272 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1924 



across the top, and a line dropped from its base to the ground meas- 

 ured exactly 37% feet. It is verj^^ evident that the unusual form of 

 this nest is due to the spread of its main supports, which diverge at 

 an angle of 70°. It should be noticed that the top of the aerie in this 

 instance is almost completely shaded by branches rising to a height 

 of 10 feet or more on all sides. 



The history of the Vermilion eagles, the fullest of which I have 

 any records, and covering a period of over 80 years, is given in 

 detail in an earlier paper.^ During that time four nests have been 

 occupied for varying periods in the township of Vermilion, at points 

 a mile or more removed from the shore of the lake. The fourth 

 and present nest (pi. 2), which has been occupied for at least 34 

 years, stands at a height of 81 feet, in a shellbark hickory which, 

 as already noticed, was more or less alive up to the spring of 1923 ; 

 it was 12 feet tall and 8I/2 feet across the top when exact measure- 

 ments were made on July 20, 1922. When examined at this time, 

 just 16 days after the young eagles were on wing, all carcasses of 

 fish, chickens, and other animals had been removed and its inside 

 depth did not exceed 4 or 5 inches ; the eaglets, in the course of many 

 weeks of exercise, had trodden its surface nearly flat. At that time 

 all the surface material, to the amount of half a bushel or more, 

 was gathered up and lowered in a sack ; this was found to consist of 

 fish and chicken bones in sparing amount, fish scales, short loose 

 sticks such as the young eagles had often been seen to use in their 

 play, fragments of cornstalks, clusters of oak twigs with the dried 

 green leaves still upon them, corresponding with what we had seen 

 the old eagles bring to their aerie, besides a miscellaneous assort- 

 ment of vegetable rubbish. Underlying this loose layer was a fairly 

 compact floor of vegetable mold, which extended some 2 or 3 feet 

 on all sides from the center of the nest and was easily dislodged 

 with the hand. 



Ill 



Though hoping to turn my attention to nest building and other 

 early phases of activity another year, I will now set down in brief 

 what happened at the Vermilion nest in the spring of 1923. When 

 Mr. Headline and his men were building the second platform of 

 our observatory on March 13-15, they were obliged to abandon 

 their work for a part of the time on account of severe gales, which 

 during that month brought down many trees in the grove and 

 threatened that of the eagles with destruction; accordingly, we 

 took the precaution of securing it as best we could by the aid of 

 steel wires. The eagles were engaged in building also, but, as Mr. 



« The Auk, Vol. XL. 1023. 



