1926] Swarth: Birds and Mammals from the- Atlin E&gion 57 



an altitude of 2200 feet, compaxed with Telegraph Creek at 540 feet, 

 and Hazelton at 973 feet, and this increase in elevation, together with 

 the more northern location, has almost eliminated at Atlin certain 

 Canadian Zone elements that are conspicuous at the more southern 

 stations. The lowlands of the Atlin region, it seems to me, are Hud- 

 sonian Zone, with but a slight infiltration of Canadian Zone species. 

 There is no definable zone between the lowlands (2200 feet altitude) 

 and the Alpine-Arctic mountain tops, with timber line between 3500 

 and 4000 feet. The same species of plants, mammals, and birds, with 

 few exceptions, range from timber line downward in suitable places 

 throughout the valleys. The converse of this, however, is not true, 

 of birds at least, for all species of birds that occur in the lowlands do 

 not range upward to timber line. Then, a further exception must be 

 made of three species of birds, Dendragapus obscurus flemingi, 

 Spizdla monticoloi ochracea, and Lanms hormiis, the former two 

 occupying in abundance, the latter in small numbers, types of country 

 that are found in some places immediately below timber line (see 

 pi. 6, fig. 4). However, making due allowance for the more decidedly 

 Hudsonian character of higher altitudes, the general tone of the 

 valleys, too, is of the Hudsonian Zone. This is exemplified in the 

 extensive stands of white spruce with such accompanying bird species 

 as the Alaska hermit thrush, Hudsonian chickadee, Canada jay, 

 goshawk, and spruce grouse, all occurring in abundance. 



In the upper Skeena Valley the Canadian Zone is dominant, as 

 demonstrated by the presence of many elements over a vast expanse of 

 country. In the upper Stikine Valley, while the Canadian Zone char- 

 acterizes the region, there are fewer bird species represented and 

 they occur over a relatively restricted area. In the lowlands of the 

 Atlin region there is but the merest infiltration of Canadian Zone 

 elements into prevailing Hudsonian Zone surroundings. 



Lakes and streams in the Atlin region all find their way into the 

 Arctic drainage, and here, too, in coming from the south, one first 

 finds a few real Arctic birds. Among such may be mentioned the 

 pair of black-throated loons we saw, apparently in two minds as to 

 nesting in the region, the northern phalarope, apparently breeding at 

 Carcross, the gyrfalcon, and the northern shrike. 



Some comparisons can be made of the status of certain species of 

 birds at Hazelton, Telegraph Creek, and Atlin. Bubo virgifimnus lago- 

 phonus is abundant at Hazelton. We secured no homed owls at Tele- 

 graph Creek, but at Atlin the breeding subspecies is the more northern 

 form, B. V. subarcticios. Dryobates vitlosus monticola is abundant at 



