94 INTRODUCTION. 



owl families, which prey upon the stragglers. Nor 

 is this similarity between the birds of the two con- 

 tinents confined only to such as inhabit the land. 

 It is a curious and unrecorded fact, that a migra- 

 tion almost equally extensive takes place among the 

 waders and swimmers. During many years resi- 

 dence, for instance, in the island of Sicily, a spot 

 peculiarly favourable for carrying on observations 

 of this nature, we never met with the purple or the 

 night herons, or the glossy ibis, except during the 

 spring or autumnal migrations ; at such times the 

 whole island may be considered like a vast preserve 

 of quails, and numerous other migratory birds. In 

 respect to the small soft-billed or fly-catching species, 

 forming part of the fly-catcher and warbler families, 

 little can be said beyond the fact that their route is 

 southward, after leaving our hedges and woods in 

 the autumn. They do not appear to take Italy or 

 Sicily in their way, which, if they ventured on the 

 shores of Northern Africa, it is more than probable 

 they would do, seeing that the configuration of those 

 countries renders them resting places, as it were, 

 for such feeble winged birds before they ventured 

 to cross the Mediterranean. Northern Africa is 

 certainly the boundary of the African bush-shrikes 

 (Malaconotus); one species, the beautiful M. bar- 

 larus, seems the most northern visitor, while its 

 southern range extends to Senegal. There must 

 be many birds peculiar to sandy deserts in the arid 

 tracks of Barbary, Algiers, &c. which would find 

 no congenial locality on the fertile shores of the 



