FALCONIDAE. 



eggs are marked, the rounder their shape is; and as he had also 

 observed, corresponding with what Hennicke') had noticed in respect 

 of Birds of Prey kept in confinement, that the sets laid by young 

 female birds are smaller in number and are marked in a lighter 

 tint than those laid by old ones, Mr. Detmers infers that sets of 

 round eggs are laid by old female birds. 



In the «/s«s-sets in my collection I can observe no connection 

 between size, intensity of the colour of the spots, and more or less 

 spherical shape. 



BUTEO BUTEO (L.). 



In general butco-eggs are characterized by spots or clusters of 

 spots, each shading from a dark to a lighter tint in the direction 

 leading from the big end to the pointed end, and either in the 

 longitudinal axis of the egg, or winding — mostly in a right- 

 handed spiral — round it. Eggs of which layer II bears bright brown 

 spots, and layer III contains but very little lime, exhibit a fine 

 reddish lilac tint. 



In Naumann it is stated that the nest sometimes contains one egg 

 which is either wholly unmarked or is marked extremely little, and 

 that it is still uncertain at what age female birds lay such eggs, 

 while of the sets which are largest in number the eggs are also 

 marked most strongly and are largest in size. Morris ^) mentions 

 a case in which the sets, which were said to be of one and the 

 same female bird, increased in intensity of colouring from year to 



') See: C. R. Hennicke, Die Raubvogel Mitteleuropas (Gcra, 1903) and E. 

 Detmers, Fortpflanzung der Raubvogel in derGefangenschaft. (Verlag F. Pfen- 

 ningstorff, Berlin). 



*) A natural history of the Nests and Eggs of British Birds (London, 1864— 65). 



