508 ANNUAL REPORT SMITHSONIAN INSTITUTION, 19 64 



standing. Just where do we logically put the dividing line between 

 what a feeding mosquito does in taking a meal of either blood or juices, 

 what a spider does to a fly, a water bug to a minnow, a robber fly to a 

 grasshopper, a sea lamprey to a lake trout or a whitefish? What a 

 killer whale or a shark or a bird of prey or a wolf does in eating some- 

 thing, alive or dead ? What a snapping turtle does when it feeds upon 

 algae, scavenge ujDon anything dead, eats the tails off live fishes on 

 a fisherman's stringer or grabs a coot by a foot ? 



Gradations exist, whichever way we look, and I shall not further 

 belabor what seems to me the pointlessness of labeling categories be- 

 yond what the facts justify. Regardless of the opportunism common 

 to a bacterial infection and a violent attack by a genuine tooth- or-talon 

 predator, the obvious differences are such as to merit separate treat- 

 ment ; and there is plenty about the phenomenon of predation that may 

 be discussed in ordinary terms of animals being sought by or escaping 

 from other forms that would kill or eat them, or, of them, if they could. 



ADAPTIVENESS OF PREDATORS 



Relatively few mammals and birds are adapted to exploit only a 

 particular kind of prey. One of these is the Everglade kite, which has 

 a hooked beak that is exactly right for extracting soft parts from the 

 shell of a single genus of snail, and so the bird lives. The Canada lynx 

 and the Arctic fox may, on occasion, be all but restricted to only certain 

 of the foods available to them, apparently because of their own lack of 

 adaptiveness ; on the other hand, their relatives, the bay lynx or bobcat 

 and the red and gray foxes of central and southern North America, 

 may readily eat a wide diversity of foods. Gray wolves having op- 

 portunities to do so may, by choice, prey almost exclusively upon white- 

 tailed deer. But predatory mammals and birds collectively are om- 

 nivorous feeders compared to the vast numbers of insects that show 

 rigid selectivity in their predatory (or parasitic) behavior. Far down 

 the phylogenetic scale are extremely host-specific viruses and bacteria, 

 as well as some showing great versatility. The virus of rabies, the 

 bacterium of tularemia, and the roundworm causing trichinosis each 

 can attack an astonishing variety of at least warm-blooded host 

 animals. 



Food preferences or hunting techniques based upon individual learn- 

 ing are not restricted to higher vertebrates, though they naturally tend 

 to be prominent among the more intelligent animals. Next to man, 

 I should say that members of the dog family — individual red foxes, 

 coyotes, gray wolves, domestic dogs — can show as much special choice 

 of prey as anything of which I know. The f avoritisms and originality 

 that some of these animals develop in their preying may at times result 

 in unusually severe local exploitation of a vulnerable prey population. 

 Even prey species that are living with notable security from other 



