90 ON THE AMERICAN DIPPER 



MY limited experience with the American Dipper precludes 

 my giving anything particularly to the point from original 

 observations. I never saw it alive excepting on one occasion, 

 when I noticed nothing in its habits not already known .In 

 the u Birds of the Northwest'' I brought together nearly all 

 the information we possess, and would refer to that work for 

 the particulars, especially respecting the nest and egg. It is a 

 common inhabitant of the Colorado Basin, in most suitable situa- 

 tions, though there are many eligible mountain streams which 

 it does not seem to inhabit. An occasional departure from its 

 usual habit has been noticed by Mr. Henshaw, who found a pair 

 inhabiting a small isolated pond in the White Mountains of 

 Arizona, seemingly as much at home in this quiet little sheet 

 of water as in the turbulent torrent 5 though he thought that,, 

 in keeping with their surroundings, they had lost somewhat of 

 their usual restlessness and energy. Such choice of still water r 

 however, must not be presumed to be very unusual, since 

 the European species is well known to frequent lakes, espe- 

 cially those which have a shingly or pebbly margin. 



NOTE. I may here allude to some interesting experiments to ascertain the 

 specific gravity of the European Dipper, made by Dr. John Davy, and pub- 

 lished in the eleventh volume (new series) of the Edinburgh New Philo- 

 sophical Journal, p. 265. The specific gravity of the bird's body alone, after 

 removal of the skin and feathers, was 1.200; iu its natural state, with the 

 feathers on, 0.724. "When under water, few air-bubbles escaped from its 

 feathers, owing probably to their resisting wetting from the oil with which 

 they are pruned, that being abundantly supplied by the large oil-gland with 

 which this bird is provided." ... " Its long bones contained a reddish 

 marrow." The specific gravity of a Wren was 0.890, which, after immersion 

 for twelve hours, had increased to 0.960. The lowest specific gravity was 

 found in the case of the Merlin-hawk 0.570. 



