54 BIRDS OF TUNISIA 



The adult birds of both sexes have pure white crowns, iinuiature 

 birds black crowns, the white crown being probably not attained 

 until after the first breeding season. While in a state of transition 

 birds may be found with black and white feathers intermingled on 

 the crown. 



In a large series of specimens of this Chat in my collection from 

 Tripoli examples may be found in the various stages of plumage. 

 Comparing the measurements of these, I find the average length of 

 wing of the white-crowned males to be 4'10 inches, that of females 

 3"80 inches, while the average wing-length of the black-crowned birds 

 is 4 inches in the case of males and 3'75 inches in that of females. 



The range of S. leucopyga appears to extend throughout the desert 

 regions of North Africa, Palestine, and Arabia, and in some parts of 

 these countries the species is abundant, and the commonest of all the 

 Chats. It is also said to occur in West Africa at Sierra Leone. 

 From Marocco I have no specimens of the species, nor any note of 

 its occurrence there, but it probably inhabits the more inland desert 

 parts of that country, as it occurs abundantly in the Algerian and 

 Tunisian Sahara. In Tripoli and Cyrenaica the species is quite one 

 of the commonest of the Chats, and my collection from these 

 countries contains examples of it obtained in various districts. In 

 North-east Africa the species is most abundant in Nubia. 



As a straggler, S. leiicojJi/ga has once been recorded as occurring 

 in Europe, a specimen of it, with the white head, having been 

 obtained by Mr. C. A. Wright in Malta (Ibis, 1874, p. 223). This 

 bird was shot on April 18th, 1872, by Signor Vitali, on some 

 rocky ground called Tal Cappuccini, on the south side of the grand 

 harbour of Valetta, and after having been set up by Signor Francesco 

 Ellul, came into Mr. Wright's possession, and was eventually 

 presented by hnu to the Royal Florence Museum of Vertebrates, 

 where it exists at present, under the Catalogue No. 1,759. 



In Tunisia, S. leucopycja is to be found only in the more southern 

 districts, but where it occurs it is by no means uncommon. It does 

 not appear to stray north of the Chott Djerid, nor have I any note 

 of its occurrence in the Regency further north than Kebili on the 

 south-east, and Tamerza on the south-west. 



Baron Erlanger appears to have found the species not uncommon 

 on the Djebel Dekamis, and in the neighbourhood of Gar-el-Areif, 

 both situated in the far south of Tunisia. 



