ARCTIC SKUA. 381 



upon natural impulse, and partly upon the necessity of their 

 following other birds upon which they so much depend for 

 their food; their dispersion in the latter part of the season, 

 is more exclusively for the purpose of feeding for it does 

 not appear that climate has very much effect upon them. 

 It is probable that these birds pair for life, as well as the 

 common skuas ; but the fact of their pairing has not been so 

 well ascertained. They do not keep so exclusively at sea as 

 the common species, but sometimes range to considerable 

 distances inland, at which times their chief subsistence is 

 upon worms and molluscous animals. 



These birds have not the decided feathers or the hawk-like 

 mottlings of the species that have been already noticed. 

 They have the head blackish brown, with the dark colour 

 covering the cheek a little below the eyes. The general 

 colour of the upper part is also brown, but with a slight 

 trace of ash colour. The sides of the neck are buff; the 

 throat, breast, and belly, white, passing into greyish ash 

 towards the vent. The cere is whitish ash; the bill bluish 

 black; the feet, of which the tarsi are an inch and three 

 quarters long, are the same colour; they have the webs large 

 and the hind toe little produced, indicating a more swimming 

 habit than that of the former species. Their instruments of 

 flight are also much produced. The entire length is twenty- 

 one inches, of which, however, nine inches are taken up by 

 the feathers of the tail, of which the middle feathers are so 

 much produced, that they extend fully three inches beyond 

 the others. The young birds have the tail feathers produced ; 

 and they are of a brownish colour. 



ARCTIC SKUA (Lestris parasiticus). 



The true Arctic skua sometimes breeds in the remoter 

 parts of the British islands, but much more rarely than 

 Richardson's, or even than the common species. It is by 



