The problem of geographical voice variability in animals is far 

 from new. The great increase of interest in this field in our time 

 can be laid to the development of complex physical, physiological and 

 ecological investigations, which have transformed bioacoustics from 

 an unsophisticated 19th century field of study into a modern, clearly 

 defined science with its own problems, tasks and methods of investiga- 

 tion. 



In regard to the practical applications of bioacoustics, the two 

 following branches are developing rapidly: bionics and studies con- 

 cerning the factors affecting the behavior of animals. In both cases 

 the geographical aspects of bioacoustics find wide application. 



Regarding bionics, bioacoustics provides material concerning the 

 means employed by animals for coding and communicating vocal informa- 

 tion under specific environmental conditions and concerning the 

 dependence of vocal communication on noise and interference against 

 the background of "sound environments," the biotope, etc. Regarding 

 the investigation of the factors governing the behavior of animals, 

 bioacoustics contributes valuable information on the specific aspects 

 of the vocal signals of various territorial (interspecific and intra - 

 specific) groupings of animals. These signals often lose their 

 universality because of the development of "local information codes." 

 The discovery and investigation of "local dialects," and the wide use 

 of recorded voices to frighten off predatory animals, have directed 

 special attention to the study of the geographical variability of the 

 mechanisms of vocal communications. 



The development of the theory of communication between animals 

 (Sinnot, 1961; Frings, 1962; and others) is an important contribution 

 to the above fields of study. The development of the science of 

 ecology, especially in its geographical and evolutionary aspects, had 

 a considerable influence on the formation of the theoretical bases of 

 bioacoustics. Here the following kinds of investigation should be 

 differentiated: the study of populations, landscape ecology, general 

 ecogenesis, and ecological-geographical isomorphism, 



All this has led to the following situation: the old theories 

 and reviews - as found, for instance, in the excellent works of F. 

 Groebbels, 1925; C. Witchell, 1896; 0. Heinroth, 1924, and other 

 workers - have become outdated. In the meantime the new data which 



