in full summer 

 moult, they had cast all their quills ; the goslings because, 

 owing to their youth, they had not yet acquired theirs. 

 Now this is the physical condition in which one finds 

 the wild-geese' of northern regions during the month of 

 August. Here in the Sudan it was in January and Feb- 

 ruary. Obviously these flightless geese had hatched their 

 broods in late autumn November or December ; whereas 

 the wild-flying majority must have followed more normal 

 habits and bred during spring and summer. 



Presumably the bulk of Sudan-breeding birds (both 



1 The exact period of the breeding-season with birds is necessarily 

 regulated by the degree of latitude. Thus in the Arctic with its short and 

 sharply defined summer, the fferiod is rigidly restricted to six or seven 

 weeks. In sub-tropical regions even in Spain it extends to as many 

 months ; in the Sudan, throughout the year ! 



