DISTRIBUTION OF AUDUBON's WARBLER 273 



which throug the forests and thickets of the entire West. It 

 is a fourth species of Dendrceca discovered by Nuttall and 

 Townseud, completing their additions to our knowledge of the 

 varied exhibitions of bird-life which compose this extensive 

 genus. Their original accounts of the bird are not entirely con- 

 sistent, nor as satisfactory in other respects as could be desired, 

 but we have gradually come into possession of the materials 

 for a tolerably complete biography. 



Not the least interesting point in the history of Audubon's 

 Warbler is its recent occurrence on the side of the continent 

 where it does not properly belong. Mr. A. M. Frazar has this 

 year published a note of his capture of a specimen at Cam- 

 bridge, Mass., on the 15th of November, 1876. As he says 

 that it was a fine male specimen, with the yellow of the throat 

 very plainly marked, there is no reason to doubt the accuracy 

 of his identification ; and we may match the case with that of 

 the Townsend's Warbler which lately wandered into Pennsylva- 

 nia. This estray aside, Audubon's Warbler has never been 

 known to come eastward beyond the line of arboreal vegetation 

 which marks the easternmost foot-hills and outlying elevations 

 of the Rocky Mountains. As soon as we fairly enter the wooded 

 tracts, as distinguished from those slight fringes of trees that 

 straggle along the water courses, we are pretty sure to- find 

 Audubon's Warbler, and we may find it anywhere, so we be in 

 the woods at the right season, thence to the Pacific. The north- 

 ern limit of its distribution is a little uncertain. The bird is 

 known to enter British Columbia, and I have myself observed 

 it on the headwaters of the Saskatchewan, on the northern 

 border of Montana. Though we have as yet no Alaskan record, 

 we should be slow to infer that it does not reach at least part 

 way through that country — as far as the Pacific fauna proper 

 extends. J), coronata is found there, Alaska being doubtless 

 the region whence come those straggling Yellow-rumps that oc- 

 casionally turn up in the Pacific region. B. auduboni is no less 

 hardy a bird than its Eastern analogue, and its northwestern 

 restriction, wherever the line may actually be drawn, is infer- 

 ably determined by the topographical rather than climatic con- 

 ditions, which are well known to carry the Eastern Province 

 proper to the very shores of the Pacific in the higher latitudes. 

 In the opposite direction, Audubon's Warbler is known to pen- 

 etrate through Mexico and to reach various portions of Central 

 America, where again, as at the far North, it greets its Eastern 

 18 B o 



