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THE POPULAR SCIENCE MONTHLY 



billed tropic bird and the sooty terns from their nests, but was careful 

 in the case of the former to avoid the thrusts of their sharp, stiletto- 

 like bills. 



To keep within the more familiar species, and nearer at home, on 

 July 18, while fishing a trout-stream, I passed two robin nests in apple 

 trees, each with three eggs, more or less incubated. Note the difference 

 in behavior on the part of their occupants, doubtless due in part to 

 difference in individuality. In passing within a few yards of nest 

 No. 1, the sitter immediately flew out in a great state of excitement, 

 and shot off her characteristic emphatic alarms. At nest No. 2 I could 



Fig. 14. Nest-cleaning in the House-when, which has the practise of removing 

 the sacs and implanting them on the hark of trees. 



see the tail of the sitter projecting over the edge of the nest, as I 

 walked under her tree. This was poked with the fishing rod, but with 

 no response. Then I separated her tail-feathers with the tip of the 

 rod, and poked harder. At this the old robin faced about and pecked 

 angrily at the rod, and snapped her bill with the address of a flycatcher. 

 Then I ruffled her already erect crest and back-feathers, only to receive 

 more thrusts and snapping from the bill, and it was only after the 

 roughest kind of treatment that this bird was finally dislodged, so that 

 I could examine her nest. 



To give a final illustration of the working of this instinct, on July 



