156 INTRODUCTION. 



which indicates this display, so common that it 

 lias given rise to it. It is produced, however, in 

 a different manner from the raising or displaying of 

 the plumes, which in fact are too short to admit of 

 their being exhibited or raised as ruffs or lengthened 

 tail-coverts ; but they have the power of changing 

 the position of the feathers by a muscular action, so 

 as to throw their brilliant reflective powers into 

 view of the spectator, or to exhibit parts which 

 were otherwise concealed ; and he likens or compares 

 this power to that possessed by some of the African 

 antelopes, which at will suddenly display concealed 

 white portions of the hair, which in that state forma 

 conspicuous pale markings. It is during this season 

 of incubation also, that any variation of notes is 

 principally shown, as among the Humming-birds, 

 the call when in search of food, or when irritated, 

 is sharp, and indicates anxiety or a restless desire to 

 obtain the object; but, unlike them, they possess 

 at times an agreeable note or warble, having con- 

 siderable melody. Vaillant states this of several 

 species, and in the Voyage of Frecynet, indica- 

 tions of them being sometimes nocturnal occur, 

 " At night they have a lengthened song, the mo- 

 dulations of which are very agreeable."* Latham 

 adds to his description of the Blue-rum ped Creeper, 

 " Said to sing as well as any Nightingale, with 

 a sweeter voice." t The Diceum hirundinaceum 

 sings in " a very animated and long-continued strain, 



* Frecynet, p. 26, f Gen. Hist., iv. p. 239. 



