INTRODUCTION 



nothing to do except wait and watch. In 

 fact, patience is one of the prime prere- 

 quisites for natnrabstic study of undisturbed 

 wild life, even when attention is limited to 

 selected birds or mammals. The essential 

 impatience of observers is one of the dom- 

 inant reasons for the growth of experimen- 

 tation in ecology; but great patience is 

 required for any adequate long-term pro- 

 gram of experimentation, the ramifications 

 of which may seem endless. 



Such considerations lead naturally to 

 thinking about the interrelations between 

 ecology and animal behavior, since the 

 active behavior of animals both in field and 

 laboratory may be striking, and behavior 

 studies can yield important indications of 

 current environmental effects. This does not 

 imply that all studies of animal behavior as 

 developed at present are directly or even 

 indirectly ecological (except in a quite re- 

 mote sense). Students of behavior are much 

 concerned with psychological problems, 

 which in turn may lead into physiology and 

 into philosophy rather than into ecology 

 proper. 



Many of the ecological phases of animal 

 behavior cluster about the central problems 

 of distribution, being concerned with the 

 closely related matter of so-called habitat 

 selection or, objectively expressed, of modal- 

 ity. Gradients of important environmental 

 factors exist in nature both on small and on 

 large or even gigantic scales. Gradients of 

 concentration of oxygen, carbon dioxide, 

 and other chemicals, including food, heat, 

 moisture, Hght and pressure, to mention no 

 more, give stimuli to which animals react. 

 The responses may be fairly direct and ori- 

 ented, amounting at times to forced move- 

 ments, or there may be random reactions of 

 the trial-and-error variety. The results may 

 either be apparent immediately or they 

 may be deferred for days, weeks, seasons, 

 years, centuries or millenia; or finally they 

 may be discoverable only in the vast per- 

 spective of geological time. Migrations such 

 as those of birds and butterflies are fre- 

 quently large-scale spectacles; in contrast, 

 important emigrations may be inconspic- 

 uous events, the effects of which have not 

 become fully apparent during recorded 

 history. 



Emigrations may have evolutionary as 

 well as contemporaneous importance. These 

 time scales sometimes blend, as they 

 do in illustrations of what is known as the 



host-selection principle (p. 615). In theory, 

 it is only a short step from the host selection 

 shown by wood-boring beetle larvae that 

 tend to live in and feed upon a particular 

 species of tree, to the more crystallized be- 

 havior shown by solitary wasps that catch, 

 sting, and oviposit on a particular kind of 

 caterpillar, grasshopper or spider. (The im- 

 phed evolution can be explained by modern 

 assumptions centering about natural selec- 

 tion.) This brings up also the problem of 

 search for the right animal to be captured, 

 stung and parasitized, in which the innate 

 behavior patterns, commonly and somewhat 

 roughly called instincts, have real and 

 far-reacliing ecological implications. (The 

 interested reader is referred to Tinbergen, 

 1942, for a behavioristic approach to the 

 subject. ) 



Some behavior patterns of higher verte- 

 brates appear to resemble innate, instinctive 

 behavior, and yet have been demonstrated 

 for certain birds to result from a specialized 

 type of early learning, called "imprinting" 

 by Lorenz (1935). Imprinting results when 

 a young animal at an impressionistic age, 

 when the learning threshold is low, is ex- 

 posed to a meaningful stimulus or to some 

 suitable substitute. Normally at such times 

 the stimulus that becomes imprinted, so to 

 speak, initiates persisting behavior that may 

 dominate the animal's activities for the rest 

 of its life. A common example concerns the 

 following of an adult of the species, often 

 the female parent. This behavior results 

 from a few contacts, or even from a single 

 contact at the proper age. In the absence of 

 the parent, the tendency to follow a given 

 individual may be imprinted by exposure to 

 some other animal at the crucial time, with 

 amusing and incongruous results. The tend- 

 ency is important in the normal building 

 of family or flock integration; the interest- 

 ing psychological mechanisms and implica- 

 tions lead beyond our scope. 



Other types of integrations with the bio- 

 logical or physical environment are also ap- 

 parent, as are many fundamental questions. 

 How does an animal find and settle in a 

 given habitat? How much so-called search 

 is involved? Is there an element of active 

 preferential choice, or, more simply, is there 

 a reaction to the relative absence of dis- 

 turbing stimuli? To what extent is the 

 behavior innate, and how much is reestab- 

 lished each generation? This leads to curi- 

 osity concerning the possible presence of 



