170 DuBois, Nesting of the Horned Grebe. LApril 



AN EXPERIENCE WITH HORNED GREBES (COLYMBUS 



AURITUS). 



BY ALEXANDER D. DUBOIS. 



Plates VIJI-X 



The southeastern portion of Teton County, Montana, lying 

 in the prairie region east of the Rocky Mountains, comprises flat 

 and rolling bench-lands, traversed at frequent intervals by coulees 

 which are tributary to the Teton and Sun Rivers. On these 

 benches are occasional shallow depressions which have no natural 

 drainage. They form transient "prairie sloughs" which may be 

 dry at one season and wet meadows or ponds of water at another. 



The slough which afforded the present observations is a crescent- 

 shaped depression, not more than ten or twelve acres in extent, 

 curving about a knoll upon which stands a homesteader's cabin. 

 There are no lakes or water courses in the immediate vicinity. 

 During the last few years the region has been rapidly transformed 

 into grain farms. At the time these notes were made the meadow 

 in question was bordered on three sides by plowed fields. The 

 spring of 1917 was an extremely rainy one, following a winter of 

 much more than normal snow-fall. In consequence, the crescent- 

 shaped meadow became a marshy sheet of water. 



On the open water of this pond two Grebes were seen on several 

 days in May. On the third of June, while walking around the 

 pond scanning its surface with a field-glass, I was suddenly amazed 

 to see a Grebe sitting upon a nest which protruded above the water 

 amid the scant vegetation. Careful examination showed the bird 

 to be Colymbus auritus. She slipped from the nest, as I slowly 

 waded toward her, and swam about in the open water, anxiously 

 watching my every movement. The interest was mutual. After 

 watching the bird for some time I went up to the nest and found 

 that it contained two eggs. Subsequent visits showed that the 

 eggs were deposited at intervals of two days; the dates of the visits 

 and number of eggs found at each visit being as follows : June 3 (2) ; 



