1926] Swarth: Birds and Mammals from the Attin B&gim 55 



in many places by tracts of swamp, grass-covered or grown up with 

 willow thickets, and the woods are interspersed with many small lakes. 

 Three or four miles east of Atlin, Lake Como, the largest of these 

 small lakes near the town, supports a considerable population of 

 water birds. 



Some four miles south of Atlin, Monarch Mountain rises (see pi. 6, 

 fig. 5), the nearest peak of a series of rounded and, for the most part, 

 not particularly rugged mountains, that border Pine Creek Valley to 

 the eastward of Atlin and the lake shore to the southward. Conditions 

 on this mountain may be briefly described, as generally applicable to 

 that type of country in this region. Poplar woods border the lowest 

 slopes of the mountain, but ascend its sides only a few hundred feet 

 before giving way to the belt of darker and denser spruce. Between 

 3500 and 4000 feet altitude spruce is largely replaced by balsam fir, 

 growing to large size at its lowest level and persisting over the summit 

 of the peak in more or less dwarfed and prostrate form. At the upper 

 edge of the spruce belt the woods become more thin, and are cleft by 

 wider and wider areas of open grass or lupine covered slopes. On 

 the summit (3800 to 5000 feet altitude) upright timber of any size 

 disappears, save in a few sheltered spots, and the scattered thickets of 

 scrubby balsam sprawling close to earth are surrounded by wide areas 

 of open ground, grass covered or here and there grown up with false 

 heather over limited damp areas. Creeping birch grows here, too, and 

 in extensive tracts; on this particular mountain I saw little that was 

 more than knee-high. 



Directly opposite the town of Atlin lies a group of three islands, 

 the nearest within a quarter of a mile from the shore, and none of 

 them more than a few acres in extent (see pi. 5, fig. 2). A striking 

 feature of these islands is the fact that of the forest trees with which 

 they are covered nearly all are balsam fir. There are relatively few 

 spruce or jack pine. On the adjacent mainland I saw no balsam at the 

 lake level. The islands are the nesting grounds of small colonies of 

 water birds (short-billed gull, Bonaparte gull, and Arctic tern) and 

 they harbor an extraordinary number of small land birds. We listed 

 fifteen species of land birds as nesting there, some of them (such as the 

 black-poll warbler) extremely scarce on the neighboring mainland. 

 These small birds, too, were rearing their young successfully, in- con- 

 trast to conditions on the mainland,, where subsequent destruction of 

 nest, eggs, or young was the usual fate of most of the nests we found. 

 On the islands there were no red squirrels, no chipmunks, and no 



