276 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1924 



it often waxes or wanes, according to rather complex conditions, 

 being frequently suppressed by any stronger instinct in those ani- 

 mals usually regarded as timid ; in birds it is commonly suppressed 

 by the instinct of guarding and pugnacity, which in many species 

 rises during the period of incubation, and like a fever, reaches a 

 climax not long after the young are hatched, and then gradually 

 subsides. Accordingly a " timid " animal under the spur of a single 

 instinct may at times become very bold, only to revert to its former 

 state. 



In the case of the eagles, as in so many other instances, this is 

 further complicated by individual experience, for, in settled com- 

 munities where such birds do not always escape persecution, great 

 caution is often acquired; and their survival under difficult condi- 

 tions shows that it stands them in good stead. The presence or 

 absence of fear is thus clearly the resultant of many factors, of 

 which individual experience is an important variable. Any climber 

 who invades the eagle's aerie, unprepared for an attack, especially 

 if the nest is placed low and in wild country, is liable to meet with 

 a surprise. At times the intruder has been badly frightened, and 

 fortunate in having only his hat snatched from his head ; ^° at othei-s, 

 perhaps, he has been menaced only, but at too close quarters for 

 personal comfort; again no hostile demonstrations whatever may 

 be made. There are always one or more independent and indeter- 

 minate variable factors to be reckoned with, and the issue will de- 

 pend on the character and experience of the individual bird. 



Captain Bendire ^^ has recorded the experience of Dr. William L. 

 Ralph on the Indian River, Fla., Avhich furnishes an interesting 

 commentary on what has just been said. This region, long famed 

 for its bird life, was described as a paradise for the eagle, at the 

 time of his visit in February, 1886, when with the aid of an assist- 

 ant he found nearly 100 occupied nests; most of these were in pine 

 trees, " generally the highest and thickest that the birds could find," 

 . and usually at a height of 50 or 60 feet, the extremes met with at 

 that point being 75 and 30 feet. Doctor Ralph could recall but one 

 instance of eagles attacking anyone; this was at a nest containing 

 two young but a few hours old and built in a large pine at Crescent 



>" Auk, Vol. XXI, p. 220. The caglos at the Sail Clemcnte Island nest, to which we 

 have already referred, were said to have had a bad reputation for viciousness. One 

 season at shcep-shoaring time, according to this writer, an employee of the wool company 

 attempted to ride to the edge of the harranca and take a look at the young eagles in their 

 rock nest ; as he did so one of the old eagles swooped down upon him and snatched his 

 hat from his head, and flying off with it dropped it into the sea. At the time of his 

 visit the writer quoted approached the nest of the same bird and took a position close 

 to the edge of the abyss, gun in hand. He was .accompanied by a small dog, whicii 

 crouched in terror beside him as he sat on the ground ; in a moment one of the eagles 

 swept down upon him and came within a foot of striking him in the face. 



" Life Histories of North American Birds, pp. 27G-278. 



