1926] Swarth: Birds and Mammals from the Atlin Region 57

an altitude of 2200 feet, compared 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 flemingt,
Spizella monticola ochracea, and Lanius borealis, 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
pl. 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 gyrfaleon, and the northern shrike.

Some comparisons can be made of the status of certain species of
birds at Hazelton, Telegraph Creek, and Atlin. Bubo virginianus lago-
phonus is abundant at Hazelton. We secured no horned owls at Tele-
graph Creek, but at Atlin the breeding subspecies is the more northern
form, B. v. subarcticus. Dryobates villosus monticola is abundant at