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 cegyptiaca). 
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. Herein 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 period 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 1 
