218 NATURAL HISTOBY COLLECTIONS IN ALASKA. 



rufous of any in the National Museum collection, excepting those from Shoalwater Bay, Washington 

 Territory, and the palest skins are those from California and the neighboring region, although Mr. 

 Eidgway informs me that specimens as dark as those from the northwest coast are taken in Cen^ 

 tral America; so that the above difference maybe merely individual ; the series from Alaska is 

 too small to settle the matter. Nothing is known of the habits of this thrush, and very little of its 

 distribution in the Territory, though it probably occurs throughout the heavily-wooded coast 

 region from its well known habitat in Washington Territory north to the vicinity of Cook's Inlet, 

 and perhaps to the limit of the wooded coast west of this locality. 



TriRDUS USTULATTTS swAiNSONii (Cab.). Olive-backcd Thrush. 



On the coast of Bering Sea, where the Gray-cheeked Thrush is abundant,this species is very 

 rare or does not occur at all. In the interior, however, it appears to increase in numbers as the 

 distance from the seacoast increases. Among a considerable series of thrushes secured there are 

 but two specimens of this bird, one of which is from Nulato and the other from Anvik, both on 

 the Yukon, several hundred miles from its mouth. Dall speaks of this as a common bird, breed- 

 ing all along the Yukon to the sea-coast, but he evidently referred to the Gray-cheeked Thrush, 

 |Hiich is abundant along the Lower Yukon ; whereas swainsoni is comparatively rare, as shown by 

 its rarity in the collections brought me by the fur traders and natives from various parts of the 

 Territory, and from the fact that I did not find it at the mouth of the Yukon during the spring of 

 1879. Among my series of alicice are a number having a distinct buff shade on the breast and 

 upon the sides of the neck, thus resembling swainsoni; and it would not be surprising to find occa 

 sional cases of crossing, since the two occupy the same territory in many places. 



The subject of this article has been found to be a common breeding species on the Upper 

 Yukon, whence eggs have been sent the Smithsonian from several points, including Fort Yukon. 

 I have seen a specimen from Anvik, which is my lowest record on the Yukon. A set of eggs was 

 brought me in June, 1878, from Nulato, and they measure respectively .89 by .65 and .94 by .67 

 inches. The ground-color is blue, exactly like the eggs of alicice, with scattered purplish shell- 

 markings and fine specks of reddish-brown, which latter are much more numerous at the larger 

 end. The nest is composed of dried grass-stems with a few fragments of moss, which is scattered 

 through the structure as if by accident. The eggs of this species and of alidm are absolutely indis- 

 tinguishable, both in size and shape, as are also the nests, according to the observations I have 

 been able to make. Both species breed together throughout, perhaps, the entire course of the 

 Yukon ; but on the lower portion of the river alicice is far more numerous. There is no record of 

 this species from the coast region of Southeastern Alaska, nor from the islands of Bering Sea; 

 nor is it likely to occur in the latter portion of the Territory, owing to its preference for a wooded 

 region. 



From the observations and collections made on the Upper Yukon, the Olive-backed Thrush 

 appears to be a common summer resident there, and thus extends its breeding range within the 

 Arctic Circle. It appears to be influenced to a great extent in its range by the presence or absence 

 of woods, and its northern limit may be marked as coinciding with the tree-limit. Alicice, on the 

 contrary, extends beyond this, wherever a bunch of dwarf willows will give it shelter, to the very 

 shores of the Arctic and Bering Seas. 



Tttedtjs aonalaschk^ Gmel. Dwarf Hermit Thrush. 



Specimens of this bird are in the National Museum collection, from various points along the 

 timbered coast of Southeastern Alaska, including Cook's Inlet, Sitka, Kadiak, and Chugatchik Bay. 

 It breeds in this part of the Territory, but appears to be limited to the mild climate and wooded 

 shores of this region, as there are no records of its occurrence beyond to the north and west. 



Mr. Eidgway has referred the Turdus aoonalascensis of Gmelinto this bird, the type of which 

 came from Unalaska Island, according to the author of the name. 



Since the Unalaska Thrush was described not a single specimen of any species of Hylodehla 

 has been found on this island by the various naturalists who have visited its shores— a fact of 

 itself calculated to raise suspicion as to the correctness of the identification of Gmelin's name. 



