254 



GLAREOLA. 



Climatic 

 distribution. 



The genus Glareola is a small one, and two-thirds of the species are tropical, though 

 one of these extends its range to some distance into the temperate zone. The distribution 

 of the species is as follows : — 



Temperate Eurasia 2 



South Australia 1 



Temperate species .... — 3 



Tropical Asia 2 



Tropical Africa 5 



Tropical species — 7 



Species of Glareola — 10 



Habits. 



Emigra- 

 tions. 



The Pratincoles are birds of very powerful flight ; like the Coursers they feed almost 

 entirely upon insects, but, unlike their nearest relations, they catch their prey on the wing. 

 They rival the Swallows in their power of flight, and in their structural modifications to 

 attain it — a most interesting case, not of affinity, but of analogy. 



The Pratincoles doiibtless originally migrated from the steppes of Siberia, one 

 party (the ancestors of G. pralincola and G. melanoptera) travelling westwards, whilst 

 another party crossed the Himalayas to the south, became differentiated into G. orien- 

 talis in India, and sent off offshoots a little later to Madagascar and Australia, which in 

 process of time were isolated (if one may use such an expressive term) into G. ocularis and 

 G. grallaria. 



When the Pratincoles were driven south by the glacial cold, it is probable that G. 

 pralincola was isolated and differentiated in the basin of the Mediterranean, and G. melano- 

 ptera in the valley of the Nile. Though the breeding-range of the latter species now 

 extends fifty degrees further east in Siberia, it still comes back, presumably, to its old 

 home every winter. 



The small tropical Pratincoles w T ere probably isolated from their larger subtropical 

 allies before the latter were dispersed by the coming on of the Post-Pliocene Glacial Epoch ; 

 and are probably the result of an early emigration from the Siberian steppes to the Indian 

 plains. The Little Indian Pratincole, as it has black feet and no nuchal collar, appears to be 

 more nearly related to the larger group than its allies are, all of whom have pale feet, and 

 when adult a nuchal collar. As it appears to be the least changed, we may presume that 

 the ancestors of 67. lactea were originally isolated in India, whence they spread westwards 

 into Africa, when the Palsearctic birds were crowded down into the Oriental Region, and 

 the struggle for existence became fast and furious. 



The African birds developed a nuchal collar, and their feet and axillaries became 

 paler. The ancestors of 67. nuchalis w r ere probably isolated in Nubia, and those of 

 67. emini on the shores of the great Equatorial lakes, whence emigrating parties crossed 



