46 STUDIES IN BIRD-MIGRATION 



a combination of influences, in which meteorological 

 conditions play an important part, more than one move- 

 ment, as we shall see, may be in progress simultaneously, 

 — a circumstance which adds much to the already compli- 

 cated series of phenomena, and to the bewilderment of 

 the observer. 



Appendix I. — List of Summer Visitors 



The following is an enumeration of the various 

 species of birds which are Summer Visitors to the 

 British Islands. Many of them are very widely 

 diffused over our area, such as the Swallow, while 

 on the other hand a few are extremely circumscribed 

 in their distribution, and of these the Marsh Warbler 

 affords a good example. 



An indication of the general Winter Retreats in 

 the western regions of the Old World is given for each 

 species. In some portion of these the cold season 

 is passed ; but at present we have no definite 

 knowledge where the British members of any species 

 spend the winter. It is highly probable, however, that 

 as each has its particular summer home, so has it also 

 a predilection for definite winter haunts : — 



Golden Oriole, Oriolus oriohis. — Tropical and South Africa. 



White Wagtail, Motacilla alba. — Southern Europe, North and North- 

 tropical Africa. 



Yellow Wagtail, Motacilla n?>7.— North-tropical, Equatorial, and 

 Southern Africa. 



Blue-headed Wagtail, Motacilla fiava. — Tropical, Equatorial, and 

 South Africa. 



Tree-Pipit, Anthus trivialis. — South Europe, Northern and Tropical 

 Africa to Transvaal. 



Red-backed Shrike, La/iii/s collnrio. — Tropical, Equatorial, and 

 South Africa to Cape Colony. 



