190 SIXTH REPORT — 1S36. 



birds preying on small quadrupeds. In the pools of water 

 which remain open all the year in the arctic seas, the uria grylle 

 and Bnmiiichii are to be found at the coldest periods, the al- 

 cadre, consequently, are the most northerly winterers. Many 

 individuals, however, of the species just named go far south in 

 the winter season, and it has been observed that the old birds 

 remain nearer the breeding stations, while the young seek their 

 food further afield. This has been ascertained also of birds be- 

 longing to other families, and more especially of the falcomdce 

 and laridcB, probably because their young are more readilj' 

 known by their peculiar plumage. In the extreme northern 

 parts of the continent the winter residents arc the/«/co islandi- 

 cus and peregrinus, stri.v nyctea Kndifunerea, and the raven, all 

 birds of prey, the linaria boreciHs, \\\\\c\\ in the winter time 

 inhabits dwarf birch or willow thickets, and picks up a subsist- 

 ence from the grass-spikes that overtop the snow, and the 

 ptarmigan, whose mode of feeding has already been alluded to. 

 The strix lapponica or cinerea and virginiana, corviis ccmadensis, 

 tetrao canadensis, and picus tridactylus, inhabit the woods all 

 the year up to their northern termination. The tetrao cana- 

 densis feeds on the evergreen leaves of the spruce-fii', and the 

 corvus canadensis, which is omnivorous, is one of the few birds 

 which lays up food for times of scarcity. As we proceed farther 

 southwards, to the banks of the Saskatchewan for instance, we 

 find large bands of willow ptarmigan {tetrao saliceti), which 

 have left their breeding-quarters in the north to winter there, 

 and the tetrao phasianellns and nmbellus, which are perma- 

 nent residents, also one or two species of parvs, some addi- 

 tional woodpeckers, two loxiae, the pj/j^rhula enucleator, the 

 corvus cristatus, and two additional owls. The emberiza ni- 

 valis, which breeds between the 65th and 75th parallels, spends 

 most of the winter on the Saskatchewan, being seldom absent 

 more than two or three weeks in the severest weather, at which 

 time it retires to the confines of the United States. 



In the neighbourhood of Philadelphia we find 44 permanently 

 resident birds, and 71 which come from the north to winter 

 there, making together 115 winterers in that locality; in sum- 

 mer the 44 residents are joined by 74 species from the south, 

 which breed in Pennsylvania, making in the aggregate 118 

 breeders ; the rest of the birds enumerated in the Philadelphian 

 fauna by the Prince of Musignano consist of 48 species, which 

 merely pass through the district in spring and fall, on their 

 way from their southern winter- quarters to their breeding- 

 places in the north; the amount of species, residents and visit- 

 ers, in that district being 281. Dr. Emmons enumerates 241 



