284 ANIMAL INTELLIGENCE. 



on or flying over the surface of the water, the gulls wait 

 till a guillemot comes to the surface with a fish, and then 

 wrest the latter from the beak of the former. In the 

 robber-tern this instinct has proceeded further, so that the 

 animal gains its subsistence entirely by plunder of other 

 terns. I have often observed this process, and it is inte- 

 resting that the common tern well knows the appearance 

 of the robber ; for no sooner does a robber-tern come up 

 than the greatest consternation is excited among a flock 

 of common terns, these flying about and screaming in a 

 frantic manner. The white-headed eagle has also de- 

 veloped the plundering instinct in great perfection, as is 

 shown by the following graphic account of Audubon : 



During spring and summer, the white-headed eagle, to procure 

 sustenance, follows a different course, and one much less suited 

 to a bird apparently so well able to supply itself without inter- 

 fering with other plunderers. No sooner does the first hawk 

 make its appearance along the Atlantic shore, or around the 

 numerous and large rivers, than the eagle follows it, and, like a 

 selfish oppressor, robs it of the hard-earned fruits of its labour. 

 Perched on some tall summit, in view of the ocean or of some 

 watercourse, he watches every motion of the osprey while on 

 the wing. When the latter rises from the water, with a fish in 

 its grasp, forth rushes the eagle in pursuit. He mounts above 

 the fish- hawk, and threatens it by actions well understood; when 

 the latter, fearing perhaps that its life is in danger, drops its 

 prey. In an instant the eagle, accurately estimating the rapid 

 descent of the fish, closes its wings, follows it with the swiftness 

 of thought, and the next moment grasps it. The prize is carried 

 off in silence to the woods, and assists in feeding the ever- 

 hungry brood of the eagle. 



The frigate pelican is likewise a professional thief, 

 and attacks the boobies not only to make them drop the 

 fish which they have newly caught, but also to disgorge 

 those which are actually in their stomachs. The latter 

 process is effected by strong punishment, which they con- 

 tinue until the unfortunate booby yields up its dinner. 

 The punishment consists in stabbing the victim with its 

 powerful beak. Catesby and Dampier have both observed 

 and described these habits, and it seems from their account 

 that the plunderer may either commit highway robbery in 



