376 The Egyptian Vulture or Neophron 
birds to enable one to form an opinion as to their size, such a mis- 
take is possible. I confess to having made it twice myself, at far 
distant places; once amid the rocky hills near Philae, during the 
Nile Expedition of 1884, and once in southern Spain. On each 
occasion, the advent on the scene of an adult Neophron in its black 
and white plumage quickly disabused me of my mistake, but | 
mention the circumstance as showing how a person well accustomed 
to both species can make a mistake. 
It is curious that whereas in Egypt and Nubia immature 
Neophrons in the brown dress swarm and at times and places 
vreatly exceed those in the white plumage, they are rarely seen 
in southern Spain save when first they leave the nest. In fact 
the proportion of adult to immature birds is overwhelming. Thus 
on 24 March 1894 | noticed twenty white to one dark brown bird 
roosting in the cork trees. Similarly throughout the whole spring 
of 1907, I saw but one dark brown bird among many scores of 
adult birds. If, as is probably the case, they do not acquire the 
adult plumage for three years, it must be concluded that only the 
adult birds migrate to Europe for the nesting season. Every 
spring they arrive in hundreds almost invariably in pairs, some- 
times ten or fifteen pairs together passing northward. The largest 
number pass during the last week in March. It is interesting to 
see how almost to a day a pair will arrive from the African coast 
and take possession of the crag where a nest was in the preceding 
year. I have seen examples of this on many occasions. 
The favourite site for the nest is in a cavern or shelf protected 
from the rain by an overhanging rock. Very rarely have I seen 
a nest which was not thus protected. I know of several situations 
which are used some years by Griffons and in others by Neophrons, 
also other sites which are used by Ravens and Neophrons. In 
justice to the Ravens I have never known them return to a place 
the year after a Neophron has defiled it, but I have often seen 
the converse. 
