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 "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; though he thought that, 

 in keeping with their surroundings, tliey had lost somewhat of 

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

 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 iuterestiug 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. 26.5. The specific gravity of the bird's body alone, after 

 removal of the skin and feathers, was f .200 ; in 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 pruued, 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 immersioa 

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

 found in the case of the Merlin-hawk — 0.570. 



